An amperometric sensor for L-cysteine based on nanostructured platform modified with 5,5 '-dithiobis-2-nitrobenzoic acid (DTNB)

Author(s)

Santhiago, Murilo ; Lima, Phabyanno Rodrigues ; Rodrigues Santos, Wilney de Jesus ; Kubota, Lauro T.

• Document type: Journal article
• Source: SENSORS AND ACTUATORS B-CHEMICAL; v. 146, n. 1, p. 8-pg., 2010-04-08.

Abstract

In this work, the activation of 5,5'-dithiobis-2-nitrobenzoic acid (DTNB) in situ is proposed, for L-cysteine electrooxidation at low overpotentials. The redox mediator was immobilized in an nanostructured platform containing multi-walled carbon nanotubes (MWCNTs), polyethylenimine (PEI) and gold nanoparticles (GNPs). The optimization of the interface was performed monitoring the R-NO/R-NHOH redox couple in which was electrogenerated in situ by cycling the potential between 0.1 and -0.7 V versus SCE at 100 mV s(-1) The kinetic parameters such as the apparent electron transfer rate constant (k(s)) and the rate constant of the reaction between L-cysteine and DTNB (k(obs)) were evaluated. The electrocatalytic oxidation oft-cysteine was studied by means of cyclic voltammetry, chronoamperometry and amperometry. The sensor presented a linear response range for CyS from 9.0 up to 250 mu molL(-1) with sensitivity of 21 nA mu mol(-1), detection and quantification limits of 2.7 and 9.1 mu mol L-1 respectively, with a response time of 0.12 s at an applied potential of 0 mV versus SCE. (c) 2010 Elsevier By. All rights reserved. (AU)

• FAPESP's process: 09/08508-8 - Development of chemical sensors based on molecularly imprinted siloxane for the determination of bioactive compounds
• Grantee: Wilney de Jesus Rodrigues Santos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral