ROS-responsive mechanically and electronically controllable conductive hydrogel sensor with NIR modulated photothermal therapy

This study illustrates the design of a cancer microenvironment-selective detection system via the monitoring of wireless pressure and strain sensing response from a reactive oxygen species (ROS)-responsive carbon dot (CD)-embedded conductive hydrogel. ROS scavenging activity and photothermal therapy (PTT) were employed to eliminate the tumor condition. The ROS-responsive hydrogel (dsCD-Hydrogel) contained diselenide-crosslinked CD, which was dismantled in the cancer microenvironment. After being free from aggregation, the fluorescence intensity, charge carrier density, and hydrogen bonding interactions were increased. As a result, the conductivity, mechanical stretchability, and strain-pressure responses were enhanced by 52%, 122%, and 91%, respectively. The dsCD-Hydrogel produced distinct electronic signals in the presence of cancer cells according to the higher strain–pressure sensitivity in the handwriting experiment compared to normal cells. Ex-situ measurements also revealed an excellent pressure-sensing response in tumor-carrying mice. The ROS scavenging activity of the dsCD-Hydrogel decreased tumor volume. Furthermore, NIR irradiation via PTT abolished the tumor, which was verified by the downregulation of tumor hypoxia by vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1α (HIF-1α) expression. To ease the monitoring procedure and acquire real-time conductivity and pressure profiles on cellphones, a wireless sensor device was deployed. Overall, a theragnostic sensor based on strain–pressure hydrogel that exhibits direct anticancer activity via PTT was successfully constructed.