Molecularly imprinted electrochemical sensor for the ultrasensitive detection of cytochrome c.

Cytochrome c (Cyt c) is an important biomarker for the early stage of apoptosis that plays a role in the diagnosis and therapy of several diseases including cancer. Here, an electrochemical sensor based on molecularly imprinted polymer (MIP) for the ultrasensitive detection of Cyt c is studied. It is prepared by electropolymerization of o-phenylenediamine in the presence of Cyt c as template, followed by solvent extraction, resulting in the formation of Cyt c recognition sites.

Advanced Electrochemical and Opto-Electrochemical Biosensors for Quantitative Analysis of Disease Markers and Viruses.

Instrumental laboratory methods for biochemical and chemical analyses have reached a high level of reliability with excellent sensitivity and specificity [...

Surface Enhanced Raman Spectroscopy With Electrodeposited Copper Ultramicro-Wires With/Without Silver Nanostars Decoration.

The electrochemical preparation of arrays of copper ultramicrowires (CuUWs) by using porous membranes as templates is critically revisited, with the goal of obtaining cheap but efficient substrates for surface enhanced Raman spectroscopy (SERS). The role of the materials used for the electrodeposition is examined, comparing membranes of anodized aluminum oxide (AAO) vs. track-etched polycarbonate (PC) as well as copper vs.

Electrochemical preconcentration coupled with spectroscopic techniques for trace lead analysis in olive oils.

In this paper we present a novel combined electrochemical-spectroscopic approach suitable to monitor trace levels of heavy metals directly in edible oils. The method is based on the electrochemical preconcentration/extraction of the analyte from the tested real matrix by cathodic deposition onto a Pt working electrode, then transfer and anodic re-oxidation of the metallic deposit to a "clean" aqueous solution, suitable for the subsequent spectroscopic analysis. The procedure has been here focused to the determination of lead in extra virgin olive oil (EVOO), performed by applying ICP-QMS or GFAAS techniques.

Electrochemical Immunosensor Based on Nanoelectrode Ensembles for the Serological Analysis of IgG-type Tissue Transglutaminase.

Celiac disease (CD) is a gluten-dependent autoimmune disorder affecting a significant percentage of the general population, with increasing incidence particularly for children. Reliable analytical methods suitable for the serological diagnosis of the disorder are urgently required for performing both the early diagnosis and the follow-up of a patient adhering to a gluten-free diet. Herein we report on the preparation and application of a novel electrochemical immunosensor based on the use of ensembles of gold nanoelectrodes (NEEs) for the detection of anti-tissue transglutaminase (anti-tTG), which is considered one reliable serological marker for CD.

Plasma Activation of Copper Nanowires Arrays for Electrocatalytic Sensing of Nitrate in Food and Water.

Electrochemical methods for nitrate detection are very attractive since they are suitable for in-field and decentralized monitoring. Copper electrodes are often used to this aim as this metal presents interesting electrocatalytic properties towards nitrate reduction. In this research, we study improvements in the electrochemical analysis of nitrate in natural water and food by taking advantage of the detection capabilities of ensembles of copper nanowire electrodes (CuWNEEs).

Electrochemosensor for Trace Analysis of Perfluorooctanesulfonate in Water Based on a Molecularly Imprinted Poly( o-phenylenediamine) Polymer.

This work is aimed at developing an electrochemical sensor for the sensitive and selective detection of trace levels of perfluorooctanesulfonate (PFOS) in water. Contamination of waters by perfluorinated alkyl substances (PFAS) is a problem of global concern due to their suspected toxicity and ability to bioaccumulate. PFOS is the perfluorinated compound of major concern, as it has the lowest suggested control concentrations.

Electrochemical preparation of standard solutions of Pb(II) ions in ionic liquid for analysis of hydrophobic samples: The olive oil case.

In this paper we present an electrochemical approach to prepare standard solutions of metal ions in a room temperature ionic liquid (IL), which can find useful application for analysis in hydrophobic matrices. The method, developed here for the case of lead ions, is based on the galvanostatic dissolution of a lead anode dipped directly in a suitable IL, namely tri-hexyl(tetradecyl)phosphonium bis (trifluoromethylsulfonyl) imide ([P][NTf]). After each oxidation step, the metal dissolution process in the IL solutions was monitored by cyclic voltammetric measurements at a glassy carbon disk electrode.

Nanobiosensing with Arrays and Ensembles of Nanoelectrodes.

