pH-sensitive hydrogels play an important role in controlled drug release applications and have the potential to impact the management of wounds. In this study, we report the fabrication of novel carboxylated agarose/tannic acid hydrogel scaffolds cross-linked with zinc ions for the pH-controlled release of tannic acid. The resulting hydrogels exhibited negligible release of tannic acid at neutral and alkaline pH and sustained release at acidic pH, where they also displayed maximum swelling. The hydrogels also displayed favorable antibacterial and anti-inflammatory properties, and a lack of cytotoxicity toward 3T3 fibroblast cell lines. In simulated wound assays, significantly greater cell migration and proliferation was observed for cells exposed to tannic acid hydrogel extracts. In addition, the tannic acid hydrogels were able to suppress NO production in stimulated human macrophages in a concentration-dependent manner, indicating effective anti-inflammatory activity. Taken together, the cytocompatibility, antibacterial, and anti-inflammatory characteristics of these novel pH-sensitive hydrogels make them promising candidates for wound dressings.

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Exploring the possibility of using inorganic faujasites in tissue engineering scaffolds is a prospective approach in regenerative medicine. Novel gelatin/hyaluronic acid (HA)/faujasite porous scaffolds with low surface energy were fabricated by lyophilization. The pore size of gelatin/HA scaffold was 50-2000 μm, whereas it was greatly reduced to 10-250 μm after incorporation of 2.4% (w/w) of faujasites in polymer matrix, GH(2.4%). Micro computed tomography analysis showed that the porosity of GH(2.4%) was 90.6%. The summative effect was ideal for growth of dermal fibroblasts and cellular attachment. XRD analysis revealed that the embedded faujasites maintained their crystallinity in the polymer matrix even though they interacted with the polymers as indicated by FT-IR analysis. Coupling with effective reinforcement of faujasites, GH(2.4%) demonstrated compression modulus of 929 ± 7 Pa and glass transition temperature of 31 ± 0.05 °C. It exhibited controlled swelling and degradation, allowing sufficient space for tissue regrowth. The latter is further supported by capability of faujasites to provide efficient oxygen supply to fibroblast cells. GH(2.4%) showed a cell viability of 91 ± 8% on NIH 3T3 fibroblast cell lines. The in vivo studies on Sprague-Dawley rats revealed its ability to enhance wound healing by accelerating re-epithelization and collagen deposition. These findings indicated its potential as excellent wound dressing material.