Analysis of Dopamine and Tyrosinase Activity on Ion‐Sensitive Field‐Effect Transistor (ISFET) Devices

Abstract

Dopamine (1) and tyrosinase (TR) activities were analyzed by using chemically modified ion-sensitive field-effect transistor (ISFET) devices. In one configuration, a phenylboronic acid functionalized ISFET was used to analyze 1 or TR. The formation of the boronate-1 complex on the surface of the gate altered the electrical potential associated with the gate, and thus enabled 1 to be analyzed with a detection limit of 7x10(-5) M. Similarly, the TR-induced formation of 1, and its association with the boronic acid ligand allowed a quantitative assay of TR to be performed. In another configuration, the surface of the ISFET gate was modified with tyramine or 1 to form functional surfaces for analyzing TR activities. The TR-induced oxidation of the tyramine- or 1-functionalized ISFETs resulted in the formation of the redox-active dopaquinone units. The control of the gate potential by the redox-active dopaquinone units allowed a quantitative assay of TR to be performed. The dopaquinone-functionalized ISFETs could be regenerated to give the 1-modified sensing devices by treatment with ascorbic acid.

Ion-Sensitive Field-Effect Transistor for Biological Sensing

“…The corresponding biosensors are based on the bi-enzyme system containing two enzymes, protease and oxidase. Recently, Freeman et al developed a chemically modified-ISFET fabricated by incorporating 3-aminophenylboronic acid for analyzing the behaviours of dopamine and tyrosinase (TR) [71]. Upon formation of the boronate–dopamine complex on the gate surface, variations in the electrical potential were clearly observed, and then the detection limit of 7 × 10 −5 M was determined, showing good performance of this system for the monitoring of dopamine and TR.…”

“…The method developed by Freeman et al . has demonstrated a label-free procedure for measuring TR activity with comparable sensitivity to previous methods [71]. A novel potentiometric biosensor allowing quantitative analysis of the proteinases through their esterase activity has been established by Biloivan et al [76].…”

Highly sensitive dopamine biosensors based on organic electrochemical transistors

“…Apart from the above methods, field effect transistors (FETs) have been found to be excellent transducers for the detection of dopamine. Recently, the dopamine detection by using ion-sensitive FET devices modified with phenylboronic acid has been reported (Freeman et al, 2007). An ultrasensitive dopamine FET sensor based on polysilicon nanowires has been demonstrated as well (Lin et al, 2008).…”

Impedimetric or Ion‐Sensitive Field‐Effect Transistor (ISFET) Aptasensors Based on the Self‐Assembly of Au Nanoparticle‐Functionalized Supramolecular Aptamer Nanostructures

“…Ion-sensitive field-effect transistor (ISFET) devices find growing interest as electronic transducers that follow biorecognition or biocatalytic transformations [25 -27]. The changes in the dielectric properties of the gate of the FET device as a result of the formation of antigenantibody [28,29] or protein-protein complexes [30], and the changes in the charge of the gate surface as a result of biocatalyzed transformations [31,32] or DNA hybridization [33 -35] were used to develop FET-based sensor devices. Also, the label-free detection of aptamer-substrate complexes was demonstrated by the dissociation of a duplex DNA through the formation of the aptamer-substrate complex on the gate surface of the FET device [6].…”