A highly sensitive electrochemical biosensor based on AuNP-modified gold electrodes for selective determination of serum levels of crosslaps.

This article explains a step-wise protocol to develop an electrochemical sensor to quantify serum levels of C-telopeptide (CTX) crosslinks also known as crosslaps in a matter of minutes and with high level of accuracy. The technique needs only one-step (incubation) and can thus be used for point of care screening. Due to the excellent electrical properties of the as-prepared immunosensor, CTX levels were successfully measured from 1 to 1000 pg/mL.

SR-XRD in situ monitoring of copper-IUD corrosion in simulated uterine fluid using a portable spectroelectrochemical cell.

The objective of this work is to study the initial corrosion of copper in the presence of gold when placed in simulated uterine fluid in order to better understand the evolution of active components of copper-IUDs. In order to carry out this study, a portable cell was designed to partially simulate the uterine environment and provide a way of tracking the chemical changes occurring in the samples in situ within a controlled environment over a long period of time using synchrotron spectroelectrochemistry. The dynamically forming crystalline corrosion products are determined in situ for a range of copper-gold surface ratios over the course of a 10-day experiment in the cell.

In-situ spectroelectrochemical characterization of the electrochemical growth and breakdown of a lead dodecanoate coating on a lead substrate.

This paper concerns a time lapse spectroelectrochemical study of the growth of lead dodecanoate layers on a lead substrate in an aqueous solution using cyclic voltammetry. In-situ synchrotron radiation X-ray diffraction measurements were carried out on station BM26A (DUBBLE) at the European Synchrotron Radiation Facility (ESRF) in France. The diffraction pattern images were taken using a two-dimensional Mar CCD camera.

Evaluation of an X-ray-excited optical microscope for chemical imaging of metal and other surfaces.

The application of a modular system for the nondestructive chemical imaging of metal and other surfaces is described using heritage metals as an example. The custom-built X-ray-excited optical luminescence (XEOL) microscope, XEOM 1, images the chemical state and short-range atomic order of the top 200 nm of both amorphous and crystalline surfaces. A broad X-ray beam is used to illuminate large areas (up to 4 mm(2)) of the sample, and the resulting XEOL emission is collected simultaneously for each pixel by a charge-coupled device sensor to form an image.

Assessment of copper corrosion from frameless copper IUDs after long-term in utero residence.

Objective: To assess the site-specific corrosive behavior of the frameless intrauterine device (IUD) following long-term exposure to the uterine environment.

Study Design: A qualitative and morphological study using X-ray diffraction (XRD) and scanning electron microscopy (SEM).

Results: Three GyneFix® IUDs that were in site up to 150 months were examined.

Corrosion of Bronzes by Extended Wetting with Single Mixed Acidic Pollutants.

The corrosion of bronzes was examined in the context of single-acid mixed-acid (as in urban acid rain) solutions. Two bi-component bronzes (copper with either 3% Sn or 7% Sn) that closely represent those of historic artifacts were immersed for five weeks in conditions designed to replicate those experienced by statues and ornaments in cities where rainfall and humidity constantly produce an electrolyte layer on the surfaces of bronzes. Ions, acids, and particles of pollutants can dissolve in this layer, resulting in a variety of harsh corrosion processes.

Real time observation of X-ray-induced surface modification using simultaneous XANES and XEOL-XANES.

In experiments preliminary to the design of an X-ray-excited optical luminescence (XEOL)-based chemical mapping tool we have used X-ray micro (4.5 × 5.2 μm) and macro (1 × 6 mm) beams with similar total fluxes to assess the effects of a high flux density beam of X-rays at energies close to an absorption edge on inorganic surfaces in air.

Self assembled films of porphyrins with amine groups at different positions: influence of their orientation on the corrosion inhibition and the electrocatalytic activity.

Self-assembled molecular films of two cobalt porphyrins with amine groups at different positions-(5,10,15,20-tetrakis-(2-aminophenyl) porphyrin-cobalt(II), [Co(II) (T(o-NH(2))PP)] and (5,10,15,20-tetrakis-(4-aminophenyl) porphyrin-cobalt(II), [Co(II)(T(p-NH(2))PP)]-were formed on a gold substrate. The functionalized surfaces were characterized using Raman spectroscopy, atomic force microscopy and electrochemical methods. Both modified gold surfaces completely mask the charge transfer of a [Fe(CN)(6)](3-/4-) redox couple in solution, indicating the layer is highly resistive in behavior.

The use of synchrotron X-rays to observe copper corrosion in real time.

