Victor Ugbetan Agbogo, Emmanuel Rotimi Sadiku, Lucey Mavhungu, Williams Kehinde Kupolati, Moipone Linda Teffo, Oryina M. Injor
Biodegradable magnesium (Mg) alloys hold great promise as temporary implant materials due to their biocompatibility and mechanical similarity to bone; however, their rapid corrosion in physiological environments limits clinical use. This paper reviews recent advances in nano-polymer bio-coatings designed to enhance the corrosion resistance and functionality of Mg-based implants. A systematic approach was adopted, examining bio-derived polymers reinforced with nanofillers such as carbon nanotubes, nanoclays, and hydroxyapatite. Quantitative findings from selected studies indicate that polymer–nanofiller hybrid coatings can reduce corrosion rates of Mg alloys by up to 65–80 % and improve adhesion strength by approximately 30–40 % compared with conventional coatings. Furthermore, hybrid bio-coatings demonstrated enhanced apatite formation, contributing to improved osseointegration. Conceptual and experimental insights are provided into electrochemical surface modification, bio-macromolecule integration, and the role of functionally graded coatings. The review concludes that nano-polymer coatings represent a sustainable and effective pathway for improving Mg-alloy implants, with future directions pointing toward 3D-printed coating systems, AI-driven coating design, and multifunctional biomedical platforms.