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Photoinactivation of Multidrug-Resistant mcr-1-Positive E. coli Using PCPDTBT Conjugated Polymer Nanoparticles under
Cynthia S A Caires1,2, Thalita H N Lima1,3, Rafael C Nascimento1
1Instituto de Física, Universidade Federal de Mato Grosso do Sul, CP 549, 79070-900 Campo Grande, MS, Brazil.
Abstract:
The issue of antimicrobial resistance is an escalating concern within the scope of global health. It is predicted that the existence of antibiotic-resistant bacteria might result in an estimated annual death of up to 10 million by 2050, along with possible economic losses ranging from 100 to 210 trillion. This study reports the production of poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] nanoparticles (PCPDTBT-NPs) by nanoprecipitation as an alternative to tackle this problem. The size, shape, and optical features of these conjugated polymer NPs were analyzed. Their efficacy as photosensitizers against nonresistant (ATCC) and multidrug-resistant mcr-1-positive Escherichia coli was assessed under white light doses of 250 and 375 J·cm-2. PCPDTBT-NPs inactivated both E. coli strains exposed to white light at an intensity of 375 J·cm-2, while no antimicrobial effect was observed in the group not exposed to white light. Reactive oxygen species and singlet oxygen were detected using DCFH-DA and DPBF probes, allowing the investigation of the photoinactivation pathways. This work showcases PCPDTBT-NPs as photosensitizers to eliminate multidrug-resistant bacteria through photodynamic inactivation employing visible light.
Insights
Antimicrobial resistance is a global health threat. This study developed poly(conjugated polymer) nanoparticles (PCPDTBT-NPs) that effectively inactivate multidrug-resistant bacteria using visible light photodynamic therapy.
Area of Science:
- Materials Science
- Nanotechnology
- Photochemistry
Background:
- Antimicrobial resistance (AMR) poses a significant global health and economic threat, with projections of millions of deaths annually by 2050.
- Existing treatments are becoming less effective against multidrug-resistant bacteria, necessitating novel therapeutic strategies.
Purpose of the Study:
- To synthesize and characterize poly[2,6-(4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b;3,4-b']dithiophene)-alt-4,7(2,1,3-benzothiadiazole)] nanoparticles (PCPDTBT-NPs).
- To evaluate the efficacy of PCPDTBT-NPs as photosensitizers for the photodynamic inactivation of both nonresistant and multidrug-resistant *Escherichia coli* strains.
- To investigate the mechanisms of photoinactivation, including the generation of reactive oxygen species.
Main Methods:
- Nanoprecipitation was used for the synthesis of PCPDTBT-NPs.
- The size, shape, and optical properties of the synthesized nanoparticles were analyzed.
- Antimicrobial efficacy was tested against *E. coli* strains under varying white light doses (250 and 375 J·cm-2).
- Reactive oxygen species (ROS) and singlet oxygen generation were detected using DCFH-DA and DPBF probes.
Main Results:
- PCPDTBT-NPs were successfully produced with characterized size, shape, and optical features.
- Exposure to white light at 375 J·cm-2 resulted in the inactivation of both nonresistant and multidrug-resistant *E. coli* strains by PCPDTBT-NPs.
- No antimicrobial effect was observed in the absence of white light.
- The generation of ROS and singlet oxygen confirmed the photodynamic inactivation mechanism.
Conclusions:
- PCPDTBT-NPs demonstrate significant potential as photosensitizers for combating multidrug-resistant bacteria.
- Visible light-activated photodynamic inactivation using these nanoparticles offers a promising alternative strategy to address the challenge of antimicrobial resistance.
