Versatile nanocomposite hydrogel induced by Au-Se interaction showing mechanically tough and multi-responsive self-healing properties

Researchers are showing a great deal of interest in hydrogels due to the presence of high-water content, self-healing variants. Despite this, research into the development of smart hydrogels that have the combination of toughness, self-healing, and responsiveness to external stimuli is still lacking. Here, tough, and intelligent nanocomposite (NC) hydrogels have been developed by utilizing modified nano-crosslinker by means of gold-selenium (Au-Se) coordination interaction. The NC hydrogels demonstrate remarkable elasticity and strength, even when exposed to notches. With the optimal formulation, the nanocomposite hydrogel can achieve a maximum elongation of 1970%, a maximum fracture stress of 2.48 MPa, and a toughness of up to 9.95 MJ/m 3 , thanks to the dynamic gold crosslinks with improved branching. The presence of this structural attributes facilitates efficient energy dissipation within the hydrogel system. Combining Au-Se interaction as a healing element and the remarkable optothermal effect of nanoparticles, NC hydrogels can be quickly self-healed in near-infrared light exposure of 2 min, achieving a self-healing efficiency of 91%. Additionally, the hydrogels demonstrate repair potential when exposed to microwave irradiation, acid solution, and ultrasound stimulus. Moreover, a multi-responsive hydrogel composed of photothermal gold nanostructures can serve as a light-controlled drug carrier, which has smart drug release ability under external light stimulation. The advantageous properties of hydrogel make it a great option for biomedical and engineering fields.