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

Towards a general solution to this problem, we report here the Microfluidic Electrochemical Aptamer-based Sensor chip wherein we integrate target-specific DNA aptamers that fold, and generate an electrochemical signal, in response to the analyte with a microfluidic detection system

James S. Swensen

2009

Scholarcy highlights

  • Previously-developed strategies for the real-time detection of small-molecule analytes have typically made use of sensors that measure changes in mass, index of refraction or charge that occur when the target molecules bind to the sensor surface
  • We report the development of the Microfluidic Electrochemical Aptamer-based Sensor chip, wherein we integrate an E-AB sensor within a miniaturized electrochemical cell, to achieve continuous, real-time monitoring of cocaine in undiluted, unmodified blood serum at physiologically-relevant concentrations and with physiologically-relevant time resolution
  • The working electrodes are functionalized with a 32-base cocaine-binding aptamer that is partially unfolded in the absence of its target molecule
  • We found that the chip rapidly responds to micromolar concentrations of cocaine in undiluted, unmodified blood serum: when challenged with 250 μM cocaine doped in serum the faradaic current increases by ~38% relative to the current observed in the absence of target
  • Sensor regeneration allows for the MECAS sensor reuse at 10 μM cocaine for more than three times in undiluted blood serum with a mean recovery of > 96% of the original signal before significant degradation is observed
  • The apparent stability of the sensing aptamer may be a result of its surface immobilization and methylene blue modification; we have previously shown that a similar electrochemical DNA-based sensor can be stored in blood serum for more than a week at room temperature without exhibiting substantial degradation
  • Microfluidic technology provides an important advantage; because the sample stream is flowing at a rate that fills the entire chamber in just 4.5 seconds, in comparison to macro-scale counterparts, the miniaturized detection chamber readily allows continuous delivery of the analyte to the sensor surface

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