Since the first reports dating back to the mid-1990s, ensembles and arrays of nanoelectrodes (NEEs and NEAs, respectively) have gained an important role as advanced electroanalytical tools thank to their unique characteristics which include, among others, dramatically improved signal/noise ratios, enhanced mass transport and suitability for extreme miniaturization. From the year 2000 onward, these properties have been exploited to develop electrochemical biosensors in which the surfaces of NEEs/NEAs have been functionalized with biorecognition layers using immobilization modes able to take the maximum advantage from the special morphology and composite nature of their surface. This paper presents an updated overview of this field.

Microscopic imaging and tuning of electrogenerated chemiluminescence with boron-doped diamond nanoelectrode arrays.

Nanoelectrode arrays (NEAs) are increasingly applied for a variety of electroanalytical applications; however, very few studies dealt with the use of NEAs as an electrochemical generator of electrogenerated chemiluminescence (ECL). In the present study, arrays of nanodisc and nanoband electrodes with different dimensions and inter-electrode distances were fabricated by e-beam lithography on a polycarbonate layer deposited on boron-doped diamond (BDD) substrates. In particular, NEAs with 16 different geometries were fabricated on the same BDD sample substrate obtaining a multiple nanoelectrode and ultramicroelectrode array platform (MNEAP).

A Sensitive Electrochemiluminescence Immunosensor for Celiac Disease Diagnosis Based on Nanoelectrode Ensembles.

We report here the design of a novel immunosensor and its application for celiac disease diagnosis, based on an electrogenerated chemiluminescence (ECL) readout, using membrane-templated gold nanoelectrode ensembles (NEEs) as a detection platform. An original sensing strategy is presented by segregating spatially the initial electrochemical reaction and the location of the immobilized biomolecules where ECL is finally emitted. The recognition scaffold is the following: tissue transglutaminase (tTG) is immobilized as a capturing agent on the polycarbonate (PC) surface of the track-etched templating membrane.

Detection of DNA Hybridization by Methylene Blue Electrochemistry at Activated Nanoelectrode Ensembles.

Nanoelectrode ensembles (NEEs) obtained by electroless gold deposition in track-etched poly-carbonate (PC) membranes are functionalized and applied for DNA hybridization detection, using methylene blue (MB) as electroactive probe. To this aim, an amine terminated (ss)DNA probe is immobilized on the PC surface of the NEE by reaction via carbodiimide and N-hydroxysulfosuccinimide. In order to increase the number of carboxylic groups present on PC and suitable for the functionalization, the surface of NEEs is oxidized with potassium permanganate.

Ensembles-of Gold Nanowires for the Anodic Stripping Voltammetric Determination of Inorganic Arsenic.

3D-ensembles of gold nanowires electrodes (3D-NEEs) are produced by electroless gold deposition in track-etched polycarbonate (PC) membranes, followed by partial etching (plama or chemical) of the polymeric membrane. These electrodes are applied to the anodic stripping voltammetric determination of inorganic As. The controlled etching of the PC template increased the gold surface area, widening the linear range of the analytical response with respect to ensembles of gold nanodisk electrodes (2D-NEEs).

Electrochemical immunosensor based on ensemble of nanoelectrodes for immunoglobulin IgY detection: application to identify hen's egg yolk in tempera paintings.

A nanostructured electrochemical biosensor for detecting proteins of interest in work of art, in particular in tempera paintings, is presented. To determine egg yolk we focus here on the determination of immunoglobulin IgY. The transducers are nanoelectrode ensembles (NEEs), prepared via membrane templated electroless deposition of gold.

Nafion® as advanced immobilisation substrate for the voltammetric analysis of electroactive microparticles: the case of some artistic colouring agents.

Voltammetry of microparticles is applied to characterise and to identify solid analytes of interest in the field of cultural heritage. Nafion® is used for the immobilisation of solid microparticles onto the surface of a glassy carbon electrode by exploiting the deposition onto the electrode surface of a micro-volume of a suspension of the microsample in polymeric solution. Cyclic voltammetry and square wave voltammetry are applied to characterise and to identify the microparticles immobilised in the Nafion® coating.

Bioelectroanalysis with nanoelectrode ensembles and arrays.

This review deals with recent advances in bioelectroanalytical applications of nanostructured electrodes, in particular nanoelectrode ensembles (NEEs) and arrays (NEAs). First, nanofabrication techniques, principles of function, and specific advantages and limits of NEEs and NEAs are critically discussed. In the second part, some recent examples of bioelectroanalytical applications are presented.

Ensembles of nanoelectrodes modified with gold nanoparticles: characterization and application to DNA-hybridization detection.

