@misc{song_corrosion_inhibition_2024, author={Song, C., Wang, C., Mercier, D., Vaghenfinazari, B., Seyeux, A., Snihirova, D., Wieland, F.D.C., Marcus, P., Zheludkevich, M.L., Lamaka, S.V.}, title={Corrosion inhibition mechanism of 2,6-pyridinedicarboxylate depending on magnesium surface treatment}, year={2024}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.corsci.2024.111867}, abstract = {2,6-pyridinedicarboxylate (2,6-PDC) was studied as corrosion inhibitor for pure magnesium. The surface was prepared either by polishing or polishing followed by treatment with 1 M NaOH solution. The results show that 2,6-PDC promotes the formation of a denser protective oxide/hydroxide layer poor in PDC. The mechanism proposed includes forming weak PDC-Mg complexes that lower the free Mg2+ concentration available for the formation of Mg(OH)2. This leads to growth of smaller Mg(OH)2 platelets that are more densely packed and hence form a more protective layer. The highest inhibition efficiency of 2,6-PDC was achieved for samples with surface hydroxylated by NaOH treatment.}, note = {Online available at: \url{https://doi.org/10.1016/j.corsci.2024.111867} (DOI). Song, C.; Wang, C.; Mercier, D.; Vaghenfinazari, B.; Seyeux, A.; Snihirova, D.; Wieland, F.; Marcus, P.; Zheludkevich, M.; Lamaka, S.: Corrosion inhibition mechanism of 2,6-pyridinedicarboxylate depending on magnesium surface treatment. Corrosion Science. 2024. vol. 229, 111867. DOI: 10.1016/j.corsci.2024.111867}} @misc{lopesmarinho_a_comparison_2024, author={Lopes Marinho, A., Kazimi, B., Cwieka, H., Willumeit-Römer, R., Moosmann, J., Zeller-Plumhoff, B.}, title={A comparison of deep learning segmentation models for synchrotron radiation based tomograms of biodegradable bone implants}, year={2024}, howpublished = {journal article}, doi = {https://doi.org/10.3389/fphy.2024.1257512}, abstract = {Introduction: Synchrotron radiation micro-computed tomography (SRμCT) has been used as a non-invasive technique to examine the microstructure and tissue integration of biodegradable bone implants. To be able to characterize parameters regarding the disintegration and osseointegration of such materials quantitatively, the three-dimensional (3D) image data provided by SRμCT needs to be processed by means of semantic segmentation. However, accurate image segmentation is challenging using traditional automated techniques. This study investigates the effectiveness of deep learning approaches for semantic segmentation of SRμCT volumes of Mg-based implants in sheep bone ex vivo. Methodology: For this purpose different convolutional neural networks (CNNs), including U-Net, HR-Net, U²-Net, from the TomoSeg framework, the Scaled U-Net framework, and 2D/3D U-Net from the nnU-Net framework were trained and validated. The image data used in this work was part of a previous study where biodegradable screws were surgically implanted in sheep tibiae and imaged using SRμCT after different healing periods. The comparative analysis of CNN models considers their performance in semantic segmentation and subsequent calculation of degradation and osseointegration parameters. The models’ performance is evaluated using the intersection over union (IoU) metric, and their generalization ability is tested on unseen datasets. Results and discussion: This work shows that the 2D nnU-Net achieves better generalization performance, with the degradation layer being the most challenging label to segment for all models.}, note = {Online available at: \url{https://doi.org/10.3389/fphy.2024.1257512} (DOI). Lopes Marinho, A.; Kazimi, B.; Cwieka, H.; Willumeit-Römer, R.; Moosmann, J.; Zeller-Plumhoff, B.: A comparison of deep learning segmentation models for synchrotron radiation based tomograms of biodegradable bone implants. Frontiers in Physics. 2024. vol. 12, 1257512. DOI: 10.3389/fphy.2024.1257512}} @misc{yeshmanova_effect_of_2024, author={Yeshmanova, G., Blawert, C., Serdechnova, M., Wieland, F.D.C., Starykevich, M., Gazenbiller, E., Höche, D., Smagulov, D., Zheludkevich, M.L.}, title={Effect of electrolyte composition on the formation of PEO coatings on AA2024 aluminium alloy}, year={2024}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.surfin.2023.103797}, abstract = {Since the electrolyte composition plays a crucial role in the plasma electrolytic oxidation (PEO) coating formation process, a systematic and in-depth study was proposed to identify an electrolyte composition for fast PEO coating growth on AA2024 alloy. Different concentration ratios of mixed alkaline electrolytes (hydroxide, silicate and phosphate) were investigated. PEO process was conducted at low constant current density of 50 mA/cm2, which is intended for lowering the energy consumption. Results demonstrated that the breakdown voltage of PEO coatings is directly proportional to the logarithm of electrolyte resistivity. The coating growth mechanism showed two main directions. The thickening of the coating mainly depends on the rapid deposition of electrolyte compounds in Si-based electrolyte, and the coating growth occurs mainly towards the electrolyte/coating interface. Contrary, in OH-, and P-based electrolytes, the inward coating growth was dominating mainly by substrate oxidation. A variety of phases as a function of different electrolyte compositions and final voltages were observed. With high final voltages (over 470 V) for coatings produced in mixed electrolytes with low concentrations of hydroxide, silicate or phosphate (2 and 6 g/L), γ-Al2O3 crystalline phase predominates in the PEO layer composition. However, only a low efficiency of coating growth can be reached. In the electrolytes with high silicate concentrations accompanied by an increase of phosphate concentration, the final voltage is around 455 V and the coating composition is dominated by an amorphous phase in combination with crystalline mullite and γ-Al2O3. High silicate-phosphate contents (18–24 g/L) in mixed electrolytes with low final voltages of about 360 V results in a fully amorphous PEO layer and significantly increases coating thickness. A combination of low content of hydroxide, high silicate with increasing content of phosphate in mixed electrolyte increases the coating thickness, and improves the density and uniformity of the overall PEO layers.}, note = {Online available at: \url{https://doi.org/10.1016/j.surfin.2023.103797} (DOI). Yeshmanova, G.; Blawert, C.; Serdechnova, M.; Wieland, F.; Starykevich, M.; Gazenbiller, E.; Höche, D.; Smagulov, D.; Zheludkevich, M.: Effect of electrolyte composition on the formation of PEO coatings on AA2024 aluminium alloy. Surfaces and Interfaces. 2024. vol. 44, 103797. DOI: 10.1016/j.surfin.2023.103797}} @misc{kasneryk_controllable_recrystallization_2024, author={Kasneryk, V., Wu, T., Rohr, H., Serdechnova, M., Mojsilovi , K., Wieland, F.D.C., Davydok, A., Gazenbiller, E., Vasili , R., Blawert, C., Stock, N., Zheludkevich, M.L.}, title={Controllable recrystallization of ZnO/ZnAl2O4 based PEO into ZIF-8 as a route for the formation of multifunctional coatings}, year={2024}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.jiec.2023.11.033}, abstract = {Nowadays, plasma electrolytic oxidation (PEO) has become widespread as an effective method for preparation of multifunctional coatings. However, the PEO coatings have numerous pores. On the one hand, their presence restricts their broad application; on the other hand, they represent an excellent platform for post-sealing allowing creating coatings with peculiar properties. In the current work, the possibility of controllable recrystallization of ZnO/ZnAl2O4 based PEO preformed on Zn Z1 alloy into ZIF-8@PEO composite coating was demonstrated for the first time. It was found that the corrosion protection, photocatalytic and photoluminescence properties of the final coatings can be modified by varying the conditions of the post-modification process, which include the amount of the organic linker (2-methylimidazole) and treatment time. This study opens an innovative approach for the formation of multifunctional coatings.}, note = {Online available at: \url{https://doi.org/10.1016/j.jiec.2023.11.033} (DOI). Kasneryk, V.; Wu, T.; Rohr, H.; Serdechnova, M.; Mojsilovi, K.; Wieland, F.; Davydok, A.; Gazenbiller, E.; Vasili, R.; Blawert, C.; Stock, N.; Zheludkevich, M.: Controllable recrystallization of ZnO/ZnAl2O4 based PEO into ZIF-8 as a route for the formation of multifunctional coatings. Journal of Industrial and Engineering Chemistry. 2024. vol. 263, 119538. DOI: 10.1016/j.jiec.2023.11.033}} @misc{zellerplumhoff_technical_note_2023, author={Zeller-Plumhoff, B., Helmholz, H., Feyerabend, F., Dose, T., Wilde, F., Hipp, A., Beckmann, F., Willumeit-Römer, R., Hammel, J.U.}, title={Technical note on the determination of degradation rates of biodegradable magnesium implants}, year={2023}, howpublished = {journal article}, doi = {https://doi.org/10.1002/maco.202313751}, abstract = {Magnesium-based alloys are emerging as a capable alternative to traditional materials for bone implant applications. The implant's degradation rate is the main indicator of their performance; however, different formulas have been reported to determine it based on three-dimensional imaging. In this technical note, we are presenting the deviation in the degradation rate determined by different equations for two sets of data and the implications for the comparison of different studies.}, note = {Online available at: \url{https://doi.org/10.1002/maco.202313751} (DOI). Zeller-Plumhoff, B.; Helmholz, H.; Feyerabend, F.; Dose, T.; Wilde, F.; Hipp, A.; Beckmann, F.; Willumeit-Römer, R.; Hammel, J.: Technical note on the determination of degradation rates of biodegradable magnesium implants. Materials and Corrosion. 2023. vol. 74, no. 7, 1116-1119. DOI: 10.1002/maco.202313751}} @misc{marek_degradation_behavior_2023, author={Marek, R., Ćwieka, H., Donohue, N., Holweg, P., Moosmann, J., Beckmann, F., Brcic, I., Schwarze, U.Y., Iskhakova, K., Chaabane, M., Sefa, S., Zeller-Plumhoff, B., Weinberg, A.M., Willumeit-Römer, R., Sommer, N.G.}, title={Degradation behavior and osseointegration of Mg–Zn–Ca screws in different bone regions of growing sheep: a pilot study}, year={2023}, howpublished = {journal article}, doi = {https://doi.org/10.1093/rb/rbac077}, abstract = {Magnesium (Mg)-based implants are highly attractive for the orthopedic field and may replace titanium (Ti) as support for fracture healing. To determine the implant–bone interaction in different bony regions, we implanted Mg-based alloy ZX00 (Mg < 0.5 Zn < 0.5 Ca, in wt%) and Ti-screws into the distal epiphysis and distal metaphysis of sheep tibiae. The implant degradation and osseointegration were assessed in vivo and ex vivo after 4, 6 and 12 weeks, using a combination of clinical computed tomography, medium-resolution micro computed tomography (µCT) and high-resolution synchrotron radiation µCT (SRµCT). Implant volume loss, gas formation and bone growth were evaluated for both implantation sites and each bone region independently. Additionally, histological analysis of bone growth was performed on embedded hard-tissue samples. We demonstrate that in all cases, the degradation rate of ZX00-implants ranges between 0.23 and 0.75 mm/year. The highest degradation rates were found in the epiphysis. Bone-to-implant contact varied between the time points and bone types for both materials. Mostly, bone-volume-to-total-volume was higher around Ti-implants. However, we found an increased cortical thickness around the ZX00-screws when compared with the Ti-screws. Our results showed the suitability of ZX00-screws for implantation into the distal meta- and epiphysis.}, note = {Online available at: \url{https://doi.org/10.1093/rb/rbac077} (DOI). Marek, R.; Ćwieka, H.; Donohue, N.; Holweg, P.; Moosmann, J.; Beckmann, F.; Brcic, I.; Schwarze, U.; Iskhakova, K.; Chaabane, M.; Sefa, S.; Zeller-Plumhoff, B.; Weinberg, A.; Willumeit-Römer, R.; Sommer, N.: Degradation behavior and osseointegration of Mg–Zn–Ca screws in different bone regions of growing sheep: a pilot study. Regenerative Biomaterials. 2023. vol. 10, rbac077. DOI: 10.1093/rb/rbac077}} @misc{espiritu_radiofrequency_induced_2023, author={Espiritu, J., Berangi, M., Cwieka, H., Iskhakova, K., Kuehne, A., Florian Wieland, D.C., Zeller-Plumhoff, B., Niendorf, T., Willumeit-Römer, R., Seitz, J.-M.}, title={Radiofrequency induced heating of biodegradable orthopaedic screw implants during magnetic resonance imaging}, year={2023}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.bioactmat.2023.01.017}, abstract = {Magnesium (Mg)-based implants have re-emerged in orthopaedic surgery as an alternative to permanent implants. Literature reveals little information on how the degradation of biodegradable implants may introduce safety implications for patient follow-up using medical imaging. Magnetic resonance imaging (MRI) benefits post-surgery monitoring of bone healing and implantation sites. Previous studies demonstrated radiofrequency (RF) heating of permanent implants caused by electromagnetic fields used in MRI. Our investigation is the first to report the effect of the degradation layer on RF-induced heating of biodegradable orthopaedic implants.}, note = {Online available at: \url{https://doi.org/10.1016/j.bioactmat.2023.01.017} (DOI). Espiritu, J.; Berangi, M.; Cwieka, H.; Iskhakova, K.; Kuehne, A.; Florian Wieland, D.; Zeller-Plumhoff, B.; Niendorf, T.; Willumeit-Römer, R.; Seitz, J.: Radiofrequency induced heating of biodegradable orthopaedic screw implants during magnetic resonance imaging. Bioactive Materials. 2023. vol. 25, 86-94. DOI: 10.1016/j.bioactmat.2023.01.017}} @misc{albaraghtheh_utilizing_computational_2023, author={Albaraghtheh, T., Hermann, A., Shojaei, A., Willumeit-Römer, R., Cyron, C.J., Zeller-Plumhoff, B.