Abstract  A novel melamine electrochemiluminescence (ECL) sensor was developed based on mesoporous SiO(2) nanospheres/Ru(bpy)(3)(2+)/Nafion modified electrodes. The homogeneous mesoporous silica nanospheres, synthesized using modified Stöber sol-gel process, were characterized by Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM) and Brunauer-Emmett-Teller (BET). The ECL and electrochemistry of the modified electrodes were investigated with tri-n-propylamine (TPA) as the coreactant. Furthermore, the mesporous SiO(2) nanospheres/Ru(bpy)(3)(2+)-based modified electrodes were used for ECL determination of melamine. The analytical performances of this ECL sensor for melamine based on its enhancement ECL emission of Ru(bpy)(3)(2+) were investigated. The results indicated that the sensor exhibited excellent performance during melamine determination with a wide linear range (7.81×10(-9)-5×10(-6) M), low detection limit (2.6×10(-9) M). The high sensitivity and stability mainly resulted from the high surface area and special structure of the mesoporous silica nanospheres. The proposed ECL approach was used to analyze the melamine content in powdered milk with satisfactory results.

Abstract  We study the energy relaxation and structural relaxation dynamics of hydrated protons in Nafion membranes at different hydration levels using femtosecond infrared transient absorption spectroscopy. At low hydration levels we observe that the excitation of the proton vibration of an Eigen-like proton hydration structure leads to a structural relaxation process in which the Eigen-like structure evolves to a Zundel-like proton hydration structure. This reorganization leads to a transfer of the proton charge and closely follows the mechanism of infrared-induced adiabatic proton transfer that has been proposed by S. Hammes-Schiffer, J. T. Hynes, and others. At high hydration levels, the spectral dynamics are dominated by vibrational energy relaxation and subsequent cooling of the proton hydration structures and the surrounding water molecules. Using a kinetic analysis of the transient spectral data, we determine the rates of proton transfer, vibrational energy relaxation, and cooling as a function of hydration level. We find that infrared-induced proton transfer occurs at all hydration levels but becomes less observable at high hydration levels due to the increasingly dominant influence of the vibrational energy relaxation.

Abstract  Direct electrochemistry of Trametes versicolor Laccase (LAC) was found at a Sonogel-Carbon electrode. The bioamplification, performed by dual immobilization of this enzyme and Mushroom Tyrosinase (TYR), of the bio-electrocatalytic reduction of O(2) was investigated. The calculated alpha transfer coefficients were 0.64 and 0.67, and the heterogeneous electron-transfer rate constants were 6.19 and 8.52 s(-1), respectively, for the individual LAC and dual LAC-TYR-based Nafion/Sonogel-Carbon bio-electrodes. The responses of the dual enzymes electrode to polyphenols were stronger than those of the individual LAC or TYR biosensors. Hypotheses are offered about the mechanism of bioamplification. The surfaces of the biosensors were also characterized by AFM.

Abstract  The hydration structure of the 'strongly bound water' around the sulfonic acid (SA) groups in Nafion, which has recently been revealed by (1)H NMR spectroscopy (Anal. Chem., 2013, 85, 7581), is studied using infrared spectroscopy with the aid of quantum chemical (QC) calculations. During a heated drying process, bulky water is firstly dehydrated, which is followed by the disappearance of the hydronium ion and the appearance of bands that have been assigned to the fully dehydrated species at 140 °C. However, a spectral simulation based on QC reveals that the spectrum at 140 °C comes from the SA group associated with a single-water molecule via two H-bonds. This implies that a thoroughly dried membrane is unavailable even at 140 °C, and the involved water corresponds to the 'strongly bound water.' The QC-analytical results are experimentally confirmed by evolved gas analysis mass spectrometry (EGA-MS). At ca. 300 °C, which is the temperature where the SA group is selectively decomposed, the molecular fragment of SO2 is observed accompanying water molecules as expected. This confirms that the last single-water molecule can remain on the SA group until the thermal decomposition.

