Electropolymerized Poly(toluidine blue O) Film Electrode for Potentiometric Biosensing

Abstract

In this study, we modified a poly(toluidine blue O) (TBO) film on a Au electrode by electropolymerization and investigated its electrical characteristics when used as a potentiometric biosensor. The fundamental properties of poly-TBO films such as immobilization density and thickness were clarified by atomic force microscopy (AFM) for different electropolymerization times. The poly-TBO film electrode with a spikelike surface, which was formed during electropolymerization, showed pH sensitivity (45.5 mV/pH) near the Nernstian response when used as a potentiometric sensor. This behavior is assumed to arise because the charge density at a spikelike film is higher than that at a smooth film. Thus, a platform based on a potentiometric biosensor with a poly-TBO film electrode can be used as a bioanalytical system to measure ionic behaviors that involve biomolecular recognition. This will enable the measurement of negatively charged sulfated glycosaminoglycan (sGAG), which is included in the extracellular matrix (ECM) generated from chondrocytes and is used as an important indicator in the development of articular cartilage in the field of regenerative medicine because of its electrostatic binding to positively charged TBO molecules.

Development of a Sensitive Self-Powered Glucose Biosensor Based on an Enzymatic Biofuel Cell

“…Next, poly(TBO) was electropolymerized on the rGO/GCE electrode surface, adapting a procedure from [ 31 ]. In particular, rGO/GCE was immersed in a solution containing 1 mM TBO and 0.1 M HCl and the electrode was swept from −0.2 to 0.6 V (vs. Ag/AgCl 3 M KCl) at a scan rate of 100 mV/s for 30 cycles.…”

Enzymatic recognition of hydrogen peroxide (H2O2) in human plasma samples using HRP immobilized on the surface of poly(arginine‐toluidine blue)‐ Fe3O4 nanoparticles modified polydopamine; A novel biosensor

“…Poly-L-arginine (P(Arg)) contains a guanidyl group with multidanate characteristics, which are able to form electrostatic interactions with negatively charged groups as well as hydrogen bonding. 34,35 Toluidine blue O (Tb), one of the phenoxazine biological dyes with amino-functional group 36 has been physically adsorbed on the surface of P(Arg) through π-π electronic interactions without changing the native structure of L-arginine. 37,38 Moreover, P(Arg)/Tb composite filmmodified glassy carbon electrode (GCE) not only induces conductive thin film for amplifying Faraday current but also provides a robust and steady layer for subsequent modification of PDA-MNPs with high surface area.…”

Biologically Coupled Gate Field-Effect Transistors Meet in Vitro Diagnostics

“…A gate insulator is often composed of oxide or nitride membranes such as Ta 2 O 5 , Al 2 O 3 , Si 3 N 4 , and SiO 2 ; therefore, hydroxyl groups at the oxide or nitride surface in a solution undergo the equilibrium reaction with hydrogen ions through protonation (−OH + H + ⇄ −OH 2 + ) and deprotonation (−OH ⇄ −O – + H + ) because the change in the surface charge is detected from the change in pH based on the principle of the field effect. , This is why the original ISFET sensor is still utilized as a pH sensor. Such ISFET sensors mostly have a silicon substrate, but a variety of semiconducting materials have recently been applied to pH-sensitive ISFET sensors, which require the gate surface in contact with the electrolyte solution to be covered by functional groups such as hydroxy groups, carboxy groups, and amino groups. − For example, a transparent amorphous oxide semiconductor (a-InGaZnO) was utilized as the channel between the transparent conductive source and drain indium tin oxide electrodes, on which SiO 2 was thinly coated as the gate insulator, in a pH-sensitive ISFET . This transparent ion-sensitive thin-film transistor (ISTFT) can continuously monitor cellular respiration as a change in pH while clearly observing cellular morphologies under an inverted microscope.…”