Study on\nthe Bioactivity Response of the Newly Developed\nZn–Cu–Mn/Mg Alloys for Biodegradable Implant Application

Scaffolds play a crucial role in bone tissue engineering\nto support\nthe defect area through bone regeneration and defect reconstruction.\nPromising tissue regeneration without negative repercussions and avoidance\nof the lifelong presence inside the body make bioresorbable metals\nprosper in the field of regenerative medicine. Recently, Zn and its\nalloys have emerged as promising biodegradable materials for their\nmoderate degradation rate and satisfactory biocompatibility. Nevertheless,\nit is very challenging for cells to adhere and grow over the Zn surface\nalone, which influences the tissue-implant integration. In this study,\nan attempt has been made to systematically investigate the bioactivity\nresponses in terms of in vitro hemocompatibility, cytotoxicity, antibacterial\nactivity, and in vivo biocompatibility of newly developed Zn–2Cu–0.5Mn/Mg\nalloy scaffolds with different surface roughness. The rough surface\nof Zn–2Cu–0.5Mg shows the highest degradation rate of\n0.16 mm/yr. The rough surface exhibits a prominent role in the adsorption\nof protein, further enhancing cell adhesion. Concentration-dependent\nalloy extract shows the highest cell proliferation for 12.5% of the\nextract with a maximum cell viability of 101% in Zn–2Cu–0.5Mn\nand 108% in Zn–2Cu–0.5Mg after 3 d. Acceptable hemolysis\npercentages (less than 5%) with promising anticoagulation properties\nare observed for all of the conditions. Enhanced antibacterial (Staphylococcus aureus and Escherichia\ncoli) activity due to a significant effect of ions\nillustrates the maximum killing effect on the bacterial colony for\nthe rough Zn–2Cu–0.5Mg alloy. In addition, it is observed\nthat for rough Zn–2Cu–0.5Mn/Mg alloys, the inflammatory\nresponse is minimal after subcutaneous implantation, and neo-bone\ntissue forms in the defect areas of the rat femur with satisfactory\nbiosafety response. The osseointegration property of the Zn–2Cu–0.5Mg\nalloy is comparable to that of the Zn–2Cu–0.5Mn alloy.\nTherefore, the rough surface of the Zn–2Cu–0.5Mg alloy\nhas the potential to enhance biocompatibility and promote better osseointegration\nactivity with host tissues for various biomedical applications.