Polyethyleneimine and quaternized ammonium polyethyleneimine: the versatile materials for combating bacteria and biofilms.

Bacterial infection has become a serious clinical concern due to the emergence of drug-resistance and biofilm formation. Therefore, it is in great demand to develop efficient antimicrobial agents to treat bacterial infection without using antibiotics. Herein, we successfully prepared four quaternized ammonium PEI (QPEI: PEI1200-C2, PEI1200-C4, PEI1200-C6 and PEI1200-C8) using the commercial available PEI1200. Both PEI and four QPEI presented broad-spectrum antimicrobial activity against Gram-negative bacteria (E. coli, and P. aeruginosa) and Gram-positive bacteria (B. amyloliquefaciens and S. aureus), especially PEI1200-C6 showed the strongest antimicrobial activity with good biocompatibility at the MIC concentrations. Besides, PEI1200-C6 showed 4-16-fold better antibacterial effect than PEI1200, and fluorescent microscope imaging demonstrated that both of them could efficiently eradicate biofilms formed by four bacterial strains in vitro. As the accessible broad-spectrum antibacterial agents, PEI1200 and PEI1200-C6 are significant candidates to treat bacterial infections or eradicate biofilms on indwelling medical devices.