Nanofiber membrane-foam composite sheet with dual pH-responsive functions of drug release and color change

Chronic wound repair remains challenging in skin regenerative medicine due to complex pathology and dynamic microenvironments. Traditional single-functional dressings fail to integrate exudate management, pH-responsive drug delivery, and inflammation monitoring, while empirical replacement disrupts microbial balance and impairs healing, making multifunctional smart dressings with high absorbency, pH-triggered release, and infection monitoring imperative. This study developed a dual pH-responsive, highly absorbent composite foam sheet using degradable wheat gluten (WG) as the primary matrix with auxiliary components-nanocellulose, glycerol, polyvinyl alcohol, and curcumin-based chromogenic capsules (Cur NC); an epigallocatechin gallate (EGCG)-loaded polyvinyl alcohol/sodium alginate (PVA/SA) electrospun nanofibrous membrane was integrated via chemical-physical methods. Its dual pH responsiveness involves pH-sensitive swelling of SA carboxyl groups and pH-dependent color changes of Cur NC. In vitro evaluations showed EGCG release of 74.22% at pH 6.5 and 96.22% at pH 8.5, with >99.99% antibacterial activity against Escherichia coli and Staphylococcus aureus; the WG/Cur NC foam exhibited color transitions (yellow at pH 4-7, darkening with pH; red to reddish-brown at pH 7.4-9), enabling visual detection of infected wounds (pH>7.4). The composite, crosslinked with CaCl 2 and negative pressure suction, had a dense interface with excellent peel strength, fracture strength, and liquid absorption. By synergizing pH-responsive drug release (nanofibers) and colorimetric monitoring (foam), this composite sheet addresses key challenges in chronic wound exudate management and infection warning, offering an innovative strategy to accelerate healing and reduce healthcare costs. • Dual pH response synergy, precise linkage of drug release and infection monitoring. • Nanofiber membrane extracellular matrix promotes cell adhesion and proliferation. • PH 6.5/8.5 drug release 74.22%/96.22%, antibacterial over 99.99%. • Foam pH4-7 yellow, 7.4-9 red, infection recognized by naked eye. • CaCl 2 cross-linking combined with negative pressure process results in excellent performance of composite sheets.