Aptamer sensor for cocaine using minor groove binder based energy transfer

We report on an optical aptamer sensor for cocaine detection. The cocaine sensitive fluorescein isothiocyanate (FITC)-labeled aptamer underwent a conformational change from a partial single-stranded DNA with a short hairpin to a double-stranded T-junction in the presence of the target. The DNA minor groove binder Hoechst 33342 selectively bound to the double-stranded T-junction, bringing the dye within the Förster radius of FITC, and therefore initiating minor groove binder based energy transfer (MBET), and reporting on the presence of cocaine. The sensor showed a detection limit of 0.2 μM. The sensor was also implemented on a carboxy-functionalized polydimethylsiloxane (PDMS) surface by covalently immobilizing DNA aptamers. The ability of surface-bound cocaine detection is crucial for the development of microfluidic sensors.

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► Cocaine is detected using an optical aptamer sensor.
► Aptamer changed from a partial single-stranded DNA with a short hairpin to a double-stranded T-junction when exposed to cocaine.
► Report the presence of cocaine using minor groove binder based energy transfer (MBET).
► MBET is between Hoechst 33342 bound to double-stranded T-junction and aptamer tethered FITC.