Acidity-Activated Charge-Convertible Silver Nanocomposites for Enhanced Bacteria-Specific Aggregation and Antibacterial Activity.

Bacterial infections has become an intractable problem to human health. To overcome this challenge, we developed an antimicrobial agent (AgNPs@PDPE) via the conjugation of a pH-responsive copolymer of PDMAEMA-b-PPEGMA onto AgNPs surface. The AgNPs@PDPE underwent an acidity-induced surface charge conversion that favored bacteria-specific aggregation and antibacterial activity improvement. The specific interaction between AgNPs@PDPE and bacteria under acidic conditions was confirmed via an electrochemical method using AgNPs@PDPE modified glassy carbon electrode as the working electrode. AgNPs@PDPE could efficiently aggregate and inhibit the growth of both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) under acidic condition. The AgNPs@PDPE could also selectively distinguish pathogenic bacteria from host cells, and this characteristic is benefical for reducing the damage to surrounding tissues in the host. Moreover, AgNPs@PDPE could promote the healing of E. coli- and S. aureus-induced infection, as proven by the histological and TNF-α immunohistochemical analyses of rat dermal wounds. The proposed antimicrobial agent could to be an alternative treatment strategy for the safe treatment of treat bacteria-induced infections in clinics.