Array of peptide-modified electrodes for the simultaneous determination of Pb(II), Cd(II) and Zn(II)

Abstract

This paper reports the development of three peptide modified sensors in which glutathione (GSH) and its fragments Cys-Gly and γ-Glu-Cys were immobilized respectively through aryl diazonium electrochemical grafting onto the surface of graphite-epoxy composite electrodes (GEC), and used for the simultaneous determination of Cd(II), Pb(II) and Zn(II). The concentration interval ranged from 0.1 to 1.5 μmol L(-1) for each metal, and the technique used was differential pulse adsorptive stripping voltammetry. This study aimed to the comparison of the information provided by one single modified electrode at both fixed and multiple pH values (pH 6.8, 7.5 and 8.2) for the simultaneous determination of the three metals, with those supplied by the three-sensor array at multiple pH values. For the processing of the voltammograms, the fast Fourier transform was selected as the preprocessing tool for data compression coupled with an artificial neural network for the modeling of the obtained responses.

A Chemically-Bound Glutathione Sensor Bioinspired by the Defense of Organisms against Heavy Metal Contamination: Optimization of the Immobilization Conditions

“…The second step, the covalent immobilization of the ligand via carbodiimide coupling, is crucial in the modification of working electrodes with different ligands through the aryl diazonium salt electrografting. In the case of electrodes modified with glutathione, slightly different conditions have been reported in the literature for this step, with concentrations of glutathione ranging from 2.5 to 5 mg/100 µL MES buffer pH 4.5, either at 4 • C or without temperature control and usually overnight [17,18,[21][22][23][24]. The influence of these three parameters (glutathione concentration, incubation temperature and incubation time) in the performance of the resulting sensor was studied taking the conditions used in [18] (2.9 mg/100 µL MES, 4 • C and overnight) as starting point and using the determination of Cd(II) and Pb(II) as a model of application.…”

“…In this regard, the literature describes different strategies including the formation of alkanethiol self-assembled monolayers (SAMs) and the molecule immobilization based on aryl diazonium salt anchored on the electrode surface, which is a more viable approach that can overcome the major limitations of SAMs and has proven its usefulness in the development of metal ion sensors [14][15][16]. For example, the development of modified sensors in which glutathione (GSH) and its fragments Cys-Gly and γ-Glu-Cys were immobilized through aryl diazonium electrochemical grafting onto the surface of graphite-epoxy composite electrodes (GEC), was used for the simultaneous determination of Cd(II), Pb(II) and Zn(II) [17]. More recently, the procedure was successfully adapted to the special characteristics of screen-printed electrodes to develop a glutathione-modified carbon nanofiber screen-printed electrode [18].…”

Crown ether-modified electrodes for the simultaneous stripping voltammetric determination of Cd(II), Pb(II) and Cu(II)

“…Nevertheless, as reported for peptides, an alternative strategy would be the crown ether immobilization on aryl diazonium salt monolayers anchored on the electrode surface resulting in a simple, flexible and valuable alternative for forming stable complexing monolayers [15,16].…”

Modified Electrodes for Determining Trace Metal Ions

“…Strategies can also be designed to let the compounds to form self-assembled monolayers (SAM) on metal electrodes or to be immobilized on other monolayers [36,37].…”