Quantitative Detection of Protein Using a Top-gate Carbon Nanotube Field Effect Transistor

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.

Review: Carbon nanotube based electrochemical sensors for biomolecules

“…Another study detected pig serum albumin as a test molecule to demonstrate a coating method that would reduce unwanted adsorption onto the CNT in the FET. Coating the SWCNT with silicon nitride after adsorbing an antibody shielded it from the effects of oxygen and water that can adsorb to the CNT, changing the gate voltage [87]. The limit of detection was 5 nM albumin.…”

Quantification of the affinities and kinetics of protein interactions using silicon nanowire biosensors

“…In this work, we used device solution transconductance ( g m = (∂ I ds )/(∂ V g,sol )| V ds ) to normalize the sensor responses 19,20 . This calibration was combined with Langmuir isotherms to form an analytical model (equation (1)) that could be used to determine the molecular binding affinities 21 . The device threshold voltage shift Δ V T can be expressed as $$\frac{\Delta I_{\mathrm{ds}}}{g_{\mathrm{normalm}}}=\Delta V_{\mathrm{normalT}}=\frac{q_{\mathrm{normalA}}}{C_0}{\left[B\right]}_{\max }\times \frac{\left[A\right]}{\left[A\right]+K_{\mathrm{normalD}}}$$ where q A is the electric charge contributed by the adsorbed analytes, K D is the equilibrium (dissociation) constant, C 0 is the analyte/channel capacitive coupling, and [ A ] and [ B ] max represent the concentrations of analytes in bulk solution and the maximum surface density of functional binding sites on the Si-NW, respectively (Fig.…”

Strategies for enhancing the analytical performance of nanomaterial-based sensors

“…Table 4 shows the main conclusions of the most significant works where different data analysis approaches are suggested to minimize the variability of nanomaterial-based sensors (i.e. The mechanism of Langmuir adsorption theory was used to relate the monolayer adsorption of an antigen (interactant/adsorbate) on their specific antibodies (ligand/adsorbent) fixed on the top gate of NT-FET devices [63] with specific surface coverage (h), and the Langmuir isotherm equation is given by The Langmuir adsorption model is the model used most to fit the experimental data obtained from nanomaterial-based sensors in order to minimize the deviceto-device variation, and its general concepts should be known.…”