}, title={Utilizing computational modelling to bridge the gap between in vivo and in vitro degradation rates for Mg-xGd implants}, year={2023}, howpublished = {journal article}, doi = {https://doi.org/10.3390/cmd4020014}, abstract = {Magnesium (Mg) and its alloys are promising materials for temporary bone implants due to their mechanical properties and biocompatibility. The most challenging aspect of Mg-based implants involves adapting the degradation rate to the human body, which requires extensive in vitro and in vivo testing. Given that in vivo tests are significantly more labour-intensive than in vitro and ethics prohibit direct experiments on animals or humans, attempts are commonly undertaken to infer conclusions on in vivo degradation behavior from in vitro experiments. However, there is a wide gap between these tests, and in vitro testing is often a poor predictor of in vivo outcomes. In the development of biodegradable Mg-based implants, considerable efforts are being made to reduce the overall time and cost of in vitro and in vivo testing. Finding a suitable alternative to predict the degradation of Mg alloys, however, remains challenging. We present computational modelling as a possible alternative to bridge the gap between in vitro and in vivo testing, thus reducing overall cost, duration and number of experiments. However, traditional modelling approaches for complex biodegradable systems are still rather time-consuming and require a clear definition of the relations between input parameters and the model result. In this study, Kriging surrogate models based on the peridynamic in vitro degradation model were developed to simulate the degradation behavior for two main alloys, Mg-5Gd and Mg-10Gd, for both in vitro and in vivo cases. Using Kriging surrogate models, the simulation parameters were calibrated to the volume loss data from in vitro and in vivo experiments. In vivo degradation of magnesium has one order of magnitude higher apparent diffusion coefficients than in vitro degradation, thus yielding the higher volume loss observed in vivo than in vitro. On the basis of the diffusivity of the Mg2+ ions modeled under in vitro degradation, Kriging surrogate models were able to simulate the in vivo degradation behavior of Mg-xGd with a ratio between 0.46 and 0.5, indicating that the surrogate-modelling approach is able to bridge the gap between in vitro and in vivo degradation rates for Mg-xGd implants.}, note = {Online available at: \url{https://doi.org/10.3390/cmd4020014} (DOI). Albaraghtheh, T.; Hermann, A.; Shojaei, A.; Willumeit-Römer, R.; Cyron, C.; Zeller-Plumhoff, B.: Utilizing computational modelling to bridge the gap between in vivo and in vitro degradation rates for Mg-xGd implants. Corrosion and Materials Degradation. 2023. vol. 4, no. 2, 274-283. DOI: 10.3390/cmd4020014}} @misc{espiritu_detailing_the_2023, author={Espiritu, J., Sefa, S., Cwieka, H., Greving, I., Flenner, S., Willumeit-Römer, R., Seitz, J.M., Zeller-Plumhoff, B.}, title={Detailing the influence of PEO-coated biodegradable Mg-based implants on the lacuno-canalicular network in sheep bone: A pilot study}, year={2023}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.bioactmat.2023.02.018}, abstract = {Utilising synchrotron-based transmission X-ray microscopy, we have characterised morphological LCN differences around uncoated and PEO-coated WE43 screws implanted into sheep bone. Bone specimens were explanted after 4, 8, and 12 weeks and regions near the implant surface were prepared for imaging. Findings from this investigation indicate that the slower degradation of PEO-coated WE43 induces healthier lacunar shapes within the LCN. However, the stimuli perceived by the uncoated material with higher degradation rates induces a greater connected LCN better prepared for bone disturbance.}, note = {Online available at: \url{https://doi.org/10.1016/j.bioactmat.2023.02.018} (DOI). Espiritu, J.; Sefa, S.; Cwieka, H.; Greving, I.; Flenner, S.; Willumeit-Römer, R.; Seitz, J.; Zeller-Plumhoff, B.: Detailing the influence of PEO-coated biodegradable Mg-based implants on the lacuno-canalicular network in sheep bone: A pilot study. Bioactive Materials. 2023. vol. 26, 14-23. DOI: 10.1016/j.bioactmat.2023.02.018}} @misc{martnez_in_vitro_2023, author={Martínez, D.C., Dobkowska, A., Marek, R., Cwieka, H., Jaroszewicz, J., Plocinski, T., Donik, C., Helmholz, H., Luthringer-Feyerabend, B., Zeller-Plumhoff, B., Willumeit-Römer, R., Swieszkowski, W.}, title={In vitro and in vivo degradation behavior of Mg-0.45Zn-0.45Ca (ZX00) screws for orthopedic applications}, year={2023}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.bioactmat.2023.05.004}, abstract = {Magnesium (Mg) alloys have become a potential material for orthopedic implants due to their unnecessary implant removal, biocompatibility, and mechanical integrity until fracture healing. This study examined the in vitro and in vivo degradation of an Mg fixation screw composed of Mg-0.45Zn-0.45Ca (ZX00, in wt.%). With ZX00 human-sized implants, in vitro immersion tests up to 28 days under physiological conditions, along with electrochemical measurements were performed for the first time. In addition, ZX00 screws were implanted in the diaphysis of sheep for 6, 12, and 24 weeks to assess the degradation and biocompatibility of the screws in vivo. Using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX), micro-computed tomography (μCT), X-ray photoelectron spectroscopy (XPS), and histology, the surface and cross-sectional morphologies of the corrosion layers formed, as well as the bone-corrosion-layer-implant interfaces, were analyzed. Our findings from in vivo testing demonstrated that ZX00 alloy promotes bone healing and the formation of new bone in direct contact with the corrosion products. In addition, the same elemental composition of corrosion products was observed for in vitro and in vivo experiments; however, their elemental distribution and thicknesses differ depending on the implant location. Our findings suggest that the corrosion resistance was microstructure-dependent. The head zone was the least corrosion-resistant, indicating that the production procedure could impact the corrosion performance of the implant. In spite of this, the formation of new bone and no adverse effects on the surrounding tissues demonstrated that the ZX00 is a suitable Mg-based alloy for temporary bone implants.}, note = {Online available at: \url{https://doi.org/10.1016/j.bioactmat.2023.05.004} (DOI). Martínez, D.; Dobkowska, A.; Marek, R.; Cwieka, H.; Jaroszewicz, J.; Plocinski, T.; Donik, C.; Helmholz, H.; Luthringer-Feyerabend, B.; Zeller-Plumhoff, B.; Willumeit-Römer, R.; Swieszkowski, W.: In vitro and in vivo degradation behavior of Mg-0.45Zn-0.45Ca (ZX00) screws for orthopedic applications. Bioactive Materials. 2023. vol. 28, 132-154. DOI: 10.1016/j.bioactmat.2023.05.004}} @misc{bruns_on_the_2023, author={Bruns, S., Krüger, D., Galli, S., Wieland, D.C.F., Hammel, J.U., Beckmann, F., Wennerberg, A., Willumeit-Römer, R., Zeller-Plumhoff, B., Moosmann, J.}, title={On the material dependency of peri-implant morphology and stability in healing bone}, year={2023}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.bioactmat.2023.05.006}, abstract = {The microstructural architecture of remodeled bone in the peri-implant region of screw implants plays a vital role in the distribution of strain energy and implant stability. We present a study in which screw implants made from titanium, polyetheretherketone and biodegradable magnesium-gadolinium alloys were implanted into rat tibia and subjected to a push-out test four, eight and twelve weeks after implantation. Screws were 4 mm in length and with an M2 thread. The loading experiment was accompanied by simultaneous three-dimensional imaging using synchrotron-radiation microcomputed tomography at 5 μm resolution. Bone deformation and strains were tracked by applying optical flow-based digital volume correlation to the recorded image sequences. Implant stabilities measured for screws of biodegradable alloys were comparable to pins whereas non-degradable biomaterials experienced additional mechanical stabilization. Peri-implant bone morphology and strain transfer from the loaded implant site depended heavily on the biomaterial utilized. Titanium implants stimulated rapid callus formation displaying a consistent monomodal strain profile whereas the bone volume fraction in the vicinity of magnesium-gadolinium alloys exhibited a minimum close to the interface of the implant and less ordered strain transfer. Correlations in our data suggest that implant stability benefits from disparate bone morphological properties depending on the biomaterial utilized. This leaves the choice of biomaterial as situational depending on local tissue properties.}, note = {Online available at: \url{https://doi.org/10.1016/j.bioactmat.2023.05.006} (DOI). Bruns, S.; Krüger, D.; Galli, S.; Wieland, D.; Hammel, J.; Beckmann, F.; Wennerberg, A.; Willumeit-Römer, R.; Zeller-Plumhoff, B.; Moosmann, J.: On the material dependency of peri-implant morphology and stability in healing bone. Bioactive Materials. 2023. vol. 28, 155-166. DOI: 10.1016/j.bioactmat.2023.05.006}} @misc{reimers_development_of_2023, author={Reimers, J., Trinh, H.C., Wiese, B., Meyer, S., Brehling, J., Flenner, S., Hagemann, J., Kruth, M., Kibkalo, L., Cwieka, H., Hindenlang, B., Lipinska-Chwalek, M., Mayer, J., Willumeit-Roemer, R., Greving, I., Zeller-Plumhoff, B.}, title={Development of a bioreactor-coupled flow-cell setup for 3D in situ nanotomography of Mg alloy biodegradation}, year={2023}, howpublished = {journal article}, doi = {https://doi.org/10.1021/acsami.3c04054}, abstract = {Functional materials feature hierarchical microstructures that define their unique set of properties. The prediction and tailoring of these require a multiscale knowledge of the mechanistic interaction of microstructure and property. An important material in this respect is biodegradable magnesium alloys used for implant applications. To correlate the relationship between the microstructure and the nonlinear degradation process, high-resolution in situ three-dimensional (3D) imaging experiments must be performed. For this purpose, a novel experimental flow cell is presented which allows for the in situ 3D-nano imaging of the biodegradation process of materials with nominal resolutions below 100 nm using nanofocused hard X-ray radiation from a synchrotron source. The flow cell setup can operate under adjustable physiological and hydrodynamic conditions. As a model material, the biodegradation of thin Mg-4Ag wires in simulated body fluid under physiological conditions and a flow rate of 1 mL/min is studied. The use of two full-field nanotomographic imaging techniques, namely transmission X-ray microscopy and near-field holotomography, is compared, revealing holotomography as the superior imaging technique for this purpose. Additionally, the importance of maintaining physiological conditions is highlighted by the preliminary results. Supporting measurements using electron microscopy to investigate the chemical composition of the samples after degradation are performed.}, note = {Online available at: \url{https://doi.org/10.1021/acsami.3c04054} (DOI). Reimers, J.; Trinh, H.; Wiese, B.; Meyer, S.; Brehling, J.; Flenner, S.; Hagemann, J.; Kruth, M.; Kibkalo, L.; Cwieka, H.; Hindenlang, B.; Lipinska-Chwalek, M.; Mayer, J.; Willumeit-Roemer, R.; Greving, I.; Zeller-Plumhoff, B.: Development of a bioreactor-coupled flow-cell setup for 3D in situ nanotomography of Mg alloy biodegradation. ACS Applied Materials and Interfaces. 2023. vol. 15, no. 29, 35600-35610. DOI: 10.1021/acsami.3c04054}} @misc{sefa_multiscale_morphological_2023, author={Sefa, S., Espiritu, J., Ćwieka, H., Greving, I., Flenner, S., Will, O., Beuer, S., Wieland, D.C.F., Willumeit-Römer, R., Zeller-Plumhoff, B.}, title={Multiscale morphological analysis of bone microarchitecture around Mg-10Gd implants}, year={2023}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.bioactmat.2023.07.017}, abstract = {The utilization of biodegradable magnesium (Mg)-based implants for restoration of bone function following trauma represents a transformative approach in orthopaedic application. One such alloy, magnesium-10 weight percent gadolinium (Mg-10Gd), has been specifically developed to address the rapid degradation of Mg while enhancing its mechanical properties to promote bone healing. Previous studies have demonstrated that Mg-10Gd exhibits favorable osseointegration; however, it exhibits distinct ultrastructural adaptation in comparison to conventional implants like titanium (Ti). A crucial aspect that remains unexplored is the impact of Mg-10Gd degradation on the bone microarchitecture. To address this, we employed hierarchical three-dimensional imaging using synchrotron radiation in conjunction with image-based finite element modelling. By using the methods outlined, the vascular porosity, lacunar porosity and the lacunar-canaliculi network (LCN) morphology of bone around Mg-10Gd in comparison to Ti in a rat model from 4 weeks to 20 weeks post-implantation was investigated. Our investigation revealed that within our observation period, the degradation of Mg-10Gd implants was associated with significantly lower (p < 0.05) lacunar density in the surrounding bone, compared to Ti. Remarkably, the LCN morphology and the fluid flow analysis did not significantly differ for both implant types. In summary, a more pronounced lower lacunae distribution rather than their morphological changes was detected in the surrounding bone upon the degradation of Mg-10Gd implants. This implies potential disparities in bone remodelling rates when compared to Ti implants. Our findings shed light on the intricate relationship between Mg-10Gd degradation and bone microarchitecture, contributing to a deeper understanding of the implications for successful osseointegration.}, note = {Online available at: \url{https://doi.org/10.1016/j.bioactmat.2023.07.017} (DOI). Sefa, S.; Espiritu, J.; Ćwieka, H.; Greving, I.; Flenner, S.; Will, O.; Beuer, S.; Wieland, D.; Willumeit-Römer, R.; Zeller-Plumhoff, B.: Multiscale morphological analysis of bone microarchitecture around Mg-10Gd implants. Bioactive Materials. 2023. vol. 30, 154-168. DOI: 10.1016/j.bioactmat.2023.07.017}} @misc{hauck_overcoming_water_2023, author={Hauck, M., Saure, L.M., Zeller-Plumhoff, B., Kaps, S., Hammel, J., Mohr, C., Rieck, L., Nia, A.S., Feng, X., Pugno, N.M., Adelung, R., Schütt, F.