Determination of Cysteine Using Cerium Dioxide-tetramethylbenzidine as a Colorimetric Probe
Oxidative cerium dioxide nanoclusters(CeO2NCs)were prepared by self-precipitation of inorganic precursor.3,3′,5,5′-tetramethylbenzidine(TMB)is oxidized by CeO2NCs to form quinone diimide(TMB2+)with a characteristic absorption peak at 652 nm,and cysteine(Cys)has a reducing effect on TMB2+.Based on these,a Cys determination method using CeO2 NCs-TMB as a colorimetric probe was established.Under the conditions of room temperature,1.0 μg/mL CeO2NCs,pH value 4.0,reaction time 18 min,and 1.2 mmol/L TMB,the absorbance of TMB2+decreased linearly with the increase of Cys concentration in the range of 3.0～50 μmol/L.This method was applied to determination of Cys in human serum samples with recoveries of 99.3％～106.2％.
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