Voltammetry of redox analytes at trace concentrations with nanoelectrode ensembles

Moretto, Ligia Maria; Pepe, Niki; Ugo, Paolo

doi:10.1016/j.talanta.2003.10.024

Cited by 59 publications

(61 citation statements)

References 28 publications

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“…2, even if the I − concentration for the NEE measurements is one order of magnitude lower than at the Au-macro, the ratio between Faradaic (peak) currents and background currents are roughly comparable, in agreement with the lowering of capacitive (background) current which characterizes NEEs' responses [38,39]. At NEEs operating under total overlap diffusion conditions, capacitive currents scale with the active area (metal surface of the nanodisks electrodes) while the Faradaic current scales with the overall geometric area of the ensemble [37]; at the Au-macro both currents increase linearly with the geometric area [43].…”

Section: Cyclic Voltammetry Of Iodidesupporting

confidence: 63%

“…The detection limits are 0.3 M at NEEs and 4 M at Au-macro electrodes. Such an improvement in detection limits at NEEs, although relevant, is not as dramatic as in other applications, described previously [36,37,39]. This is related to the fact that iodide is an analyte difficult to determine at NEEs, since its oxidation takes place at potential values quite close to the oxidation limit of the potential window accessible at this kind of nanoelectrodes [39].…”

Section: Discussionmentioning

confidence: 80%

“…Recent researches [35][36][37][38][39] showed that the use of the socalled nanoelectrode ensembles (NEE) can improve the performances of electrochemical determinations thanks to dramatically improved signal to background current ratios with respect to other electrode systems [39]. NEEs are useful electrochemical tools for biosensors development [40,41], for the measurement of (high) charge transfer rate constants [35] and for solving adsorption related problems [36].…”

Section: Introductionmentioning

confidence: 99%

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Gold nanoelectrode ensembles for direct trace electroanalysis of iodide

Pereira

Moretto

Leo

et al. 2006

Analytica Chimica Acta

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A procedure for the standardization of ensembles of gold nanodisk electrodes (NEE) of 30 nm diameter is presented, which is based on the analytical comparison between experimental cyclic voltammograms (CV) obtained at the NEEs in diluted solutions of redox probes and CV patterns obtained by digital simulation. Possible origins of defects sometimes found in NEEs are discussed. Selected NEEs are then employed for the study of the electrochemical oxidation of iodide in acidic solutions. CV patterns display typical quasi-reversible behavior which involves associated chemical reactions between adsorbed and solution species. The main CV characteristics at the NEE compare with those observed at millimeter sized gold disk electrodes (Au-macro), apart a slight shift in E 1/2 values and slightly higher peak to peak separation at the NEE. The detection limit (DL) at NEEs is 0.3 M, which is more than one order of magnitude lower than DL at the Au-macro (4 M). The mechanism of the electrochemical oxidation of iodide at NEEs is discussed. Finally, NEEs are applied to the direct determination of iodide at micromolar concentration levels in real samples, namely in some ophthalmic drugs and iodized table salt.

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Section: Cyclic Voltammetry Of Iodidesupporting

confidence: 63%

Section: Discussionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

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Gold nanoelectrode ensembles for direct trace electroanalysis of iodide

Pereira

Moretto

Leo

et al. 2006

Analytica Chimica Acta

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“…Note that the sensitivity of classical immunochemical assays, such as Western blotting, is not high enough to detect the HER2 analyte in 1:10 or 1:50 diluted samples, while good electrocatalytic signals were detected with the T-NEE, specifically in the most diluted samples examined here, where the HER2 concentration was approximately 0.04 ng/ l. In principle, detection limits at NEEs can be further lowered by pulsed voltammetry (Moretto et al, 2004). These encouraging results prompted us to test a preliminary real application, that is the analysis of a breast cancer lysate.…”

Section: Both Effects Increase By Increasing H 2 O 2 Concentration (Nmentioning

confidence: 89%

Nanoelectrode ensembles as recognition platform for electrochemical immunosensors