}, title={Overcoming water diffusion limitations in hydrogels via microtubular graphene networks for soft actuators}, year={2023}, howpublished = {journal article}, doi = {https://doi.org/10.1002/adma.202302816}, abstract = {Hydrogel-based soft actuators can operate in sensitive environments, bridging the gap of rigid machines interacting with soft matter. However, while stimuli-responsive hydrogels can undergo extreme reversible volume changes of up to ≈90%, water transport in hydrogel actuators is in general limited by their poroelastic behavior. For poly(N-isopropylacrylamide) (PNIPAM) the actuation performance is even further compromised by the formation of a dense skin layer. Here it is shown, that incorporating a bioinspired microtube graphene network into a PNIPAM matrix with a total porosity of only 5.4% dramatically enhances actuation dynamics by up to ≈400% and actuation stress by ≈4000% without sacrificing the mechanical stability, overcoming the water transport limitations. The graphene network provides both untethered light-controlled and electrically powered actuation. It is anticipated that the concept provides a versatile platform for enhancing the functionality of soft matter by combining responsive and 2D materials, paving the way toward designing soft intelligent matter.}, note = {Online available at: \url{https://doi.org/10.1002/adma.202302816} (DOI). Hauck, M.; Saure, L.; Zeller-Plumhoff, B.; Kaps, S.; Hammel, J.; Mohr, C.; Rieck, L.; Nia, A.; Feng, X.; Pugno, N.; Adelung, R.; Schütt, F.: Overcoming water diffusion limitations in hydrogels via microtubular graphene networks for soft actuators. Advanced Materials. 2023. 2302816. DOI: 10.1002/adma.202302816}} @misc{soujon_fundamental_study_2022, author={Soujon, M., Kallien, Z., Roos, A., Zeller-Plumhoff, B., Klusemann, B.}, title={Fundamental study of multi-track friction surfacing deposits for dissimilar aluminum alloys with application to additive manufacturing}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.matdes.2022.110786}, abstract = {Friction surfacing is an emerging solid-state coating technology based on frictional heat induced plastic deformation at the tip of a consumable metallic stud that allows to deposit layers with a fine-grained recrystallized microstructure at temperatures below the melting point. The generation of sound, defect-free metallurgical joints between multiple adjacent overlapping friction surfacing deposits, also referred to as multi-track friction surfacing, from dissimilar aluminum alloys is the focus of this experimental work. An extensive volumetric defect analysis is carried out for various overlap configurations, including post-processing strategies in order to assess the inter-track bonding integrity using microscopic characterization techniques and micro-computed tomography. The effect of layer arrangement and overlap distance on the volumetric defect formation in both inter-track and layer-to-substrate interface is quantified and discussed. Post-processing via hybrid friction diffusion bonding process demonstrates a significant reduction in defect volume ratio, proving higher material efficiency. The gained knowledge was used to successfully build a multi-track multi-layer friction surfacing stack, demonstrating the suitability of this process for large-scale additive manufacturing components. The subsequent mechanical analysis reveals excellent homogeneous isotropic tensile properties of the additive structure in the range of the base material tensile strength.}, note = {Online available at: \url{https://doi.org/10.1016/j.matdes.2022.110786} (DOI). Soujon, M.; Kallien, Z.; Roos, A.; Zeller-Plumhoff, B.; Klusemann, B.: Fundamental study of multi-track friction surfacing deposits for dissimilar aluminum alloys with application to additive manufacturing. Materials & Design. 2022. vol. 219, 110786. DOI: 10.1016/j.matdes.2022.110786}} @misc{krger_highresolution_ex_2022, author={Krüger, D., Galli, S., Zeller-Plumhoff, B., Wieland, F., Peruzzi, N., Wiese, B., Heuser, P., Mossmann, J., Wennerberg, A., Willumeit-Römer, R.}, title={High-resolution ex vivo analysis of the degradation and osseointegration of Mg-xGd implant screws in 3D}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.bioactmat.2021.10.041}, abstract = {Our results showed that Mg-5Gd degraded faster and less homogeneously than Mg-10Gd. Both alloys gradually form a stable degradation layer at the interface and were surrounded by new bone tissue. The results were correlated to in vitro data obtained from the same material and shape. The average bone-to-implant contact of the Mg-xGd implants was comparable to that of Ti and higher than for PEEK. The results suggest that both Mg-xGd alloys are suitable as materials for bone implants.}, note = {Online available at: \url{https://doi.org/10.1016/j.bioactmat.2021.10.041} (DOI). Krüger, D.; Galli, S.; Zeller-Plumhoff, B.; Wieland, F.; Peruzzi, N.; Wiese, B.; Heuser, P.; Mossmann, J.; Wennerberg, A.; Willumeit-Römer, R.: High-resolution ex vivo analysis of the degradation and osseointegration of Mg-xGd implant screws in 3D. Bioactive Materials. 2022. vol. 13, 37-52. DOI: 10.1016/j.bioactmat.2021.10.041}} @misc{nourisa_cppyabm_an_2022, author={Nourisa, J., Zeller-Plumhoff, B., Willumeit-Römer, R.}, title={CppyABM: An open-source agent-based modeling library to integrate C++ and Python}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.1002/spe.3067}, abstract = {Agent-based modeling (ABM) has been extensively used to study the collective behavior of systems emerging from the interaction of numerous independent individuals called agents. Python and C++ are commonly used for ABM thanks to their unique features; the latter offers superior performance while the former provides ease-of-use and rich libraries in data science, visualization, and machine learning. We present the framework CppyABM that unifies these features by providing identical ABM semantic and development styles in both C++ and Python as well as the essential binding tools to expose a certain functionality from C++ to Python. The binding feature allows users to tailor and further extend a type or function within Python while it is originally defined in C++. Using CppyABM, users can choose either C++ or Python depending on their expertise and the specialty of the model or combine them to benefit from the advantages of both languages simultaneously. We provide showcases of CppyABM capabilities using several examples in computational biology, ecology, and virology. These examples are implemented in different formats using either C++ or Python or a combination of both to provide a comparison between the performance of implementation scenarios. The results of the example show a clear performance advantage of the models entirely or partly implemented in C++ compared to purely Python-based implementations.}, note = {Online available at: \url{https://doi.org/10.1002/spe.3067} (DOI). Nourisa, J.; Zeller-Plumhoff, B.; Willumeit-Römer, R.: CppyABM: An open-source agent-based modeling library to integrate C++ and Python. Software: Practice & Experience. 2022. vol. 52, no. 6, 1337-1351. DOI: 10.1002/spe.3067}} @misc{zellerplumhoff_computational_modelling_2022, author={Zeller-Plumhoff, B., AlBaraghtheh, T., Höche, D., Willumeit-Römer, R.}, title={Computational modelling of magnesium degradation in simulated body fluid under physiological conditions}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.jma.2021.11.014}, abstract = {Magnesium alloys are highly attractive for the use as temporary implant materials, due to their high biocompatibility and biodegradability. However, the prediction of the degradation rate of the implants is difficult, therefore, a large number of experiments are required. Computational modelling can aid in enabling the predictability, if sufficiently accurate models can be established. This work presents a generalized model of the degradation of pure magnesium in simulated body fluid over the course of 28 days considering uncertainty aspects. The model includes the computation of the metallic material thinning and is calibrated using the mean degradation depth of several experimental datasets simultaneously. Additionally, the formation and precipitation of relevant degradation products on the sample surface is modelled, based on the ionic composition of simulated body fluid. The computed mean degradation depth is in good agreement with the experimental data (NRMSE=0.07). However, the quality of the depth profile curves of the determined elemental weight percentage of the degradation products differs between elements (such as NRMSE=0.40 for phosphorus vs. NRMSE=1.03 for magnesium). This indicates that the implementation of precipitate formation may need further developments. The sensitivity analysis showed that the model parameters are correlated and which is related to the complexity and the high computational costs of the model. Overall, the model provides a correlating fit to the experimental data of pure Mg samples of different geometries degrading in simulated body fluid with reliable error estimation.}, note = {Online available at: \url{https://doi.org/10.1016/j.jma.2021.11.014} (DOI). Zeller-Plumhoff, B.; AlBaraghtheh, T.; Höche, D.; Willumeit-Römer, R.: Computational modelling of magnesium degradation in simulated body fluid under physiological conditions. Journal of Magnesium and Alloys. 2022. vol. 10, no. 4, 965-978. DOI: 10.1016/j.jma.2021.11.014}} @misc{hauck_fabrication_and_2022, author={Hauck, M., Dittmann, J., Zeller-Plumhoff, B., Madurawala, R., Hellmold, D., Kubelt, C., Synowitz, M., Held-Feindt, J., Adelung, R., Wulfinghoff, S., Schütt, F.}, title={Fabrication and Modelling of a Reservoir-Based Drug Delivery System for Customizable Release}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.3390/pharmaceutics14040777}, abstract = {Localized therapy approaches have emerged as an alternative drug administration route to overcome the limitations of systemic therapies, such as the crossing of the blood–brain barrier in the case of brain tumor treatment. For this, implantable drug delivery systems (DDS) have been developed and extensively researched. However, to achieve an effective localized treatment, the release kinetics of DDS needs to be controlled in a defined manner, so that the concentration at the tumor site is within the therapeutic window. Thus, a DDS, with patient-specific release kinetics, is crucial for the improvement of therapy. Here, we present a computationally supported reservoir-based DDS (rDDS) development towards patient-specific release kinetics. The rDDS consists of a reservoir surrounded by a polydimethylsiloxane (PDMS) microchannel membrane. By tailoring the rDDS, in terms of membrane porosity, geometry, and drug concentration, the release profiles can be precisely adapted, with respect to the maximum concentration, release rate, and release time. The release is investigated using a model dye for varying parameters, leading to different distinct release profiles, with a maximum release of up to 60 days. Finally, a computational simulation, considering exemplary in vivo conditions (e.g., exchange of cerebrospinal fluid), is used to study the resulting drug release profiles, demonstrating the customizability of the system. The establishment of a computationally supported workflow, for development towards a patient-specific rDDS, in combination with the transfer to suitable drugs, could significantly improve the efficacy of localized therapy approaches.}, note = {Online available at: \url{https://doi.org/10.3390/pharmaceutics14040777} (DOI). Hauck, M.; Dittmann, J.; Zeller-Plumhoff, B.; Madurawala, R.; Hellmold, D.; Kubelt, C.; Synowitz, M.; Held-Feindt, J.; Adelung, R.; Wulfinghoff, S.; Schütt, F.: Fabrication and Modelling of a Reservoir-Based Drug Delivery System for Customizable Release. Pharmaceutics. 2022. vol. 14, no. 4, 777. DOI: 10.3390/pharmaceutics14040777}} @misc{vaghefinazari_exploring_the_2022, author={Vaghefinazari, B., Lamaka, S.V., Blawert, C., Serdechnova, M., Scharnagl, N., Karlova, P., Wieland, D.C.F., Zheludkevich, M.L.}, title={Exploring the corrosion inhibition mechanism of 8-hydroxyquinoline for a PEO-coated magnesium alloy}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.corsci.2022.110344}, abstract = {In this study, the corrosion inhibition effect of 8-hydroxyquinoline (8HQ) on a PEO-coated AZ21 magnesium alloy is explored. The interaction of 8HQ molecules with both bare AZ21 and PEO layer was thoroughly scrutinized during the exposure to a corrosive NaCl electrolyte using different characterization methods, including EIS, SEM, Raman spectroscopy, and XRD. The corrosion inhibition mechanism stems from the extensive precipitation of the insoluble complex between 8HQ molecules and Mg2+ on top of the PEO layer, which leads to subsequently inhibition-enhancing phenomena, including modification of the corrosion products and re-precipitation of the PEO amorphous phase.}, note = {Online available at: \url{https://doi.org/10.1016/j.corsci.2022.110344} (DOI). Vaghefinazari, B.; Lamaka, S.; Blawert, C.; Serdechnova, M.; Scharnagl, N.; Karlova, P.; Wieland, D.; Zheludkevich, M.: Exploring the corrosion inhibition mechanism of 8-hydroxyquinoline for a PEO-coated magnesium alloy. Corrosion Science. 2022. vol. 203, 110344. DOI: 10.1016/j.corsci.2022.110344}} @misc{sefa_assessing_the_2022, author={Sefa, S., Wieland, F., Helmholz, H., Zeller-Plumhoff, B., Wennerberg, A., Moosmann, J., Willumeit-Römer, R., Galli, S.