Polymyxin E-Modified Conjugated Polymer Nanoparticle for Photodynamic and Photothermal Combined Antimicrobial Therapy

The irrational or excessive use of antibiotics causes the emergence of bacterial resistance, making antibiotics less effective or ineffective. As the number of resistant antibiotics increases, it is crucial to develop new strategies and innovative approaches to potentiate the efficacy of existing antibiotics. Prior to this, we discovered that some of the traditional antibiotics produce reactive oxygen species (ROS) under specific light exposure. In this paper, we report a multifunctional polymeric nanoparticle (F8IC NPs-PME) that combines targeted and photodynamic-photothermal therapy (PDT-PTT) in one device. The PME on the surface of F8IC enables the selective binding of F8IC NPs-PME to the surface of Gram-negative bacteria. In addition, PME and F8IC can generate ROS and photothermia under near-infrared light excitation, respectively. The results showed that the sterilization efficiency of F8IC NPs-PME at a concentration of 8 μg/mL was as high as 94.7% against kanamycin-resistant E. coli under 808 nm near-infrared light irradiation (0.8 W/cm², 10 min). This antimicrobial strategy can achieve efficient bacteria killing with a low dosage of antibiotics and opens up a new avenue for fighting bacterial resistance.