ZnO Nanoparticle-Infused Vaterite Coatings: A Novel Approach for Antimicrobial Titanium Implant Surfaces

Loss of implant function is a common complication in orthopaedic and dental surgery. Among the primary causes of implant failure are peri-implant infections which often result in implant removal. This study demonstrates the development of a new antimicrobial titanium coating with ZnO nanoparticles of various sizes and morphologies immobilised in poly(allylamine hydrochloride) and alginate multilayers, combined with epitaxially grown vaterite crystals. The coated samples were characterised with various methods (FTIR, XRD, SEM) and surface properties were evaluated via water contact angle and surface charge measurements. Zinc ion release was quantified using ICP-MS. The antimicrobial efficacy of the coatings was tested against <i>Staphylococcus aureus</i>, <i>Staphylococcus epidermidis</i>, and <i>Candida albicans</i> while the biocompatibility was tested with preosteoblast cells (MC3T3-E1). Results demonstrated the successful preparation of a calcium carbonate/ZnO composite coating with epitaxially grown vaterite on titanium surfaces. The Zn ions released from ZnO nanoparticles dramatically influenced the morphology of vaterite where a new flower-like morphology was observed. The coated titanium surfaces exhibited robust antimicrobial activity, achieving over 90% microbial viability reduction for <i>Staphylococcus aureus</i>, <i>Staphylococcus epidermidis</i>, and <i>Candida albicans</i>. Importantly, the released Zn²⁺ concentrations remained below the cytotoxicity limit for MC3T3-E1 cells, showing potential for safe and effective implant applications.