Backbone-Regulated Cationic Conjugated Polymers for Combating and Monitoring Pathogenic Bacteria

Three cationic conjugated polymers (PMNT based on thiophene, PBF based on BODIPY, and oligomer OPV based on phenylethlene) were utilized to interact with pathogenic microorganisms via hydrophobic interactions and electrostatic interactions to realize photodynamic antimicrobial effects under white light irradiation because they could sensitize oxygen to generate reactive oxygen species (ROS) that would increase the permeability of the bacterial membrane and damage bacteria. ROS detection reveals that BODIPY-based PBF mainly generates singlet oxygen through a type II process, which needs sufficient oxygen, and phenylethlene-based OPV primarily produces ROS via a type I process, which could occur in a hypoxic environment. OPV could kill more than 98% of pathogenic Staphylococcus aureus (S. aureus) at a low concentration of 0.5 μM and PBF could reach the same killing efficiency at a concentration of 1 μM under white light (65 mW/cm2) irradiation for 10 min. By changing the structure of the polymers, the sterilization could be regulated and the effect of low concentration sterilization could be achieved. At the same time, these polymers are used to rapidly detect pathogenic microorganisms within 30 min because of their excellent fluorescence properties. These cationic conjugated polymers with various backbone structures have important value and application prospects for the integration of diagnosis and treatment of pathogenic S. aureus in various conditions with different oxygen content.