A Polymeric Liquid Membrane Electrode Responsive to 3,3′,5,5′-Tetramethylbenzidine Oxidation for Sensitive Peroxidase/Peroxidase Mimetic-Based Potentiometric Biosensing

Abstract

The oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) has great utility in bioanalysis such as peroxidase/ peroxidase mimetic-based biosensing. In this paper, the behaviors of TMB oxidation intermediates/products in liquid/liquid biphasic systems have been investigated for the first time. The free radical, charge transfer complex, and diimine species generated by TMB oxidation are all positively charged under acidic and near-neutral conditions. Electron paramagnetic resonance and visible absorbance spectroscopy data demonstrate that these cationic species can be effectively transferred from an aqueous phase into a water-immiscible liquid phase functionalized by an appropriate cation exchanger. Accordingly, sensitive potential responses of TMB oxidation have been obtained on a cation exchanger-doped polymeric liquid membrane electrode under mildly acidic and near-neutral conditions. By using the membrane electrode responsive to TMB oxidations, two sensitive potentiometric biosensing schemes including the peroxidase-labeled sandwich immunoassay and Gquadruplex DNAzyme-based DNA hybridization assay have been developed. The obtained detection limits for the target antigen and DNA are 0.02 ng/mL and 0.1 nM, respectively. Coupled with other advantages such as low cost, high reliability, and ease of miniaturization and integration, the proposed polymeric liquid membrane electrode holds great promise as a facile and efficient transducer for TMB oxidation and related biosensing applications.

Recent advances in potentiometric biosensors

“…Qin's group found that the G-quadruplex/hemin DNAzyme-catalyzed oxidative coupling of monomeric phenols can induce large potential signals on quaternary ammonium salt-doped polymeric membrane electrodes. Two label-free potentiometric DNA assay protocols based on the Gquadruplex/hemin DNAzyme have been developed with sensitivities higher than those of colorimetric and fluorometric method [101,102].…”

Determination of Solubility of 4-(2-Hydroxyethyl)-1-piperazineethanesulfonic Acid and its Sodium Salt in Acetonitrile and Voltammetric Investigation of Sulphonamide Drugs in Different Solvents in Their Absence and Presence

“…Water was present in each solution in 50 v/v% by solubility determination of sodium salt of HEPES. The calibration solutions were prepared in 25 cm 3 flasks by placing 12.5 cm 3 of acetonitrile and then the necessary volumes of aqueous stock solution of solute were added. Finally the flasks were filled to the mark with water.…”

“…This buffer was used in a vast number of studies. In many intra-and extracellular electrochemical studies it served as an appropriate choice [1][2][3][4] and in protein based detection applications [5,6].…”

The Use of a β-lactamase-based Conductimetric Biosensor Assay to Detect Biomolecular Interactions

“…Secondly, pH and ionic strength in biofluids can vary significantly and consequently result in important variations in the response and increase the background noise of the biosensors 32 . This is why, various research groups have tried to develop nanotechnologies to decrease the sizes of electrochemical sensor elements in order to increase the signal-to-noise ratio for the processes that occur at the interface of the device 33,34,35 . As a consequence, it is also possible to develop antibody molecules labeled with several molecules of the same enzyme to increase the signal resulting from the binding of one molecule to its target 32 .…”