title: Label-free colorimetric sensor for mercury(II) and DNA on the basis of mercury(II) switched-on the oxidase-mimicking activity of silver nanoclusters.
abstract: In this paper, a novel colorimetric biosensor for Hg(2+) and DNA molecules is presented based on Hg(2+) stimulated oxidase-like activity of bovine serum albumin protected silver clusters (BSA-Ag NCs). Under mild conditions, Hg(2+) activated BSA-Ag NCs to show high catalytic activity toward the oxidation of 3,3',5, 5'-tetramethylbenzidine (TMB) using ambient dissolved oxygen as an oxidant. The oxidase-like activity of BSA-Ag NCs was "switched-on" selectively in the presence of Hg(2+), which permitted a novel and facile colorimetric sensor for Hg(2+). As low as 25 nmol L(-1)Hg(2+) could be detected with a linear range from 80 nmol L(-1) to 50 mmol L(-1). In addition, the sensing strategy was also employed to detect DNA molecules. Hg(2+) is known to bind very strongly and specifically with two DNA thymine bases (T) to form thymine-Hg(2+)-thymine (T-Hg(2+)-T) base pairs. The hairpin-structure was disrupted and Hg(2+) ions were released after hybridization with the DNA target. By coupling the Hg(2+) switched-on the oxidase-mimicking activity of BSA-Ag NCs, we developed a novel label-free strategy for facile and fast colorimetric detection of DNA molecules. More important, target DNA can be detected as low as 10 nmol L(-1) with a linear range from 30 to 225 nmol L(-1). Compared with other methods, this method presents several advantages such as the independence of hydrogen peroxide, high sensitivity and good selectivity, avoiding any modification or immobilization of DNA, which holds a great potential of metal NCs for clinical application in biosensing and biotechnology.
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China. Electronic address: glwang@jiangnan.edu.cn.
authors.forename: Guang-Li
authors.initials: GL
authors.lastname: Wang
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Lu-Yi
authors.initials: LY
authors.lastname: Jin
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Xiu-Ming
authors.initials: XM
authors.lastname: Wu
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Yu-Ming
authors.initials: YM
authors.lastname: Dong
authors.affiliation: The Key Laboratory of Food Colloids and Biotechnology, Ministry of Education, School of Chemical and Material Engineering, Jiangnan University, Wuxi 214122, PR China.
authors.forename: Zai-Jun
authors.initials: ZJ
authors.lastname: Li
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D003124:Colorimetry; D004247:DNA / Q000032:analysis*; D008628:Mercury / Q000032:analysis*; D053768:Metal Nanoparticles; D018716:Molecular Mimicry; D010088:Oxidoreductases / Q000737:chemistry*; D012710:Serum Albumin, Bovine / Q000737:chemistry; D012835:Silver Nitrate / Q000737:chemistry*
chemical_list: D012710:Serum Albumin, Bovine; D004247:DNA; D012835:Silver Nitrate; D010088:Oxidoreductases; D008628:Mercury; C029823:mercuric acetate
keywords: Catalytic activity; DNA detection; Enzyme mimetics; Mercury(II) detection; Silver nanoclusters