}, title={Assessing the long-term in vivo degradation behavior of magnesium alloys - a high resolution synchrotron radiation micro computed tomography study}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.3389/fbiom.2022.925471}, abstract = {Biodegradable magnesium (Mg) implants are emerging as a potential game changer in implant technology in situations where the implant temporarily supports the bone thereby avoiding secondary surgery for implant removal. However, the consequences of the alteration in the degradation rate to bone healing and the localization of degradation and alloying products in the long term remain unknown. In this study, we present the long-term osseointegration of three different biodegradable Mg alloys, Mg-10Gd, Mg-4Y-3RE and Mg-2Ag, which were implanted into rabbit femur for 6 and 9 months. In addition, we have investigated the effect of blood pre-incubation on the in vivo performance of the aforementioned alloys. Using high-resolution synchrotron radiation based micro computed tomography, the bone implant contact (BIC), bone volume fraction (BV/TV) and implant morphology were studied. The elemental traces have been characterized using micro X-ray fluorescence. Qualitative histological evaluation of the surrounding bone was also performed. Matured bone formed around all three implant types and Ca as well as P which represent parts of the degradation layer were in intimate contact with the bone. Blood pre-incubation prior to implantation significantly improved BIC in Mg-2Ag screws at 9 months. Despite different implant degradation morphologies pointing toward different degradation dynamics, Mg-10Gd, Mg-4Y-3RE and Mg-2Ag induced a similar long-term bone response based on our quantified parameters. Importantly, RE elements Gd and Y used in the alloys remained at the implantation site implying that they might be released later on or might persist in the implantation site forever. As the bone formation was not disturbed by their presence, it might be concluded that Gd and Y are non-deleterious. Consequently, we have shown that short and mid-term in vivo evaluations do not fully represent indicators for long-term osseointegration of Mg-based implants.}, note = {Online available at: \url{https://doi.org/10.3389/fbiom.2022.925471} (DOI). Sefa, S.; Wieland, F.; Helmholz, H.; Zeller-Plumhoff, B.; Wennerberg, A.; Moosmann, J.; Willumeit-Römer, R.; Galli, S.: Assessing the long-term in vivo degradation behavior of magnesium alloys - a high resolution synchrotron radiation micro computed tomography study. Frontiers in Biomaterials Science. 2022. vol. 1, 925471. DOI: 10.3389/fbiom.2022.925471}} @misc{sommer_implant_degradation_2022, author={Sommer, N., Hirtzberger, D., Paar, L., Berger, L., Cwieka, H., Schwarze, U., Herber, V., Okutan, B., Bodey, A., Willumeit-Römer, R., Zeller-Plumhoff, B., Löffler, J., Weinberg, A.}, title={Implant degradation of low-alloyed Mg–Zn–Ca in osteoporotic, old and juvenile rats}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.actbio.2022.05.041}, abstract = {Implant removal is unnecessary for biodegradable magnesium (Mg)-based implants and, therefore, the related risk for implant-induced fractures is limited. Aging, on the other hand, is associated with low bone-turnover and decreased bone mass and density, and thus increased fracture risk. Osteoporosis is accompanied by Mg deficiency, therefore, we hypothesized that Mg-based implants may support bone formation by Mg2+ ion release in an ovariectomy-induced osteoporotic rat model. Hence, we investigated osseointegration and implant degradation of a low-alloyed, degrading Mg–Zn–Ca implant (ZX00) in ovariectomy-induced osteoporotic (Osteo), old healthy (OH), and juvenile healthy (JH) groups of female Sprague Dawley rats via in vivo micro-computed tomography (µCT). For the Osteo rats, we demonstrate diminished trabecular bone already after 8 weeks upon ovariectomy and significantly enhanced implant volume loss, with correspondingly pronounced gas formation, compared to the OH and JH groups. Sclerotic rim development was observed in about half of the osteoporotic rats, suggesting a prevention from foreign-body and osteonecrosis development. Synchrotron radiation-based µCT confirmed lower bone volume fractions in the Osteo group compared to the OH and JH groups. Qualitative histological analysis additionally visualized the enhanced implant degradation in the Osteo group. To date, ZX00 provides an interesting implant material for young and older healthy patients, but it may not be of advantage in pharmacologically untreated osteoporotic conditions.}, note = {Online available at: \url{https://doi.org/10.1016/j.actbio.2022.05.041} (DOI). Sommer, N.; Hirtzberger, D.; Paar, L.; Berger, L.; Cwieka, H.; Schwarze, U.; Herber, V.; Okutan, B.; Bodey, A.; Willumeit-Römer, R.; Zeller-Plumhoff, B.; Löffler, J.; Weinberg, A.: Implant degradation of low-alloyed Mg–Zn–Ca in osteoporotic, old and juvenile rats. Acta Biomaterialia. 2022. vol. 147, 427-438. DOI: 10.1016/j.actbio.2022.05.041}} @misc{kasneryk_formation_and_2022, author={Kasneryk, V., Poschmann, M.P.M., Serdechnova, M., Dovzhenko, G., Wieland, D.C.F., Karlova, P., Naacke, T., Starykevich, M., Blawert, C., Stock, N., Zheludkevich, M.L.}, title={Formation and structure of ZIF-8@PEO coating on the surface of zinc}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.surfcoat.2022.128733}, abstract = {Recently, plasma electrolytic oxidation (PEO) found broad application as a multi-purpose process to create effective corrosion and wear resistant coatings on various metallic substrates. The exceptional properties of metal organic frameworks (MOFs) put them also in focus as perspective materials for corrosion protection. In this work, the formation of a novel ZIF-8@PEO coating is reported for the first time. It was synthesized by controllable recrystallization of a PEO layer formed on zinc alloy Z1 into ZIF-8 in the presence of 2-methylimidazole organic linkers. The multi-stage mechanism of PEO to ZIF-8 rearrangement is proposed. Cross section, glow discharge optical emission spectroscopy and nano-focused synchrotron X-ray diffraction demonstrated that varying of synthesis parameters, the ZIF-8@PEO coating with different distribution of ZIF-8 through PEO layer can be prepared. Based on the results of laser scanning microscopy, the surface smoothing was observed with increasing the degree of the PEO-to-ZIF-8 rearrangement. Containing two components, the novel ZIF-8@PEO coating is expected to combine admirable physical-chemical properties of both PEO and ZIF-8. Such a feature can open the way for its potential application not only for corrosion protection, but also for photo- and heterogeneous catalysis.}, note = {Online available at: \url{https://doi.org/10.1016/j.surfcoat.2022.128733} (DOI). Kasneryk, V.; Poschmann, M.; Serdechnova, M.; Dovzhenko, G.; Wieland, D.; Karlova, P.; Naacke, T.; Starykevich, M.; Blawert, C.; Stock, N.; Zheludkevich, M.: Formation and structure of ZIF-8@PEO coating on the surface of zinc. Surface and Coatings Technology. 2022. vol. 445, 128733. DOI: 10.1016/j.surfcoat.2022.128733}} @misc{karlova_comparison_of_2022, author={Karlova, P., Serdechnova, M., Blawert, C., Lu, X., Mohedano, M., Tolnai, D., Zeller-Plumhoff, B., Zheludkevich, M.L.}, title={Comparison of 2D and 3D Plasma Electrolytic Oxidation (PEO)-Based Coating Porosity Data Obtained by X-ray Tomography Rendering and a Classical Metallographic Approach}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.3390/ma15186315}, abstract = {In this work, the porosity of plasma electrolytic oxidation (PEO)-based coatings on Al- and Mg-based substrates was studied by two imaging techniques—namely, SEM and computer microtomography. Two approaches for porosity determination were chosen; relatively simple and fast SEM surface and cross-sectional imaging was compared with X-ray micro computed tomography (microCT) rendering. Differences between 2D and 3D porosity were demonstrated and explained. A more compact PEO coating was found on the Al substrate, with a lower porosity compared to Mg substrates under the same processing parameters. Furthermore, huge pore clusters were detected with microCT. Overall, 2D surface porosity calculations did not show sufficient accuracy for them to become the recommended method for the exact evaluation of the porosity of PEO coatings; microCT is a more appropriate method for porosity evaluation compared to SEM imaging. Moreover, the advantage of 3D microCT images clearly lies in the detection of closed and open porosity, which are important for coating properties.}, note = {Online available at: \url{https://doi.org/10.3390/ma15186315} (DOI). Karlova, P.; Serdechnova, M.; Blawert, C.; Lu, X.; Mohedano, M.; Tolnai, D.; Zeller-Plumhoff, B.; Zheludkevich, M.: Comparison of 2D and 3D Plasma Electrolytic Oxidation (PEO)-Based Coating Porosity Data Obtained by X-ray Tomography Rendering and a Classical Metallographic Approach. Materials. 2022. vol. 15, no. 18, 6315. DOI: 10.3390/ma15186315}} @misc{nourisa_the_osteogenetic_2022, author={Nourisa, J., Zeller-Plumhoff, B., Willumeit-Römer, R.}, title={The osteogenetic activities of mesenchymal stem cells in response to Mg2+ ions and inflammatory cytokines: a numerical approach using fuzzy logic controllers}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.1371/journal.pcbi.1010482}, abstract = {Magnesium (Mg2+) ions are frequently reported to regulate osteogenic activities of mesenchymal stem cells (MSCs). In this study, we propose a numerical model to study the regulatory importance of Mg2+ ions on MSCs osteoblastic differentiation in the presence of an inflammatory response. A fuzzy logic controller was formulated to receive the concentrations of Mg2+ ions and the inflammatory cytokines of TNF-α, IL-10, IL-1β, and IL-8 as cellular inputs and predict the cells’ early and late differentiation rates. Five sets of empirical data obtained from published cell culture experiments were used to calibrate the model. The model successfully reproduced the empirical data regarding the concentration- and phase-dependent effect of Mg2+ ions on the differentiation process. In agreement with the experiments, the model showed the stimulatory role of Mg2+ ions on the early differentiation phase, once administered at low concentration, and their inhibitory role on the late differentiation phase. The numerical approach used in this study suggested 6–8 mM as the most effective concentration of Mg2+ ions in promoting the early differentiation process. Also, the proposed model sheds light on the fundamental differences in the behavioral properties of cells cultured in different experiments, e.g. differentiation rate and the sensitivity of the cultured cells to stimulatory signals such as Mg2+ ions. Thus, it can be used to interpret and compare different empirical findings. Moreover, the model successfully reproduced the nonlinearities in the concentration-dependent role of the inflammatory cytokines in early and late differentiation rates. Overall, the proposed model can be employed in studying the osteogenic properties of Mg-based implants in the presence of an inflammatory response.}, note = {Online available at: \url{https://doi.org/10.1371/journal.pcbi.1010482} (DOI). Nourisa, J.; Zeller-Plumhoff, B.; Willumeit-Römer, R.: The osteogenetic activities of mesenchymal stem cells in response to Mg2+ ions and inflammatory cytokines: a numerical approach using fuzzy logic controllers. PLoS Computational Biology. 2022. vol. 18, no. 9, e1010482. DOI: 10.1371/journal.pcbi.1010482}} @misc{newham_reply_to_2022, author={Newham, E., Gill, P.G., Benton, M.J., Brewer, P., Gostling, N.J., Haberthür, D., Jernvall, J., Kankanpää, T., Kallonen, A., Navarro, C., Pacureanu, A., Richards, K., Robson Brown, K., Schneider, P., Suhonen, H., Tafforeau, P., Williams, K., Zeller-Plumhoff, B., Corfe, I.J.}, title={Reply to: Revisiting life history and morphological proxies for early mammaliaform metabolic rates}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.1038/s41467-022-32716-z}, abstract = {In an article examining the physiology of Early Jurassic mammaliaform stem-mammals, we used proxies for basal and maximum metabolic rate, providing evidence that two key fossil mammaliaforms had metabolic rates closer to modern reptiles than modern mammals1. Meiri and Levin2 questioned the use of our proxy for basal metabolic rate – terrestrial species maximum lifespan in the wild. Here, we explore the evidence behind these differences in viewpoint, and rebut specific points raised by these authors.}, note = {Online available at: \url{https://doi.org/10.1038/s41467-022-32716-z} (DOI). Newham, E.; Gill, P.; Benton, M.; Brewer, P.; Gostling, N.; Haberthür, D.; Jernvall, J.; Kankanpää, T.; Kallonen, A.; Navarro, C.; Pacureanu, A.; Richards, K.; Robson Brown, K.; Schneider, P.; Suhonen, H.; Tafforeau, P.; Williams, K.; Zeller-Plumhoff, B.; Corfe, I.: Reply to: Revisiting life history and morphological proxies for early mammaliaform metabolic rates. Nature Communications. 2022. vol. 13, no. 1, 5564. DOI: 10.1038/s41467-022-32716-z}} @misc{zellerplumhoff_oxygensensitive_nanoparticles_2022, author={Zeller-Plumhoff, B., Akkineni, A.R., Helmholz, H., Orlov, D., Mosshammer, M., Kühl, M., Willumeit-Römer, R., Gelinsky, M.}, title={Oxygen-sensitive nanoparticles reveal the spatiotemporal dynamics of oxygen reduction during magnesium implant biodegradation}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.1038/s41529-022-00302-9}, abstract = {Magnesium (Mg) alloys are becoming increasingly important in the biomedical field as temporary bone implants. However, the biodegradation process of Mg alloys is highly complex and recent findings suggest that oxygen (O2) consumption is non-negligible. In this study, we give experimental proof of O2 consumption during Mg degradation under physiological conditions. Specifically, we study pure Mg, Mg–6 wt%Ag and Mg–5 wt%Gd in Hanks’ balanced salt solution and Dulbecco’s modified Eagle’s medium. We show that O2 consumption and hydrogen evolution are inversely correlated and that O2 concentrations remain below 7.5% in certain cases, which could have significant implications for bone healing.}, note = {Online available at: \url{https://doi.org/10.1038/s41529-022-00302-9} (DOI). Zeller-Plumhoff, B.; Akkineni, A.; Helmholz, H.; Orlov, D.; Mosshammer, M.; Kühl, M.; Willumeit-Römer, R.; Gelinsky, M.: Oxygen-sensitive nanoparticles reveal the spatiotemporal dynamics of oxygen reduction during magnesium implant biodegradation. npj Materials Degradation. 2022. vol. 6, no. 1, 95. DOI: 10.1038/s41529-022-00302-9}} @misc{albaraghtheh_in_silico_2022, author={Albaraghtheh, T., Willumeit-Römer, R., Zeller-Plumhoff, B.