Carbon dot- and gold nanocluster-based three-channel fluorescence array sensor: Visual detection of multiple metal ions in complex samples

Heavy metal pollution has gradually become one of the most serious problems in global environmental pollution and can invade the environment, food, and medicine, eventually causing irreversible damage to the human body. Herein, we construct a multichannel visual fluorescence array sensor based on N-doped carbon dots (NCDs) and gold nanocluster (AuNCs). The sensor comprehensively considered the aggregation-induced enhanced fluorescence (AIE) effect of AuNCs, the electron transfer (ET) effect of NCDs, and the fluorescence resonance energy transfer (FRET) effect of AuNCs@NCDs. It was further combined with PLSDA and PLSR to realize rapid and accurate detection of multiple metal ions in tap water, traditional Chinese medicine (TCM), and soil. The LODs of Cd2+, Pb2+, and Hg2+ were 0.15 mu mol/L, 0.20 mu mol/L and 0.09 mu mol/L, respectively. Simultaneously, we proposed an adjustable fluorescence spectral logic device to meet the different determination requirements towards heavy metals. The analysis result of metal ions can be directly achieved by the four output types, NOT (0, 0, 0), Cd2+ (1, 1, 0), Pb2+ (1, 0, 0) and Hg2+ (0, 0, 1). More interestingly, Cd2+ and Pb2+ can be removed by simple centrifugation or sedimentation, which can be observed through the Tyndall effect. Accordingly, we not only constructed the sensing method of multiple metal ions but also proposed a new strategy for future research on the migration of heavy metal ions from complex environments to TCM.