Electrochemical Fabrication of Randomly Nanoarrayed Electrodes to Enhance Sensitivity and Selectivity of Sensors

Abstract

Increasing sensitivity and selectivity, as well as, long-term durability of electrochemical sensors are the reasons for designing active layers on electrodes. Significant advances in this field originate from the chemical approach to nanotechnology, involving bottom-up synthetic pathways to generate nanostructured materials on electrode surfaces. In this work randomly nanoarrayed electrodes were fabricated and electrochemically characterized.This was achieved by depositing gold nanoparticles, AuNPs on bare glassy carbon, from 0.1 mmol/L KAuCl₄ in H₂SO₄ using chronoamperometry followed by surface passivation through reduction of in situ prepared nitrophenyl diazonium cation. To increase the number of nucleated metal nanoparticles self assembly monolayers (SAMs) of 2-mercaptoetha nol (2-ME) was used during three deposition steps. The nitrophenyl grafted film was characte- rized by cyclic voltammetry and has shown a significant blocking property towards Fe(CN)₆^-3 probe. The nanoholes were produced by stripping the deposited gold nanoparticles (AuNPs) and their response to common probes such as hydroquinone and ruthenium hexamine chloride were studied at different scan rates in comparison with the signal obtained at bare glassy carbon. The improvement in selectivity is atributed to controlling the charge of insulation layer made from nitrophenyl film.

Determination of dopamine hydrochloride, DA and Chlorpromazine hydrochloride, CPZ was made with their respective limit of detection 7.4