A functionalized nanofluidic channel and method for functionalization that provides control over the ionic environment and geometry of the nanofluidic channel with the immobilization of biomolecules on the inner surface of the channel and use of high ionic concentration solutions. In one embodiment, the surface charge of the nanochannel is controlled with the immobilization of a protein such as streptavidin in the nanochannel. In another embodiment, the biomolecules are receptors and changes in nanochannel conductance indicates ligand binding events. The functionalized nanofluidic channel can be easily adapted for use with microchannel arrays.