Visible-Light-Excited Fluorescent Hydrogel Tapes for Dual-Channel Copper Ions Recognition

Incorporating aggregation-induced emission (AIE) molecules into hydrogels that exhibit ion-responsive and visible light excitation while maintaining good luminescence is challenging. To address this, we designed an ion-sensitive fluorescent hydrogel using an aggregation-induced phase separation strategy. We synthesized a tetraphenylethylene derivative (TPEBPy) with a long-chain alkene and copolymerized it with hydroxyethyl methacrylate (HEMA) and acrylic acid (AAc) through free-radical copolymerization. Because of the extended π-conjugated structure and AIE effect of the TPEBPy molecules, the synthesized fluorescent p(HEMA-co-AAc-TPEBPy) hydrogels exhibit excitation in the visible range (415 nm).This strategy requires only 0.1 mol % of TPEBPy molecules to achieve a sensitive threshold for specific recognition of copper ions as low as 10–5 M. By analyzing the fluorescence lifetime results, we determined the distribution of fluorescent molecules within the hydrogel, distinguishing between the aggregated and dispersed states. Additionally, this fluorescent hydrogel demonstrates the capability for visual colorimetric and fluorescence dual-channel detection of copper ions.