Coupling phenolic redox chemistry and graphenic conductivity in alginate hydrogels: Charge storage mapped by impedance as a biomarker of wound healing

This study reports a metal-free, redox-capacitive alginate hydrogel (Alg/rGO/PA) engineered by coupling reduced graphene oxide (rGO) conductivity with proanthocyanidin (PA) redox chemistry for wound-healing applications. The network was fabricated through sequential Ca²⁺ ionic and borate-diol dynamic crosslinking, while PA-rGO co-assembly via π-π interactions and hydrogen bonding generated conductive, phenolic-rich microdomains. This architecture produced a homogeneous, mechanically stable matrix (tan δ < 0.3; τ₁/e > 240 s) with controlled biodegradation (15-20% mass loss over 21 days). Electrochemical analyses (EIS/CV) revealed reduced charge-transfer resistance and enhanced pseudocapacitive behavior, enabling impedance-mapped charge storage as a quantitative surrogate of the material's redox-buffering capacity. Consistently, Alg/rGO/PA showed a marked antioxidant enhancement (ABTS = 35.3%; ORAC = 24.6 mmol TE/g), >70% antibacterial activity against E. coli and S. aureus, low hemolysis (<2%), and high fibroblast metabolic activity (128 ± 6%). Functionally, the hydrogel accelerated in vitro scratch closure (92.9% at 48 h) and achieved 96.7% closure in a porcine full-thickness wound model at 21 days, with organized collagen deposition and minimal inflammation, performing comparably to a commercial dressing. Overall, these results demonstrate that integrating phenolic redox centers with graphenic conductivity in alginate enables a bioelectroactive dressing whose impedance-derived charge-storage metrics track regenerative outcomes, supporting charge storage mapping as a functional biomarker for guided dermal repair.