Land-contrast self-referencing interferometric protein microarray

Abstract

We present a nonfluorescent protein microarray, the land-contrast BioCD, on which interferometric contrast is induced by a patterned substrate rather than by patterned protein. The substrate is an oxidized silicon wafer with etched spot patterns. Within the spots the SiO2 thickness is 140 nm and on the land it is 77 nm. The spot and the land have equal reflectance but opposite interferometric quadrature responses for protein layer. Protein is evenly immobilized on the entire chip and detected by reflectometry. The contrast between spot and land is directly converted to protein thickness.