Mercury-Induced Switching of Enzyme Mimetic Activity of Platinum/Gold Nanoparticles

• Main Authors: Chao-Wei Tseng, 曾超偉
• Other Authors: Chih-Ching Huang
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/93676174172956086458

碩士 === 國立臺灣海洋大學 === 生物科技研究所 === 100 === In this dissertation, bimetallic platinum/gold nanoparticles (Pt/Au NPs) were found to exhibit peroxidase mimetic activity, and the deposition of mercury was found to switch the enzymatic activity to catalase-like. Based on this phenomenon, we developed a new method for detecting mercury ions through the deposition of mercury ions on bimetallic Pt/Au NPs to switch the catalytic activity of Pt/Au NPs. Pt/Au NPs were easy to prepare through reduction of Au3+ and Pt4+ by sodium citrate in a one-pot synthesis. The peroxidase catalytic activity of the Pt/Au NPs was controlled by varying the ratios of Pt to Au. The Pt0.1/Au NPs (prepared with the [Au3+]/[Pt4+] molar ratio of 9.0/1.0) showed excellent oxidation catalysis for the H2O2-mediated oxidation of Amplex Red (AR) to resorufin. The peroxidase catalytic activity of Pt0.1/Au NPs was switched to catalase-like in the presence of mercury ions in a 5.0 mM tris(hydroxymethyl)aminomethane (Tris)-borate solution (pH 7.0) through the deposition of Hg on the particle surfaces owing to the strong AuHg metallic bond. Under optimal solution conditions[5.0 mM Tris-borate (pH 7.0), H2O2 (50 mM), and AR (10 M)] and in the presence of the masking agents polyacrylic acid and tellurium nanowires (Te NW), the Pt0.1/Au NPs allowed the selective detection of inorganic mercury (Hg2+) and methylmercury ions (MeHg+) at concentrations as low as several nanomolars. This simple, fast, and cost-effective system enabled selective determination of the concentrations of Hg2+ and MeHg+ in tap, pond, and stream waters.