Photodynamic, UV-curable and fibre-forming polyvinyl alcohol derivative with broad processability and staining-free antibacterial capability

TL;DR

This paper introduces a novel PVA derivative with conjugated photosensitizers enabling stain-free antibacterial photodynamic therapy, processable into various wound dressing formats with demonstrated efficacy and cellular safety.

Contribution

The study develops a new PVA-based material with covalently attached photosensitizers, allowing broad processability, effective antibacterial action, and cellular tolerability for wound dressing applications.

Findings

Achieved covalent coupling of toluidine blue to PVA with minimal release.

Demonstrated UV-induced antibacterial activity with up to 2.13 log reduction of S. aureus.

Confirmed cytocompatibility of UV-cured films and fibres with fibroblasts.

Abstract

Antimicrobial photodynamic therapy (APDT) is a promising antibiotic-free strategy for broad-spectrum infection control in chronic wounds, minimising bacterial resistance risks. However, rapid photosensitiser diffusion, tissue staining, side toxicity, and short-lived antimicrobial effects present significant clinical limitations for integrating APDT into wound dressings. To address these challenges, we present the design of a bespoke polyvinyl alcohol (PVA) derivative conjugated with both phenothiazine and methacrylate functionalities, enabling staining-free antibacterial photodynamic effects, cellular tolerability and processability into various wound dressing formats, including films, textile fibres and nanoscale coatings. Tosylation of PVA is leveraged for the covalent coupling of toluidine blue, as confirmed by UV-Vis spectroscopy and the minimal release of TB in vitro. UV-induced network formation is exploited to accomplish cast films and nanoscale integrated wound dressing coatings. UV curing is also successfully coupled with an in-house wet spinning process to realise individual, water-insoluble fibres as the building blocks of fibrous wound dressings. A fluorometric assay supports the generation of reactive oxygen species when the UV-cured samples are exposed to work, but not UV, light, yielding a mean log10 reduction of up to 2.13 in S. aureus, and the complete eradication of P. aeruginosa. Direct and extract cytotoxicity tests with UV-cured films and fibres demonstrate the viability of L929 fibroblasts following 60-min light irradiation and 72-hour cell culture. The bespoke molecular architecture, broad processability and cellular tolerability of this PVA derivative are highly attractive aiming to integrate durable staining-free photodynamic capability in a wide range of healthcare technologies, from chronic wound dressings up to minimally invasive localised therapy.