Aptamer-based microcantilever biosensor for ultrasensitive detection of tumor marker nucleolin.

We present an aptamer-based microcantilever biosensor for label-free detection of nucleolin. The sensor cantilevers in the microcantilever array were functionalized with nucleolin aptamer (AS1411) while the reference cantilevers were modified by 6-mercapto-1-hexanol (MCH) to eliminate environmental disturbances. The interaction between nucleolin and AS1411 induced surface stress changes, resulting in a differential deflection between sensor and reference cantilevers. The amplitude of differential cantilever deflection had a good linear relationship with the nucleolin concentration ranging from 10 nM to 250 nM with a correlation coefficient of 0.999. The detection limit was about 1.0 nM, at a signal-to-noise ratio of 3. The aptamer-based microcantilever sensor demonstrated good selectivity and was facile, rapid, and reagentless. Our results show the potential for the application of microcantilever biosensor system as a powerful tool to detect tumor markers with high sensitivity and specificity.