Abstract  A prototype amperometric immunosensor was evaluated based on the adsorption of antibodies onto perpendicularly oriented assemblies of single wall carbon nanotubes called SWNT forests. The forests were self-assembled from oxidatively shortened SWNTs onto Nafion/iron oxide coated pyrolytic graphite electrodes. The nanotube forests were characterized using atomic force microscopy and resonance Raman spectroscopy. Anti-biotin antibody strongly adsorbed to the SWNT forests. In the presence of a soluble mediator, the detection limit for horseradish peroxidase (HRP) labeled biotin was 2.5 pmol ml(-1) (2.5 nM). Unlabelled biotin was detected in a competitive approach with a detection limit of 16 nmol ml(-1) (16 microM) and a relative standard deviation of 12%. The immunosensor showed low non-specific adsorption of biotin-HRP (approx. 0.1%) when blocked with bovine serum albumin. This immunosensing approach using high surface area, patternable, conductive SWNT assemblies may eventually prove useful for nano-biosensing arrays.

Abstract  A novel amperometric sensor and chromatographic detector for determination of parathion has been fabricated from a multi-wall carbon nano-tube (MWCNT)/Nafion film-modified glassy-carbon electrode (GCE). The electrochemical response to parathion at the MWCNT/Nafion film electrode was investigated by cyclic voltammetry and linear sweep voltammetry. The redox current of parathion at the MWCNT/Nafion film electrode was significantly higher than that at the bare GCE, the MWCNT-modified GCE, and the Nafion-modified GCE. The results indicated that the MWCNT/Nafion film had an efficient electrocatalytic effect on the electrochemical response to parathion. The peak current was proportional to the concentration of parathion in the range 5.0x10(-9)-2.0x10(-5) mol L(-1). The detection limit was 1.0x10(-9) mol L(-1) (after 120 s accumulation). In high-performance liquid chromatography with electrochemical detection (HPLC-ED) a stable and sensitive current response was obtained for parathion at the MWCNT/Nafion film electrode. The linear range for parathion was over four orders of magnitude and the detection limit was 6.0x10(-9) mol L(-1). Application of the method for determination of parathion in rice was satisfactory.

Abstract  In this paper, a simple one-step electrodeposition method is described to fabricate chitosan-Prussian blue-multiwall carbon nanotubes-hollow PtCo nanochains (CS-PB-MWNTs-H-PtCo) film onto the gold electrode surface, then glucose oxidase (GOD) and Nafion were modified onto the film subsequently to fabricate a glucose biosensor. The morphologies and electrochemistry of the composite were investigated by using Fourier transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM) and electrochemical techniques including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. The performances of the biosensor have been investigated by chronoamperometry method under the optimized conditions. This biosensor showed a linear response to glucose range from 1.5 μM to 1.12 mM with a detection limit of 0.47 μM (S/N=3), a high sensitivity of 23.4 μA mM(-1) cm(-2), and a fast response time. The apparent Michaelis-Menten constant (K(M)(app)) was 1.89 mM. In addition, the biosensor also exhibited strong anti-interference ability, excellent stability and good reproducibility.

Abstract  A highly ordered mesoporous Nafion membrane with a remarkable water retention ability was synthesized via a micelle templating method with self-assembled Pluronic F108 surfactants and its capability to operate under completely dry gas streams is demonstrated.

Abstract  Electrochemically active composite film that contains multiwalled carbon nanotubes (MWCNTs), Nafion (NF), and poly(malachite green) (PMG) has been synthesized on glassy carbon electrode (GCE), gold, and indium tin oxide (ITO) electrodes by potentiodynamic method. The presence of MWCNTs in the composite film (MWCNT-NF-PMG) enhances the surface coverage concentration (Γ) of PMG by fivefold. Similarly, an electrochemical quartz crystal microbalance study revealed enhancement in the deposition of PMG at MWCNT-NF film when compared with bare and only NF modified electrodes. The surface morphology of the composite film was studied using atomic force microscopy, which revealed that the PMG incorporated on MWCNT-NF film. The composite film exhibited enhanced electrocatalytic activity toward the mixture of biochemical compounds catechol and quinol. The electrocatalytic responses of analytes at MWCNT-NF-PMG composite film were measured using both cyclic voltammetry (CV) and differential pulse voltammetry (DPV). From electrocatalysis studies, well-separated voltammetric peaks were obtained at the composite film for catechol and quinol with a peak separation of 147mV. The sensitivity values of the composite film toward catechol and quinol by the DPV technique were 0.4 and 3.2mAmM(-1)cm(-2), respectively, which are higher than the values obtained by the CV technique. Similarly, the above-mentioned values are better than the previously reported electroanalytical values for the same analytes.

