Antimicrobial activity and synergistic antibacterial mechanism of a combination of zinc and rare-earth scandium against Escherichia coli

In this study, rare-earth elements Sc and Zn were deposited on an advanced functional antimicrobial amorphous silica composite (ASC) using the sol–gel method at room temperature. The optimal preparation conditions were determined to achieve the maximum antibacterial activity by evaluating single factors. The optimal Zn2+ and Sc3+ concentrations were found to be 0.9 mol·L–1 and 3 mmol·L–1, respectively. The results show that the Zn-Sc ASC is amorphous and porous. ICP analysis indicated 1.81% Zn and 0.058% Sc (wt%). The antibacterial activity of Zn ASC after adding rare-earth element Sc increased from 65% to 90%. The synergistic antibacterial effect between Sc and Zn ASC can be attributed to the increased specific surface area of Zn ASC owing to the addition of Sc and the enhanced loading of Zn2+ on ASC producing more reactive oxygen species (ROS).