Aqueous-phase stable CsPbBr3 nanocrystals and quaternary chitosan co-assembled by electrostatic interaction for synergistic photocatalytic antimicrobial

Bacterial infections have become one of the major threats to human life and health. More and more attention has been paid to the development of efficient photocatalytic antibacterial materials. Halide perovskite nanocrystals (NCs) have excellent optical properties, resulting in good application prospects in the field of photocatalytic antibacterial. Here, we developed a photocatalytic antimicrobial agent (PAA) by self-assembling NH4PF6 ligand-regulated CsPbBr3 NCs with quaternary chitosan into nanoparticles. NH4PF6 can effectively passivate CsPbBr3 NCs and improve their optical properties, including photoluminescence quantum yield and fluorescence lifetime. On the other hand, due to the hydrogen bond between NH4PF6 and water molecules, NH4PF6–CsPbBr3 NCs can be completely dispersed in water and remain stable. The coordination of PF6− causes the surface of NH4PF6–CsPbBr3 NCs to be negatively charged. Therefore, we use the electrostatic interaction between NH4PF6–CsPbBr3 NCs and positively charged quaternary chitosan to assemble nanoparticles to achieve enhanced antibacterial activity. The reactive oxygen species generated by NCs under visible light and the positive charge of quaternary chitosan have a synergistic effect against Escherichia coli. This study shows that stable aqueous perovskites have great potential in PAA and are worthy of further exploration.