Abstract  A novel disposable amperometric biosensor strip for determination of blood alcohol concentration (BAC) with small volume of sample has been constructed using screen-printed electrodes (SPE), nanocomposite film and alcohol dehydrogenase (ADH). Firstly, the GNPs-MWCNT-Nafion nanocomposite film modified on a working electrode was made of Nafion-117, multi-wall carbon nanotubes (MWCNT) and gold nanoparticles (GNPs). After that Meldola's blue (MB) acted as an electron transfer mediator and the mixed solution of ADH, nicotinamide adenine dinucleotide (NAD(+)) were modified in order on the nanocomposite film. At last, a hydrophilic membrane which had an eyehole in center was placed at the outermost of the working area to make a reaction tank of 5 μL, then the hydrophilic membrane/ADH-NAD(+)/GNPs-MWCNT-MB-Nafion/SPE was prepared. The detection of BAC can be accomplished with 5 μL of blood sample obtained precisely by siphonage. Optimum conditions of the biosensor were experimentally determined by varying several important parameters: working potential, solution pH value, environmental temperature and interferences. Experimental results indicated that the biosensor possessed a good accuracy and stability, the linear response range was 2.0 × 10(-4) to 25 × 10(-3)mol/L and the detection limit of the biosensor was 5.0 × 10(-5)mol/L (S/N=3). In the measurement of blood samples, the proposed biosensor had excellent detection performance for measuring BAC and showed a good correlation with gas chromatography. The prepared biosensor strip can be valid for the analysis of BAC.

Abstract  The direct electrochemistry of myoglobin (Mb) entrapped in the Nafion film on a multi-walled carbon nanotubes (MWCNTs) modified carbon ionic liquid electrode (CILE) had been investigated in this paper. By using a hydrophilic ionic liquid of 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMBF(4)) as the modifier, a high-performance basal electrode was fabricated and further modified by MWCNTs, Mb and Nafion by a step-by-step casting method. Spectroscopic results indicated that the Mb molecule on the surface of MWCNTs/CILE retained its native structure. Cyclic voltammetric results showed that a pair of well-defined quasi-reversible redox peaks appeared in the pH 7.0 phosphate buffer solution (PBS), which was attributed to the direct electron transfer of Mb heme Fe(III)/Fe(II) redox couples with the modified electrode. The Nafion/Mb/MWCNTs/CILE gave excellent electrocatalytic activity towards different substrates including trichloroacetic acid (TCA), hydrogen peroxide (H(2)O(2)) and sodium nitrite (NaNO(2)).

Abstract  Electrical impedance properties of different type of carbon nanotubes based bulk electrodes have been investigated to develop chemical and biosensors. The bulk composite electrodes were fabricated with single-wall and multi-wall carbon nanotubes involving ionic conducting host polymer, Nafion, by using traditional solution-casting techniques. Under the various amounts of buffer solution, resistance and capacitance of the electrodes were measured with LCR meter and their characteristics due to ionic conducting host polymer were investigated by means of electrokinetic analysis. The capacitance values showed drastic change while the resistances only changed within few percent ranges. Electrical impedance measurement provided rapid and simple sensing mechanism to develop chemical sensor and biosensors with bulk nano electrodes.

Abstract  The structure of the Nafion ionomer used in proton-exchange membranes of H2/O2 fuel cells has long been contentious. Using a recently introduced algorithm, we have quantitatively simulated previously published small-angle scattering data of hydrated Nafion. The characteristic ‘ionomer peak’ arises from long parallel but otherwise randomly packed water channels surrounded by partially hydrophilic side branches, forming inverted-micelle cylinders. At 20 vol% water, the water channels have diameters of between 1.8 and 3.5 nm, with an average of 2.4 nm. Nafion crystallites (∼10 vol%), which form physical crosslinks that are crucial for the mechanical properties of Nafion films, are elongated and parallel to the water channels, with cross-sections of ∼(5 nm)². Simulations for various other models of Nafion, including Gierke’s cluster and the polymer-bundle model, do not match the scattering data. The new model can explain important features of Nafion, including fast diffusion of water and protons through Nafion and its persistence at low temperatures. [ABSTRACT FROM AUTHOR] Copyright of Nature Materials is the property of Nature Publishing Group and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts)

