Gold nanoclusters immobilized paper for visual detection of zinc in whole blood and cells by coupling hydride generation with headspace solid phase extraction

A novel visual detection method was developed for the determination of zinc (Zn) in whole blood and cells using gold nanoclusters (AuNCs) immobilized paper. The detection of Zn was based on a headspace-solid phase extraction (HS-SPE), visible fluorescence from the AuNCs coated paper was quenched by ZnH2 generated from hydride generation (HG). The potential mechanism was investigated by using X-ray photoelectron spectroscopy (XPS) and Density Functional Theory (DFT). The selectivity was significantly increased because the zinc hydride was effectively separated from sample matrices by hydride generation. A limit of detection (LOD) of 3 μg L−1 Zn2+ and a relative standard deviation (RSD, n = 7) of 2% at a concentration of 50 μg L−1 of Zn2+ were obtained when using a commercial fluorescence spectrophotometer as the detector. In visual detection, as low as 20 μg L−1 of Zn2+ in biological samples can be easily discriminated from the blank with the naked eye. The proposed method retains several unique advantages, including straightforward, rapid, affordable and equipment-free for visual detection.