pinecone/core-2020-05-10-deduplication huggingface dataset:
Fe3+/Fe2+ mycobactin-complex electrochemistry as an approach to determine mycobactin levels in urine.

Mycobacterium acquire iron by producing siderophores called mycobactins, with an extremely high affinity complexation of Fe3+. The iron complex shows distinctive electrochemistry predicting 18 orders of magnitude greater affinity of the mycobactin for Fe3+ than Fe2+. A heterogeneous standard rate constant, ks of the order of 10−5 cm s−1 confirms quasi reversible electrochemistry and based on the equilibrium in the presence of excess solution Fe3+/Fe2+ the oxidation and reduction peaks for the siderophore complex could be calibrated for ferric mycobactin J (FeMJ). FeMJ spiked urine collected from cows showed a matrix effect on the current peak height. For example, 240±15 µM FeMJ was estimated in 600 µM spiked urine. However, in the presence of excess solution Fe(acac)3 the same sample yielded an estimated 580±25 µM FeMJ.This study was supported by the Tuberculosis ResearchSection of Clifton E. Barry III as part of the Intramural Research Program of the National Institute of Allergy andInfectious Diseases, U.S. National Institutes of Health in the form of a stipend for author NSM.This is the accepted manuscript of a paper published in Electroanalysis Special Issue: Mátrafüred 2014 – International Conference on Electrochemical Sensors Volume 27, Issue 3, pages 833–842, March 2015, DOI: 10.1002/elan.20140056
Origin of Low Detection Limit and High Selectivity of Roche Accu‐Chek Test Strips that Enables Measurement of Tear Glucose Levels

Tear glucose measurements have been suggested as a potential alternative to blood glucose monitoring for diabetic patients. While previous work has reported a correlation between blood and tear glucose levels in humans, this link has not been thoroughly established and additional clinical studies are needed. We recently reported that Roche’s electrochemical Accu‐Chek blood glucose test strips exhibit far superior analytical performance over other commercial brands, with the low detection limit and high selectivity required for quantitating tear glucose levels. Herein, we evaluate the origin of the high sensitivity and selectivity of the Roche test strips and show that the use of pyrroloquinoline quinone (PQQ)‐dependent glucose dehydrogenase (GDH) as an active enzyme reagent in combination with a nitrosoaniline derivative as an electron transfer mediator are primarily responsible for the low limit of quantification (LOQ) (ca. 9 µM) and enhanced selectivity achieved with these strips
Electrochemical Characterization of Clean Shape-Controlled Pt Nanoparticles Prepared in Presence of Oleylamine/Oleic Acid

A collection of shape-controlled Pt nanoparticles has been prepared using two different and previously described methodologies, both using oleylamine/oleic acid as capping material/solvent. A new decontamination protocol is presented to effectively clean the surface of the different nanoparticles thus allowing a full exposure of their surface area and consequently to make the most of their surface structure dependent reactivity. Subsequently, the clean shape-controlled Pt nanoparticles have been electrochemically characterized and their electrocatalytic properties evaluated towards some surface structure reactions of interest. The results indicate that the full characterization of the surface structure cannot be done exclusively by the available microscopy techniques, since it is very difficult to determine the presence of surface defects. Additional surface characterization probes, such as those provided by electrochemical surface sensitive reactions, have been used to assess the surface structure of the samples.This work has been financially supported by the MICINN (Feder) of Spain and Generalitat Valencia through Projects CTQ2013-44083-P and PROMETEOII/2014/013, respectively
Square-Wave Voltammetry of Electroinactive Surfactants

Under the influence of previously published and some new theoretical results, potential- dependent adsorption and desorption of model electroinactive surfactants Triton X-100 (T-X-100 or polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether) and sodium dodecyl sulfate (SDS) on the static mercury drop electrode (SMDE) were studied by square-wave voltammetry (SWV). Although (according to the theory) the resulting current – potential curve should consist of two highly separated peaks, only desorption signal could be seen on each experimentally obtained voltammogram, most probably because of the limitations concerning the available potential range. Different properties of the recorded peak are in good agreement with the theory indicating that square-wave voltammetry could be treated as a potential tool for tensammetric studies of electroinactive surface active substances
“Green Electrodes” Modified with Au Nanoparticles Synthesized in Glycerol, as Electrochemical Nitrite Sensor

