Gold nanoparticles modified GC electrodes: electrochemical behaviour dependence of different neurotransmitters and molecules of biological interest on the particles size and shape (original) (raw)
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Electrochemical detection of dopamine and cytochrome c at a nanostructured gold electrode
Electrochimica Acta, 2010
A nanostructured gold surface consisting of closely packed outwardly growing spikes is investigated for the electrochemical detection of dopamine and cytochrome c. A significant electrocatalytic effect for the electrooxidation of both dopamine and ascorbic acid at the nanostructured electrode was found due to the presence of surface active sites which allowed the detection of dopamine in the presence of excess ascorbic acid to be achieved by differential pulse voltammetry. By simple modification with a layer of Nafion, the enhanced electrocatalytic properties of the nanostructured surface was maintained while increasing the selectivity of dopamine detection in the presence of interfering species such as excess ascorbic and uric acids. Also, upon modification of the nanostructured surface with a monolayer of cysteine, the electrochemical response of immobilised cytochrome c in two distinct conformations was observed. This opens up the possibility of using such a nanostructured surface for the characterisation of other biomolecules and in bio-electroanalytical applications.
Journal of The Electrochemical Society, 2010
An effective electrochemical sensor for the selective determination of dopamine ͑DA͒ in the presence of ascorbic acid ͑AA͒ and uric acid ͑UA͒ in 0.04 mol L −1 universal buffer solution ͑pH 7.4͒ is introduced. The sensor is based on a carbon paste ͑CP͒ electrode modified with gold nanoparticles. In a mixture of DA, AA, and UA, the sensor shows high selective response toward DA and no response for AA or UA. The effect of various experimental parameters including time of deposition of gold nanoparticles on the CP electrode, pH, and scan rate on the voltammetric response of DA was investigated. At the optimum conditions, the concentration of DA was determined using differential pulse voltammetry in a linear range of 1.0 ϫ 10 −7 to 5.0 ϫ 10 −6 mol L −1 and 5.0 ϫ 10 −6 to 1.3 ϫ 10 −4 mol L −1 with correlation coefficients of 0.9995 and 0.9988 and a detection limit of 5.9 ϫ 10 −9 and 8.2 ϫ 10 −8 mol L −1 , respectively. The modified electrode can be used for the determination of DA spiked into human serum samples, and excellent recovery results were obtained over a wide concentration range of DA. Moreover, validation parameters, such as reproducibility, sensitivity, and recovery were evaluated successfully in the determination of DA in diluted human urine.
International Journal of Electrochemical Science, 2011
Department of Chemical Technology, University of Jo hannesburg, P.O. Box 17011, Doornfontein, 2028, South Africa Department of Chemistry, Obafemi Awolowo University Ile-Ife, Nigeria. School of Applied Sciences & Engineering, Monash Un iversity, Gippsland Campus, Churchill 3842, Victoria, Australia. Monash Centre for Electron Microscopy, Monash Unive rsity, Clayton campus, Victoria 3800, Australia. E-mail: Ayenimo71@yahoo.com
Applied Surface Science, 2017
Nanometer-scale gold particles exhibit size-dependent electronic properties with important sensing and biosensing applications. In the same way, a lot of analytes show some type of surface-sensitive reaction and the electrode material has a strong influence on the catalytic activity. In this work we study the kinetics and electrochemistry of electrodes with size controlled gold nanoparticles, obtained by electrodeposited amidoferrocenylpoly(propyleneimine) dendrimers of two generations as templates, and the kinetics and the analytical response to the oxidation of dopamine. We demonstrate that the four-types of modified electrodes show good catalytic responses toward the oxidation of dopamine via different processes in relation with the absence or presence of gold nanoparticles and their size. The best response was obtained with the largest nanoparticles, obtained with the first generation dendrimer-template at 0.3 V vs. SCE, with three linear ranges (0-70, 70-600 and 600-1000 M), with sensitivities 585.7; 466.0 and 314.3 A/mM cm 2 , and limit of detection of 0.01 M. The effect of interfering substances has been studied by differential pulse voltammetry and the developed sensor has been successfully used for the determination of dopamine in a commercial dopamine hydrochloride injection and in spiked Human urine.
