Multiple label-free biodetection and quantitative DNA-binding assays on a nanomechanical cantilever array

TLDR

The study presents a cantilever microarray capable of detecting multiple unlabeled biomolecules at nanomolar concentrations within minutes. The platform uses microfabricated silicon cantilevers where ligand‑receptor binding induces nanomechanical bending that is optically detected in situ. The arrays achieve sequence‑specific detection of unlabeled DNA in 80‑fold excess of nonmatching background, discriminate 3′/5′ overhangs, resolve femtomole amounts at 75 nM, and provide mechanical thermodynamic data consistent with solution measurements.

Abstract

We report a microarray of cantilevers to detect multiple unlabeled biomolecules simultaneously at nanomolar concentrations within minutes. Ligand-receptor binding interactions such as DNA hybridization or protein recognition occurring on microfabricated silicon cantilevers generate nanomechanical bending, which is detected optically in situ . Differential measurements including reference cantilevers on an array of eight sensors can sequence-specifically detect unlabeled DNA targets in 80-fold excess of nonmatching DNA as a background and discriminate 3′ and 5′ overhangs. Our experiments suggest that the nanomechanical motion originates from predominantly steric hindrance effects and depends on the concentration of DNA molecules in solution. We show that cantilever arrays can be used to investigate the thermodynamics of biomolecular interactions mechanically, and we have found that the specificity of the reaction on a cantilever is consistent with solution data. Hence cantilever arrays permit multiple binding assays in parallel and can detect femtomoles of DNA on the cantilever at a DNA concentration in solution of 75 nM.