Preparation and Synergistic Antibacterial Effect of Zinc and Cerium Co-Doped Silica

In this study, a SiO₂ support was modified with zinc and cerium to obtain a material with excellent antibacterial properties. The optimal preparation conditions resulting in the highest antibacterial efficiency (c_Zn = 0.83 M, c_Ce = 0.005 M, reaction time = 1.6 h) were identified by applying response surface methodology. The antibacterial experiments were carried out based on the coating plate method using Escherichia coli. Scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS) analyses revealed an evenly distributed composition with a lamellar structure in the samples. Further analysis through X-ray photoelectron spectroscopy (XPS) indicated that zinc and cerium were successfully modified onto the silica carriers in the form of oxides. The high percentage of Ce⁴⁺/Ce³⁺ ions promotes an increase in anti-inflammatory cytokines and a decrease in pro-inflammatory cytokines, thereby enhancing antimicrobial properties. The detection of ion dissolution and specific surface area and particle size explained that the addition of cerium promoted the loading and release of antimicrobial zinc ions. The introduction of cerium into the ZnO lattice results in the replacement of zinc atomic sites with cerium atomic sites. This substitution causes disorganization in the arrangement of zinc ions in certain regions, leading to a weakening of the Zn–O bond and an increased release of zinc ions. The content of zinc ions increased from 1.06% to 1.79%, which increased the specific surface area of the composites from 214.50803 m²/g to 308.86977 m²/g, which gave the materials high adsorption properties, thus improving their antimicrobial performance. Combined with the positive synergistic effect factor and synergistic coefficient of 1.89 calculated by the response surface method, it was observed that a notable synergistic effect exists between zinc and cerium.