A new environmentally friendly Au nanoparticles (Au NPs) synthesis in glycerol by using ultraviolet irradiation and without extra-added stabilizers is described. The synthesis proposed in this work may impact on the non-polluting production of noble nanoparticles with simple chemicals normally found in standard laboratories. These Au NPs were used to modify a carbon paste electrode (CPE) without having to separate them from the reaction medium. This green electrode was used as an electrochemical sensor for the nitrite detection in water. At the optimum conditions the green sensor presented a linear response in the 2.0×10−7–1.5×10−5 M concentration range, a good detection sensitivity (0.268 A L mol−1), and a low detection limit of 2.0×10−7 M of nitrite. The proposed modified green CPE was used to determine nitrite in tap water samples
Microwire chronoamperometric determination of concentration, diffusivity, and salinity for simultaneous oxygen and proton reduction

A microwire chronoamperometric method is reported employing a 25μm diameter platinum microwire for multi-parameter electroanalysis with digital simulation-based evaluation (employing DigiElch 4.F). Concentration and diffusion coefficient data are obtained for the reduction of oxygen and for the reduction of protons individually and simultaneously in saline (0.1M to 4.0M NaCl) electrolyte media. The diffusion coefficient and concentration data for oxygen allows salinity levels to be estimated. The microwire chronoamperometry method offers versatility and precision due to (i) a slow approach to steady state (when compared to microdisc methods) and (ii) insignificant viscosity effects (when compared to hydrodynamic methods)
Study of a novel bisnaphthalimidopropyl polyamine as electroactive material for perchlorate-selective potentiometric sensors.

In this work, the new polyamine bisnaphthalimidopropyl-4,4'-diaminodiphenylmethane is proposed as a new ionophore for perchlorate potentiometric sensors. The optimal formulation for the membrane comprised of 12 mmol kg-1 of the ionophore, and 68 % (w/w) of 2-nitrophenyl phenyl ether as plasticizer and 31 % (w/w) of high molecular weight PVC. The sensors were soaked in water for a week to allow leakage of anionic impurities and for one day in a perchlorate solution (10-4 mol L-1) to improve reproducibility due to its first usage. The stability constant for the ionophore-perchlorate association in the membrane, log ?IL1=3.18?0.04, ensured a performance characterized by the slope of 54.1 (?0.7) mV dec-1 to perchlorate solutions with concentrations between 1.24?10-7 and 1.00?10-3 mol L-1. The sensors are insensitive to pH between 3.5 to 11.0, they have a practical detection limit of 7.66 (?0.42) ?10-8 mol L-1 and a response time below 60 s for solutions with perchlorate concentrations above 5?10-6 mol L-1. The accuracy of the results was confirmed by the analysis of the contaminant in a certified reference water sample.EPSRC UK National Mass Spectrometry Facility, Institute of Mass Spectrometry, Swansea University for Mass Spectral Analysis, European Union, National Funds. Grant Numbers: C/EQB/LA0006/2013, NORTE-07-0124-FEDER-000067, QREN-NANOQU?MICA, FCT/CAPES n?354/1
Determination of Allura Red and Tartrazine in Food Samples by Sequential Injection Analysis Combined with Voltammetric Detection at Antimony Film Electrode

An antimony film electrode prepared on-line and installed as part of a sequential injection system, was used as an electrochemical detector to determine azo dyes in food samples.The influence of several flow varia-bles were evaluated using a centra lcomposite design.In optimal conditions, the linear range of the calibration curve varied from 1–5 mM, with a limit of detection limit of 0.3 mM. The relative standard deviation of analytical repeatability was < 5.0 %.The method was validated by comparing the results obtained with those provided by HPLC; no significant difference were seen.Junta de Castilla y León Proyecto VA171U1
Quantitative analysis of active pharmaceutical ingredients (APIs) using a potentiometric electronic tongue in a SIA flow system

