title: A colorimetric assay for measuring iodide using Au@Ag core-shell nanoparticles coupled with Cu(2+).
abstract: Au@Ag core-shell nanoparticles (NPs) were synthesized and coupled with copper ion (Cu(2+)) for the colorimetric sensing of iodide ion (I(-)). This assay relies on the fact that the absorption spectra and the color of metallic core-shell NPs are sensitive to their chemical ingredient and dimensional core-to-shell ratio. When I(-) was added to the Au@Ag core-shell NPs-Cu(2+) system/solution, Cu(2+) can oxidize I(-) into iodine (I2), which can further oxidize silver shells to form silver iodide (AgI). The generated Au@AgI core-shell NPs led to color changes from yellow to purple, which was utilized for the colorimetric sensing of I(-). The assay only took 10 min with a lowest detectable concentration of 0.5 μM, and it exhibited excellent selectivity for I(-) over other common anions tested. Furthermore, Au@Ag core-shell NPs-Cu(2+) was embedded into agarose gels as inexpensive and portable "test strips", which were successfully used for the semi-quantitation of I(-) in dried kelps.
authors.affiliation: State Key Laboratory of Heavy Oil Processing & College of Science, China University of Petroleum (East China), Qingdao 266555, China. Electronic address: xmuzjb@163.com.
authors.forename: Jingbin
authors.initials: J
authors.lastname: Zeng
authors.affiliation: State Key Laboratory of Heavy Oil Processing & College of Science, China University of Petroleum (East China), Qingdao 266555, China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Cao
authors.affiliation: The Key Laboratory of Analysis and Detection Technology for Food Safety of the MOE, College of Chemistry, Fuzhou University, Fuzhou 350002, China.
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Lu
authors.affiliation: Karlsruhe Institute of Technology (KIT), Institute for Biological Interfaces (IBG-1), Hermann-von-Helmholtz-Platz, 76344 Eggenstein-Leopoldshafen, Germany.
authors.forename: Xu-Dong
authors.initials: XD
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Heavy Oil Processing & College of Science, China University of Petroleum (East China), Qingdao 266555, China.
authors.forename: Qianru
authors.initials: Q
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Heavy Oil Processing & College of Science, China University of Petroleum (East China), Qingdao 266555, China.
authors.forename: Cong-Ying
authors.initials: CY
authors.lastname: Wen
authors.affiliation: State Key Laboratory of Heavy Oil Processing & College of Science, China University of Petroleum (East China), Qingdao 266555, China.
authors.forename: Jian-Bo
authors.initials: JB
authors.lastname: Qu
authors.affiliation: State Key Laboratory of Heavy Oil Processing & College of Science, China University of Petroleum (East China), Qingdao 266555, China.
authors.forename: Cunguang
authors.initials: C
authors.lastname: Yuan
authors.affiliation: State Key Laboratory of Heavy Oil Processing & College of Science, China University of Petroleum (East China), Qingdao 266555, China. Electronic address: zfyancat@upc.edu.cn.
authors.forename: Zi-Feng
authors.initials: ZF
authors.lastname: Yan
authors.affiliation: Department of Chemistry and the MOE Key Laboratory of Spectrochemical Analysis & Instrumentation, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Chen
mesh_terms: D002413:Cations, Divalent / Q000737:chemistry; D003124:Colorimetry / Q000191:economics / Q000379:methods*; D003300:Copper / Q000737:chemistry*; D060766:Drinking Water / Q000032:analysis*; D006046:Gold / Q000737:chemistry*; D007454:Iodides / Q000032:analysis*; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D011934:Reagent Strips / Q000032:analysis; D012685:Sepharose / Q000737:chemistry; D012834:Silver / Q000737:chemistry*
chemical_list: D002413:Cations, Divalent; D060766:Drinking Water; D007454:Iodides; D011934:Reagent Strips; D012834:Silver; D006046:Gold; D003300:Copper; D012685:Sepharose
keywords: Agarose gels; Au@Ag core–shell nanoparticles; Colorimetric; Dried kelps; Iodide ion