A Novel Polythiophene-Conjugated Polymer Photocatalyst Under Visible Light for Killing Multidrug-Resistant Bacteria

The photocatalytic antibacterial method is one of the most effective and “green” methods for treating multidrug resistant (MDR) bacteria-caused infections. The most critical scientific question is how to improve the antibacterial efficiency of photosensitizers (PS). Herein, an organic-conjugated-polymer photocatalyst poly((E)-5-(2,5-dihydroxy-4-methylphenyl)-5′-(2-(5-methylthiophen-2-yl)vinyl)-[2,2'-bithiophene]-4-carboxylic acid) (PTH-COOH-(OH) 2 ) has been successfully synthesized. A new route for developing highly active organic-conjugated-polymer photocatalysts for environmental purification via the proper expansion of the backbone conjugate structure and the introduction of effective groups such as carboxyl and hydroxyl groups is proposed. The visible-light photocatalytic activities of PTH-COOH-(OH) 2 were evaluated against methicillin-resistant Staphylococcus aureus ( MRSA ), Staphylococcus epidermidis ( S. epidermidis ) and Escherichia coli ( E. coli ) under LED white light. A very high antimicrobial efficiency was achieved for optimized 0.3 mg mL −1 PTH-COOH-(OH) 2 under visible light illumination. Over 7 log of MRSA was killed in 3 h, 7 log of S. epidermidis was killed in 3 h, and 93.3% decomposition of E. coli was achieved in 3 h. These photoantimicrobial effectiveness values are among the most widely published for conjugated polymer photocatalysts. The findings of trapping studies and electron spin resonance (ESR) spectroscopic investigations indicated that during the photocatalytic antimicrobial process, ·OH, 1 O 2 , ·O 2 − , and e − are largely reactive oxygen species (ROS). Importantly, following recycling processes, the PTH-COOH-(OH) 2 photocatalyst demonstrated satisfactory stability and excellent photocatalytic activity. Graphical Abstract The organic-conjugated-polymer photocatalysts poly((E)-5-(2,5-dihydroxy-4-methylphenyl)-5′-(2-(5-methylthiophen-2-yl)vinyl)-[2,2′-bithiophene]-4-carboxylic acid) (PTH-COOH-(OH) 2 ) is successfully synthesized using the Stille coupling reaction. PTH-COOH-(OH) 2 exhibits more outstanding photocatalytic antibacterial activity and stability, and has broad-spectrum antibacterial efficacy that can kill Gram-positive bacteria ( MRSA , Staphylococcus epidermidis ) and Gram-negative bacteria ( Escherichia coli) under visible light irradiationtreat. The highly photocatalytic antibacterial active is developed via the proper expansion of the backbone conjugate structure and the introduction of effective groups such as carboxyl and hydroxyl groups.