Electrical detection of protein using gold nanoparticles and nanogap electrodes

A method of electrically detecting of protein described is developed using self-assembled multilayer gold nanoparticles (AuNPs) on a SiO₂/Si substrate between gold electrodes. Electrical measurements are performed at room temperature using a probe station. A monoclonal antibody is immobilized on the top surface of the first layer of AuNPs (14nm). The second layer of AuNPs is formed through specific binding among a target antigen [hepatitis C virus, (HCV)], the monoclonal antibody, and the conjugate of a AuNP-polyclonal antibody. Once the specific binding among the monoclonal antibody, target antigen, and polyclonal antibody occurs, a significant electric current is detected through multilayer self-assembled gold nanoparticles between nanogap electrodes. No significant current (<1 pA) can be measured through a monolayer of AuNPs. A significant difference between the IV curves of the monolayer and the multilayer of AuNPs is used to identify whether the target antigen exists in the tested sample.