Nitric oxide releasing ecologically friendly tannic acid based antibacterial hydrogel as flexible electronics

Tannic acid-based hydrogels hold significant promise in biomedical applications due to their excellent antioxidant and biocompatibility properties. However, their use in flexible electronics, particularly in applications requiring high sterilizability, remains in its infancy. In this study, we developed flexible, antibacterial, and conductive tannic acid (TA) and poly(vinyl alcohol) (PVA) hydrogels, reinforced through strong hydrogen bonding and incorporating polypyrrole (PPy) and S-nitrosoglutathione (GSNO). These hydrogels exhibit outstanding properties, including excellent molding capability, rapid self-healing, superior elasticity, and reversible adhesion to various biological tissues. Notably, at a mere 1 mm thickness, the hydrogel demonstrates exceptional adhesive strength, supporting up to 4 kg on an area of less than 10 cm². The GSNO-doped PVA-TA-G₃-PPy₂ hydrogels sustain efficient and prolonged nitric oxide (NO) release for up to 48 hours, achieving remarkable antibacterial efficacy (> 99 %) against S. aureus and E. coli. In electrical performance tests, the hydrogel exhibits precise and rapid monitoring capabilities for both macroscopic body movements and subtle physiological signals, such as carotid pulses, swallowing, and blinking. It achieves an impressive response time of 0.1 seconds, high capacitance, and exceptional electrical stability over 4000 cycles. The remarkable combination of mechanical strength, antibacterial activity, and electrical performance positions these NO-releasing TA-based hydrogels as highly promising materials for next-generation biomedical devices and flexible electronics.