Antibacterial Effect of Chitosan-Modified Fe3O4 Nanozymes on Acinetobacter baumannii

The aim of this study was to determine whether the antibacterial activity of chitosan-modified Fe 3 O 4 (CS@Fe 3 O 4 ) nanomaterials against Acinetobacter baumannii ( A. baumannii ) is mediated through changes in biofilm formation and reactive oxygen species (ROS) production. For this purpose, the broth dilution method was used to examine the effect of CS@Fe 3 O 4 nanoparticles on bacterial growth. The effects of CS@Fe 3 O 4 nanoparticles on biofilm formation were measured using a semi-quantitative crystal violet staining assay. In addition, a bacterial ROS detection kit was used to detect the production of ROS in bacteria. The results showed that CS@Fe 3 O 4 nanoparticles had a significant inhibitory effect on the colony growth and biofilm formation of drug-resistant A. baumannii ( p < 0.05). The ROS stress assay revealed significantly higher ROS levels in A. baumannii subjected to CS@Fe 3 O 4 nanoparticle treatment than the control group ( p < 0.05). Thus, we demonstrated for the first time that CS@Fe 3 O 4 nanoparticles had an inhibitory effect on A. baumannii in vitro, and that the antibacterial effect of CS@Fe 3 O 4 nanoparticles on drug-resistant A. baumannii was more significant than on drug-sensitive bacteria. Our findings suggest that the antibacterial mechanism of CS@Fe 3 O 4 nanoparticles is mediated through inhibition of biofilm formation in drug-resistant bacteria, as well as stimulation of A. baumannii to produce ROS. In summary, our data indicate that CS@Fe 3 O 4 nanoparticles could be used to treat infections caused by drug-resistant A. baumannii .