The structures and antibacterial properties of nano-SiO2 supported silver/zinc–silver materials

Objectives The aims of this study were to investigate the structures and antibacterial properties of two kinds of sterilizing nano-SiO2 specimens. Methods The specimens were synthesized by adsorption methodology. One of them was synthesized by adsorbing silver cation onto nano-SiO2 carrier (silver-loading nano-SiO2 specimen (SLS)), and the other one by co-adsorbing zinc and silver cations onto the same kind of carrier (zinc–silver-loading nano-SiO2 specimen (SLZS)). Chemical compositions of these specimens were estimated. The structure and morphology of the specimens were determined by X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). Also, the antibacterial properties of the specimens were examined. Results The amount of silver loaded in SLZS was approximate to that of SLS. Consequently, it can be proved that the amount of nano-SiO2 adsorbed silver cation did not change with the addition of zinc cation. The obvious differences were not observed among the XRD patterns for each specimen. So it was possible to confirm no formation of new phase(s) after Ag+/Zn2+ absorption. The loaded silver and zinc existed as nano-particles, as observed by HRTEM. Antibacterial properties of SLS and SLZS were excellent against Escherichia coli and S. faecalis. The antibacterial effect of the same antibacterial agent against E. coli or S. faecalis was different. In addition, the antibacterial effect of SLZS was better than that of SLS. Significance These results suggested SLS and SLZS can be effectively incorporated in dental resin-based materials to provide antibacterial activity against bacteria.