}, title={In silico studies of magnesium-based implants: A review of the current stage and challenges}, year={2022}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.jma.2022.09.029}, abstract = {In silico methods to study biodegradable implants have recently received increasing attention due to their potential in reducing experimental time and cost. An important application case for in silico methods are magnesium (Mg)-based biodegradable implants, as they represent a powerful alternative to traditional materials used for temporary orthopaedic applications. Controlling Mg alloy degradation is critical to designing an implant that supports the bone healing process. To simulate different aspects of this biodegradation process, several mathematical models have been proposed with the ultimate aim of replacing laboratory experiments with computational modeling. In this review, we provide a comprehensive and critical discussion of the published models and their performance with respect to capturing the complexity of the biodegradation process. This complexity is presented initially. Additionally, the present review discusses the different approaches of optimizing and quantifying the different sources of errors and uncertainties within the proposed models.}, note = {Online available at: \url{https://doi.org/10.1016/j.jma.2022.09.029} (DOI). Albaraghtheh, T.; Willumeit-Römer, R.; Zeller-Plumhoff, B.: In silico studies of magnesium-based implants: A review of the current stage and challenges. Journal of Magnesium and Alloys. 2022. vol. 10, no. 11, 2968-2996. DOI: 10.1016/j.jma.2022.09.029}} @misc{zellerplumhoff_evaluating_the_2021, author={Zeller-Plumhoff, B., Laipple, D., Slominska, H., Iskhakova, K., Longo, E., Hermann, A., Flenner, S., Greving, I., Storm, M., Willumeit-Römer, R.}, title={Evaluating the morphology of the degradation layer of pure magnesium via 3D imaging at resolutions below 40 nm}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.bioactmat.2021.04.009}, abstract = {Magnesium is attractive for the application as a temporary bone implant due to its inherent biodegradability, non-toxicity and suitable mechanical properties. The degradation process of magnesium in physiological environments is complex and is thought to be a diffusion-limited transport problem. We use a multi-scale imaging approach using micro computed tomography and transmission X-ray microscopy (TXM) at resolutions below 40 nm. Thus, we are able to evaluate the nanoporosity of the degradation layer and infer its impact on the degradation process of pure magnesium in two physiological solutions. Magnesium samples were degraded in simulated body fluid (SBF) or Dulbecco's modified Eagle's medium (DMEM) with 10% fetal bovine serum (FBS) for one to four weeks. TXM reveals the three-dimensional interconnected pore network within the degradation layer for both solutions. The pore network morphology and degradation layer composition are similar for all samples. By contrast, the degradation layer thickness in samples degraded in SBF was significantly higher and more inhomogeneous than in DMEM+10%FBS. Distinct features could be observed within the degradation layer of samples degraded in SBF, suggesting the formation of microgalvanic cells, which are not present in samples degraded in DMEM+10%FBS. The results suggest that the nanoporosity of the degradation layer and the resulting ion diffusion processes therein have a limited influence on the overall degradation process. This indicates that the influence of organic components on the dampening of the degradation rate by the suppression of microgalvanic degradation is much greater in the present study.}, note = {Online available at: \url{https://doi.org/10.1016/j.bioactmat.2021.04.009} (DOI). Zeller-Plumhoff, B.; Laipple, D.; Slominska, H.; Iskhakova, K.; Longo, E.; Hermann, A.; Flenner, S.; Greving, I.; Storm, M.; Willumeit-Römer, R.: Evaluating the morphology of the degradation layer of pure magnesium via 3D imaging at resolutions below 40 nm. Bioactive Materials. 2021. vol. 6, no. 12, 4368-4376. DOI: 10.1016/j.bioactmat.2021.04.009}} @misc{nidadavolu_pore_characterization_2021, author={Nidadavolu, E., Krüger, D., Zeller-Plumhoff, B., Tolnai, D., Wiese, B., Feyerabend, F., Ebel, T., Willumeit-Römer, R.}, title={Pore characterization of PM Mg–0.6Ca alloy and its degradation behavior under physiological conditions}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.jma.2020.05.006}, abstract = {Several material parameters affect degradation characteristics of Mg and its alloys under physiological conditions. Porous Mg materials are interesting for their simultaneous degradation and drug delivery capabilities. However, an increase in pore surface area is detrimental to both degradation resistance and subsequent mechanical properties. The present work aims at determining the threshold porosity value in Mg–0.6Ca specimens produced by powder metallurgy (PM) below which low degradation rates persist with acceptable mechanical properties. Seven different porous Mg–0.6Ca specimens containing both closed and open pore structures were fabricated with porosities ranging from 3% to 21%. Degradation profiles were obtained via a semi static immersion test over 16 days under physiological conditions using Dulbecco's modified Eagle's medium with Glutamax and 10% fetal bovine serum as supplements. The results are related to morphological pore parameters like pore size distribution, pore interconnectivity and pore curvatures that were quantified using an ex situ µCT analysis. In general, with decreasing porosity a decrease in pore interconnectivity is seen followed by rounding of the pores. Low degradation rates (MDR < 0.3 mm/year) are observed in specimens until 10% porosity, however, the upper bound for reproducible degradation is observed to be in specimens until 12% porosity. This porosity level also marks the transition from closed to open pore nature with a simultaneous change in pore interconnectivity from less than 10% to greater than 95%, below and above this porosity level, respectively. The tensile strength and elongation to failure recorded for specimens with 10% porosity were 70 MPa and 2%, respectively displaying positive traits of both homogenous degradation and mechanical properties. The results suggest that high pore interconnectivity is the dominant factor controlling degradation and mechanical properties in porous Mg-0.6Ca specimens. The results also indicate a good sintering response of Mg-0.6Ca specimens providing further material development towards biomaterial applications.}, note = {Online available at: \url{https://doi.org/10.1016/j.jma.2020.05.006} (DOI). Nidadavolu, E.; Krüger, D.; Zeller-Plumhoff, B.; Tolnai, D.; Wiese, B.; Feyerabend, F.; Ebel, T.; Willumeit-Römer, R.: Pore characterization of PM Mg–0.6Ca alloy and its degradation behavior under physiological conditions. Journal of Magnesium and Alloys. 2021. vol. 9, no. 2, 686-703. DOI: 10.1016/j.jma.2020.05.006}} @misc{zellerplumhoff_exploring_key_2021, author={Zeller-Plumhoff, B., Gile, M., Priebe, M., Slominska, H., Boll, B., Wiese, B., Würger, T., Willumeit-Römer, R., Meißner, R.}, title={Exploring key ionic interactions for magnesium degradation in simulated body fluid – A data-driven approach}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.corsci.2021.109272}, abstract = {We have studied the degradation of pure magnesium wire in simulated body fluid and its subsets under physiological conditions to enable the prediction of the degradation rate based on the medium's ionic composition. To this end, micro-computed tomography and scanning electron microscopy with energy-dispersive X-ray spectroscopy were used, followed by a tree regression analysis. A non-linear relationship was found between degradation rate and the precipitation of calcium salts. The mean absolute error for predicting the degradation rate was 1.35 mm/yr. This comparatively high value indicates that ionic interactions were exceedingly complex or that an unknown parameter determining the degradation may exist.}, note = {Online available at: \url{https://doi.org/10.1016/j.corsci.2021.109272} (DOI). Zeller-Plumhoff, B.; Gile, M.; Priebe, M.; Slominska, H.; Boll, B.; Wiese, B.; Würger, T.; Willumeit-Römer, R.; Meißner, R.: Exploring key ionic interactions for magnesium degradation in simulated body fluid – A data-driven approach. Corrosion Science. 2021. vol. 182, 109272. DOI: 10.1016/j.corsci.2021.109272}} @misc{ignjatovi_formation_of_2021, author={Ignjatović, S., Blawert, C., Serdechnova, M., Karpushenkov, S., Damjanović, M., Karlova, P., Wieland, D.C.F., Starykevich, M., Stojanović, S., Damjanović-Vasilić, L., Zheludkevich, M.L.}, title={Formation of multi-functional TiO2 surfaces on AA2024 alloy using plasma electrolytic oxidation}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.apsusc.2020.148875}, abstract = {It was found that the coating thickness and surface morphology are strongly dependent on the PEO processing time. However, the phase composition is not much affected by the treatment time and the main coating phase is rutile with a smaller amount of anatase. Adding additional anatase in the form of particles increases the amount of anatase in the coatings. The additional particle addition has only minor effect on the corrosion resistance, but reduces the wear resistance remarkably. Interestingly, the addition of anatase particles and the PEO treatment time are not effective in increasing the photocatalytic activities of the samples.}, note = {Online available at: \url{https://doi.org/10.1016/j.apsusc.2020.148875} (DOI). Ignjatović, S.; Blawert, C.; Serdechnova, M.; Karpushenkov, S.; Damjanović, M.; Karlova, P.; Wieland, D.; Starykevich, M.; Stojanović, S.; Damjanović-Vasilić, L.; Zheludkevich, M.: Formation of multi-functional TiO2 surfaces on AA2024 alloy using plasma electrolytic oxidation. Applied Surface Science. 2021. vol. 544, 148875. DOI: 10.1016/j.apsusc.2020.148875}} @misc{ignjatovic_the_influence_2021, author={Ignjatovic, S., Blawert, C., Serdechnova, M., Karpushenkov, S., Damjanovic, M., Karlova, P., Dovzhenko, G., Wieland, F., Zeller-Plumhoff, B., Starykevich, M., Stojanovic, S., Damjanovic-Vasilic, L., Zheludkevich, M.}, title={The Influence of In Situ Anatase Particle Addition on the Formation and Properties of Multifunctional Plasma Electrolytic Oxidation Coatings on AA2024 Aluminum Alloy}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.1002/adem.202001527}, abstract = {Plasma electrolytic oxidation (PEO) with in‐situ anatase particle addition was applied to functionalize the surface of AA2024 alloy. A base potassium titanium‐oxide oxalate dihydrate aqueous electrolyte was used with up to 30 g/L anatase particle addition. The coatings’ morphology and phase composition as a function of the anatase concentration in the electrolyte were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD) and glow discharge optical emission spectroscopy (GDOES). Photocatalytic activity, stability in chloride solution and tribological properties were also determined. The main coating forming phases are anatase and rutile on top of a mixed interface region consisting of TiAl2O5 as reaction product between the TiO2 and an Al2O3 barrier layer on top of the Al substrate. The mixed layer is extending with increasing amount of particles added, due to intensified discharges. In addition, anatase to rutile phase ratio increases due to the additional anatase particles in the electrolyte. Thus, the photocatalytic activity is improving with the particle addition. The coatings’ mechanical resistance is dropping first before increasing again with more particles added. Chemical and restored mechanical stability seems to be related to the extended mixed interface formation, which strengthen the bond to the substrate when more particles are added.}, note = {Online available at: \url{https://doi.org/10.1002/adem.202001527} (DOI). Ignjatovic, S.; Blawert, C.; Serdechnova, M.; Karpushenkov, S.; Damjanovic, M.; Karlova, P.; Dovzhenko, G.; Wieland, F.; Zeller-Plumhoff, B.; Starykevich, M.; Stojanovic, S.; Damjanovic-Vasilic, L.; Zheludkevich, M.: The Influence of In Situ Anatase Particle Addition on the Formation and Properties of Multifunctional Plasma Electrolytic Oxidation Coatings on AA2024 Aluminum Alloy. Advanced Engineering Materials. 2021. vol. 23, no. 6, 2001527. DOI: 10.1002/adem.202001527}} @misc{arndt_microengineered_hollow_2021, author={Arndt, C., Hauck, M., Wacker, I., Zeller-Plumhoff, B., Rasch, F., Taale, M., Shaygan Nia, A., Feng, X., Adelung, R., Schröder, R., Schütt, F., Selhuber-Unkel, C.}, title={Microengineered Hollow Graphene Tube Systems Generate Conductive Hydrogels with Extremely Low Filler Concentration}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.1021/acs.nanolett.0c04375}, abstract = {The fabrication of electrically conductive hydrogels is challenging as the introduction of an electrically conductive filler often changes mechanical hydrogel matrix properties. Here, we present an approach for the preparation of hydrogel composites with outstanding electrical conductivity at extremely low filler loadings (0.34 S m–1, 0.16 vol %). Exfoliated graphene and polyacrylamide are microengineered to 3D composites such that conductive graphene pathways pervade the hydrogel matrix similar to an artificial nervous system. This makes it possible to combine both the exceptional conductivity of exfoliated graphene and the adaptable mechanical properties of polyacrylamide. The demonstrated approach is highly versatile regarding porosity, filler material, as well as hydrogel system. The important difference to other approaches is that we keep the original properties of the matrix, while ensuring conductivity through graphene-coated microchannels. This novel approach of generating conductive hydrogels is very promising, with particular applications in the fields of bioelectronics and biohybrid robotics.}, note = {Online available at: \url{https://doi.org/10.1021/acs.nanolett.0c04375} (DOI). Arndt, C.; Hauck, M.; Wacker, I.; Zeller-Plumhoff, B.; Rasch, F.; Taale, M.; Shaygan Nia, A.; Feng, X.; Adelung, R.; Schröder, R.; Schütt, F.; Selhuber-Unkel, C.: Microengineered Hollow Graphene Tube Systems Generate Conductive Hydrogels with Extremely Low Filler Concentration. Nano Letters. 2021. vol. 21, no. 8, 3690-3697. DOI: 10.1021/acs.nanolett.0c04375}} @misc{baltruschat_scaling_the_2021, author={Baltruschat, I.M., Ćwieka, H., Krüger, D., Zeller-Plumhoff, B., Schlünzen, F., Willumeit-Römer, R., Moosmann, J., Heuser, P.