Metal Nanocomposites for Targeting the Cell Wall of Escherichia Coli

Abstract

Ag nanocomposites (NAs) have been reported to cause irreversible damage to pathogenic bacteria. However, its antibacterial efficiency is relatively weak, furthermore, these nanocomposites also exhibit higher toxicity, and their detailed antibacterial mechanism is yet to be discovered. In short, the challenges for the practical applications of Ag nanocomposite materials involve enhancing their antibacterial activity, reducing their cytotoxicity to body cells, and elucidating the mechanism of antibacterial action. This study synthesized a core-shell structured ZnFe2O4@Cu-ZIF-8@Ag (FUA) nanocomposite with high antibacterial activity and low cytotoxicity. In just 20 mins, the antibacterial rate of 100 μg/mL of the prepared nanocomposites reached 99.99% against Escherichia coli (E. coli) and tetracycline-resistant E. coli (T-E. coli). The E. coli inactivation ability of the nanocomposites was because of the slow release of Cu2+, Zn2+, and Ag+ synergistically generate •OH from FUA in an aerobic environment, •OH has a significant impact on antibacterial activity.  The released metal ions synergistically •OH that damages the bacterial cell wall, leaking electrolytes and ions. Moreover, the toxicity of FUA is significantly reduced compared with NA. This study is expected to inspire the design of more silver-based nanocomposite materials for the inactivation of drug-resistant bacteria.

Keywords: Nanocomposites, Antibacterial activity, Escherichia coli, Metal ions, Phospholipid bilayer