Electrical Detection of Silicon Binding Protein-Protein A Using a p-MOSFET Sensor

摘要

We have focused on silica binding protein(SBP)-tagged protein A as a key element for bio-sensing since this combined protein can act as an anchor for variety of target bio-molecules on Si and SiO_2 surfaces In this work, we confirmed the change in the surface potential with an attachment of SBP-tagged protein A on Si and SiO_2, and clearly observed an increase in conductivity of undoped poly-Si thin film on thermally -grown SiO_2 just after the attachment of silica binding protein-protein A on the surface. These results can be attributable to the change in the surface band bending of the poly-Si film. In p-channel FETs with a SiO_2/Si_3N_4 gate dielectric, the drain current was significantly decreased by the attachment of the SBP-tagged protein A. Observed decrease in the drain current can be interpreted in terms of screening of pre-existing negative charges at the interface between SiO_2 and Si_3N_4 and in the Si_3N_4 film with the attachment of electrically-polarized SBP-protein A.