An advanced potentiometric electronic tongue and Sequential Injection Analysis (SIA) measurement system was applied for the quantitative analysis of mixtures containing three active pharmaceutical ingredients (APIs): acetaminophen, ascorbic acid and acetylsalicylic acid, in the presence of various amounts of caffeine as interferent. The flow-through sensor array was composed of miniaturized classical ion-selective electrodes based on plasticized PVC membranes containing only ion exchangers. Partial Least Squares (PLS) analysis of the steady-state sensor array responses, measured in API mixtures prepared by the SIA system permitted a correct quantitative analysis of acetylsalicylic acid and ascorbic acid. Further optimization using multiway PLS fed by dynamic responses without additional feature extraction did not improve significantly the resolution of acetaminophen. Lastly, the chemometric treatment, involving the extraction of dynamic components of the transient response employing the Wavelet transform, the removal of less-significant coefficients by means of Causal Index pruning and training of an Artificial Neural Network (ANN) with the selected coefficients, allowed the simultaneous determination of all the three studied APIs, while counterbalancing any interference due to caffeine
Simultaneous voltammetric determination of heavy metals by use of crown ether-modified electrodes and chemometrics

A three-sensor array consisting of a graphite-epoxy composite electrode (GEC), 4-carboxybenzo-18-crown-6-GEC and 4- carboxybenzo-15-crown-5-GEC was employed for the simultaneous determination of Cd(II), Pb(II) and Hg(II) by differential pulse anodic stripping voltammetry (DPASV). Sensors were firstly studied for the determination of Hg(II); secondly, peak current responses confirmed that all sensors showed differentiated response for the three considered metals. A response model was developed to resolve mixtures of Cd(II), Pb(II) and Hg(II) at the μg L⁻¹ level; Discrete Wavelet Transform was selected as preprocessing tool and artificial neural network used for the modelling of the obtained responses
Control of Electron-transfer in Immunonanosensors by Using Polyclonal and Monoclonal Antibodies

The design and operation of biosensors is not trivial. For instance, variation in the output signal during monitoring of analytes can not usually be controlled. Hence, if such control were possible, and could be triggered on demand, it would greatly facilitate system design and operation. Herein, we report the design of two types of voltamperometric immunosensors, in which the magnitude of the current output signal (differential pulse voltammetry [DPV]) can be increased or decreased as needed. The designed systems use monoclonal and polyclonal anti-human IgG antibodies, conjugated to monopodal ferrocene-modified gold nanoparticles that are casted onto screen-printed carbon electrodes (Ab/mFcL/AuNPs/SPCEs). Upon addition of human IgG as antigen, the systems exhibit opposite responses according to the Ab: the current decreases when monoclonal Ab is used, whereas it increases when polyclonal Ab is used. We attributed the former response to inhibition of electron-transfer (due to the formation of a protein layer), and the latter response, to a global increase in electron transfer (induced by the aggregation of gold nanoparticles). These effects were confirmed by studying a custom-made lipoic acid-based bipodal ligand, which confirmed that the increase in current is effectively induced by the aggregation of the modified nanoparticles (pAb/mFcL/AuNPs). Both sensors have large dynamic ranges, although the pAb-based one was found to be 3.3-times more sensitive. Tests of selectivity and specificity for ovalbumin, α-lactalbumin and serum bovine albumin showed that the immunosensors are highly selective and specific, even in the presence of up to 1000-fold levels of potentially competitive proteins. The limit of detection for human IgG using the pAb/mFcL/AuNP bioconjugate was estimated to be 0.85 ng/mL. The pAb/mFcL/AuNPs-based biosensor has used to determine amounts of human IgG in real sample
Generator-collector voltammetry at dual-plate gold-gold microtrench electrodes as diagnostic tool in ionic liquids

Ionic liquids provide high viscosity solvent environments with interesting voltammetric characteristics and new electrochemical mechanisms. Here, a gold-gold dual-plate microtrench electrode is employed in generator-collector mode to enhance viscosity-limited currents in ionic liquids due to fast feedback within small inter-electrode gaps (5μm inter-electrode gap, 27μm microtrench depth) and to provide a mechanistic diagnosis tool. Three redox systems in the ionic liquid BMIm+BF4- are investigated: (i) ferrocene oxidation, (ii) oxygen reduction, and (iii) 2-phenyl-naphthyl-1,4-dione reduction. Both transient and steady state voltammetric responses are compared. Asymmetric diffusion processes, reaction intermediates, and solubility changes in the ionic liquid are revealed
All-Polystyrene 3D-Printed Electrochemical Device with Embedded Carbon Nanofiber – Graphite – Polystyrene Composite Conductor