}, title={Scaling the U-net: segmentation of biodegradable bone implants in high-resolution synchrotron radiation microtomograms}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.1038/s41598-021-03542-y}, abstract = {Highly accurate segmentation of large 3D volumes is a demanding task. Challenging applications like the segmentation of synchrotron radiation microtomograms (SRμCT) at high-resolution, which suffer from low contrast, high spatial variability and measurement artifacts, readily exceed the capacities of conventional segmentation methods, including the manual segmentation by human experts. The quantitative characterization of the osseointegration and spatio-temporal biodegradation process of bone implants requires reliable, and very precise segmentation. We investigated the scaling of 2D U-net for high resolution grayscale volumes by three crucial model hyper-parameters (i.e., the model width, depth, and input size). To leverage the 3D information of high-resolution SRμCT, common three axes prediction fusing is extended, investigating the effect of adding more than three axes prediction. In a systematic evaluation we compare the performance of scaling the U-net by intersection over union (IoU) and quantitative measurements of osseointegration and degradation parameters. Overall, we observe that a compound scaling of the U-net and multi-axes prediction fusing with soft voting yields the highest IoU for the class “degradation layer”. Finally, the quantitative analysis showed that the parameters calculated with model segmentation deviated less from the high quality results than those obtained by a semi-automatic segmentation method.}, note = {Online available at: \url{https://doi.org/10.1038/s41598-021-03542-y} (DOI). Baltruschat, I.; Ćwieka, H.; Krüger, D.; Zeller-Plumhoff, B.; Schlünzen, F.; Willumeit-Römer, R.; Moosmann, J.; Heuser, P.: Scaling the U-net: segmentation of biodegradable bone implants in high-resolution synchrotron radiation microtomograms. Scientific Reports. 2021. vol. 11, no. 1, 24237. DOI: 10.1038/s41598-021-03542-y}} @misc{gapeeva_electrochemical_surface_2021, author={Gapeeva, A., Vogtmann, J., Zeller-Plumhoff, B., Beckmann, F., Gurka, M., Carstensen, J., Adelung, R.}, title={Electrochemical Surface Structuring for Strong SMA Wire–Polymer Interface Adhesion}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.1021/acsami.1c00807}, abstract = {Active hybrid composites represent a novel class of smart materials used to design morphing surfaces, opening up new applications in the aircraft and automotive industries. The bending of the active hybrid composite is induced by the contraction of electrically activated shape memory alloy (SMA) wires, which are placed with an offset to the neutral axis of the composite. Therefore, the adhesion strength between the SMA wire and the surrounding polymer matrix is crucial to the load transfer and the functionality of the composite. Thus, the interface adhesion strength is of great importance for the performance and the actuation potential of active hybrid composites. In this work, the surface of a commercially available one-way effect NiTi SMA wire with a diameter of 1 mm was structured by selective electrochemical etching that preferably starts at defect sites, leaving the most thermodynamically stable surfaces of the wire intact. The created etch pits lead to an increase in the surface area of the wire and a mechanical interlocking with the polymer, resulting in a combination of adhesive and cohesive failure modes after a pull-out test. Consequently, the force of the first failure determined by an optical stress measurement was increased by more than 3 times when compared to the as-delivered SMA wire. The actuation characterization test showed that approximately the same work capacity could be retrieved from structured SMA wires. Moreover, structured SMA wires exhibited the same shape of the stress–strain curve as the as-delivered SMA wire, and the mechanical performance was not influenced by the structuring process. The austenite start As and austenite finish Af transformation temperatures were also not found to be affected by the structuring process. The formation of etching pits with different geometries and densities was discussed with regard to the kinetics of oxide formation and dissolution.}, note = {Online available at: \url{https://doi.org/10.1021/acsami.1c00807} (DOI). Gapeeva, A.; Vogtmann, J.; Zeller-Plumhoff, B.; Beckmann, F.; Gurka, M.; Carstensen, J.; Adelung, R.: Electrochemical Surface Structuring for Strong SMA Wire–Polymer Interface Adhesion. ACS Applied Materials and Interfaces. 2021. vol. 13, no. 18, 21924-21935. DOI: 10.1021/acsami.1c00807}} @misc{zellerplumhoff_utilizing_synchrotron_2021, author={Zeller-Plumhoff, B., Tolnai, D., Wolff, M., Greving, I., Hort, N., Willumeit-Römer, R.}, title={Utilizing Synchrotron Radiation for the Characterization of Biodegradable Magnesium Alloys—From Alloy Development to the Application as Implant Material}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.1002/adem.202100197}, abstract = {Magnesium alloys are highly attractive for their application as structural materials as well as medical implants. A range of alloying systems exists which are investigated e.g. in terms of alloy microstructure changes, in particular during different processing steps or mechanical testing, and in terms of the associated corrosion performance of the material. Synchrotron radiation and in particular synchrotron radiation micro computed tomography and nanotomography yield a unique opportunity to investigate such changes and processes in 3D at high resolution and in situ, thus significantly broadening our knowledge base. In this review we demonstrate the benefits of using synchrotron radiation for the investigation of magnesium alloys with particular respect to its application as a biodegradable implant. We review advances in experimental environments for in situ testing, and cover all stages of materials testing in which synchrotron radiation has been used, i.e. from developing and processing of the material, to corrosion testing and assessing implant integration and stability ex vivo. This review incorporates advances both in micro- and nanotomographic imaging regimes and further includes complementary techniques, such as X-ray diffraction, small angle X-ray scattering, X-ray fluorescence and diffraction tomography. Finally, we provide an outlook into future developments.}, note = {Online available at: \url{https://doi.org/10.1002/adem.202100197} (DOI). Zeller-Plumhoff, B.; Tolnai, D.; Wolff, M.; Greving, I.; Hort, N.; Willumeit-Römer, R.: Utilizing Synchrotron Radiation for the Characterization of Biodegradable Magnesium Alloys—From Alloy Development to the Application as Implant Material. Advanced Engineering Materials. 2021. vol. 23, no. 11, 2100197. DOI: 10.1002/adem.202100197}} @misc{nourisa_magnesium_ions_2021, author={Nourisa, J., Zeller-Plumhoff, B., Helmholz, H., Luthringer-Feyerabend, B., Ivannikov, V., Willumeit-Römer, R.}, title={Magnesium ions regulate mesenchymal stem cells population and osteogenic differentiation: A fuzzy agent-based modeling approach}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.csbj.2021.07.005}, abstract = {Mesenchymal stem cells (MSCs) are proliferative and multipotent cells that play a key role in the bone regeneration process. Empirical data have repeatedly shown the bioregulatory importance of magnesium (Mg) ions in MSC growth and osteogenesis. In this study, we propose an agent-based model to predict the spatiotemporal dynamics of the MSC population and osteogenic differentiation in response to Mg2+ ions. A fuzzy-logic controller was designed to govern the decision-making process of cells by predicting four cellular processes of proliferation, differentiation, migration, and mortality in response to several important bioregulatory factors such as Mg2+ ions, pH, BMP2, and TGF-β1. The model was calibrated using the empirical data obtained from three sets of cell culture experiments. The model successfully reproduced the empirical observations regarding live cell count, viability, DNA content, and the differentiation-related markers of alkaline phosphate (ALP) and osteocalcin (OC). The simulation results, in agreement with the empirical data, showed that Mg2+ ions within 3–6 mM concentration have the highest stimulation effect on cell population growth. The model also correctly reproduced the stimulatory effect of Mg2+ ions on ALP and its inhibitory effect on OC as the early and late differentiation markers, respectively. Besides, the numerical simulation shed light on the innate cellular differences of the cells cultured in different experiments in terms of the proliferative capacity as well as sensitivity to Mg2+ ions. The proposed model can be adopted in the study of the osteogenesis around Mg-based implants where ions released due to degradation interact with local cells and regulate bone regeneration.}, note = {Online available at: \url{https://doi.org/10.1016/j.csbj.2021.07.005} (DOI). Nourisa, J.; Zeller-Plumhoff, B.; Helmholz, H.; Luthringer-Feyerabend, B.; Ivannikov, V.; Willumeit-Römer, R.: Magnesium ions regulate mesenchymal stem cells population and osteogenic differentiation: A fuzzy agent-based modeling approach. Computational and Structural Biotechnology Journal. 2021. vol. 19, 4110-4122. DOI: 10.1016/j.csbj.2021.07.005}} @misc{hindenlang_evaporation_kinetics_2021, author={Hindenlang, B., Gapeeva, A., Baum, M., Kaps, S., Saure, L., Rasch, F., Hammel, J., Moosmann, J., Storm, M., Adelung, R., Schütt, F., Zeller-Plumhoff, B.}, title={Evaporation kinetics in highly porous tetrapodal zinc oxide networks studied using in situ SRµCT}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.1038/s41598-021-99624-y}, abstract = {Tetrapodal zinc oxide (t-ZnO) is used to fabricate polymer composites for many different applications ranging from biomedicine to electronics. In recent times, macroscopic framework structures from t-ZnO have been used as a versatile sacrificial template for the synthesis of multi-scaled foam structures from different nanomaterials such as graphene, hexagonal boron nitride or gallium nitride. Many of these fabrication methods rely on wet-chemical coating processes using nanomaterial dispersions, leading to a strong interest in the actual coating mechanism and factors influencing it. Depending on the type of medium (e.g. solvent) used, different results regarding the homogeneity of the nanomaterial coating can be achieved. In order to understand how a medium influences the coating behavior, the evaporation process of water and ethanol is investigated in this work using in situ synchrotron radiation-based micro computed tomography (SRµCT). By employing propagation-based phase contrast imaging, both the t-ZnO network and the medium can be visualized. Thus, the evaporation process can be monitored non-destructively in three dimensions. This investigation showed that using a polar medium such as water leads to uniform evaporation and, by that, a homogeneous coating of the entire network.}, note = {Online available at: \url{https://doi.org/10.1038/s41598-021-99624-y} (DOI). Hindenlang, B.; Gapeeva, A.; Baum, M.; Kaps, S.; Saure, L.; Rasch, F.; Hammel, J.; Moosmann, J.; Storm, M.; Adelung, R.; Schütt, F.; Zeller-Plumhoff, B.: Evaporation kinetics in highly porous tetrapodal zinc oxide networks studied using in situ SRµCT. Scientific Reports. 2021. vol. 11, no. 1, 20272. DOI: 10.1038/s41598-021-99624-y}} @misc{meyer_degradation_analysis_2021, author={Meyer, S., Wolf, A., Sanders, D., Iskhakova, K., Ćwieka, H., Bruns, S., Flenner, S., Greving, I., Hagemann, J., Willumeit-Römer, R., Wiese, B., Zeller-Plumhoff, B.}, title={Degradation Analysis of Thin Mg-xAg Wires Using X-ray Near-Field Holotomography}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.3390/met11091422}, abstract = {Magnesium–silver alloys are of high interest for the use as temporary bone implants due to their antibacterial properties in addition to biocompatibility and biodegradability. Thin wires in particular can be used for scaffolding, but the determination of their degradation rate and homogeneity using traditional methods is difficult. Therefore, we have employed 3D imaging using X-ray near-field holotomography with sub-micrometer resolution to study the degradation of thin (250 μm diameter) Mg-2Ag and Mg-6Ag wires. The wires were studied in two states, recrystallized and solution annealed to assess the influence of Ag content and precipitates on the degradation. Imaging was employed after degradation in Dulbecco’s modified Eagle’s medium and 10% fetal bovine serum after 1 to 7 days. At 3 days of immersion the degradation rates of both alloys in both states were similar, but at 7 days higher silver content and solution annealing lead to decreased degradation rates. The opposite was observed for the pitting factor. Overall, the standard deviation of the determined parameters was high, owing to the relatively small field of view during imaging and high degradation inhomogeneity of the samples. Nevertheless, Mg-6Ag in the solution annealed state emerges as a potential material for thin wire manufacturing for implants.}, note = {Online available at: \url{https://doi.org/10.3390/met11091422} (DOI). Meyer, S.; Wolf, A.; Sanders, D.; Iskhakova, K.; Ćwieka, H.; Bruns, S.; Flenner, S.; Greving, I.; Hagemann, J.; Willumeit-Römer, R.; Wiese, B.; Zeller-Plumhoff, B.: Degradation Analysis of Thin Mg-xAg Wires Using X-ray Near-Field Holotomography. Metals. 2021. vol. 11, no. 9, 1422. DOI: 10.3390/met11091422}} @misc{krger_assessing_the_2021, author={Krüger, D., Zeller-Plumhoff, B., Wiese, B., Yi, S., Zuber, M., Wieland, F., Moosmann, J., Willumeit-Römer, R.