Assessing the mechanism of action of synthetic nanoengineered antimicrobial polymers against the bacterial membrane of Pseudomonas aeruginosa

The lack of appropriate antimicrobials to tackle multidrug-resistant Gram-negative bacteria poses an escalating threat to modern medicine. Addressing this urgent issue, we have recently developed synthetic nanoengineered antimicrobial polymers (SNAPs), inspired by the physicochemical properties of antimicrobial peptides. Our findings have demonstrated that SNAPs are potent antimicrobial agents characterized by low toxicity and cost-effective large-scale production. In this study, we elucidate the mechanism of action of two distinct SNAPs, which vary in length and charge distribution. Focusing on the Gram-negative pathogen Pseudomonas aeruginosa LESB58, a hypervirulent strain prevalent in cystic fibrosis patients, we employ advanced high-resolution imaging techniques and neutron reflectometry to uncover the precise interactions between SNAPs and the bacterial cell envelope. Our research identifies lipopolysaccharide as a critical target, detailing architecture-specific envelope disruptions, such as asymmetry loss, pore formation, and membrane dissolution. These insights into the structure-function relationships of SNAPs pave the way for the rational design of tailored antimicrobial polymers with specific targeted mechanisms of action.