Investigation of Regenerable Gold Nanocluster as Free Radical Scavenger

• Main Authors: Yun-Yu Chen, 陳韻宇
• Other Authors: Cheng-An Lin
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/fxqy55

碩士 === 中原大學 === 生物醫學工程研究所 === 106 === Free radicals are the factors that induce the cell''s aging and produce related diseases, which can have a serious impact on the organism. Antioxidants have the ability to prevent and inhibit the free radicals. Gold nanocluster is also known as an artificial antioxidant, not only does it have a unique optical property but it can also react with a variety of free radicals, as a biological probe. In this study we have reported a ''one-pot synthesis'' procedure to prepare fluorescent gold nanoclusters conjugated by lipoic acid, and further determined the surface structure, physical and chemical properties and the ability to scavenge free radicals. The trend of inhibiting free radicals was compared with vitamin C and gold nanoclusters, using 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and hydrogen peroxide reacted with gold nanoclusters, respectively, then renewal of the gold nanoclusters by common antioxidants from the body. In addition, X-ray photoelectron spectroscopy and Ellman''s Reagent were used to measure the change in the surface of the gold nanoclusters during the redox process. The study found that the size of gold nanoclusters is about 2.32nm, with ultrabright luminescence, long-term and stable inhibition of DPPH. Comparing DPPH radical with hydrogen peroxide, we have found that both of them can oxidize gold nanoclusters, that is, they lose their ability to scavenge free radicals. They showed different spectral effects, indirectly found that the gold nanoclusters have a redox state. Finally, addition of glutathione to reduce the oxidation state of the gold nanoclusters and have the property to scavenge free radical again, but the fluorescence intensity decreased. However, the change of valence state of gold is closely related to the fluorescence intensity during the redox process. Ellman''s Reagent also confirmed that GSH is involved in the reduction reaction and the in vivo circulation is implemented in this material. Moreover, the gold nanocluster can be regenerated by the biological cycle, ensuring gold nanoclusters have more applications and value.