Ultrasensitive, label-free, and real-time immunodetection using silicon field-effect transistors

Abstract

Ultrasensitive, label-free, and real-time prostate-specific antigen (PSA) sensor was developed using n -type silicon nanowire-based structures configured as field-effect transistors using the conventional “top-down” semiconductor processes. Specific binding of PSA with antibody of PSA (anti-PSA) immobilized on the Si surface through covalent linkage leads to a conductivity change in response to variations of electric field at the surface. The conductance changes depending on PSA concentrations and p H values in solution according to isoelectric point of PSA provide the evidence of the real-time detection of 1 fg ∕ ml PSA. The authors also explored the sensitivity of PSA immunodetection depending on both Si–field-effect transistors (FET) dimensions and doping concentrations to provide strategy for fabrication of an ultrasensitive Si-FET biosensor.