Ultrasensitively photoelectronchemical determination of cysteine and coenzyme A with CdSe quantum dots-covered ZnO nanorods photoelectrode

摘要

A new photoelectrochemical system was fabricated by incorporating the cysteine or coenzyme A as electron donor into photoelectrochemical reaction of the nanostructured CdSe/ZnO photoelectrode to develop a photoelectrochemical method for the ultrasensitive determination of the cysteine and coenzyme A. The CdSe/ZnO photoelectrode was prepared by covering the CdSe quantum dots on the surface of ZnO nanorods arrays. The property of photoelectrode was investigated as photosensitive interface and electron acceptor, and its photoelectrochemical reaction was study with substrate. Under the 20 mW/cm(2) 410 nm visible light illuminations, the sensitive photocurrent response to the cysteine or coenzyme A was obtained at bias voltage 0 V. After the optimized experimental conditions, the photocurrent was proportional to the concentration of cysteine or the logarithm of coenzyme A concentration in the range of 1.00 x 10(-2)-20.0 mu mol/L and 2.00 x 10(-2)-50.0 mu mol/L, respectively. The detection sensitivity was 71.7 nA/mu mol/L for cysteine. The detection limit was estimated to be 6.00 x 10(-3) mu mol/L (S/N = 3) and 1.00 x 10(-2) mu mol/L (S/N = 3) for cysteine and coenzyme A, respectively. The other amino acids or common coenzymes were not interfering with the determination of cysteine and coenzyme A. Compared with other methods for the determination of cysteine and coenzyme A, the proposed method exhibits a wide measurement range, high sensitivity, and low cost. (c) 2018 Elsevier Ltd. All rights reserved.