Mucelli

Zamuner

Tormen

et al. 2008

Biosensors and Bioelectronics

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a b s t r a c tIn this study we demonstrate the possibility to prepare highly sensitive nanostructured electrochemical immunosensors by immobilizing biorecognition elements on nanoelectrode ensembles (NEEs) prepared in track-etch polycarbonate membranes. The gold nanodisk electrodes act as electrochemical transducers while the surrounding polycarbonate binds the antibody-based biorecognition layer. The interaction between target protein and antibody is detected by suitable secondary antibodies labelled with a redox enzyme. A redox mediator, added to the sample solution, shuttles electrons from the nanoelectrodes to the biorecognition layer, so generating an electrocatalytic signal. This allows one to fully exploit the highly improved signal-to-background current ratio, typical of NEEs. In particular, the receptor protein HER2 was studied as the target analyte. HER2 detection allows the identification of breast cancer that can be treated with the monoclonal antibody trastuzumab. NEEs were functionalized with trastuzumab which interacts specifically with HER2. The biorecognition process was completed by adding a primary antibody and a secondary antibody labelled with horseradish peroxidase. Hydrogen peroxide was added to modulate the label electroactivity; methylene blue was the redox mediator generating voltammetric signals. NEEs functionalized with trastuzumab were tested to detect small amounts of HER2 in diluted cell lysates and tumour lysates.

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“…(i) Total geometric area (A geom ): Overall area (nanodisks plus bare membrane area) of the ensemble exposed to the sample solution; typical values for this parameter range from 0.008 to 0.580 cm 2 (91). A geom is determined by the dimension of the hole punched into the insulator (see Figure 16.2.8).…”

Section: Current Signals Of Nanoelectrode Ensemblesmentioning

confidence: 99%

Template Deposition of Metals

Ugo

Moretto

2007

Handbook of Electrochemistry

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Template synthesis is a relatively simple and easy procedure which has made the fabrication of rather sophisticated nanomaterials accessible to almost any laboratory. Template synthesis requires access to instrumentation capable of metal sputtering and electrochemical deposition. The characterization of the fabricated nanostructures can be done using instrumental techniques including spectrophotometry, voltammetry, optical microscopy, atomic force microscopy, and electronic microscopies (scanning electron microscopy (SEM) and transmission electron microscopy (TEM)).The method is based on the simple but effective idea that the pores of a host material can be used as a template to direct the growth of new materials. Historically, template synthesis was introduced by Possin (1) and refined by Williams and Giordano (2) who prepared different metallic nanowires with widths as small as 10 nm within the pores of etched nuclear damaged tracks in mica. It was further developed by Martin's group (3-5) and followed by others (6) with the number of examples and applications (7) continually increasing. The nanoporous membranes usually employed as templates are alumina or track-etched polymeric membranes which are widely used as ultrafiltration membranes. Recently, metal nanostructures have also been obtained using the pores created by self-assembly in block copolymer structures under the influence of electric fields and high temperatures (8, 9).The first part of this section focuses on the main characteristics and fabrication techniques used for obtaining templating membranes and depositing metal nanostructures by suitable electroless and electrochemical procedures. Methods such as sol-gel (10-12) or chemical vapor deposition (10, 13), which have been used primarily for the template deposition of carbon, oxides, or semiconducting-based materials, will not be considered here in detail. The second part of the section focuses on the electrochemical properties of the fabricated nanomaterials with emphasis on the characteristics and applications of nanoelectrode ensembles (NEEs). Templating membranes 16.2.2

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Voltammetry of redox analytes at trace concentrations with nanoelectrode ensembles

Cited by 59 publications

References 28 publications

Gold nanoelectrode ensembles for direct trace electroanalysis of iodide

Gold nanoelectrode ensembles for direct trace electroanalysis of iodide

Nanoelectrode ensembles as recognition platform for electrochemical immunosensors

Template Deposition of Metals

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