Surface plasmon resonance sensors utilizing microfabricated channels

Surface plasmon resonance (SPR) scanning and imaging measurements have many applications in chemical and biological sensing. In this paper, we have used SPR to study protein adsorption onto chemically modified gold surfaces. We present a method for using a patterned photobiotin probe in microfluidic channels for sensing proteins with SPR. Each flow cell in a chip is 15 μm×90 μm×6 mm, giving a sample volume of 8 nl. The flow cell is created using conventional photolithographic and etching techniques, employing an adhesive UV resin to hold a fused silica coverslip in place. To improve the selectivity and label proteins, photobiotin patterns are modified by UV illumination at 365 nm onto self-assembled monolayers (SAMs) of cysteamine on gold in the fluidic channels. The specific adsorption of the protein avidin onto the photobiotin layer is monitored with the SPR scanning technique, which is extremely sensitive to the index of refraction of the adjacent medium.