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Aptamer Functionalized Microcantilever Sensors for Cocaine Detection

2011; American Chemical Society; Volume: 27; Issue: 23 Linguagem: Inglês

10.1021/la202067y

1520-5827

Kyung-Ho Kang, Ashish Sachan, Marit Nilsen‐Hamilton, Pranav Shrotriya,

Molecular Junctions and Nanostructures

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.