Gold Nanocluster-Based\nSelf-Assembly Fluorescence Microbeads for\nSensor Array Discrimination of Multicomponent Metal Ions

Benefiting\nfrom easy visualization and simultaneous detection of multiple targets,\nfluorescence microbeads are commonly used as fluorescence-sensing\nelements to detect pollutants in the environment. However, the application\nof fluorescence microbead-based sensor arrays is still limited because\nfluorescence dyes always suffer from self-quenching, photobleaching,\nand spectral overlap. Herein, three kinds of gold nanoclusters (Au\nNCs) were assembled with polystyrene microspheres (PS NPs) by electrostatic\ninteraction to prepare fluorescence microbeads (PS-Au NCs), developing\na sensor array for the simultaneous analysis of multiple metal ions.\nIn this work, different PS-Au NCs showed an enhancing or quenching\nfluorescence response to various metal ions, owing to distinct binding\ncapacities. Combined with the recognition algorithm from linear discriminant\nanalysis (LDA) and hierarchical cluster analysis (HCA), this sensor\nassay could realize single-component and multicomponent qualitative\ndetection for 8 kinds of heavy metal ions (HMIs) including Cu<sup>2+</sup>, Co<sup>2+</sup>, Pb<sup>2+</sup>, Hg<sup>2+</sup>, and\nCe<sup>3+</sup>. Particularly, the large surface area of PS NPs could\nprovide a direct reaction microenvironment to improve the efficiency\nof the detection process. Meanwhile, the fluorescence property of\nAu NCs could also be enhanced by a partially effective aggregation-induced\nemission (AIE) effect to give better fluorescence signal output. Under\noptimal conditions, 8 kinds of heavy metals and their multicomponent\nmixtures could be identified at concentrations as low as 0.62 μM.\nMeanwhile, the analytical performance of this sensor assay in water\nsamples was also verified, meeting the requirement of actual analysis.\nThis study provides a great potential and practical example of single-batch,\nmulticomponent identification for HMIs.