Polymeric membranes conditioning for sensors applications: mechanism and influence on analytes detection

Abstract

In this work, we studied an ion-exchange membrane based on an inert polymer skeleton in which it is dispersed and anchored a molecule with charged groups able to discriminate and bind positive or negatively charged ions present in a sample. In order to be ready to work, electromembranes need a complex procedure called activation or conditioning. Although most of the known literature looks at the subject from an electrochemical point of view, we put forward a structural approach. Membrane conditioning, in fact, is considered a required step to improve sensor performances and to allow the collection of reproducible data. Even if this operation is carefully followed by all the operators working with sensors equipped with a membrane, it looks like that a thoroughly explanation of the working mechanism and a detailed balance of cost and gains has still not been carried out. As a consequence, we suggest a bulk or membrane approach, where the landscape is mainly characterized by the longrange structure of the membrane itself. Our findings suggest that membrane conditioning has to be carried out carefully and the advantages of this pre-treatment can be appreciated especially for very low concentration measurements. The need for the conditioning mainly results from the necessity of a complete permeation of all the different tortuous channels constituting the membrane itself.

Analytical Assessment of Sodium Isfet Based Sensors for Sweat Analysis

“…2E and F). As it has been extensively reported [34,35], the conditioning step before the use of ion-selective potentiometric devices was critical. At first, the ISFETs were stored dry, and they were just conditioned in a 1 mM NaCl solution for 30 min before the first calibration.…”

Circumventing Traditional Conditioning Protocols in Polymer Membrane-Based Ion-Selective Electrodes

“…Reagents. 4-tert-Butylcalix [4]arene-tetraacetic acid tetraethyl ester (sodium ionophore X), o-xylylenebis(N,N-diisobutyldithiocarbamate) (copper(II) ionophore I), potassium tetrakis-[3,5-bis(trifluoromethyl)phenyl]borate (KTFPB), sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaTFPB), tridodecylmethylammonium nitrate (TDMANO 3 ), bis(2ethylhexyl)sebacate (DOS), high molecular weight poly(vinyl chloride) (PVC), and tetrahydrofuran (THF), all of Selectophore grade, were purchased from Sigma-Aldrich. [9]-Mercuracarborand-3 (MC3) was synthesized in house as described previously.…”

“…Anion R org – remains in the membrane, thereby rendering the membrane permselective while preserving the charge balance . In a typical experimental protocol for the preparation of ion-selective membranes, the ion-exchange process is obtained by conditioning (soaking) the membrane in an aqueous solution containing the ion I + (traditional protocol) …”

“…3 In a typical experimental protocol for the preparation of ion-selective membranes, the ion-exchange process is obtained by conditioning (soaking) the membrane in an aqueous solution containing the ion I + (traditional protocol). 4 Significant effort in the ISEs field has been spent on researching ways to miniaturize 5−9 and optimize/simplify the preparation of ISEs. 10−14 Reducing or eliminating the need for the conditioning step prior to the use of the electrodes is an important step for devising a simple, practical protocol for mass production of ISEs.…”

DNA-Polylactide Modified Biosensor for Electrochemical Determination of the DNA-Drugs and Aptamer-Aflatoxin M1 Interactions

“…Polymers are often used in the assembly of biosensors [17,18] and electrochemical sensors [19,20]. Depending on the polymer structure and properties, they can mechanically support receptors and redox labels [20,21,22,23], participate in the ion-exchange reactions [24], or prevent electrode poisoning and biofouling [25]. Cellulose derivatives, gelatin and Nafion are mostly mentioned in electrochemical sensors assembly.…”