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An Enzyme- and Label-Free Fluorescence Aptasensor for Detection of Thrombin Based on Graphene Oxide and G-Quadruplex

1
College of Life Sciences, Shaanxi Normal University, Xi´an 710119, China
2
School of Computer Science, Shaanxi Normal University, Xi´an 710119, China
*
Author to whom correspondence should be addressed.
Sensors 2019, 19(20), 4424; https://doi.org/10.3390/s19204424
Received: 9 September 2019 / Revised: 1 October 2019 / Accepted: 10 October 2019 / Published: 12 October 2019
(This article belongs to the Section Biosensors)
An enzyme- and label-free aptamer-based assay is described for the determination of thrombin. A DNA strand (S) consisting of two parts was designed, where the first (Sa) is the thrombin-binding aptamer and the second (Se) is a G-quadruplex. In the absence of thrombin, Sa is readily adsorbed by graphene oxide (GO), which has a preference for ss-DNA rather than for ds-DNA. Upon the addition of the N-methyl-mesoporphyrin IX (NMM), its fluorescence (with excitation/emission at 399/610 nm) is quenched by GO. In contrast, in the presence of thrombin, the aptamer will bind thrombin, and thus, be separated from GO. As a result, fluorescence will be enhanced. The increase is linear in the 0.37 nM to 50 µM thrombin concentration range, and the detection limit is 0.37 nM. The method is highly selective over other proteins, cost-effective, and simple. In our perception, it represents a universal detection scheme that may be applied to other targets according to the proper choice of the aptamer sequence and formation of a suitable aptamer-target pair. View Full-Text
Keywords: thrombin detection; fluorescence; aptamer; N-methyl-mesoporphyrin IX (NMM) thrombin detection; fluorescence; aptamer; N-methyl-mesoporphyrin IX (NMM)
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Wei, Y.; Wang, L.; Zhang, Y.; Dong, Y. An Enzyme- and Label-Free Fluorescence Aptasensor for Detection of Thrombin Based on Graphene Oxide and G-Quadruplex. Sensors 2019, 19, 4424.

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