Label-free protein recognition two-dimensional array using nanomechanical sensors

We demonstrate two-dimensional multiplexed real-time, label-free anti body-antigen binding assays by optically detecting nanoscale motions of two-dimensional arrays of microcantilever beams. Prostate specific antigen (PSA) was assayed using antibodies covalently bound to one surface of the cantilevers by two different surface chemistries, while the nonreaction surfaces were passivated by poly(ethylene glycol)-silane. PSA as low as 1 ng/mL was detected while 2 mg/mu l of bovine serum albumin induced only negligible deflection on the cantilevers.