A photoelectrochemical aptasensor constructed with core-shell CuS-TiO2 heterostructure for detection of microcystin-LR

Publication date: 15 October 2018
Source:Biosensors and Bioelectronics, Volume 117
Author(s): Yunfei Tang, Yun Chai, Xiaoqiang Liu, Lele Li, Liwei Yang, Peipei Liu, Yanmei Zhou, Huangxian Ju, Yunzhi Cheng
In this work, a CuS-TiO2 heterojunction composite was prepared by dispersedly depositing CuS nanoparticles on TiO2 nanospheres surface with a hydrothermal method, and was then used to construct a photoelectrochemical (PEC) aptasensor for sensitive detection of microcystin-LR (MC-LR) in aquatic environment. The energy bands of CuS nanoparticles and spherical anatase TiO2 were well matched, which enhanced the photo-to-current conversion efficiency. The composite exhibited the enhanced visible light absorption, the improved separation of photo-generated charges, and the reduced self-aggregation of CuS nanoparticles, leading to the enhanced photocurrent response. The PEC aptasensor was constructed by immobilizing CuS-TiO2 composite on ITO electrode with chitosan film that further covalently bound aminated aptamer. After the target, microcystin-LR (MC-LR) as an analyte model, was captured by the aptamer on the aptasensor, it could be oxidized by the photo-generated hole to impede the electron-hole recombination and further amplify the photocurrent. The PEC aptasensor showed superior analytical performance for MC-LR with a linear range of 5.0 × 10⁻⁵ nM to 250 nM and a detection limit of 2.0 × 10⁻⁵ nM. The detection results with the aptasensor for practical water samples indicated its promising application in environmental monitoring.



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