}, title={Assessing the microstructure and in vitro degradation behavior of Mg-xGd screw implants using µCT}, year={2021}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.jma.2021.07.029}, abstract = {Although differences were observed in the degree of screw's near surface microstructure being influenced from machining, the degradation rates of both materials appeared to be suitable for application in orthopedic implants. From the degradation homogeneity point of view no obvious contrast was detected between both alloys. However, the higher degradation depth ratios between the crests and roots of Mg-5Gd ratios may indicated a less homogeneous degradation of the screws of these alloys on contract to the ones made of Mg-10Gd alloys. Due to its lower degradation rates, its more homogeneous microstructure, its weaker texture and better degradation performance extruded Mg-10Gd emerged more suitable as implant material than Mg-5Gd.}, note = {Online available at: \url{https://doi.org/10.1016/j.jma.2021.07.029} (DOI). Krüger, D.; Zeller-Plumhoff, B.; Wiese, B.; Yi, S.; Zuber, M.; Wieland, F.; Moosmann, J.; Willumeit-Römer, R.: Assessing the microstructure and in vitro degradation behavior of Mg-xGd screw implants using µCT. Journal of Magnesium and Alloys. 2021. vol. 9, no. 6, 2207-2222. DOI: 10.1016/j.jma.2021.07.029}} @misc{zellerplumhoff_nanotomographic_evaluation_2020, author={Zeller-Plumhoff, B., Robisch, A., Pelliccia, D., Longo, E., Slominska, H., Hermann, A., Krenkel, M., Storm, M., Estrin, Y., Willumeit-Römer, R., Salditt, T., Orlov, D.}, title={Nanotomographic evaluation of precipitate structure evolution in a Mg–Zn–Zr alloy during plastic deformation}, year={2020}, howpublished = {journal article}, doi = {https://doi.org/10.1038/s41598-020-72964-x}, abstract = {Magnesium and its alloys attract increasingly wide attention in various fields, ranging from transport to medical solutions, due to their outstanding structural and degradation properties. These properties can be tailored through alloying and thermo-mechanical processing, which is often complex and multi-step, thus requiring in-depth analysis. In this work, we demonstrate the capability of synchrotron-based nanotomographic X-ray imaging methods, namely holotomography and transmission X-ray microscopy, for the quantitative 3D analysis of the evolution of intermetallic precipitate (particle) morphology and distribution in magnesium alloy Mg–5.78Zn–0.44Zr subjected to a complex multi-step processing. A rich history of variation of the intermetallic particle structure in the processed alloy provided a testbed for challenging the analytical capabilities of the imaging modalities studied. The main features of the evolving precipitate structure revealed earlier by traditional light and electron microscopy methods were confirmed by the 3D techniques of synchrotron-based X-ray imaging. We further demonstrated that synchrotron-based X-ray imaging enabled uncovering finer details of the variation of particle morphology and number density at various stages of processing—above and beyond the information provided by visible light and electron microscopy.}, note = {Online available at: \url{https://doi.org/10.1038/s41598-020-72964-x} (DOI). Zeller-Plumhoff, B.; Robisch, A.; Pelliccia, D.; Longo, E.; Slominska, H.; Hermann, A.; Krenkel, M.; Storm, M.; Estrin, Y.; Willumeit-Römer, R.; Salditt, T.; Orlov, D.: Nanotomographic evaluation of precipitate structure evolution in a Mg–Zn–Zr alloy during plastic deformation. Scientific Reports. 2020. vol. 10, 16101. DOI: 10.1038/s41598-020-72964-x}} @misc{zellerplumhoff_analysis_of_2020, author={Zeller-Plumhoff, B., Malich, C., Krueger, D., Campbell, G., Wiese, B., Galli, S., Wennerberg, A., Willumeit-Römer, R., Wieland, D.C.F.}, title={Analysis of the bone ultrastructure around biodegradable Mg–xGd implants using small angle X-ray scattering and X-ray diffraction}, year={2020}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.actbio.2019.11.030}, abstract = {Magnesium alloys are increasingly researched as temporary biodegradable metal implants in bone applications due to their mechanical properties which are more similar to bone than conventional implant metals and the fact that Magnesium occurs naturally within the body. However, the degradation processes in vivo and in particular the interaction of the bone with the degrading material need to be further investigated. In this study we are presenting the first quantitative comparison of the bone ultrastructure formed at the interface of biodegradable Mg–5Gd and Mg–10Gd implants and titanium and PEEK implants after 4, 8 and 12 weeks healing time using two-dimensional small angle X-ray scattering and X-ray diffraction. Differences in mineralization, orientation and thickness of the hydroxyapatite are assessed. We find statistically significant (p < 0.05) differences for the lattice spacing of the (310)-reflex of hydroxyapatite between titanium and Mg–xGd materials, as well as for the (310) crystal size between titanium and Mg–5Gd, indicating a possible deposition of Mg within the bone matrix. The (310) lattice spacing and crystallite size further differ significantly between implant degradation layer and surrounding bone (p < 0.001 for Mg–10Gd), suggesting apatite formation with significant amounts of Gd and Mg within the degradation layer.}, note = {Online available at: \url{https://doi.org/10.1016/j.actbio.2019.11.030} (DOI). Zeller-Plumhoff, B.; Malich, C.; Krueger, D.; Campbell, G.; Wiese, B.; Galli, S.; Wennerberg, A.; Willumeit-Römer, R.; Wieland, D.: Analysis of the bone ultrastructure around biodegradable Mg–xGd implants using small angle X-ray scattering and X-ray diffraction. Acta Biomaterialia. 2020. vol. 101, 637-645. DOI: 10.1016/j.actbio.2019.11.030}} @misc{kalanda_smallangle_neutron_2019, author={Kalanda, N., Haramus, V.M., Avdeev, M., Zheludkevich, M.L., Yarmolich, M., Serdechnova, M., Wieland, D.C.F., Petrov, A., Zhaludkevich, A., Sobolev, N.}, title={Small‐Angle Neutron Scattering and Magnetically Heterogeneous State in Sr2FeMoO6–δ}, year={2019}, howpublished = {journal article}, doi = {https://doi.org/10.1002/pssb.201800428}, abstract = {Single‐phase strontium ferromolybdate (Sr2FeMoO6–δ) samples with different degrees of the superstructural ordering of the Fe/Mo cations (P) are obtained from partially reduced SrFeO3–х, SrMoO4 precursors by the solid‐state technology. The study of the temperature dependences of the magnetization measured in the field‐cooling and zero‐field‐cooling modes indicated an inhomogeneous magnetic state of the samples. The presence of magnetic regions of different nature has also been revealed by the small‐angle neutron scattering. For the Sr2FeMoO6–δ samples with different P values and for all values of the magnetic field induction up to 1.5 T and of the scattering vector in the interval 0.1 > q > 0.002 Å−1, the analytical dependence I ∼ q–α obeys the Porod law (α ≈ 4), which corresponds to an object with a smooth and well‐marked surface and polydisperse grain size. Deviations from the Porod law in the q > 0.1 Å−1 region and a weakening of the neutron scattering in applied magnetic fields may be ascribed to magnetic inhomogeneities with diameters D < 6 nm, which are partially destroyed/oriented by magnetic fields В ≥ 1.5 T. It is established that the magnetic homogeneity of the Sr2FeMoO6–δ compound is enhanced with increasing superstructural ordering of the Fe/Mo cations.}, note = {Online available at: \url{https://doi.org/10.1002/pssb.201800428} (DOI). Kalanda, N.; Haramus, V.; Avdeev, M.; Zheludkevich, M.; Yarmolich, M.; Serdechnova, M.; Wieland, D.; Petrov, A.; Zhaludkevich, A.; Sobolev, N.: Small‐Angle Neutron Scattering and Magnetically Heterogeneous State in Sr2FeMoO6–δ. Physica Status Solidi B. 2019. vol. 256, no. 5, 1800428. DOI: 10.1002/pssb.201800428}} @misc{bouali_layered_double_2019, author={Bouali, A.C., Straumal, E.A., Serdechnova, M., Wieland, D.C.F., Starykevich, M., Blawert, C., Hammel, J.U., Lermontov, S.A., Ferreira, M.G.S., Zheludkevich, M.L.}, title={Layered double hydroxide based active corrosion protective sealing of plasma electrolytic oxidation/sol-gel composite coating on AA2024}, year={2019}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.apsusc.2019.07.117}, abstract = {This work reports a novel approach for growing layered double hydroxide (LDH) films on any plasma electrolytic oxidation (PEO) coated AA2024 independently of the nature of the PEO coating. The specific PEO coating chosen to carry out this work is considered to be not suitable for direct LDH growth because of phase composition and morphological features. In this paper, we describe a new methodology that consists of covering the PEO coating with a thin layer of aluminum oxide based xerogel as the source of aluminate ions for subsequent in-situ LDH growth. X-ray diffraction (XRD) and scanning electron microscope (SEM) images showed a successful formation of LDHs on the surface. An improvement in terms of active corrosion protection was also demonstrated by electrochemical impedance spectroscopy (EIS) and scanning vibrating electrode technique (SVET).}, note = {Online available at: \url{https://doi.org/10.1016/j.apsusc.2019.07.117} (DOI). Bouali, A.; Straumal, E.; Serdechnova, M.; Wieland, D.; Starykevich, M.; Blawert, C.; Hammel, J.; Lermontov, S.; Ferreira, M.; Zheludkevich, M.: Layered double hydroxide based active corrosion protective sealing of plasma electrolytic oxidation/sol-gel composite coating on AA2024. Applied Surface Science. 2019. vol. 494, 829-840. DOI: 10.1016/j.apsusc.2019.07.117}} @misc{zander_influence_of_2019, author={Zander, T., Wieland, D.C.F., Raj, A., Salmen, P., Dogan, S., Dedinaite, A., Haramus, V.M., Schreyer, A., Claesson, P.M., Willumeit-Römer, R.}, title={Influence of high hydrostatic pressure on solid supported DPPC bilayers with hyaluronan in the presence of Ca2+ ions}, year={2019}, howpublished = {journal article}, doi = {https://doi.org/10.1039/C9SM01066A}, abstract = {The molecular mechanisms responsible for outstanding lubrication of natural systems, like articular joints, have been the focus of scientific research for several decades. One essential aspect is the lubrication under pressure, where it is important to understand how the lubricating entities adapt under dynamic working conditions in order to fulfill their function. We made a structural investigation of a model system consisting of two of the molecules present at the cartilage interface, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and hyaluronan, at high hydrostatic pressure. Phospholipid layers are found at the cartilage surfaces and are able to considerably reduce friction. Their behavior under load and varied solution conditions is important as pressures of 180 bar are encountered during daily life activities. We focus on how divalent ions, like Ca2+, affect the interaction between DPPC and hyaluronan, as other investigations have indicated that calcium ions influence their interaction. It could be shown that already low amounts of Ca2+ strongly influence the interaction of hyaluronan with DPPC. Our results suggest that the calcium ions increase the amount of adsorbed hyaluronan indicating an increased electrostatic interaction. Most importantly, we observe a modification of the DPPC phase diagram as hyaluronan absorbs to the bilayer which results in an Lα-like structure at low temperatures and a decoupling of the leaflets forming an asymmetric bilayer structure.}, note = {Online available at: \url{https://doi.org/10.1039/C9SM01066A} (DOI). Zander, T.; Wieland, D.; Raj, A.; Salmen, P.; Dogan, S.; Dedinaite, A.; Haramus, V.; Schreyer, A.; Claesson, P.; Willumeit-Römer, R.: Influence of high hydrostatic pressure on solid supported DPPC bilayers with hyaluronan in the presence of Ca2+ ions. Soft Matter. 2019. vol. 15, no. 36, 7295-7304. DOI: 10.1039/C9SM01066A}} @misc{dedinaite_biolubrication_synergy_2019, author={Dedinaite, A., Wieland, D.C.F., Beldowski, P., Claesson, P.M.}, title={Biolubrication synergy: Hyaluronan – Phospholipid interactions at interfaces}, year={2019}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.cis.2019.102050}, abstract = {The manner in which nature has solved lubrication issues has fascinated scientists for centuries, in particular when considering that lubrication is achieved in aqueous media. The most outstanding system in this respect is likely the synovial joint, where close to frictionless motion is realized under different loads and shear rates. This review article focuses on two components present in the synovial area, hyaluronan and phospholipids. We recapitulate what has been learned about their interactions at interfaces from recent experiments, with focus on results obtained using reflectivity techniques at large scale facilities. In parallel, modelling experiments have been carried out and from these efforts new detailed knowledge about how hyaluronan and phospholipids interact has been gained. In this review we combine findings from modelling and experiments to gain deeper insight. Finally, we summarize what has been learned of the lubrication performance of mixtures of phospholipids and hyaluronan.}, note = {Online available at: \url{https://doi.org/10.1016/j.cis.2019.102050} (DOI). Dedinaite, A.; Wieland, D.; Beldowski, P.; Claesson, P.: Biolubrication synergy: Hyaluronan – Phospholipid interactions at interfaces. Advances in Colloid and Interface Science. 2019. vol. 274, 102050. DOI: 10.1016/j.cis.2019.102050}} @misc{zellerplumhoff_quantitative_characterization_2018, author={Zeller-Plumhoff, B., Helmholz, H., Feyerabend, F., Dose, T., Wilde, F., Hipp, A., Beckmann, F., Willumeit-Roemer, R., Hammel, J.}, title={Quantitative characterization of degradation processes in situ by means of a bioreactor coupled flow chamber under physiological conditions using time-lapse SRMueCT}, year={2018}, howpublished = {journal article}, doi = {https://doi.org/10.1002/maco.201709514}, abstract = {Magnesium and its alloys have in recent years emerged as a promising alternative to titanium-based implants for medical applications due to favorable degradation properties and good biocompatibility. The degradation of materials is currently investigated by studying different samples of the same material at different time points after degradation in a medium. This study is presenting a high-resolution time-lapse investigation of Mg-2Ag in culture medium using synchrotron radiation-based micro-computed tomography over the course of 5 days. The design of the custom-built corrosion cell and bioreactor are described. The computed degradation rate after 5 days is in agreement with the literature. SRµCT enables the segmentation of cracks forming in the degradation layer due to stresses and hydrogen development.