A Microfluidic Affinity Cocaine Sensor

We present a novel microfluidic sensor that is capable of detecting trace cocaine concentrations and is fully regenerable at modest temperatures. The sensor exploits affinity aptamers (synthetic DNA/RNA oligonucleotides), labeled with a fluorophore and immobilized onto polymer microbeads as a highly sensitive cocaine receptor medium. The device demonstrates the capability of detecting native cocaine concentrations as low as 100 pM, with an eight-orders-of-magnutide dynamic range. By way of enriching rarefied cocaine samples, this detection limit is further improved to 10 pM. Additionally, the device utilizes temperature-dependent reversibility of aptamer-analyte binding to regenerate the sensor surface at a relatively modest temperature (40degC). This feature allows repeated reuse of the sensor without loss in functionality.