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Colorimetric Strategy for Highly Sensitive and Selective Simultaneous Detection of Histidine and Cysteine Based on G-Quadruplex-Cu(II) Metalloenzyme

Wu, Changtong, Fan, Daoqing, Zhou, Chunyang, Liu, Yaqing, Wang, Erkang
Analytical chemistry 2016 v.88 no.5 pp. 2899-2903
DNA, catalytic activity, colorimetry, copper, cysteine, detection limit, histidine
In this present work, we proposed a colorimetric strategy for simultaneous detection of histidine and cysteine based on G-quadruplex-Cu(II) metalloenzyme for the first time. Because of the adding of histidine or cysteine, the formation of G-quadruplex-Cu(II) metalloenzyme will be disturbed, thus the catalytic activity to TMB-H₂O₂ reaction is inversely proportional to the concentration of histidine or cysteine. With this strategy, the limit of detection in experimental measurement for histidine and cysteine is 10 nM and 5 nM, respectively, which are both lower than previous colorimetric arrays. With the help of NEM, cysteine is alkylated and the reaction between Cu²⁺ is inhibited, so the selectivity can also be guaranteed. The cost is quite low since the developed array is label free and enzyme free by using low-cost DNA and Cu²⁺. More importantly, the colorimetric detection operation is very simple without any further modification process.