A highly sensitive electrochemical aptasensor for cocaine detection based on CRISPR-Cas12a and terminal deoxynucleotidyl transferase as signal amplifiers

Elsevier

Available online 29 January 2022, 123276

Talanta
doi.org/10.1016/j.talanta.2022.123276Get rights and content

Highlights

Using the signal amplification elements of TdT and CRISPR-Cas12a, an electrochemical aptasensor was introduced.

The biosensor indicated a vast linear detection range of 40 pM–150 nM with a LOD of 15 pM to cocaine.

The approach has the advantages of very low detection limit with simple operation.

The biosensor holds great electrochemical performance to be used for cocaine detection in actual samples.

Abstract

Cocaine is one of the mainly used illegal drugs in the world. Using the signal amplification elements of terminal deoxynucleotidyl transferase (TdT) and CRISPR-Cas12a, a highly sensitive and simple electrochemical aptasensor was introduced for cocaine quantification. When, no cocaine existed in the sample, the 3′-end of complementary strand of aptamer (CS) was extended by TdT, leading to the activation of CRISPR-Cas12a and remaining of very short oligonucleotides on the working electrode. So, the current signal was remarkably promoted. With the presence of cocaine, CS left the electrode surface. Thus, nothing changed following the incubation of TdT and CRISPR-Cas12a and the Aptamer/Cocaine complex presented on the electrode. Consequently, the [Fe(CN)6]3-/4- could not freely reach the electrode surface and the signal response was weak. Under optimal situations, the biosensor revealed a wide linear relation from 40 pM to 150 nM with detection limit of 15 pM for cocaine. The sensitivity of the analytical system was comparable and even better than other reported methods for cocaine detection. The designed method displayed excellent cocaine selectivity. The aptasensor could work well for cocaine assay in serum samples. So, the aptasensor is expected to be an efficient analytical method with broad applications in the determination of diverse analytes.

Keywords

Serum

CRISPR-Cas12a

Aptamer

TdT

Signal amplification

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© 2022 Published by Elsevier B.V.

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