A photothermal antibacterial hydrogel based on a "nano-bridge" strategy with high toughness and self-healing capacity

Constructing integrated multifunctional hydrogels with both high toughness and diverse functionalities is beneficial for the development of flexible antibacterial materials and wearable sensors. However, current hydrogels often fail to achieve a synergistic balance among toughness, antibacterial activity, and sensing responsiveness, limiting their practical applications. Herein, a "nano-bridge" strategy is proposed to fabricate a double-network hydrogel system (PHS-CT) composed of a covalent polyacrylamide network and a dynamic borate-crosslinked hydroxypropyl guar gum/sodium alginate network. The incorporated Cu-TA nanosheets serve not only as "structural bridges" to enhance the crosslinking density and mechanical performance (strain up to 1997.7%, toughness up to 1.53 MJ/m³), but also as "functional bridges" to enable photothermal conversion and improved antibacterial activity (bacterial killing rate of 99.0% against E. coli under NIR irradiation). In addition, benefiting from the dynamic reversibility of borate ester bonds as well as the re-forming capability of hydrogen bonds at the fracture interface, the hydrogel exhibits favorable self-healing ability (self-healing efficiency up to 91.0%), and can function as a flexible strain sensor capable of accurately detecting both large-scale and subtle deformations. This strategy provides a feasible strategy for constructing multifunctional dual-network hydrogels, and may be useful for photothermal antibacterial and flexible sensing applications.