Electrophoretic deposition of hydroxyapatite derived from blue crab shell/chitosan/hyaluronic acid composite coating on 316L stainless steel for biomedical applications

Bone fractures represent a significant health problem with increasing prevalence, often caused by direct trauma such as transportation accidents. Stainless steel 316L (SS316L) is commonly employed as a bone implant material due to its mechanical properties, yet it is prone to bacterial infection (osteomyelitis) and toxic ion release from corrosion. To address these issues, composite coatings of hydroxyapatite (HAp), chitosan (CS), and hyaluronic acid (HA) (HAp: CS: HA) were developed to enhance bioactivity, antibacterial performance, and corrosion resistance. Electrophoretic deposition (EPD) was employed using SS316L as the cathode and carbon as the anode under applied voltages of 15, 25, 35, 45, and 55 V, with varying HAp:CS:HA ratios. Visual observations identified the optimal condition at 35 V and a ratio of 3:1:1 (w/w), yielding a uniform coating. FTIR analysis confirmed the presence of HAp, CS, and HA, with functional groups including C–O, P–O, OH^–, N–H, and C=O. Bioactivity tests in simulated body fluid (SBF) revealed apatite formation, indicated by the shift of P–O peaks (1013.8–1028.7 cm^–1). Degradation test show that the 5:1:1 composition provided the highest resistance, with a minimal degradation rate of 0.036%. Antibacterial assays against Staphylococcus aureus showed that the 1: 5:1 ratio (w/w) achieved the largest inhibition zone (10 mm). Potentiodynamic polarization tests confirmed the lowest corrosion rate (0.00702 mmpy) at the 5:1:1 ratio (w/w). Overall, these findings demonstrate that HAp/CS/HA composite coatings produced via EPD can significantly enhance corrosion resistance, bioactivity, and antibacterial properties of SS316L implants, making them promising candidates for improved orthopedic applications.