title: A very low potential electrochemical detection of L-cysteine based on a glassy carbon electrode modified with multi-walled carbon nanotubes/gold nanorods.
abstract: A nanohybrid platform built with multi-walled carbon nanotubes and gold nanorods, prepared via a cationic surfactant-containing seed-mediated sequential growth process, in aqueous solution, on a glassy carbon substrate has been successfully developed to be used in the electrocatalytic oxidation of L-cysteine (Cys). The nanohybrid was characterized by transmission electron microscopy, Raman spectroscopy and electrochemical measurements. Cyclic voltammetry results had shown that the modified electrode allows the oxidation of Cys at a very low anodic potential (0.00 V vs. Ag/AgCl). The kinetic constant kcat for the catalytic oxidation of Cys was evaluated by chronoamperometry and provided a value of 5.6×10(4) L mol(-1) s(-1). The sensor presents a linear response range from 5.0 up to 200.0 µmol L(-1), detection limit of 8.25 nmol L(-1) and a sensitivity of 120 nA L µmol(-1).
authors.affiliation: Instituto de Química e Biotecnologia, Universidade Federal de Alagoas, 57072-900 Maceió, AL, Brazil; Instituto Nacional de Ciência e Tecnologia de Bioanalítica, UNICAMP, C. Postal 6154, 13084-971 Campinas, SP, Brazil.
authors.forename: Francisco de Assis dos Santos
authors.initials: Fde A
authors.lastname: Silva
authors.forename: Monique Gabriella Angelo
authors.initials: MG
authors.lastname: da Silva
authors.forename: Phabyanno Rodrigues
authors.initials: PR
authors.lastname: Lima
authors.forename: Mario Roberto
authors.initials: MR
authors.lastname: Meneghetti
authors.forename: Lauro Tatsuo
authors.initials: LT
authors.lastname: Kubota
authors.forename: Marilia Oliveira Fonseca
authors.initials: MO
authors.lastname: Goulart
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D002244:Carbon / Q000737:chemistry*; D003545:Cysteine / Q000097:blood*; D055664:Electrochemical Techniques / Q000295:instrumentation*; D004566:Electrodes; D005898:Glass / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D043942:Nanotubes / Q000737:chemistry / Q000648:ultrastructure; D037742:Nanotubes, Carbon / Q000737:chemistry / Q000648:ultrastructure
chemical_list: D037742:Nanotubes, Carbon; D002244:Carbon; D006046:Gold; D003545:Cysteine
keywords: Chemically modified electrodes; Electrocatalysis; Gold nanorods; MWCNT; l-cysteine