title: Ultrasensitive colorimetric detection of Cu2+ ion based on catalytic oxidation of L-cysteine.
abstract: As an essential element, copper ion (Cu(2+)) plays important roles in human beings for its participation in diverse metabolic processes as a cofactor and/or a structural component of enzymes. However, excessive uptake of Cu(2+) ion gives rise to the risk of certain diseases. So, it is important to develop simple ways to monitor and detect Cu(2+) ion. In this study, a simple, facile colorimetric sensor for the ultrasensitive determination of Cu(2+) ion was developed based on the following principle: L-cysteine and 1-chloro-2,4-dinitrobenzene (CDNB) could be conjugated to form the yellow product 2,4-dinitrophenylcysteine (DNPC), which was measurable at 355nm; however, upon addition of Cu(2+) ion, the absorbance of DNPC would be decreased owing to the Cu(2+) ion catalytic oxidation of L-cysteine to L-cystine in the presence of O2. Thus, the colorimetric detection of Cu(2+) ion could be achieved. The optimal pH, buffer, temperature and incubation time for the colorimetric sensor were obtained of pH 6.8 in 0.1M HEPES solution, 90 °C and 50 min, respectively. A good linearity within the range of 0.8-10 nM (r = 0.996) was attained, with a high detectability up to 0.5nM. Analyses of Cu(2+) ion in drinking water, lake water, seawater and biological samples were carried out and the method performances were found to agree well with that obtained by ICP-MS. The developed simple colorimetric sensor proved applicable for Cu(2+) ion determination in real samples with high sensitivity and selectivity.
authors.affiliation: Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China; University of Chinese Academy of Sciences, Beijing 100049, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Yin
authors.affiliation: Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China.
authors.forename: Bowei
authors.initials: B
authors.lastname: Li
authors.affiliation: Key Laboratory of Ecological Geochemistry, Ministry of Land and Resources, National Research Center for Geoanalysis, Beijing 100037, China.
authors.forename: Xiaochun
authors.initials: X
authors.lastname: Wang
authors.affiliation: Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China. Electronic address: wwzhang@yic.ac.cn.
authors.forename: Weiwei
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Coastal Environmental Processes and Ecological Remediation, Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, China. Electronic address: lxchen@yic.ac.cn.
authors.forename: Lingxin
authors.initials: L
authors.lastname: Chen
mesh_terms: D002413:Cations, Divalent / Q000032:analysis; D003124:Colorimetry / Q000379:methods*; D003300:Copper / Q000032:analysis*; D003545:Cysteine / Q000737:chemistry*; D060766:Drinking Water / Q000032:analysis; D006801:Humans; D060106:Lakes / Q000032:analysis; D057230:Limit of Detection; D010084:Oxidation-Reduction; D012623:Seawater / Q000032:analysis; D012758:Shellfish / Q000032:analysis
chemical_list: D002413:Cations, Divalent; D060766:Drinking Water; D003300:Copper; D003545:Cysteine
keywords: Catalytic oxidation; Colorimetric detection; Cu(2+) ion; l-cysteine