Quaternary Ammonium Salt Carboxymethyl Chitosan/Sodium Oxidized Alginate/Tannic Acid/Sodium Tetraborate Hydrogel Dressings with Self-Healing, Antioxidant and Responsive Release of Tannic Acid

Infected wound repair remains a global healthcare challenge, primarily due to bacterial infection and a pathological microenvironment characterized by elevated glucose levels and oxidative stress. In this work, a quaternized carboxymethyl chitosan (QCMCS)/oxidized sodium alginate (OSA)/tannic acid (TA)/sodium tetraborate (STB) hydrogel was developed for controlled TA release and diabetic wound repair. The QCMCS/OSA/TA/STB hydrogel exhibited potent antibacterial activity, with inhibition rates exceeding 99% against <i>S. aureus</i> and MRSA and 86% against <i>E. coli</i>, arising from the synergistic action of QCMCS and TA. Meanwhile, the introduction of TA enhanced antioxidant performance (radical scavenging rates of 66.72% and 93.16% against DPPH and ABTS, respectively), and STB reinforced mechanical strength with a compressive resistance of 140.78 kPa through a dual cross-linking network. In vitro biocompatibility evaluations demonstrated that the hemolysis ratios of all hydrogels were below 5%, and the survival rate of Human umbilical vein endothelial cells (HUVECs) was over 93%. Reversible borate ester linkages between STB and the catechol groups of TA protect TA from oxidative degradation and allow stimulus-responsive release under elevated glucose and oxidative conditions. This responsive hydrogel represents a promising multifunctional platform for diabetic wound management.