Construction Of Several Fluorescence Sensor Based On Gold Nanocluster And Their Applications In Small Molecule Detection

Fluorescent materials have broad application prospects in biochemical analysis and biomedical imaging fields due to their unique optical properties.Compared with conventional fluorescent materials,Gold nanoclusters?AuNCs?display many interesting characteristics such as good water solubility,large Stokes shifts,good biocompatibility and ease of synthesis.In the construction of fluorescent sensors,AuNCs has received extensive attention from researchers.Compared with AuNCs,the fluorescent properties of upconversion nanoparticles?UCNPs?with large anti-Stokes shifts are also noticeable.Therefore,several simple,economical,highly sensitive and selective fluorescence sensors were constructed based on AuNCs and AuNCs-UCNPs complexes for the detection of organophosphorus pesticides?OPs?and hydrogen sulfide?H₂S?.The research contents are as follows:1.A simple and economical AuNCs-based fluorescence sensor was designed for the detection of OPs.The template of bovine serum albumin-stabilized gold?BSA-AuNCs?was digested by trypsin,resulting in aggregation of BSA-AuNCs and thus their fluorescence quenched.While the activity of trypsin was irreversibly inhibited in the presence of OPs,the fluorescence quenching efficiency of BSA-AuNCs was decreased.Under the optimal conditions,the detection limits of OPs reached 0.037 ng mL^-1.Moreover,the sensing method had been successfully utilized in the detection of OPs in real food samples.2.Synthesis of AuNCs-UCNPs composites with Up/down conversion fluorescence properties has been development.The UCNPs core was coated with silica layer by a microemulsion method,and AuNCs was modified to the UCNPs@SiO₂ surface by amidation reaction.This joint strategy via interfacial modification and composition engineering provides a facile guideline for stabilizing AuNCs and improving the fluorescence property of UCNPs.AuNCs-UCNPs composite with Up/down conversion fluorescence properties have broad application prospects in cell imaging and biosensing.3.A simple fluorescence sensor based on AuNCs-UCNPs composite for sensitive and selective detection of H₂S was developed.Due to the good affinity of gold and sulfide,the outermost AuNCs layer of AuNCs-UCNP can easily interact with S^2-to form Au₂S.After the formation of Au₂S,the distance between the adjacent AuNCs is shortened,resulting in aggregation of AuNCs and inducing quenching effects.This sensor exhibits excellent sensitivity?the detection limits is 1.25?M?and selectivity toward H₂S,which is successfully applied to H₂S detection in spiked real water samples.