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 semiquantitative 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.