title: Aptamer functionalized microcantilever sensors for cocaine detection.
abstract: A cocaine-specific aptamer was used as a receptor molecule in a microcantilever-based surface stress sensor for detection of cocaine molecules. An interferometric technique that relies on measuring differential displacement between two microcantilevers (a sensing/reference pair) was utilized to measure the cocaine/aptamer binding induced surface stress changes. Sensing experiments were performed for different concentrations of cocaine from 25 to 500 μM in order to determine the sensor response as a function of cocaine concentration. In the lower concentration range from 25 to 100 μM, surface stress values increased proportionally to coverage of aptamer/cocaine complexes from 11 to 26 mN/m. However, as the cocaine concentration was increased beyond 100 μM, the surface stress values demonstrated a weaker dependence on the affinity complex surface coverage. On the basis of a sensitivity of 3 mN/m for the surface stress measurement, the lowest detectable threshold for the cocaine concentration is estimated to be 5 μM. Sensing cantilevers could be regenerated and reused because of reversible thermal denaturation of aptamer.
authors.affiliation: Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: Kyungho
authors.initials: K
authors.lastname: Kang
authors.forename: Ashish
authors.initials: A
authors.lastname: Sachan
authors.forename: Marit
authors.initials: M
authors.lastname: Nilsen-Hamilton
authors.forename: Pranav
authors.initials: P
authors.lastname: Shrotriya
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D003042:Cocaine / Q000032:analysis*; D013499:Surface Properties
chemical_list: D052157:Aptamers, Nucleotide; D003042:Cocaine