Charge microenvironment and bioactivity of in situ-formed PEG-RGD dual hydrogel dressings promote wound healing†

Healing of large skin wounds involves a complex biological process with overlapping phases, facing challenges from fibroblast proliferation, immune response, and extracellular matrix (ECM) remolding. Hydrogel dressings serve as temporary barriers protecting injured tissue from exogenous infections while providing an advantageous microenvironment for cellular regeneration. However, traditionally molded hydrogels through catalyzed or triggered crosslinking into fixed size and strength prior to treatment struggle to integrate tightly with irregular wound surfaces, leading to dressing detachment and wound exposure in areas with high curvature and mobility. Here, we designed CGRGDGC peptide enantiomers, incorporating with 4 arm-PEG-maleimide, to in situ form functional and morphologically matching dual-phasic hydrogel dressing. In situ elastic hydrogel dressing forms within 10 min after applying, with a storage modulus of 1300 Pa and internal porous networks. The peptide incorporation increased the surface potential to ∼370 mV, twice that of PEG hydrogels. The bioactive L-peptide hydrogel exhibited strongest immunomodulation and skin regeneration enhancement, while the non-bioactive D-peptide hydrogel also showed significant promotion compared to the PEG hydrogel. We demonstrated that both the charge microenvironment and bioactivity of hydrogel dressing regulate the immune response and promote wound healing after skin injury. This research provides novel insights and strategies showing that non-ligand peptide sequences achieve biological functions by modulating molecular potential and that adjusting the charge microenvironment and incorporating bioactive peptides through peptide phase introduction enhance skin regeneration.