Positively Charged Donor–Acceptor Type Thieno[3,4-b]pyrazine-Based Conjugated Polymer for Near-Infrared Light Triggered Rapid and Efficient Photothermal Therapy of Sterilization

Diseases caused by antibiotic-resistant pathogenic bacteria are seriously threatening human health. Therefore, the development of new antimicrobial materials and treatment strategies is urgently needed. Herein, we designed and synthesized a donor–acceptor (D-A) structured conjugated polymer Poly(TP-T), which is functionalized with a positively charged side chain for selective contact with bacterial cells through electrostatic interaction for rapid and efficient near-infrared light-activated photothermal antimicrobial therapy. Under 808 nm laser irradiation, Poly(TP-T)-based nanoparticles exhibit a high photothermal conversion efficiency of 48.7% and thus excellent and broad-spectrum antimicrobial activity with almost 100% inhibition ratio against both Gram-(+) bacteria ( S. aureus ) and Gram-(−) bacteria ( E. coli ) within a few minutes. This work broadens the range of photoactive materials that can be used for highly efficient antimicrobial phototherapy and offers insight into the relationship between the polymer structure and phototherapeutic performances.