3 years ago

Photoelectrochemical determination of the activity of alkaline phosphatase by using a CdS@graphene conjugate coupled to CoOOH nanosheets for signal amplification

Weisu Kong, Qingqing Tan, Haiyu Guo, Han Sun, Xia Qin, Fengli Qu

Abstract

A method is described for photoelectrochemical determination of the activity of alkaline phosphatase (ALP). It employs an indium tin oxide (ITO) electrode modified a CdS quantum dots@graphene (CdS@GR) composite and hexagonal cobalt oxyhydroxide (CoOOH) nanosheets. The CdS@GR nanocomposite was synthesized by assembling the CdS quantum dots onto a GO film to receive a basic photocurrent response of the ITO. This is further improved by covering it with CoOOH nanosheets. Secondly, 2-phospho-L-ascorbic acid (AAP) is added as a substrate for ALP. Its hydrolysis yields ascorbic acid which reduces CoOOH to form cobalt(II) ion. As a result, the CoOOH nanosheets decompose. This is accompanied by a reduction of the photocurrent. The effect was used to design a selective and sensitive assay of determination of the activity of ALP. Under the optimized experimental conditions, response is linear in the 10 to 300 U·L−1ALP activity range. The detection limit is 1.5 U·L−1 at a signal-to-noise ratio of 3.

Graphical abstract

Indium tin oxide (ITO) was coted with CdS@graphene and CoOOH to obtain a material with superior photoelectrochemical properties. The detection of alkaline phosphatase (ALP) was accomplished by using 2-phospho-L-ascorbic acid (AAP) which is hydrolyzed by ALP to release ascorbic acid (AA) which reduces CoOOH to Co2+.

Publisher URL: https://link.springer.com/article/10.1007/s00604-018-3182-y

DOI: 10.1007/s00604-018-3182-y

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