A Turn-On Fluorescent Sensor for Selective and Sensitive Detection of Alkaline Phosphatase Activity with Gold Nanoclusters Based on Inner Filter Effect

In this work, a novel approach for simple and sensitive determination of alkaline phosphatase (ALP) is developed on the basis of an inner filter effect of <i>p</i>-nitrophenylphosphate (PNPP) on the fluorescence of gold nanoclusters (AuNCs). AuNCs with a high quantum yield of 12% were synthesized by one-pot strategy and were directly applied as fluorescent substance. When AuNCs were mixed with PNPP, the fluorescence of the AuNCs was remarkably quenched or was decreased via the inner filter effect since the absorption spectrum of PNPP overlaps well with the excitation spectrum of the AuNCs. While in the presence of ALP, PNPP was catalytically hydrolyzed into <i>p</i>-nitrophenol, which has different absorption characteristics from those of PNPP, resulting in the recovery of the AuNCs fluorescence. Thus, a novel “turn-on” fluorescent sensor for detecting ALP was established with a detection limit as low as 0.002 U/L (signal-to-noise ratio of 3). The turn-on fluorescent sensor exhibits many merits such as high sensitivity, excellent selectivity, and high signal output because of the low background signals. In addition, the developed sensing method was successfully applied to investigate ALP inhibitors and ALP determination in serum samples. A good linear relationship was obtained in the range from 0.02 to 50 U/L, and satisfactory recoveries at four spiking levels of ALP ranged from 95% to 106% with precision below 5%. The very simple sensing approach proposed here should promote the development of fluorescence turn-on chemosensors for chemo/biodetection

Cell-Permeable Au@ZnMoS₄ Core–Shell Nanoparticles: Toward a Novel Cellular Copper Detoxifying Drug for Wilson’s Disease

A layer-by-layer self-assembly method leads to the formation of Au@ZnMoS₄ core–shell nanoparticles (NPs). The PEGylated Au@ZnMoS₄ NPs are highly water-dispersible, exhibit no cytotoxicity, and can penetrate the cell membrane to selectively remove copper­(I) ions from HepG2 cells in the presence of other endogenous and biologically essential metal ions, including Mg²⁺, Ca²⁺, Mn²⁺, and Fe²⁺, demonstrating their potential as a novel intracellular copper detoxifying agent