Abstract  A new amperometric biosensor, based on deposition of glucose oxidase (GOD) onto crystalline gold (Au) nanoparticle modified multiwalled carbon nanotube (MWNT) electrode, is presented. MWNTs have been synthesized by catalytic chemical vapor decomposition of acetylene over rare-earth-based AB2 (DyNi2) alloy hydride catalyst. Purified MWNTs have been decorated with nanocrystalline Au metal clusters using a simple chemical reduction method. The characterization of metal-decorated CNTs has been done using X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy (TEM), high-resolution TEM, and energy-dispersive X-ray analysis. Amperometric biosensor fabricated by depositing GOD over Nafion-solubilized Au-MWNT electrode retains its biocatalytic activity and offers fast and sensitive glucose quantification. The performance of the biosensor has been studied using cyclic voltammetry, amperometry, and hydrodynamic voltammetry, and the results have been discussed. The fabricated glucose biosensor exhibits a linear response up to 22 mM glucose and a detection limit of 20 microM.

Abstract  A novel highly sensitive biosensor for the direct and simultaneous determination of superoxide anion radical (O2-) and nitrite (NO2-) was developed by incorporation of carbon nanotube (CNT) solubilized in nafion in polypyrrole (PPy) matrix on Pt electrode followed by immobilization of Cu,ZnSOD (SOD1) on it. The CNT/PPy nanocomposite electrode enhanced the immobilization of SOD1 and promoted the electron transfer of SOD1 minimizing its fouling effect. The surface morphological images of PPy and CNT-PPy nanocomposite on Pt electrode were obtained by scanning electron microscopy exhibiting highly microporous structures. The electrochemical behavior of the biosensor investigated by cyclic voltammetry revealed that the SOD1 immobilized electrode showed characteristic of SOD1 quasi-reversible redox peaks with a formal potential of +0.065 V vs. Ag/AgCl. The biosensor exhibited a linear response over the concentration range from 0.1 to 750 μM, with a detection limit of 0.1±0.03 μM for O2- and a corresponding linear range of 0.5-2000 μM, with a detection limit of 0.5±0.025 μM for NO2-. In addition, the biosensor exhibited high sensitivity, good reproducibility and retained stability over 30 days. This modified electrode was quite effective not only in detecting O2- and NO2- independently but also determining the concentration of O2- and NO2- simultaneously in vitro and from cancer cells.

Abstract  A novel flow injection analysis (FIA) system suitable for measurement of S-nitrosothiols (RSNOs) in blood plasma is described. In the proposed (FIA) system, samples and standards containing RSNO species are injected into a buffer carrier stream that is mixed with the reagent stream containing 3,3'-dipropionicdiselenide (SeDPA) and glutathione (GSH). SeDPA has been shown previously to catalytically decompose RSNOs in the presence of a reducing agent, such as GSH, to produce nitric oxide (NO). The liberated NO is then detected downstream by an amperometric NO sensor. This sensor is prepared using an electropolymerized m-phenylenediamine (m-PD)/resorcinol and Nafion composite films at the surface of a platinum electrode. Using optimized flow rates and reagent concentrations, detection of various RSNOs at levels in the range of 0.25-20 μM is possible. For plasma samples, detection of background sensor interference levels within the samples must first be carried out using an identical FIA arrangement, but without the added SeDPA and GSH reagents. Subtraction of this background sensor current response allows good analytical recovery of RSNOs spiked into animal plasma samples, with recoveries in the range of 90.4-101.0%.

Abstract  Electrospun Ru(bpy)(3)(2+)-doped Nafion (ERDN) nanofibers were successfully fabricated by a one-step electrospinning technique. The diameters of the nanofibers range from 120 nm to 220 nm. The ERDN nanofibers, evenly distributed on the substrate with their random orientations, form a porous 3-D structure nanofibrous membrane. Compared to continuous thin films, the obtained nanofibrous membrane maintains a higher surface-area-to-volume ratio, a larger amount of immobilized-Ru(bpy)(3)(2+), and a better stability of the Ru(bpy)(3)(2+) immobilization. As a result, the nanofibers' ECL signal is enhanced approximately 15-fold and stable (does not change during continuous CV scans for 50 cycles). As a sensing platform, the nanofibers can sensitively detect low concentration phenolic compounds by monitoring the phenol-dependent ECL intensity change. The detection limit for phenol is 1.0 nM based on a signal/noise ratio >3, which is comparable or better than that in reported phenol assays. In addition, the nanofibers exhibit excellent ECL behaviors on Au, Pt, GC and ITO electrodes. A great potential for ERDN nanofibers-based ECL sensors is offered.

