Detecting Biorecognition Events at Blocked Interface Polymeric Membrane Ion‐Selective Electrodes Using Electrochemical Impedance Spectroscopy and Atomic Force Microscopy

Abstract

Immobilization of a biorecognition element onto a polymeric membrane ion-selective electrode (ISE) using a selfassembly approach may provide scope for a novel biosensor technology platform based on the altered potentiometric response at the blocked ISE interface. In this paper, the authors have investigated the influence of solution adsorption of the model biorecognition element, avidin-biotin, on the electrode kinetics of a conventional polymeric membrane Ca 2þ ISE using atomic force microscopy (AFM) coupled with electrochemical impedance spectroscopy (EIS). It is demonstrated that solution adsorption of avidin followed by biotin incorporation leads to a demonstrable biorecognition event characterized by an impediment in the Ca 2þ ion transfer kinetics of the modified ISE surface. This kinetic principle is amenable to biosensing using pulsed chronopotentiometric polymeric ISEs, which is an established dynamic electrode technique for use with polymeric membrane ISEs.

Comparative Electrochemical Study of N‐, C‐terminal and Integral Centrin on Adsorption and Metal‐Binding Properties

“…The fitting procedure shows that a better agreement between theoretical and experimental data. After the protein is added to the solution, the recorded EIS spectrum are fitted to an electrical equivalent circuit comprised of two time constants in parallel, as shown in Figure d (inset), which is characteristic of an insulating layer over a conducting surface and yield the best fit among several other circuits. The Equivalent circuit (Inset in Figure d) is consisting of a electrolyte resistance ( R s ), an adsorbed protein resistance ( R f ), an adsorbed protein capacitance as a constant phase element (CPE 1 ), a double‐layer capacitance as a constant phase element (CPE 2 ), a charge transfer resistance ( R ct ) and a Warburg impedance ( Z w ).…”

Development of a disposable paper-based potentiometric immunosensor for real-time detection of a foodborne pathogen

“…Conversely, this work intends to use a label-free sensing mechanism based on the blocking surface principle whereupon a controlled ionic flux is disturbed by a biorecognition event at an ISE polymer membrane surface, triggering an EMF change (Gyurcsanyi et al, 2003;Pawlak et al, 2015). Hence, the PSE development faces an extra challenge of maintaining the practical and functional design of all solid state ISE (De Marco et al, 2008;Ozdemir et al, 2013), despite the need of developing a controlled passive ion flow from the inner side of the sensing membrane towards the sample solution (Supporting Information, S1). To the best of our knowledge, this detection method has never been explored using a paper-based platform.…”

“…The key point to establish and apply the proposed sensing mechanism is to reach a stable steady-state potential. In this specific condition, by mathematical deduction from Fick' s first law, any changes in EMF caused by an impediment in marker ion transfer kinetics can be correlated with a specific biorecognition event at aqueous layer (De Marco et al, 2008;Ozdemir et al, 2013). To explore this mechanism, it is necessary to promote a controlled passive flow of a marker ion through the sensing membrane.…”

Electrochemical Impedance Spectroscopy of Ion-Selective Membranes: Artifacts in Two-, Three-, and Four-Electrode Measurements

“…Electrochemical impedance spectroscopy (EIS) has been used to study ion-selective electrodes since the 1980s. − The frequency dependence of the impedance of ion-selective electrodes (ISEs) − makes it possible to determine a number of membrane and interfacial properties, including bulk resistances, double layer capacitances, charge transfer resistances, and Warburg impedances. Often, impedance spectroscopy is used in combination with other experimental techniques to study complex phenomena, such as in the case of solid-contact ion-selective membranes. − Early studies used cells with two AgCl-coated Ag plates of large surface areas as electrodes, immersed into two electrolyte solutions separated by the ion-selective membrane of interest . Because of their large surface area, these electrodes have low charge transfer resistances and low bulk resistances.…”

“…It is now more common for EIS measurements to be acquired using four-electrode cells, which allows for better control of the applied potential and reduction of undesired impedance artifacts that arise in two-electrode measurements. − The expectation is that the applied AC current flows from one working electrode through the ion-selective membrane to another working electrode, while the resulting AC voltage across the ion-selective membrane is observed with two separate reference electrodes. However, as discussed in this contribution, four-electrode EIS may also suffer from artifacts (i.e., features in the EIS spectra that are not associated with the sensing membrane but result from the measuring electrodes and/or instrumentation), which may or may not be apparent to the user. ,, Moreover, even though four-electrode cells are generally expected to provide data of higher quality, they are often avoided by users due to the difficulty of introducing a fourth electrode into an existing device, as for example in the case of solid-contact ISEs. − This has led to numerous reports of EIS with three-electrode cells, which exhibit their own artifacts. − In addition, many reports that include EIS characterization of ISEs lack experimental details, often not even mentioning the number of electrodes used. Curiously, the first publication on EIS of ISE membranes shows a four-electrode cell, but data from two-electrode measurements are presented …”