Structural property and bioactivity evaluation of reactive oxygen species hydrogels loaded with different polyphenols

A multifunctional hydrogel system was constructed using gelatin, oxidized sodium alginate, and thioketal‌ via a Schiff base reaction. Three polyphenols with distinct chemical structures, 6'-O-Caffeoylarbutin (CA), gallic acid (GA), and tannic acid (TA), were loaded into the hydrogel. The physicochemical properties and bioactivities of hydrogels were systematically investigated. Results showed that the GA-loaded hydrogel exhibited a uniform honeycomb-like porous structure and displayed the optimal antioxidant activity, with an ABTS radical scavenging rate as high as 96.51%. The CA-loaded hydrogel possessed the best mechanical properties. All three hydrogels formed inhibition zones against Staphylococcus aureus and displayed favorable biocompatibility. Thioketal‌ endowed the hydrogel with the ability to release on demand in response to reactive oxygen species, and significantly enhances clearance capacity for O₂^- and ·OH of hydrogels. All polyphenol-loaded hydrogels exhibited radical scavenging rates exceeding 63%. This dual-network hydrogel can serve as an ideal carrier to achieve stable loading, controlled release of active polyphenols, showing potential applications in delivery systems.