Design of pH‑sensitive alginate–carbopol hydrogel patches for wound healing applications

Smart wound dressings capable of responding to environmental stimuli of biological origin offer a promising strategy for infection management and accelerated healing. In this work, pH-sensitive hydrogel patches composed of alginate and Carbopol were developed for controlled release of a model antiseptic ingredient, the methylene blue agent. The systems were designed aiming to remain stable under acidic conditions (pH 5), favorable to wound healing, and to undergo swelling, erosion, and drug release under alkaline conditions (pH 8), which are typically associated with bacterial infection. Experimental characterization included swelling, erosion, and release studies under static (constant pH) and dynamically changing pH conditions. The realized composite patches showed minimal release at pH 5 and a rapid, complete release of methylene blue at pH 8, driven by pH-induced erosion. Then, a mathematical model was developed to describe the system's behavior and successfully reproduced experimental data using a minimal set of adjustable parameters. The mathematical modeling approach adopted in this study was able to describe the experimental release kinetics with good accuracy when all kinetic rate constants were optimally fitted to the data confirming the erosion controlled release. These results highlight the potential of Carbopol–alginate composites as effective pH-responsive wound dressings demonstrating controlled pH-triggered release behavior.