Continuous, Real-Time Monitoring of Cocaine in Undiluted Blood Serum via a Microfluidic, Electrochemical Aptamer-Based Sensor

• Published in: Journal of the American Chemical Society Vol. 131; no. 12; pp. 4262 - 4266
• Main Authors: Swensen, James S, Xiao, Yi, Ferguson, Brian S, Lubin, Arica A, Lai, Rebecca Y, Heeger, Alan J, Plaxco, Kevin W, Soh, H. Tom
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 01.04.2009
• Subjects: Aptamers, Nucleotide; Biosensing Techniques - instrumentation; Cocaine - analysis; Cocaine - blood; DNA - chemistry; Dose-Response Relationship, Drug; Electrochemistry - instrumentation; Electrochemistry - methods; Equipment Design; Humans; Microfluidic Analytical Techniques; Microfluidics - instrumentation; Optics and Photonics; Serum; Time Factors
• ISSN: 0002-7863; 1520-5126
• DOI: 10.1021/ja806531z

The development of a biosensor system capable of continuous, real-time measurement of small-molecule analytes directly in complex, unprocessed aqueous samples has been a significant challenge, and successful implementation has been achieved for only a limited number of targets. Toward a general solution to this problem, we report here the Microfluidic Electrochemical Aptamer-based Sensor (MECAS) chip wherein we integrate target-specific DNA aptamers that fold, and thus generate an electrochemical signal, in response to the analyte with a microfluidic detection system. As a model, we demonstrate the continuous, real-time (∼1 min time resolution) detection of the small-molecule drug cocaine at near physiological, low micromolar concentrations directly in undiluted, otherwise unmodified blood serum. We believe our approach of integrating folding-based electrochemical sensors with miniaturized detection systems may lay the groundwork for the real-time, point-of-care detection of a wide variety of molecular targets.