Antimicrobial and biocompatibility assessment of platinum-based metal alloy coatings for total joint arthroplasty

Periprosthetic joint infection (PJI) is a challenging complication in orthopedic surgery, driven by bacterial biofilm formation on implant surfaces. With rising antimicrobial resistance, antibacterial coatings that do not rely on antibiotics are urgently needed. Platinum-based coatings offer exceptional chemical inertness, corrosion resistance, and mechanical stability, making them potential candidates for articulating implant surfaces subjected to high friction. This study investigated the antimicrobial potential of three platinum-based alloys: platinum‑iridium (PtIr), platinum‑zirconium (PtZr), and platinum‑copper (PtCu). These alloys were sputter-coated onto titanium substrates, producing thin (∼85 nm) and smooth (Ra ∼24 nm) coatings. The composition of the coatings was analyzed using energy-dispersive X-ray spectroscopy (EDX), and ion release was quantified via inductively coupled plasma optical emission spectrometry (ICP-OES). Cytotoxicity was assessed according to ISO 10993-5, using fibroblast viability assays, which confirmed biocompatibility. Antibacterial properties were evaluated by exposing the coatings to Staphylococcus aureus and Escherichia coli inocula. After a 4-hour incubation period, adherent bacteria were quantified. The PtCu coating achieved a 1-log reduction in bacterial adherence, while PtIr and PtZr coatings displayed no significant antibacterial effects. Although the current Pt-based alloy coatings did not achieve the clinically required antibacterial effect, the findings provide insights into their potential. Enhancing the copper content in PtCu alloys could improve antibacterial efficacy. Additionally, incorporating other known antibacterial metals, such as silver or zinc, into Pt-based alloys and increasing their weight percentage in the coating could further enhance antibacterial properties.