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An Label-Free Aptamer-Fluorophore Assembly for Rapid and Specific Detection of Cocaine in Biofluids

NCJ Number
Analytical Chemistry Volume: 86 Issue: 22 Dated: November 2014 Pages: 11100-11106
Date Published
November 2014
7 pages

This article reports a rapid and specific aptamer-based method for one-step cocaine detection with minimal reagent requirements.


The study demonstrated that the sensor developed in the project can detect cocaine within seconds at concentrations as low as 200 nM, which is 50-fold lower than existing assays based on target-induced conformational change. More importantly, the assay used achieved cocaine detection in body fluids, with a limit of detection of 10.4, 18.4, and 36 ìM in undiluted saliva, urine, and serum samples, respectively. The feasibility of aptamer-based detection has been demonstrated with sensors that operate via target-induced conformational change mechanisms, but these have generally exhibited limited target sensitivity. The authors discovered that the cocaine-binding aptamer MNS-4.1 can also bind the fluorescent molecule 2-amino-5,6,7-trimethyl-1,8-naphthyridine (ATMND) and thereby quench its fluorescence. They subsequently introduced sequence changes into MNS-4.1 to engineer a new cocaine-binding aptamer (38-GC) that exhibits higher affinity to both ligands, with reduced background signal and increased signal gain. Using this aptamer, the authors developed a new sensor platform that relies on the cocaine-mediated displacement of ATMND from 38-GC as a result of competitive binding. (Publisher abstract modified)

Date Published: November 1, 2014