A new method to increase the active area (A(act)) of nanoelectrode ensembles (NEEs) is described. To this aim, gold nanoparticles (AuNPs) are immobilized onto the surface of NEEs using cysteamine as a cross-linker able to bind the AuNPs to the heads of the nanoelectrodes to obtain the so-called AuNPs-NEEs. The analysis of the cyclic voltammograms recorded in pure supporting electrolyte showed that the presence of the nanoparticles reflects in an, approximately, ten-times increase in the electrochemically active area of the ensemble.

Functionalized ensembles of nanoelectrodes as affinity biosensors for DNA hybridization detection.

A novel electrochemical biosensor for DNA hybridization detection based on nanoelectrode ensembles (NEEs) is presented. NEEs are prepared by electroless deposition of gold into the pores of a templating track-etched polycarbonate (PC) membrane. The wide surface of the templating membrane surrounding the nanoelectrodes is exploited to bind the capture DNA probes via amide coupling with the carboxylic groups present on the PC surface.

Voltammetry of redox analytes at trace concentrations with nanoelectrode ensembles.

Gold nanoelectrodes ensembles (NEEs) have been prepared by electroless plating of Au nanoelectrode elements within the pores of a microporous polycarbonate template membrane. Cyclic voltammograms recorded in (ferrocenylmethyl) trimethylammonium hexafluorophosphate (FA(+) PF(6)(-)) solutions showed that these NEEs operate in the "total-overlap" response regime, giving well resolved peak shaped voltammograms. Experimental results show that the faradaic/background currents ratios at the NEE are independent on the total geometric area of the ensemble, so that NEE can be enlarged or miniaturized at pleasure without influencing the very favorable signal/noise ratio.

Epifluorescence imaging of electrochemically switchable Langmuir-Blodgett films of Nafion.

A combination of electrochemistry and luminescence methods was exploited to obtain information on the electrochemical activity and homogeneity of Nafion Langmuir-Blodgett films. The redox behavior of the Ru(bpy)3(2+) probe incorporated in the Nafion film was monitored by epifluorescence microscopy. The photoluminescent images, recorded by a charge-coupled device (CCD) camera, reflect the distribution of the probe in the film, which resulted as very uniform, particularly in comparison with spin-coated films.

Gold nanoelectrode ensembles for direct trace electroanalysis of iodide.

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.

Electrochemistry of cytochrome c incorporated in Langmuir-Blodgett films of Nafion and Eastman AQ 55.

Ultrathin films of Nafion and Eastman-AQ 55 loaded with cytochrome c (cyt c) were obtained and transferred on indium tin oxide (ITO) electrodes via the Langmuir-Blodgett (LB) technique. The pressure-area isotherms for mixed ionomer-protein films indicate that the miscibility of cyt c in the interfacial layer is better for Nafion than for AQ 55. Interestingly, these composite films maintain the electroactivity of cyt c without requiring the addition of promoters or mediators.

Sulfide as a confounding factor in toxicity tests with the sea urchin Paracentrotus lividus: comparisons with chemical analysis data.

Sperm cell and embryo toxicity tests with the sea urchin Paracentrotus lividus were performed to assess the toxicity of sulfide, which is considered a confounding factor in toxicity tests. For improved information on the sensitivity of these methods to sulfide, experiments were performed in the same aerobic conditions used for testing environmental samples, with sulfide concentrations being monitored at the same time by cathodic stripping voltammetry. New toxicity data for sulfide expressed as median effective concentration (EC50) and no-observed-effect concentration (NOEC) are reported.

Ionomer-coated electrodes and nanoelectrode ensembles as electrochemical environmental sensors: recent advances and prospects.

This Minireview focuses on recent advances in the use of ionomer-coated electrodes and nanoelectrode ensembles for the determination of redox ions at trace concentration level with special stress on applications for environmental monitoring. After an overview on the most recent developments of ionomer-coated electrodes, attention is directed towards their use for speciation analysis in environmental samples. In particular, some examples such as the selective determination of inorganic and metallorganic species of different toxicity and the redox state speciation of multiply charged ions are discussed.

Electrochemical measurement of mercury concentration profiles in the pore-waters of sediments of the Venice Lagoon by ion-exchange voltammetry at polymer modified electrodes.

Glassy carbon electrodes modified with coatings of poly-[1-methyl-3-(pyrrol-1-ylmethyl)pyridinium], poly-MPP, were employed for preconcentrating and detecting the anionic complex HgCl4(2-), which is the prevailing inorganic Hg(II) species in salt waters such as the pore-waters of sediments here examined. The application of ion-exchange voltammetry at poly-MPP coated electrodes in combination with an in situ pore-water sampler allowed the measurement of concentration vs. depth profiles for mercury dissolved in the pore-waters of a salt-marsh and of a mud-flat located in a polluted area of the Venice Lagoon.