Light-activated oxidize-mimicking nanozyme for inhibition of pathogenic Escherichia coli

Here we demonstrate the nanozyme properties of histidine-containing carbon nanodots as externally tunable antibacterial agents through irradiation with visible (VIS) light. The correlative (light and electron) microscopic analysis of treated Escherichia coli O157:H7 revealed that the positive charged carbon nanoparticles might readily adsorb at slightly acid pH on the negative charged cellular envelope of bacteria, and thus, inhibit their growth with over 80% efficiency under illumination with VIS light. The reason was that under VIS irradiation in the range 400-500 nm the adsorbed nanoparticles behaved as effective oxidase-mimicking enzymes and generated reactive oxygen species on the labeled cells. Thus, the light-activated artificial nanozyme caused serious physical damaging of bacterial envelope, which was leading to irreversible cellular inhibition. The outcomes of this study are likely to broaden the scope of designed photoactive carbon nanozymes as powerful antibacterial agents against the emergence of antibiotic and multidrug-resistant strains, as well as proposing of new strategies for infection control.