Carbon nanofibres (CNFs) and graphite flake microparticles were added to thermoplastic polystyrene polymer with the aim of making new conductive blends suitable for 3D-printing. Various polymer/carbon blends were evaluated for suitability as printable, electroactive material. An electrically conducting polystyrene composite was developed and used with commercially available polystyrene (HIPS) to manufacture electrodes suitable for electrochemical experiments. Electrodes were produced and evaluated for cyclic voltammetry of aqueous 1,1’-ferrocenedimethanol and differential pulse voltammetry detection of aqueous Pb2+ via anodic stripping. A polystyrene/CNF/graphite (80/10/10 wt%) composite provides good conductivity and a stable electrochemical interface with well-defined active geometric surface area. The printed electrodes form a stable interface to the polystyrene shell, give good signal to background voltammetric responses, and are reusable after polishing
Electrothermal Annealing of Catalytic Platinum Microwire Electrodes:Towards Membrane-Free pH 7 Glucose Micro-Fuel Cells

Surface activation and cleaning of platinum micro-wires of 25 micron diameter has been achieved by a short one-second electrothermal annealing treatment in air at 0.3 A (to orange glow). Voltammetric data suggest a decrease in the electrochemically active surface area with annealing time and a change in surface structure towards the Pt(100) crystalline face. The impact of electrothermal annealing on the electrocatalytic activity towards (i) oxygen reduction and (ii) glucose oxidation in pH 7 phosphate buffered aqueous solutions is investigated. In contrast to as-received platinum, annealed platinum produces an electrocatalytic response towards glucose oxidation with increasing glucose concentration. A short one-second anneal step is just as effective in enhancing catalysis as prolonged electrochemical cleaning in sulphuric acid. Finally, by combining a non-annealed and an annealed microwire electrode, a very simple membrane-free micro-fuel cell system is devised operating in phosphate buffer at pH 7 with linearly increasing power output reaching 2.2 nW cm−2 for high glucose levels of 0.5 M
2D Hexagonal Boron Nitride (2D-hBN) Explored as a Potential Electrocatalyst for the Oxygen Reduction Reaction

This is the peer reviewed version of the following article: Khan, Aamar F., et. al. (2017). 2D Hexagonal Boron Nitride (2D-hBN) Explored as a Potential Electrocatalyst for the Oxygen Reduction Reaction. Electroanalysis, 29(2), 622-634. DOI: 10.1002/elan.201600462, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1002/elan.201600462/abstract. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-ArchivingCrystalline 2D hexagonal Boron Nitride (2D-hBN) is explored as a potential electrocatalyst towards the oxygen reduction reaction (ORR) when electrically wired via a drop-casting approach upon a range of carbon based electrode surfaces; namely, glassy carbon (GC), boron-doped diamond (BDD), and screen-printed graphitic electrodes (SPEs). We consider the ORR in acidic conditions and critically evaluate the performance of unmodified and 2D-hBN modified electrodes, implementing coverage studies (commonly neglected in the literature) in order to ascertain the true impact of this novel nanomaterial. The behaviour of 2D-hBN towards the ORR is shown to be highly dependent upon both the underlying carbon substrate and the coverage/mass utilised. 2D-hBN modified SPEs are found to exhibit the most beneficial response towards the ORR, reducing the peak potential by ca. 0.28 V when compared to an unmodified/bare SPE. Such improvements at this supporting substrate are inferred due to favourable 2D-hBN interaction with ridged surfaces exposing a high proportion of edge regions/sites, where conversely, we show that relatively smooth substrate surfaces (such as GC) are less conducive towards successful 2D-hBN immobilisation. In this paper, we reveal for the first time (in the specific case of using a rough supporting substrate) that 2D-hBN gives rise to beneficial electrochemical behaviour towards the ORR. Unfortunately, this material is not considered an electrocatalyst for use within fuel cells given that the estimated number of electrons transferred during the ORR ranges between 1.90–2.45 for different coverages, indicating that the ORR at 2D-hBN predominantly produces hydrogen peroxide. 2D-hBN does however have potential and should be explored further by those designing, fabricating and consequently electrochemically testing modified electrocatalysts towards the ORR
A peptide nucleic acid (PNA)-DNA ferrocenyl intercalator for electrochemical sensing

