No abstract

High-stability sensing of proteins of pig serum albumin (PSA) was achieved using an insulator-covered carbonnanotube field-effect transistor (CNT-FET) with a top-gate structure. The sensitivity limit of this CNT-FET PSA sensor is at least 5 nmol/L PSA solution. A layer of silicon nitride deposited on the top-gate structure provides an n-type characteristic and a highly stable CNT-FET. Since the CNT is covered with a silicon nitride layer, it is isolated from oxygen, water, and other contaminants. The equilibrium constant of the PSA/ anti-PSA reaction, which indicates the strength of the binding energy between PSA and anti-PSA fixed on the Au top-gate electrode, was calculated to be 1.2 × 10 7 L/mol using the Langmuir equation fitting.

The effect of the selective adsorption of pig serum albumin as an antigen on the electrical properties of a carbon nanotube channel field effect transistor on which anti-pig serum albumin was immobilized as an antibody by physisorption in phosphate buffer solution has been investigated. We have succeeded in real-time detection of the adsorption of pig serum albumin on anti-pig serum albumin as a decrease in the conductance of the carbon nanotube channel field effect transistor, by a label-free process.