Logic Control of Enzyme-Like Gold Nanoparticles for Selective Detection of Lead and Mercury Ions

• Published in: Analytical chemistry (Washington) Vol. 86; no. 4; pp. 2065 - 2072
• Main Authors: Lien, Chia-Wen, Tseng, Yu-Ting, Huang, Chih-Ching, Chang, Huan-Tsung
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 18-02-2014
• Subjects: Analytical chemistry; Aqueous solutions; Construction; Enzymes; Gates (circuits); Gold; Gold - chemistry; Heavy Ions; Integrated circuits; Ions; Lead (metal); Lead - analysis; Logic; Mercury (metal); Mercury - analysis; Metal Nanoparticles - chemistry; Nanoparticles; Nanostructure; Oxidation; Peroxidase - chemistry; Platinum; Water Pollutants, Chemical - analysis
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/ac4036789

Functional logic gates based on lead ions (Pb2+) and mercury ions (Hg2+) that induce peroxidase-like activities in gold nanoparticles (Au NPs) in the presence of platinum (Pt4+) and bismuth ions (Bi3+) are presented. The “AND” logic gate is constructed using Pt4+/Pb2+ as the input and the peroxidase-like activity of the Au NPs as the output; this logic gate is denoted as “Pt4+/Pb2+(AND)–Au NPPOX”. When Pt4+ and Pb2+ coexist, strong metallophilic interactions (between Pt and Pb atoms/ions) and aurophilic interactions (between Au and Pb/Pt atoms/ions) result in significant increases in the deposition of Pt and Pb atoms/ions onto the Au NPs, leading to enhanced peroxidase-like activity. The “INHIBIT” logic gate is fabricated by using Bi3+ and Hg2+ as the input and the peroxidase-like activity of the Au NPs as the output; this logic gate is denoted as “Bi3+/Hg2+(INHIBIT)–Au NPPOX”. High peroxidase-like activity of Au NPs in the presence of Bi3+ is a result of the various valence (oxidation) states of Bi3+ and Au (Au+/Au0) atoms on the nanoparticle’s surface. When Bi3+ and Hg2+ coexist, strong Hg–Au amalgamation results in a large decrease in the peroxidase-like activity of the Au NPs. These two probes (Pt4+/Pb2+(AND)–Au NPPOX and Bi3+/Hg2+(INHIBIT)–Au NPPOX) allow selective detection of Pb2+ and Hg2+ down to nanomolar quantities. The practicality of these two probes has been validated by analysis of Pb2+ and Hg2+ in environmental water samples (tap water, river water, and lake water). In addition, an integrated logic circuit based on the color change (formation of reddish resorufin product) and generation of O2 bubbles from these two probes has been constructed, allowing visual detection of Pb2+ and Hg2+ in aqueous solution.