Silver (I) and Silver (II) Oxide Films for Biomedical Implants: Synthesis, Stability, Ion Release, and Antibacterial Efficacy.

Abstract

Coatings of silver compounds with higher dissolution rates than metallic silver offer a promising approach for delivering Ag⁺ ions to prevent medical implant device-associated infections. In this study, we investigate the synthesis and characterization of single-phase, silver (I) oxide (Ag₂O) and silver (II) oxide (AgO) for potential antimicrobial applications. The synthesis of these materials leverages the higher stability of Ag₂O in comparison to AgO. The formation of AgO requires a low landing energy of the adatoms, achieved through gas phase scattering and rapid quenching when landing. Alternatively, higher landing energies cause re-sputtering of oxygen, which favors the formation of Ag₂O. Higher chamber pressures during deposition increase the number of inelastic collisions, thereby reducing the energy of the adatoms influencing phase formation. A combination of energy dispersive spectroscopy, microstructural imaging, X-ray diffraction (XRD), and high-temperature XRD confirms this result. To evaluate antimicrobial potential, silver ion release (elution) was measured in water, Luria-Bertani broth, and tryptic soy broth. Elution rates were highest in water, but in all media, both oxides elute significantly more Ag⁺ ions than metallic silver coatings. Antimicrobial assays clearly show potent and broad-spectrum activity of silver oxides against both clinical and multidrug-resistant bacteria, confirming their potential as effective antimicrobial coatings for implanted devices.