}, note = {Online available at: \url{https://doi.org/10.1002/maco.201709514} (DOI). Zeller-Plumhoff, B.; Helmholz, H.; Feyerabend, F.; Dose, T.; Wilde, F.; Hipp, A.; Beckmann, F.; Willumeit-Roemer, R.; Hammel, J.: Quantitative characterization of degradation processes in situ by means of a bioreactor coupled flow chamber under physiological conditions using time-lapse SRMueCT. Materials and Corrosion. 2018. vol. 69, no. 3, 298-306. DOI: 10.1002/maco.201709514}} @misc{wieland_complex_solutions_2017, author={Wieland, D.C.F., Zander, T., Haramus, V.M., Krywka, C., Dedinaite, A., Claesson, P., Willumeit-Roemer, R.}, title={Complex solutions under shear and pressure: a rheometer setup for X-ray scattering experiments}, year={2017}, howpublished = {journal article}, doi = {https://doi.org/10.1107/S1600577517002648}, abstract = {A newly developed high-pressure rheometer for in situ X-ray scattering experiments is described. A commercial rheometer was modified in such a way that X-ray scattering experiments can be performed under different pressures and shear. First experiments were carried out on hyaluronan, a ubiquitous biopolymer that is important for different functions in the body such as articular joint lubrication. The data hint at a decreased electrostatic interaction at higher pressure, presumably due to the increase of the dielectric constant of water by 3% and the decrease of the free volume at 300 bar.}, note = {Online available at: \url{https://doi.org/10.1107/S1600577517002648} (DOI). Wieland, D.; Zander, T.; Haramus, V.; Krywka, C.; Dedinaite, A.; Claesson, P.; Willumeit-Roemer, R.: Complex solutions under shear and pressure: a rheometer setup for X-ray scattering experiments. Journal of Synchrotron Radiation. 2017. vol. 24, no. 3, 646-652. DOI: 10.1107/S1600577517002648}} @misc{golub_solution_structure_2017, author={Golub, M., Hejazi, M., Koelsch, A., Lokstein, H., Wieland, D.C.F., Zouni, A., Pieper, J.}, title={Solution structure of monomeric and trimeric photosystem I of Thermosynechococcus elongatus investigated by small-angle X-ray scattering}, year={2017}, howpublished = {journal article}, doi = {https://doi.org/10.1007/s11120-017-0342-6}, abstract = {The structure of monomeric and trimeric photosystem I (PS I) of Thermosynechococcus elongatus BP1 (T. elongatus) was investigated by small-angle X-ray scattering (SAXS). The scattering data reveal that the protein–detergent complexes possess radii of gyration of 58 and 78 Å in the cases of monomeric and trimeric PS I, respectively. The results also show that the samples are monodisperse, virtually free of aggregation, and contain empty detergent micelles. The shape of the protein–detergent complexes can be well approximated by elliptical cylinders with a height of 78 Å. Monomeric PS I in buffer solution exhibits minor and major radii of the elliptical cylinder of about 50 and 85 Å, respectively. In the case of trimeric PS I, both radii are equal to about 110 Å. The latter model can be shown to accommodate three elliptical cylinders equal to those describing monomeric PS I. A structure reconstitution also reveals that the protein–detergent complexes are larger than their respective crystal structures. The reconstituted structures are larger by about 20 Å mainly in the region of the hydrophobic surfaces of the monomeric and trimeric PS I complexes. This seeming contradiction can be resolved by the addition of a detergent belt constituted by a monolayer of dodecyl-β-D-maltoside molecules. Assuming a closest possible packing, a number of roughly 1024 and 1472 detergent molecules can be determined for monomeric and trimeric PS I, respectively. Taking the monolayer of detergent molecules into account, the solution structure can be almost perfectly modeled by the crystal structures of monomeric and trimeric PS I.}, note = {Online available at: \url{https://doi.org/10.1007/s11120-017-0342-6} (DOI). Golub, M.; Hejazi, M.; Koelsch, A.; Lokstein, H.; Wieland, D.; Zouni, A.; Pieper, J.: Solution structure of monomeric and trimeric photosystem I of Thermosynechococcus elongatus investigated by small-angle X-ray scattering. Photosynthesis Research. 2017. vol. 133, no. 1-3, 163-173. DOI: 10.1007/s11120-017-0342-6}} @misc{golub_solution_structure_2017, author={Golub, M., Combet, S., Wieland, D.C.F., Soloviov, D., Kuklin, A., Lokstein, H., Schmitt, F.-J., Olliges, R., Hecht, M., Eckert, H.-J., Pieper, J.}, title={Solution structure and excitation energy transfer in phycobiliproteins of Acaryochloris marina investigated by small angle scattering}, year={2017}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.bbabio.2017.01.010}, abstract = {The structure of phycobiliproteins of the cyanobacterium Acaryochloris marina was investigated in buffer solution at physiological temperatures, i.e. under the same conditions applied in spectroscopic experiments, using small angle neutron scattering. The scattering data of intact phycobiliproteins in buffer solution containing phosphate can be well described using a cylindrical shape with a length of about 225 Å and a diameter of approximately 100 Å. This finding is qualitatively consistent with earlier electron microscopy studies reporting a rod-like shape of the phycobiliproteins with a length of about 250 (M. Chen et al., FEBS Letters 583, 2009, 2535) or 300 Å (J. Marquart et al., FEBS Letters 410, 1997, 428). In contrast, phycobiliproteins dissolved in buffer lacking phosphate revealed a splitting of the rods into cylindrical subunits with a height of 28 Å only, but also a pronounced sample aggregation. Complementary small angle neutron and X-ray scattering experiments on phycocyanin suggest that the cylindrical subunits may represent either trimeric phycocyanin or trimeric allophycocyanin. Our findings are in agreement with the assumption that a phycobiliprotein rod with a total height of about 225 Å can accommodate seven trimeric phycocyanin subunits and one trimeric allophycocyanin subunit, each of which having a height of about 28 Å. The structural information obtained by small angle neutron and X-ray scattering can be used to interpret variations in the low-energy region of the 4.5 K absorption spectra of phycobiliproteins dissolved in buffer solutions containing and lacking phosphate, respectively.}, note = {Online available at: \url{https://doi.org/10.1016/j.bbabio.2017.01.010} (DOI). Golub, M.; Combet, S.; Wieland, D.; Soloviov, D.; Kuklin, A.; Lokstein, H.; Schmitt, F.; Olliges, R.; Hecht, M.; Eckert, H.; Pieper, J.: Solution structure and excitation energy transfer in phycobiliproteins of Acaryochloris marina investigated by small angle scattering. Biochimica et Biophysica Acta: Bioenergetics. 2017. vol. 1858, no. 4, 318-324. DOI: 10.1016/j.bbabio.2017.01.010}} @misc{raj_lubrication_synergy_2017, author={Raj, A., Wang, M., Zander, T., Wieland, D.C.F., Liu, X., An, J., Haramus, V.M., Willumeit-Roemer, R., Fielden, M., Claesson, P.M., Dedinaite, A.}, title={Lubrication synergy: Mixture of hyaluronan and dipalmitoylphosphatidylcholine (DPPC) vesicles}, year={2017}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.jcis.2016.10.091}, abstract = {Phospholipids and hyaluronan have been implied to fulfil important roles in synovial joint lubrication. Since both components are present in synovial fluid, self-assembly structures formed by them should also be present. We demonstrate by small angle X-ray scattering that hyaluronan associates with the outer shell of dipalmitoylphophatidylcholine (DPPC) vesicles in bulk solution. Further, we follow adsorption to silica from mixed hyaluronan/DPPC vesicle solution by Quartz Crystal Microbalance with Dissipation measurements. Atomic Force Microscope imaging visualises the adsorbed layer structure consisting of non-homogeneous phospholipid bilayer with hyaluronan/DPPC aggregates on top. The presence of these aggregates generates a long-range repulsive surface force as two such surfaces are brought together. However, the aggregates are easily deformed, partly rearranged into multilayer structures and partly removed from between the surfaces under high loads. These layers offer very low friction coefficient (<0.01), high load bearing capacity (≈23 MPa), and self-healing ability. Surface bound DPPC/hyaluronan aggregates provide a means for accumulation of lubricating DPPC molecules on sliding surfaces.}, note = {Online available at: \url{https://doi.org/10.1016/j.jcis.2016.10.091} (DOI). Raj, A.; Wang, M.; Zander, T.; Wieland, D.; Liu, X.; An, J.; Haramus, V.; Willumeit-Roemer, R.; Fielden, M.; Claesson, P.; Dedinaite, A.: Lubrication synergy: Mixture of hyaluronan and dipalmitoylphosphatidylcholine (DPPC) vesicles. Journal of Colloid and Interface Science. 2017. vol. 488, 225-233. DOI: 10.1016/j.jcis.2016.10.091}} @misc{nyrow_bulk_sensitive_2016, author={Nyrow, A., Sternemann, C., Tse, J.S., Weis, C., Sahle, C,J., Mende, K., Wieland, D.C.F., Cerantola, V., Gordon, R.A., Spiekermann, G., Regier, T., Wilke, M., Tolan, M.}, title={Bulk sensitive determination of the Fe3+/FeTot-ratio in minerals by Fe L2/3-edge X-ray Raman scattering}, year={2016}, howpublished = {journal article}, doi = {https://doi.org/10.1039/C5JA00261C}, abstract = {We present the first measurements of the iron L2/3-edge of the compounds FeO, Fe2O3, and Fe3O4 at ambient pressure and of FeCO3 at high pressures of 2.4 and 40 GPa using a diamond anvil cell by X-ray Raman scattering spectroscopy, a bulk sensitive probe of soft X-ray absorption edges making use of hard X-rays. We show that the spectral shape of the Fe L2/3-edge can be analyzed quantitatively to reveal the oxidation state of iron in matter. Consequently, in situ X-ray Raman scattering spectroscopy at the iron L-edge at high pressure and temperature opens exciting perspectives to characterize the local coordination, oxidation, and spin state of iron at high pressure and temperature, conditions that are of relevance for e.g. geological sciences or chemical processing.}, note = {Online available at: \url{https://doi.org/10.1039/C5JA00261C} (DOI). Nyrow, A.; Sternemann, C.; Tse, J.; Weis, C.; Sahle, C.; Mende, K.; Wieland, D.; Cerantola, V.; Gordon, R.; Spiekermann, G.; Regier, T.; Wilke, M.; Tolan, M.: Bulk sensitive determination of the Fe3+/FeTot-ratio in minerals by Fe L2/3-edge X-ray Raman scattering. Journal of Analytical Atomic Spectrometry. 2016. vol. 31, no. 3, 815-820. DOI: 10.1039/C5JA00261C}} @misc{wieland_studying_solutions_2016, author={Wieland, D.C.F., Haramus, V.M., Zander, T., Krywka, C., Wang, M., Dedinaite, A., Claesson, P.M., Willumeit-Roemer, R.}, title={Studying solutions at high shear rates: a dedicated microfluidics setup}, year={2016}, howpublished = {journal article}, doi = {https://doi.org/10.1107/S1600577515024856}, abstract = {The development of a dedicated small-angle X-ray scattering setup for the investigation of complex fluids at different controlled shear conditions is reported. The setup utilizes a microfluidics chip with a narrowing channel. As a consequence, a shear gradient is generated within the channel and the effect of shear rate on structure and interactions is mapped spatially. In a first experiment small-angle X-ray scattering is utilized to investigate highly concentrated protein solutions up to a shear rate of 300000 s-1. These data demonstrate that equilibrium clusters of lysozyme are destabilized at high shear rates.}, note = {Online available at: \url{https://doi.org/10.1107/S1600577515024856} (DOI). Wieland, D.; Haramus, V.; Zander, T.; Krywka, C.; Wang, M.; Dedinaite, A.; Claesson, P.; Willumeit-Roemer, R.: Studying solutions at high shear rates: a dedicated microfluidics setup. Journal of Synchrotron Radiation. 2016. vol. 23, no. 2, 480-486. DOI: 10.1107/S1600577515024856}} @misc{zander_the_influence_2016, author={Zander, T., Wieland, D.C.F., Raj, A., Wang, M., Nowak, B., Krywka, C., Dedinaite, A., Claesson, P.M., Haramus, V.M., Schreyer, A., Willumeit-Roemer, R.}, title={The influence of hyaluronan on the structure of a DPPC—bilayer under high pressures}, year={2016}, howpublished = {journal article}, doi = {https://doi.org/10.1016/j.colsurfb.2016.02.040}, abstract = {The superior lubrication properties of synovial joints have inspired many studies aiming at uncovering the molecular mechanisms which give rise to low friction and wear. However, the mechanisms are not fully understood yet, and, in particular, it has not been elucidated how the biolubricants present at the interface of cartilage respond to high pressures, which arise during high loads of joints. In this study we utilize a simple model system composed of two biomolecules that have been implied as being important for joint lubrication. It consists of a solid supported dipalmitoylphosphatidylcholin (DPPC) bilayer, which was formed via vesicles fusion on a flat Si wafer, and the anionic polysaccharide hyaluronan (HA). We first characterized the structure of the HA layer that adsorbed to the DPPC bilayers at ambient pressure and different temperatures using X-ray reflectivity (XRR) measurements. Next, XRR was utilized to evaluate the response of the system to high hydrostatic pressures, up to 2 kbar (200 MPa), at three different temperatures. By means of fluorescence microscopy images the distribution of DPPC and HA on the surface was visualized. Our data suggest that HA adsorbs to the headgroup region that is oriented towards the water side of the supported bilayer. Phase transitions of the bilayer in response to temperature and pressure changes were also observed in presence and absence of HA. Our results reveal a higher stability against high hydrostatic pressures for DPPC/HA composite layers compared to that of the DPPC bilayer in absence of HA.}, note = {Online available at: \url{https://doi.org/10.1016/j.colsurfb.2016.02.040} (DOI). Zander, T.; Wieland, D.; Raj, A.; Wang, M.; Nowak, B.; Krywka, C.; Dedinaite, A.; Claesson, P.; Haramus, V.; Schreyer, A.; Willumeit-Roemer, R.: The influence of hyaluronan on the structure of a DPPC—bilayer under high pressures. Colloids and Surfaces B. 2016. vol. 142, 230-238. DOI: 10.1016/j.colsurfb.2016.02.040}}