Chemical, biological, and antibacterial characterization of silica glass containing silver and gold nanoparticles

The aim of this study has been the preparation of sol-gel glasses with potential antibacterial properties. Bioactive glasses containing different percentages of silver and gold nanoparticles have been synthesized via the sol-gel method. The obtained glasses have 0.5, 1, 1.5, and 2 wt% silver as well as a constant amount of gold nanoparticles (AuNP) added as colloidal solution (15 wt%). Fourier Transform Infrared (FTIR) spectroscopy was used to characterize the materials. Scanning electron microscopy (SEM) has been used to investigate the surface of each sample. Moreover, the materials have been characterized in order to verify their antibacterial activities as well as their bioactivity and cytocompatibility as a function of Ag and Au content. SEM/EDX analysis has shown that the samples are bioactive because they are able to stimulate hydroxyapatite nucleation on their surface when soaked in a simulated body fluid (SBF). WST-8 assay of 3T3 cells, placed in contact with the material extracts, has showed that the glass does not induce cytotoxicity. Staphylococcus epidermidis and Pseudomonas aeruginosa strains have been used for the evaluation of the antibacterial properties of each sample. The experimental data have shown that all synthesized materials have antibacterial activity. However, the two bacterial strains respond differently to the materials. The data show that the presence of AuNP causes a decrease in the antibacterial activity of Ag+ ions.