A ferrocenyl intercalator was investigated to develop an electrochemical DNA biosensor employing a peptide nucleic acid (PNA) sequence as capture probe. After hybridization with single strand DNA sequence, a naphthalene diimide intercalator bearing ferrocene moieties (FND) was introduced to bind with the PNA-DNA duplex and the electrochemical signal of the ferrocene molecules was used to monitor the DNA recognition. Electrochemical impedance spectroscopy was used to characterize the different modification steps. Differential pulse voltammetry was employed to evaluate the electrochemical signal of the FND intercalator related to its interaction with the complementary PNA-DNA hybrid. The ferrocene oxidation peaks were utilised for the target DNA quantification. The developed biosensor demonstrated a good linear dependence of FND oxidation peak on DNA concentration in the range 1 fM to 100 nM of target DNA, with a low detection limit of 11.68 fM. Selectivity tests were also investigated with a non-complementary DNA sequence, indicating that the FND intercalator exhibits a selective response to the target PNA-DNA duplex
A voltammetric electronic tongue for the quantitative analysis of quality parameters in wastewater

The use of a voltammetric electronic tongue for the quantitative analysis of quality parameters in influent wastewater from
a wastewater treatment plant (WWTP) that treats domestic and industrial wastewater is proposed. The electronic
voltammetric tongue consists of a set of four noble electrodes (iridium, rhodium, platinum and gold) housed inside a
stainless steel cylinder. These noble metals have high durability and are low maintenance-demanding, as required for
developing future automated equipment. A pulse voltammetry study was conducted in 35 wastewater samples to
determine ammonia (NH4
+-N), nitrates (NO3
--N), total phosphate (tot-P), soluble chemical oxygen demand (CODs) and
conductivity. These parameters were also determined in these samples by routine analytical methods in the WWTP
laboratory. A partial least squares (PLS) analysis was run to obtain a model to predict each parameter. Twenty-five
samples were included in the calibration set and 10 in the validation set. Calibration and validation sets were selected
randomly, except for the extreme values of each parameter, which were included in the calibration set. Variable selection
was performed on the voltammetric data using Genetic Algorithms in the calibration data set for each parameter. The
electronic tongue showed good predictive power to determine the concentrations of NH4
+-N, NO3
--N and tot-P and CODs.The financial support for this work was provided by the
Spanish Ministry of Economy and Competitivity though
Project e-TONGUE4WAT (IPT-2012-0069-310000)
INNPACTO and by European Union FEDER funds.
Financial support from the Spanish Government (Project
MAT2012-38429-C04) and the Generalitat Valencia
(Project PROMETEOII/2014/047) is also gratefully
acknowledged
New insight into the EC’ mechanism of uric acid regeneration in the presence of ascorbic acid on a poly(3,4-ethylenedioxithiophene) modified gold electrode

A gold electrode surface was functionalized by means of an electropolymerized conductive poly(3,4-ethylenedioxythiophene) (PEDOT) organic layer. This modified electrode was used for the electrochemical detection of ascorbic (AA) and uric (UA) acids in an aqueous mixture with a selectivity around 340 mV. The electrochemical reactions kinetics were limited by AA diffusion and UA adsorption at the electrode surface, respectively. Following a previous study ([Electrochem Comm., 2011, 13, 423-425]) cyclic voltammetry was used to provide a better understanding of the EC' mechanism of regeneration of UA by AA. Experiments particularly showed that allantoin (i.e. the final product of UA oxidation) is not actually involved in the synergic mechanism but rather the oxidized UA product diimine which is adsorbed at the electrode surface