Observation of an anomalous mass effect in microcantilever-based biosensing caused by adsorbed DNA.

Quantifying adsorbed mass using resonance frequency variation in a microcantilever is an established technique. However, when applied to adsorbed mass determination in liquids, the resonance frequency variations represent several contributions. While the discrepancy between the apparent and real adsorbed mass is negligible for measurements in air, it can be significant in liquids. Here we present an anomalous effect of adsorbed DNA on the resonance frequency of microcantilevers which cannot be explained using current models. Our findings suggest that the measured frequency shifts may be explained on the basis of a hydrodynamic interaction caused by the adsorbed molecules on the cantilever.