A dual-action nanocoating system for corrosion and microbial protection of Mg-AZ31 Alloy: Towards a new generation of smart orthopedic implants with advanced nanotechnology-driven biointerfaces

Abstract

This study reports the development of a smart dual-action nanocoating system for enhancing the corrosion resistance and antimicrobial performance of Mg-AZ31 alloy for orthopedic implant applications. FTIR analysis confirmed successful cross-linking of the polymeric network, with a characteristic carbonyl peak at 1716 cm⁻¹, indicating the formation of a stable encapsulation matrix. FE-SEM revealed nanocapsules with sizes ranging from 46.2 to 305.7 nm, forming a dense “cauliflower-like” structure with finer features down to 28.64 nm, promoting surface roughness and bioactivity. Electrochemical evaluation demonstrated a significant shift in corrosion potential from approximately −700 mV (bare alloy) to −260 mV for coated samples, achieving a high corrosion protection efficiency of 93.75%. Antibacterial testing using Zone of Inhibition (ZOI) assays showed strong inhibitory effects against Staphylococcus aureus, effectively preventing biofilm formation. EDX analysis confirmed hydroxyapatite formation with an ideal Ca/P ratio of 1.67, indicating excellent bioactivity. The coating also exhibited superior adhesion, classified as 5B according to ASTM standards, with no observable peeling. These results demonstrate that the developed nanocoating provides synchronized corrosion protection, antimicrobial activity, and biointegration, offering a promising strategy for next-generation biodegradable orthopedic implants. Furthermore, advanced nanotechnology design enables controlled drug release, nanoscale surface tuning, and intelligent responsiveness to physiological stimuli, significantly enhancing implant performance and long-term stability.