Synthesis And Application Of Fluorescent Metal Nanoclusters

Metal nanoclusters, composed of several to tens of atoms of gold, silver and other metals, are relatively stable aggregates. Compared to conventional fluorescent material, such as organic fluorescent dyes, quantum dots, nanoparticles, metal nanoclusters possess strong light stability, emission wavelength tunable, good biocompatibility, and easy preparation. Therefore, metal nanoclusters have broad application prospects in the environment testing, cell labeling and imaging and other fields.Based on the widely use of metal nanoclusters in fluorescence detection, papain-templated metal nanocluster were used as the research objects in this paper, we investigated the preparation of metal nanoclusters and the possibility of fluorescent detection of inorganic ions in environment. Details as follows:(1) Based on the fluorescence quenching of papain-directed gold nanocluster induced by sulfide ions, we expand the scope of application of papain-directed gold nanoclusters on fluorescence detection.The experimental results showed that the nanoclusters were very sensitive to sulfide ions. Under the optimized experimental conditions, the proposed gold nanoclusters facilitated detection of sulfide ions in the linear range of 0.5 – 80.0 μM; the limit of detection was 0.38 μM at a signal-to-noise ratio of 3. Selectivity experimental analysis found that the gold nanoclusters had good selectivity for sulfide ions. The quenching mechanism is the special reaction between gold nanoclusters and sulfide ions, and the formation of Au2 S precipitates cause fluorescence quenching. Thus, we have successfully explored a new method for the detection of sulfide ions.(2) A new type of copper nanoclusters were synthesized by using papain as the template, and the synthesis of copper nanoclusters should be used for fluorescence detection of ferric ions. With papain as the template, we successfully synthesized a new type of copper nanoclusters. By spectral analysis, we found the nanocluster has excellent fluorescent properties, and can keep the good stability under the influence of various factors. With the fluorescence reaction between copper nanoclusters and ferric ions, we also found that the copper nanoclusters could be used as a fluorescent sensor for the detection of ferric iron. The detection mechanism involves the electron transfer between the copper nanoclusters and ferric ion, and the aggregation of nanoparticles. By analyses the sensitivity of the detection system, the detection range of the copper nanoclusters is from 0.5 to 300 μM, and the limit of detection is 0.29 μM.