Multifunctional Fluorescent Microgel-Embedded Hydrogels for Temperature and X-Ray Sensing

Stimuli-responsive aggregation-induced emission luminogen (AIEgen)-based hydrogels exhibit tunable fluorescent signals in response to external stimuli, providing a suitable platform for sensing. As the largest sensory organ in the body, the response of skin temperature and X-ray dosage is crucial in predicting and diagnosing a range of diseases, and effective cancer radiotherapy. In this study, dual-responsive hydrogels are prepared by incorporating ratiometric fluorescent AIEgen-based microgels into polyvinyl alcohol (PVA). Experimental and molecular dynamics (MD) simulation results indicate that the AIEgen-based microgels enhance the mechanical and adhesive strength of the PVA hydrogels while maintaining good biocompatibility. Variations in temperature or X-ray exposure affect the chemical structure of the co-monomer or disulfide/diselenium-containing crosslinkers, which influences the molecular motion of the synthesized AIEgen; the other fluorescent molecules are unaffected. Consequently, the ratiometric fluorescent signals emitted by the AIE microgel-embedded hydrogels exhibit spectral and visual variations in response to changes in temperature and X-ray exposure. Applying support vector machine (SVM) regression, the hydrogel can achieve improved spectral accuracy. The hydrogel is shown to accurately sense skin temperature and effectively map radiotherapy dose levels.