Abstract  In order to choose an appropriate cell-wall material (CWM) isolation procedure in grapes cv. Monastrell, four different standard procedures have been tested, and a comparison made of the amount of cell-wall material obtained, its composition and morphology. The CWM was isolated as the 70% ethanol insoluble residue (de Vries method), as the absolute ethanol insoluble residue filtered sequentially through nylon mesh (Nunan method), as the insoluble residue in sodium deoxycholate-phenol-acetic acid-water (Selvendran method) and as the N-[2-hydroxyethyl]-piperazine-N'-2-ethanesulfonic acid (HEPES) insoluble residue (Vidal method). All extractions were done in triplicate and the efficiency of the extractive procedure established. Carbohydrates, proteins, and phenolic compounds were analysed, as the main constituents of CWM. The morphology of the isolated CWM was visualized by scanning electron microscopy (SEM). The Selvendran method had the highest efficiency, while the Nunan method had the lower one. Regarding the carbohydrates composition, the four different CWM were rich in uronic acids and glucose, together with varying amounts of arabinose, xylose, mannose and galactose. The Selvendran method had the lower value of total carbohydrates and the CWM shows more plasmatic membrane impurities in SEM images. The chemical results of the Vidal and de Vries methods were quite similar, but the Vidal method was more time consuming than the de Vries method. According to the results, the de Vries method was chosen to produce a representative cell-wall material fraction from Monastrell grapes skin.

Abstract  The cellular mechanisms enabling baroreceptors to transduce wall distortion into axonal discharge are unknown but might involve stretch-activated ion channels. Gadolinium (Gd3+, 10 microM) blocks stretch-activated channels in several preparations. Here we tested Gd3+ effects on discharge responses of 15 single-fiber baroreceptors in vitro. We simultaneously measured discharge, pressure, and aortic diameter at Gd3+ concentrations from 0.001 to 400 microM. High levels of Gd3+ added to a bicarbonate-buffered perfusate (Krebs) slightly shifted the pressure-discharge relation (less than 4 mmHg, n = 3, P = 0.01) without affecting slope or discharge frequency at threshold. Gd3+ in Krebs variably altered the pressure-diameter relation. Because 500 microM Gd3+ produced visible precipitate in Krebs, we tested Gd3+ in a simpler perfusate using N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES). Gd3+ in HEPES (n = 10) induced minor, but statistically significant, average increases in threshold (less than +5-7%) and no changes in gain. However, prolonged HEPES exposure alone (n = 2) produced similar shifts. Electron microscopy verified that Gd3+ diffused from the lumen to reach extracellular locations near baroreceptor endings. We conclude that 1) HEPES perfusate alone reversibly depresses baroreceptor discharge and 2) Gd3+ has no direct effects on baroreceptors. Thus it appears that aortic baroreceptor mechanotransduction must utilize a different class of stretch-activated ion channels.

Abstract  An organic-phase enzyme electrode (OPEE) based on horseradish peroxidase (HRP) immobilized within Nafion on spectroscopic graphite was investigated in acetonitrile. The amperometric electrode response to hydrogen peroxide and cumene hydroperoxide present was found to be the result of the reduction of oxygen, produced upon enzymatic decomposition of both hydroperoxides (i.e., by the catalase-like activity of HRP). The electrode response was found to depend linearly on the hydroperoxide concentration up to 700 microM within the range of potentials from -200 to -400 mV (versus Ag|AgCl). Detection limits of approximately 45 microM for H2O2 and 100 microM for cumene hydroperoxide were determined under the selected experimental conditions. Nernstian dependence (the open circuit voltage of HRP-based electrode versus logarithm of H2O2 concentration) was obtained between 0.2 and 2.0 mM, with a slope of approximately 23 mV per logarithmic unit, suggesting a catalase-like, two-electron disproportionation of the substrate in acetonitrile.

Abstract  A highly sensitive amperometric gas-phase nitric oxide (NO) sensor based on a Pt working electrode chemically deposited on a Nafion film is described. The Pt electrode is chemically deposited on a Nafion 117 membrane by impregnating the film with Pt(NH3)(4)(2+) ions, which are then exposed to NaBH4 to precipitate conductive Pt metal. The sensor was characterized with a mass-flow controlled 1 ppm NO standard gas and has an electrochemical surface area of 34 +/- 9 cm(2), low limits of detection (4.3 +/- 1.1 ppb) and a fast response time (<5s) toward changes in gas phase NO levels. Good correlation was found for measurements with the new amperometric Pt-Nafion sensor vs. chemiluminescence results for detecting the rates of NO release from Carbosil2080A polymer films doped with S-nitroso-N-acetylpenicillamine (R = 0.999, m = 0.999, n = 6) and for electrochemical reduction of nitrite to NO (R = 0.999, m = 0.938, n = 3) mediated by a copper(II)-tri(2-pyridylmethyl) amine complex. (C) 2015 Elsevier B.V. All rights reserved.

