A novel ratiometric fluorescent sensor array based on the copper clusters hydrogels coupling of DNA

Hydrogels with DNA possess flexible and designable 3D cross-linked polymer networks, which generate numerous specific stimulus–response characteristics through reasonable design for the potential sensor array applications. Unfortunately, the complementary fragments of specific nucleotide sequences that form cross-links in the hydrogels with DNA often come across these problems of instability and high-cost, leading to a serious impediment to further application. Herein, we construct a novel ratiometric fluorescence sensor array to discriminate and quantify metal ions based on the hydrogels with DNA. The dual-emission hydrogels with DNA were synthesized by the self-assembly reaction of agarose, low-cost nonspecific sequence double-stranded DNA, and optically active copper nanoclusters (Cu NCs) with aggregation-induced emission (AIE) effect. Interestingly, different metal ions could precisely regulate the skeleton network of the hydrogels with DNA, leading to the change of their skeleton network and thus showing the distinguishing FL responses of the hydrogels with DNA. As a proof-of-concept demonstration, the ratiometric fluorescence sensor array was used to discriminate four metal ions (Pb²⁺, Co²⁺, Ni²⁺, and Cr(VI)) at multiple concentrations and metal ion mixtures. It exhibited a good linearity in quantitative analysis and reproducibility. Such a simple and high-sensitivity sensor array has been successfully applied to the high-through discrimination of toxic metal ions in environmental and serum samples.