Dissection of the antibacterial mechanism of zinc oxide nanoparticles with manipulable nanoscale morphologies

Despite the extensive uses of ZnO nanoparticles as promising antimicrobial agents to tackle the severe microbial infections, the systematic antibacterial studies on ZnO nanoparticles with manipulable nanoscale morphologies at the genetic expression level remain ill-defined. In this study, via a controllable thermal decomposition, ZnO nanoparticles of different morphologies were facilely prepared. Additionally, the surface PEGylation of ZnO was conducted to obtain the nanoparticles of low biotoxicity. While all the prepared ZnO nanoparticles exhibited the significantly chemical activities, the pronounced antibacterial effect of obtained ZnO nanoparticles was also identified, in which the ultra-small ones (similar to 5 nm) showed the best performance. Moreover, the antibacterial activities of ZnO nanoparticles were studied by bacterial nucleic acid leakage, alkaline phosphatase, biofilm and reactive oxygen species (ROS) assays. Furthermore, the transcriptome analysis of ZnO nanoparticles with different morphologies against Escherichia coli (E. coli) revealed the underlying antibacterial mechanism involved the signal transduction, material transport, energy metabolism and other biological processes. Therefore, the cost-effective preparation of ZnO nanoparticles with distinct morphological features provides insights for the development of application specific antibacterial agents.