Compiling modules of photosensitizers and quaternary phosphonium blocks into material networks <i>via</i> a co-polymerization strategy: an effective way to fabricate antimicrobial agents against drug resistance

Quaternary ammonium and phosphonium compounds have been widely used as two important classes of antimicrobial agents worldwide. However, over-reliance and misuse of the limited antimicrobial agents have driven the development and spread of resistance of bacteria to these materials. Thus, overcoming the growing bacterial drug resistance is a challenging work in ensuring public health. In this work, we compiled two modules comprising photosensitizers and quaternary phosphonium blocks integrated into material networks <i>via</i> a co-polymerization method, resulting in desired antimicrobial materials with the capability to generate reactive oxygen species (ROS) and exhibiting high affinity towards negatively charged bacterial membranes. This synergistic effect enabled ROS to destroy bacterial membranes within an effective migration distance. As a result, poly(TPAs-2&P⁺-4) was optimized as a promising antibacterial agent, which demonstrated superior bacteria killing and imaging abilities against four bacteria lines, namely, <i>E. coli</i>, methicillin-resistant <i>S. aureus</i>, <i>E. faecalis</i> and <i>P. aeruginosa.</i> The minimum inhibitory concentration (MIC) was determined as 75 μg mL^-1 for <i>E. coli</i> and methicillin-resistant <i>S. aureus</i> and 150 and 350 μg mL^-1 for <i>E. faecalis</i> and <i>P. aeruginosa</i>, respectively.