Chinese Journal of Catalysis, 2014
A novel electrochemical sensor was fabricated by electrodeposition of gold nanoparticles on a poly(L-methionine) (PMT)-modified glassy carbon electrode (GCE) to form a nano-Au/PMT composite-modified GCE (nano-Au/PMT/GCE). Scanning electron microscopy and electrochemical techniques were used to characterize the composite electrode. The modified electrode exhibited considerable electrocatalytic activity towards the oxidation of dopamine (DA) and uric acid (UA) in phosphate buffer solution (pH = 7.00). Differential pulse voltammetry revealed that the electrocatalytic oxidation currents of DA and UA were linearly related to concentration over the range of 5.0 × 10 -8 to 10 -6 mol/L for DA and 7.0 × 10 -8 to 10 -6 mol/L for UA. The detection limits were 3.7 × 10 -8 mol/L for DA and 4.5 × 10 -8 mol/L for UA at a signal-to-noise ratio of 3. According to our experimental results, nano-Au/PMT/GCE can be used as a sensitive and selective sensor for simultaneous determination of DA and UA.
A simple electrochemical deposition strategy is proposed for the preparation of gold nanoparticles (Au NPs) at the electrode surface using biopolymer pectin as stabilizing agent. The formation of the nanoparticles was confirmed by scanning electron microscopy (SEM), UV-visible spectroscopy and X-ray diffraction (XRD) studies. A pectin-stabilized, gold nanoparticle film-modified glassy carbon electrode (pectin–Au NP/GCE) was prepared, which exhibited excellent electrocatalytic ability towards oxidation of dopamine (DA). At the pectin–Au NP/GCE, the redox couple corresponding to the redox reaction of DA was observed at the formal potential of 0.20 V with highly enhanced peak currents. A thin layer of nafion coating was applied on the pectin–Au NP composite to improve its selectivity. Two linear ranges of detection were found: (1) 20 nM to 0.9 mM with a limit of detection (LOD) of 6.1 nM, (2) 0.9 mM to 1 mM with a LOD of 0.64 mM. The fabricated sensor selectively detects DA even in the presence of high concentrations of interferents. Moreover, practical feasibility of the sensor was addressed in pharmaceutical samples, which presented appreciable recovery results. The main advantages of the sensor are its very simple and green fabrication approach, roughed and stable structure, and fast and highly reproducible detection of dopamine.
Indian Journal of Chemistry -Section A
In this study, we have synthesized a composite using carbon material derived from bio-inspired onion peel morphology like 2D trigona carbon nano petals (TCP) incorporated with ferrocene (FC). The FC is added with the purpose of improving the electrochemical behaviour of TCP. Further, to increase the number of electrochemically active sites in the composite, gold nanoparticles (AuNPs) were again decorated on TCP/FC, and thus derived electrochemically active TCP/FC/AuNPs nanocomposite. We have characterized the properties and surface morphology of this nanocomposite through spectroscopic and microscopic techniques. Further, using this nanocomposite for surface modification of glassy carbon electrode, we have developed an efficient GCE-TCP/FC/AuNPs electrode. The electrochemical efficiency of this electrode has been inspected through sensing and quantification of pharmaceutically valuable biomolecule dopamine through CV, DPV and square wave voltammetry techniques. The observed CV results reveals that the newly designed GCE-TCP/FC/AuNPs electrode has an ability to detect the dopamine with wide linear range of concentration from 5.96 × 10-6 to 0.1 × 10-4 M and its limit of detection was 2.9 × 10-6 M under 0.1 M phosphate buffer medium (pH 7.0). Therefore, it is important to mention here that this newly fabricated electrode can very well be used for real time sample analysis for sensing and detection of dopamine as it plays a key role in the neurotransmission and causes several diseases.
DOAJ (DOAJ: Directory of Open Access Journals), 2010
The electrochemical behavior at a mercury electrode of dopamine (DA) in the presence of citrate was investigated in aqueous solution, using cyclic voltammetry and alternating current polarography. The influence of the composition of the supporting electrolyte, citrate concentration and pH was evaluated. At potentials more positive than 250 mV DA and Hg are oxidized yielding, in the presence of citrate, dopaminoquinone (DQ) and Hg(II). Hg(II) reacts with the DA forming DQ, leucodopaminochrome (LDC) and dopaminochrome (DC). DQ undergoes further reduction at 200 mV. Citrate, in the form of Cit 3− , stabilizes the DC formed and this new electroactive compound suffers further reduction at −250 mV. This reaction pathway inhibits the formation of polymerized films on the surface of solid state electrodes and allows the determination of DA using the mercury electrode.