A non-antibiotic organic coating on ZA6-1 surface releasing different concentrations of sodium dodecyl sulphate/levulinic acid for orthopaedic application

Bone implantation surgery is often accompanied by bacterial infection, resulting in infectious bone non-union, pathological fracture and other serious consequences, which will aggravate the pain of patients. A non-antibiotic coating consisting of sodium dodecyl sulphate (SDS) and levulinic acid (LA) with different concentrations was prepared by the authors on the zinc–aluminium alloy (ZA6-1) using a wet chemistry treatment for orthopaedic application. The influence of SDS/LA concentrations on the surface morphology, composition and performance of the developed coating was investigated. The results showed that as-prepared coating on a zinc alloy surface could improve the substrate's corrosion resistance and increase the degradation rate from 0.82 to 19.70 μm/year upon raising the SDS/LA concentration. Furthermore, higher hydrophilicity (<14°), better cell proliferation (>100%) and morphology, as well as good cell adhesion and differentiation (ALP >95% for 7 days) were observed on coated zinc alloys. The increased SDS/LA concentration slightly weakens the biocompatibility and enhances the antibacterial performance of coated zinc alloys due to the synergistic effect of SDS/LA. Overall, the coating comprising 6 wt.% SDS and 9 wt.% LA showed excellent antibacterial action with a high level of biocompatibility, confirming its potential application for orthopaedic implants.