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Updated: Sep 7, 2025
High-throughput Identification of Bacteria Repellent Polymers for Medical Devices
Published on: November 5, 2016
Polythiophene as a near full pH photo-antimicrobial
Yunhe Lang1, Ying Wang1, Ronghui Zhou2
1Analytical & Testing Centre, State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610041, China. wupeng@scu.edu.cn.
Abstract:
Microbial infections are currently one of the world's major public health concerns, the evolution of which has resulted in the development of multiple tolerances (not just drug or antibiotic resistance), including pH (from extremely acidic to alkaline). Currently various types of antimicrobials have been developed. Although effective, they seldom work in the full pH range due to the existence of acid-/base-reaction sites. Here, we found that polythiophene (PT10), a cationic polymer, was capable of both broad-spectrum photo-antimicrobial activity (Gram positive, Gram negative, Fungal, and cyano-bacteria) and broad pH responsiveness (constant 1O2 generation at pH 2-13). The half-maximal inhibitory concentrations (IC50) of PT10 for bacteria living in acidic, neutral, and alkaline media were generally lower than 2 μg mL-1 (except M. aeruginosa, pH 12, ∼30 μg mL-1), which were much lower than common antibiotics and other photosensitizers. Besides, the excellent photostability of PT10 allowed long-term light irradiation for antimicrobial performance. In real-world applications, PT10 was explored for the successful in vivo therapy of oral Candidiasis infection under extreme acidic conditions (pH < 3) and the removal of M. aeruginosa at pH 12. Such near full pH, broad-spectrum photo-antimicrobial activity of polythiophene is appealing for extremely acidic or alkaline applications, such as oral infections, vaginitis, and blooms.
Insights
A novel cationic polymer, polythiophene (PT10), demonstrates broad-spectrum photo-antimicrobial activity across a wide pH range (2-13). This offers a promising solution for infections in diverse environments, outperforming traditional antibiotics.
Area of Science:
- Materials Science
- Microbiology
- Photochemistry
Background:
- Microbial infections pose a global health challenge, with pathogens developing resistance to antimicrobials and exhibiting tolerance to various environmental conditions, including extreme pH.
- Existing antimicrobials often fail in broad pH ranges due to acid-/base-reaction sites, limiting their efficacy in diverse applications.
Purpose of the Study:
- To investigate the photo-antimicrobial activity and pH responsiveness of a cationic polymer, polythiophene (PT10).
- To evaluate the potential of PT10 as a broad-spectrum antimicrobial agent effective across a wide pH range.
Main Methods:
- Synthesis and characterization of polythiophene (PT10).
- Assessment of PT10's photo-antimicrobial efficacy against Gram-positive bacteria, Gram-negative bacteria, fungi, and cyanobacteria under varying pH conditions (pH 2-13).
- Evaluation of PT10's photostability and *in vivo* therapeutic potential.
Main Results:
- PT10 exhibited constant singlet oxygen generation across a broad pH range (2-13).
- PT10 demonstrated broad-spectrum photo-antimicrobial activity with low half-maximal inhibitory concentrations (IC50 < 2 μg mL⁻¹) for most tested microbes, significantly outperforming conventional antibiotics and photosensitizers.
- Successful *in vivo* treatment of oral Candidiasis under acidic conditions (pH < 3) and removal of *M. aeruginosa* at pH 12 were achieved.
Conclusions:
- Polythiophene (PT10) presents a novel, pH-versatile, broad-spectrum photo-antimicrobial agent.
- Its efficacy across extreme pH conditions makes it highly suitable for challenging applications like oral infections and environmental microbial control.