Abstract  The development of a mass spectrometer-based continuous emission monitor (MS-CEM) for organic emissions from combustion devices is described, and results are presented from evaluations of the device at Louisiana State University. Besides the mass spectrometer, the monitor consisted of a heat-traced line, vacuum pump, particulate filters, and a Nafion dryer to remove water from the sample gas. The MS-CEM was tested by step injection of a mixture of organic compounds into the baghouse inlet of a pilot-scale rotary kiln incinerator, and the stack-gas effluent was monitored. In addition, the mixture of organic compounds was pulse injected into a second sampling line to simulate transient emissions of products of incomplete combustion during operational upsets. Results show that the response time for each organic components was less than 2 min. The accuracy of the monitoring device was affected by the flow rate, the organic mixture preparation measurement, and the evaporation of each component between the time of mixing of the VOCs and the time of injection into the sampling line.

Abstract  Native beta- and gamma-cyclodextrin bound to silica (ChiraDex-beta and ChiraDex-gamma) were packed into capillaries and used for enantiomer separation by capillary electrochromatography (CEC) under aqueous and nonaqueous conditions. Negatively charged analytes (dansyl-amino acids) were resolved into their enantiomers by nonaqueous CEC (NA-CEC). The addition of a small amount of water to the nonaqueous mobile phase enhanced the enantioselectivity but increased the elution time. The choice of the background electrolyte (BGE) determined the direction of the electroosmotic flow (EOF). With 2-(N-morpholino) ethanesulfonic acid (MES) or triethylammonium acetate (TEAA) as BGE an inverse EOF (anodic EOF) was observed while with phosphate a cathodic EOF was found. The apparent pH (pH*), the concentration of the BGE, and the nature of the mobile phase strongly influenced the elution time, the theoretical plate number and the chiral separation factor of racemic analytes.

Abstract  A PtRu@TiO2-hollow nanocomposite for the detection of biomolecules was synthesized by chemical reduction. First, poly(styrene-co-vinylphenylboronic acid), PSB, was prepared as a template (approximately 250 nm) by surfactant-free emulsion polymerization. Second, PSB/TiO2 core-shell spheres were prepared by sol-gel reaction. Finally, TiO2 hollow spheres (TiO2-H) were then formed after removing the PSB template by calcination at 450 degrees C under air atmosphere. To prepare the electrocatalyst, PtRu nanoparticles (NPs) were deposited onto the TiO2-H surface by chemical reduction. The prepared PtRu@TiO2-H nanocomposite was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), and elemental analysis. A non-enzymatic sensor was fabricated by depositing the as-prepared PtRu@TiO2-H nanocomposite on the surface of a glassy carbon electrode (GCE), which was prepared by a hand casting method with Nafion solution as a binder. The sensor was tested as a biomolecule sensor, especially for the detection of glucose and dopamine. The cyclic voltammograms (CV) obtained during the oxidation studies revealed that the PtRu@TiO2-H nanocomposite showed better catalytic function toward the oxidation of dopamine. The sensing range of the non-enzymatic sensor for glucose was 5.0-100 mM in a phosphate buffer. The results demonstrated the potential usefulness of this bimetallic@TiO2-H bifunctional catalyst for biosensor applications.

Abstract  Protein S-nitrosylation is considered as one of the molecular mechanisms by which nitric oxide regulates signaling events and protein function. The present review presents an updated method which allows for the site-specific detection of S-nitrosylated proteins in vivo. The method is based on enrichment of S-nitrosylated proteins or peptides using organomercury compounds followed by LC-MS/MS detection. Technical aspects for determining the reaction and binding efficiency of the mercury resin that assists enrichment of S-nitrosylated proteins are presented and discussed. In addition, emphasis is given to the specificity of the method by providing technical details for the generation of four chemically distinct negative controls. Finally it is provided an overview of the key steps for generation and evaluation of mass spectrometry derived data.