Protein adsorption and biodegradation behaviour of Mg–3Zn/HA for biomedical application

Orthopaedic implants demand a new domain of biodegradable materials to avoid second surgery after healing and stress shielding – problems that are associated with clinically used metallic implants. Magnesium (Mg) is a suitable replacement for avoiding stress shielding and second surgery in load-bearing orthopaedic applications. However, the main challenge with magnesium is its high corrosion rate in the physiological environment. Biodegradable magnesium-based composites reinforced with hydroxyapatite (HA) can help in improving corrosion resistance. An effort has been taken here to improve the degradation behaviour and bioactivity of magnesium–HA composites prepared through conventional sintering. Immersion tests in simulated body fluid and fetal bovine serum reveal ∼22% improvement in corrosion resistance in the latter case. The interaction of proteins with the biomaterial surface is of crucial importance in implants as adsorbed proteins define immediate cell attachment and proliferation on the surfaces. In this study, the mechanism of protein adsorption on composites is also analysed. It was observed that ∼40% more protein was adsorbed by the 5 wt% HA-reinforced composite (M5H) in 3 h compared to the structure without HA (M0H). Adsorption of more proteins on the surface of M5H implants indicates better cell proliferation ability and better corrosion resistance, making them a very promising candidate for biodegradable orthopaedic implants.