Colorimetric pH-responsive nanofibrous hydrogels for in vitro monitoring of wound infection

Effective wound management is crucial for improving patient outcomes, particularly through timely detection of infections and monitoring of wound conditions. Addressing this critical need, this research develops nanofibrous hydrogels integrated with an indicator dye for real-time monitoring of wounds via a colorimetric method. A new double network nanofibrous hydrogels based on polyvinyl alcohol (PVA) and a phosphine oxide-based pH-sensitive hydrogel (namely PVA/Gel-A) with improved properties were produced through electrospinning. Their properties were examined through SEM, ICP-OES, FTIR, surface zeta potential, and mechanical analysis. Scanning electron microscopy and Brunauer–Emmett–Teller analysis confirmed the presence of smooth, bead free nanofibers with a mesoporous structure. The swelling ratio and surface zeta potential analysis further demonstrated the presence of anionic-cationic interpenetrating polymer networks (IPNs) in PVA/Gel-A compared to pristine PVA and Gel-A alone. Increasing the Gel-A content enhances moisture absorption in a dual system of PVA/Gel-A nanofibrous hydrogels. Compared to pristine PVA nanofibers, the PVA/Gel-A (1 : 1) nanofibers displayed enhancements in elastic modulus, tensile strength, and elongation of 216%, 154.5%, and 58%, respectively. It shows considerable strength while maintaining ductility, which is essential for flexible and durable applications. Then, the dye-doped PVA/Gel-A nanofibrous hydrogels, using bromothymol blue (BTB) as a pH-sensitive dye, were fabricated with and without a complexing agent. Their colorimetric and release behaviors were evaluated at different pH levels. The cationic complexing agent effectively prevented dye leaching, releasing less than 10% and ensuring chemical stability and accurate pH sensing. These IPNs can visibly indicate wound infections, resulting in the development of colorimetric nanofibrous hydrogels that monitor pH variations for smart wound dressing applications. In vitro cytotoxicity assessment applying keratinocytes demonstrates no toxic effects, underscoring their potential for safe clinical applications.