Mass-sensing, multianalyte microarray immunoassay with imaging detection. Clin. Chem

costs by decreasing reagent consumption, but it is less apparent that miniaturized assays can simultaneously exceed the sensitivity of macroscopic techniques by analyte “harvesting ” to exploit the total analyte mass available in a sample. Capture reagents (avidin or anti-bodies) immobilized in 200-mm diameter zones are shown to substantially deplete analyte from a liquid sample during a 1–3-h incubation, and the assays that result sense the total analyte mass in a sample rather than its concentration. Detection of as few as 105 mole-cules of analyte per zone is possible by fluorescence imaging in situ on the solid phase using a near-infrared dye label. Single and multianalyte mass-sensing sand-wich array assays of the IgG subclasses show the sensi-tivity and specificity of ELISA methods but use les