Zinc Phosphate Microparticles against Nosocomial and Oral Bacteria: Synthesis, Analytical Characterization, and Biocompatibility

Nosocomial bacteria represent a significant global health problem. In addition, oral pathogens causing oral infections, such as periodontitis and peri-implantitis, are the main cause of the failure of oral implant treatments, mainly due to bacterial resistance related to the indiscriminate use of antibiotics in recent years. Therefore, identifying antimicrobial and biocompatible agents, such as some zinc-derived compounds, represents a promising alternative to the development of new antibacterial biomaterials. In this study, zinc phosphate microparticles were synthesized by chemical precipitation and characterized by FTIR, DLS, TEM, XRD, and XPS. Their antibacterial effect was evaluated against nosocomial and oral bacteria, while their biocompatibility was assessed using human fibroblasts and osteoblasts. The results showed zinc phosphate microparticles with elongated morphologies, a hopeite crystal structure with an average crystallite size of about 35 nm, a hydrodynamic diameter of approximately 4.8 μm, and a ζ-potential close to neutrality. Regarding the antibacterial properties, zinc phosphate microparticles showed high antibacterial activity against the eight different bacterial species evaluated. In almost all species, an inhibition percentage close to 100% was observed, depending on the concentration, while in the biocompatibility tests, particle concentrations between 0.05 and 0.4 mg/mL were not cytotoxic to either of the eukaryotic cell types evaluated. These findings suggest that zinc phosphate microparticles synthesized by chemical precipitation possess antibacterial properties against pathogens associated with nosocomial and oral infections and exhibit biocompatibility with human fibroblasts and osteoblasts. Therefore, zinc phosphate microparticles have the potential for diverse applications in the medical and dental fields due to their antibacterial properties and biocompatibility.