Visible-Light-Excited\nFluorescent Hydrogel Tapes for\nDual-Channel Copper Ions Recognition

Incorporating aggregation-induced\nemission (AIE) molecules\ninto\nhydrogels that exhibit ion-responsive and visible light excitation\nwhile maintaining good luminescence is challenging. To address this,\nwe designed an ion-sensitive fluorescent hydrogel using an aggregation-induced\nphase separation strategy. We synthesized a tetraphenylethylene derivative\n(TPEBPy) with a long-chain alkene and copolymerized it with hydroxyethyl\nmethacrylate (HEMA) and acrylic acid (AAc) through free-radical copolymerization.\nBecause of the extended π-conjugated structure and AIE effect\nof the TPEBPy molecules, the synthesized fluorescent p(HEMA-<i>co</i>-AAc-TPEBPy) hydrogels exhibit excitation in the visible\nrange (415 nm).This strategy requires only 0.1 mol % of TPEBPy molecules\nto achieve a sensitive threshold for specific recognition of copper\nions as low as 10<sup>–5</sup> M. By analyzing the fluorescence\nlifetime results, we determined the distribution of fluorescent molecules\nwithin the hydrogel, distinguishing between the aggregated and dispersed\nstates. Additionally, this fluorescent hydrogel demonstrates the capability\nfor visual colorimetric and fluorescence dual-channel detection of\ncopper ions.