Near-Infrared Molecular Photosensitizer Decorated with Quaternary Ammonium for High-Efficiency Photothermal Treatment of Bacterial Infections

Abstract

In recent years, pathogenic infections have been a growing health threat due to the proliferation of drug-resistant bacteria, so photothermal therapy (PTT) has gained considerable interest in biological and medical fields, owing to its noninvasive and highly effective properties. However, it is hard to achieve selective bacteria targeting while generating a large amount of heat at infected sites. Cationic electrostatic interaction is considered to be a common antimicrobial strategy. Herein, an organic molecule named RT-MN was synthesized with four positively charged quaternary ammonium salts that can bind to negatively charged bacteria. Under near-infrared 808 nm laser irradiation, RT-MN could be efficiently converted into a large amount of heat to eradicate bacteria. In addition, its good water solubility and biological safety proved that RT-MN has excellent biological application prospects. Overall, four such positively charged photosensitizer RT-MN, as a non-antibiotic treatment for resistant bacteria, could be promising for the exploration of highly effective antibacterial agents.

Trends in Photothermal Nanostructures for Antimicrobial Applications

“…Subsequently, the in vivo antibacterial ability was successfully demonstrated in an MRSA-infected mouse skin wound model. The good biocompatibility of RT-MN combined with NIR irradiation successfully reduced the sizes of infected wounds and facilitated healing via an anti-inflammatory response and increased collagen secretion [234]. Similarly, NIR-irradiated Au@CD-based membranes effectively eradicated bacteria at the wound site, reduced the risk of bacterial infection, suppressed inflammation, and improved collagen deposition and angiogenesis, facilitating wound closure via a photothermal antimicrobial effect.…”

Recent Progress of Photothermal Therapy Based on Conjugated Nanomaterials in Combating Microbial Infections

“…Water-soluble conjugated oligomers are usually composed of two parts, a hydrophobic conjugated main chain and a hydrophilic branch chain, which could be a neutral polyethylene glycol (PEG) chain or an alkyl with a positively charged quaternary ammonium/quaternary phosphorus salt end [80]. He et al [81] synthesized a water-soluble PTA (PCE = 51%) modified with an ammonium group, which could trap negatively charged bacteria through electrostatic interaction and destroy the stability of the membrane. Under NIR light irradiation (808 nm, 1 W•cm −2 , 10 min), the survival rate of both MRSA and E. coli treated with PTA was only 1%.…”