Photoelectrochemical aptasensor for thrombin based on Au-rGO-CuS as signal amplification elements
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ORIGINAL PAPER
Photoelectrochemical aptasensor for thrombin based on Au-rGO-CuS as signal amplification elements Lina Zou 1 & Lingxi Yang 2 & Yi Zhan 1 & Di Huang 1 & Baoxian Ye 1 Received: 8 October 2019 / Accepted: 7 June 2020 # Springer-Verlag GmbH Austria, part of Springer Nature 2020
Abstract A photoelectrochemical platform for thrombin determination was developed based on Au-rGO-CuS as multiple signal amplification elements. CuInS2 QDs was used to sensitize burr-shape TiO2 (b-TiO2) to obtain a strong photocurrent. Under the specific recognition between aptamer and thrombin, a sandwichlike structure was formed and the Au-rGO-CuS-labeled aptamer (S2@Au-rGO-CuS) was immobilized on the electrode surface. This induced a sharp decrease in photocurrent. The phenomenon is mainly due to the fact that CuS NPs can competitively consume the light energy and electron donor with CuInS2/b-TiO2. The rGO can increase the amount of CuS NPs and the Au NPs can accelerate charge transferring which depress the recombination of photogenerated electrons and holes in CuS to further enhance the competitive capacity of CuS. The sandwichlike structure has a steric hindrance effect. Therefore, the S2@Au-rGO-CuS has a multiple signal amplification function for thrombin determination. Under optimal conditions, the PEC aptasensor exhibited a wide linear concentration range from 0.1 pM to 10 nM with a low detection limit of 30 fM (S/N = 3) for thrombin. Besides, the designed aptasensor performed well in the assay of human serum sample, indicating good potential for the determination of thrombin in real samples. Keywords Photoelectrochemical . Aptasensor . Sandwich . Thrombin . CuInS2 . TiO2 . Au-rGO-CuS . Signal amplification
Introduction Photoelectrochemical (PEC) sensing determination is a developed technique with a lower background signal and noteworthy advantages in sensitivity [1, 2] due to the complete separation of the excitation signal and detection signal, wherein light is used to excite photoactive materials while the produced photocurrent as the determination signal [3, 4]. Photoactive materials with high photocurrent conversion efficiency are essential for ultrasensitive detection [5]. In order to get good performance photoactive materials, coupling
Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00604-020-04380-x) contains supplementary material, which is available to authorized users. * Lina Zou [email protected] 1
College of Chemistry, Zhengzhou University, Zhengzhou 450001, People’s Republic of China
2
Zhumadian Hydrology and Water Resource Survery Bureau of Henan Province, Zhumadian 463000, People’s Republic of China
different band gap semiconductors are frequently used [6]. This strategy can not only promote the utilization of white light but also facilitate charge separation, thus can improve the photocurrent conversion efficiency. Among this strategy, TiO2 NPs decorated with quantum dots (QDs) have been rapidly developed as an effective sensitization method [7, 8]. H
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