ROS/pH dual-responsive tannic acid-coated nanoparticle-integrated hyaluronic acid hydrogel for antibacterial and pro-healing effects on diabetic wounds in vitro

Abstract

Diabetic chronic wounds remain a leading cause of non-traumatic lower-extremity amputation, driven by four concurrent pathological processes: multidrug-resistant bacterial infection, excessive reactive oxygen species (ROS), sustained pro-inflammatory macrophage polarization, and impaired neovascularization. Conventional wound dressings address only one or two of these processes, and no single-target approach can interrupt this self-reinforcing pathological network. To address this limitation, we designed TAZNP/ADH-OHA Gel, a ROS/pH dual-responsive composite hydrogel dressing. Mesoporous silica nanoparticles (MSNs) were co-loaded with the antimicrobial peptide Pexiganan (AMP, EE% = 90.10%) and Zn2+ (EE% = 33.71%), then coated with a tannic acid-Zn2+ metal-phenolic network (TA-Zn2+ MPN) to form TAZNP nanoparticles, which were subsequently embedded in a dynamically crosslinked ADH-HA/OHA hydrazone hydrogel matrix. The resulting scaffold exhibited interconnected macroporosity, stable viscoelastic properties (G′ > G″, 0.1–10 Hz), a yield strain of ∼175%, tissue adhesion of 3.97 kPa, and an equilibrium swelling ratio of 250–300%. Cumulative AMP release increased from 69.10% under physiological conditions (pH 7.4) to 94.93% under combined diabetic wound conditions (pH 6.0 + 10 mM H2O2 + 25 mM glucose), with Zn2+ reaching 86.41% under identical conditions. Early-stage kinetic analysis further demonstrated highly synchronized AMP/Zn2+ release, with apparent release-rate ratios ranging from 1.05 to 1.22 across the tested microenvironments. In vitro assays demonstrated effective antibacterial and anti-biofilm activity against S. aureus and E. coli, with TAZNP/ADH-OHA Gel outperforming free TAZNP and ADH-OHA Gel alone. The composite hydrogel protected HSFs and HUVECs against high-glucose cytotoxicity, restored HSF wound closure from 37.44% to 70.79%, and rescued HUVEC tube formation, restoring total tube length from 5615.88 µm to 15 486.40 µm and number of segments from 26.68 to 249.33. In LPS-stimulated RAW264.7 macrophages, iNOS and TNF-α mRNA were reduced to 0.59-fold and 0.61-fold, while Arg-1 and IL-10 were elevated to 4.13-fold and 5.12-fold. Flow cytometry confirmed genuine M1-to-M2 phenotypic switching, with the M1 proportion reduced from 60.61% to 25.92% and the M2 proportion increased from 35.11% to 75.44%. These results demonstrate that TAZNP/ADH-OHA Gel integrates microenvironment-responsive synchronized co-delivery with antibacterial, antioxidant, pro-angiogenic, and immunomodulatory activities, providing a promising multifunctional platform for diabetic wound management.