A label-free aptamer-fluorophore assembly for rapid and specific detection of cocaine in biofluids

Daniel Roncancio, Haixiang Yu, Xiaowen Xu, Shuo Wu, Ran Liu, Joshua Debord, Xinhui Lou, Yi Xiao

Research output: Contribution to journalArticlepeer-review

92 Scopus citations


We report a rapid and specific aptamer-based method for one-step cocaine detection with minimal reagent requirements. 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. We have 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. We 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, we have developed a new sensor platform that relies on the cocaine-mediated displacement of ATMND from 38-GC as a result of competitive binding. We demonstrate that our sensor 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, our assay achieves successful cocaine detection in body fluids, with a limit of detection of 10.4, 18.4, and 36 μM in undiluted saliva, urine, and serum samples, respectively.

Original languageEnglish (US)
Pages (from-to)11100-11106
Number of pages7
JournalAnalytical Chemistry
Issue number22
StatePublished - Nov 18 2014
Externally publishedYes

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Publisher Copyright:
© 2014 American Chemical Society.


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