A Bilayer Thermoresponsive Hydrogel Dressing Integrating Temperature Sensing and Temperature-Triggered Drug Release for Intelligent Wound Management

Chronic wounds are associated with a complex and dynamic microenvironment, requiring wound dressings with both monitoring and therapeutic functions. Herein, a bilayer thermoresponsive hydrogel dressing was fabricated by sequentially integrating an upper gelatin-chitosan/tannic acid (GEL-CS/TA) protective layer with a lower levofloxacin (LVN)-loaded poly(N-isopropylacrylamide-co-acrylic acid) (P(NIPAM-AA))/c-MWCNTs sensing/drug-delivery layer. The morphology, chemical structure, mechanical properties, interfacial adhesion, swelling, water retention, thermoresponsiveness, electrical properties, drug release, antibacterial activity, and antioxidant activity of the hydrogels were systematically investigated. SEM and FTIR confirmed the successful formation of the bilayer hydrogel. The peeling test showed that the hydrogel exhibited stable interfacial adhesion strength. Molecular dynamics (MD) simulations further revealed good interfacial adhesion between the hydrogel layers. The optimized lower layer exhibited a lower critical solution temperature (LCST) of 39 °C and provided an efficient conductive network. The layer showed reversible temperature-dependent resistance changes with low resistance drift. Meanwhile, the LVN-loaded lower layer exhibited temperature-triggered drug release behavior. The optimized upper layer showed enhanced water retention and high DPPH radical-scavenging efficiency, while the LVN-loaded lower layer exhibited temperature-enhanced radical-scavenging activity. The bilayer hydrogel showed effective antibacterial activity against Escherichia coli and Staphylococcus aureus. These findings provide a feasible strategy for developing intelligent wound dressings with integrated protection, temperature sensing, and responsive drug delivery.