Recent progress in Mg-based alloys as a novel bioabsorbable biomaterials for orthopedic applications

Traditional orthopedic metal implants,such as titanium(Ti),Ti alloys,and cobalt-chromium(Co-Cr)alloys,cannot be degraded in vivo.Fracture patients is must always suffer a second operation to remove the implants.Moreover,stress shielding,or stress protection occurs when traditional orthopedic metal implants are applied in fractures surgery.The mechanical shunt produced by traditional orthopedic metal implants can cause bone loss over time,resulting in decreased bone strength and delayed fracture healing.Biodegradable metals that‘biocorrode’are currently attracting significant interest in the orthopedics field due to their suitability as temporary implants.As one of the biodegradable metals,magnesium(Mg)and Mg alloys have gained interest in the field of medicine due to their low density,excellent biocompatibility,high bioresorbability,and proper mechanical properties.Additionally,Mg ions released from the metal implants can promote osteogenesis and angiogenesis during the degradation process in vivo,which is substantially better for orthopedic fixation than other bioinert metal materials.Therefore,this review focuses on the properties,fabrication,biological functions,and surface modification of Mg-based alloys as novel bioabsorbable biomaterials for orthopedic applications.

Mechanical characterization of rose bengal and green light crosslinked collagen scaffolds for regenerative medicine

Collagen is one of the most important biomaterials for tissue engineering approaches.Despite its excellent biocompatibility,it shows the non-negligible disadvantage of poor mechanical stability.Photochemical crosslinking with rose bengal and green light(RGX)is an appropriate method to improve this property.The development of collagen laminates is helpful for further adjustment of the mechanical properties as well as the controlled release of incorporated substances.In this study,we investigate the impact of crosslinking and layering of two different collagen scaffolds on the swelling behavior andmechanical behavior inmicro tensile tests to obtain information on its wearing comfort(stiffness,strength and ductility).The mechanical stability of the collagen material after degradation due to cell contact is examined using thickness measurements.There is no linear increase or decrease due to layering homologous laminates.Unexpectedly,a decrease in elongation at break,Young’s modulus and ultimate tensile strength are measured when the untreated monolayer is compared to the crosslinked one.Furthermore,we can detect a connection between stability and cell proliferation.The results show that with variation in number and type of layers,collagen scaffolds with tailored mechanical properties can be produced.Such a multi-layered structure enables the release of biomolecules into inner or outer layers for biomedical applications.