We have developed and tested two complementary methods for making time-lapse synchrotron X-ray diffraction (XRD) measurements of the growth of synthetic corrosion layers using a protocol for producing copper(I) chloride (nantokite), on copper as a test. In the first method, a copper coupon was spin-coated with saturated copper(II) chloride solution in air while the surface was characterized in real time using XRD with a fast one-dimensional (1-D) detector. In the second, a droplet of the same reagent was suspended from an X-ray-transparent window in a hermetically sealed cell and the coupon was brought into contact with this while XRD diffractograms were acquired with a charge-coupled device (CCD) camera.

Development of a highly sensitive and robust Cor a 9 specific enzyme-linked immunosorbent assay for the detection of hazelnut traces.

Allergy to tree nuts represents an acute health problem. Sensitized people can be inadvertently exposed to hidden allergens resulting from cross-contamination of foods. For this reason, reliable and highly sensitive analytical methods are needed to be developed for control and labeling of food ingredients and products.

Electrochemical determination of hydrogen peroxide with cytochrome c peroxidase and horse heart cytochrome c entrapped in a gelatin hydrogel.

A novel and versatile method, based on a membrane-free enzyme electrode in which both the enzyme and a mediator protein are entrapped in a gelatine hydrogel was developed for the fabrication of biosensors. As a proof of principle, we prepared a hydrogen peroxide biosensor by successfully entrapping both horse heart cytochrome c (HHC) and Saccharomyces cerevisae cytochrome c peroxidase (CCP) in a gelatin matrix which is immobilized on a gold electrode. This electrode was first pretreated with 6-mercaptohexanol.

Self-assembled supramolecular array of polymeric phthalocyanine on gold for the determination of hydrogen peroxide.

This Article describes for the first time the formation of a supramolecular self-assembled monolayer of polymeric phthalocyanine (poly(CuPc)) onto a gold substrate. The latter is established through the interaction of the cyano group, belonging to the poly(CuPc), with the metal substrate. The functionalized gold substrate was characterized using Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and electrochemical methods.

Electrochemical study of gelatin as a matrix for the immobilization of horse heart cytochrome c.

The aim of this paper is to emphasize the strength of gelatin as a stable matrix for redox enzymes. Cyclic voltammetry has been applied for a detailed electrochemical study of horse heart cytochrome c (HHC) entrapped in a gelatin matrix immobilized on a gold electrode. The influence of the HHC concentration, the mass percentage of the gelatin and the nature of the gelatin on the electrochemical behaviour of HHC have been described in detail.

The coordinated use of synchrotron spectroelectrochemistry for corrosion studies on heritage metals.

Corrosion is a major source of degradation in heritage metal objects, and any remedial measures are subject to a strong (Western) ethic that favors conservation as opposed to restoration. Accordingly, major scientific challenges exist for developing appropriate treatment methods to stabilize and protect artifacts after they are recovered from an archaeological site, both before and during their display or storage in a museum. Because inappropriate treatments can cause irreversible damage to irreplaceable objects, it is crucial that the chemical processes involved are fully understood and characterized before any preservation work is undertaken.

Static secondary ion mass spectrometry (S-SIMS) for the characterization of surface components in mineral particulates.

The feasibility of static secondary ion mass spectrometry (S-SIMS) for the detection of molecule specific information from complex materials, such as natural clay and soil samples, has been investigated. Ion trap (IT), as well as triple quadrupole (TQ) instruments, have been used for mass analysis. Secondary ion images have been acquired using time-of-flight (TOF) S-SIMS.

The electrochemical detection of Ru(II) in a methyl methacrylate solution.

This article describes the voltammetric behaviour of RuCl(2)(PPh(3))(3) in a methyl methacrylate (MMA) solution. Acquiring this type of information is only possible when the ohmic resistance can be kept sufficiently low. Therefore, the conductivity study of pure methyl methacrylate and a tetrabutylammonium tetrafluoroborate (TBABF(4)) methyl methacrylate solution has been described as well.

Optically detected X-ray absorption spectroscopy measurements as a means of monitoring corrosion layers on copper.

XANES and EXAFS information is conventionally measured in transmission through the energy-dependent absorption of X-rays or by observing X-ray fluorescence, but secondary fluorescence processes, such as the emission of electrons and optical photons (e.g., 200-1000 nm), can also be used as a carrier of the XAS signatures, providing complementary information such as improved surface specificity.

Ozonization and cyclic voltammetry as efficient methods for the regeneration of gelatin-coated SPR chips.

The application of ozonization and cyclic voltammetry for the regeneration of gold chips containing a chemisorbed gelatin layer is reported. The efficiency of the regeneration process was analyzed using various surface analysis techniques indicating a complete removal of the biopolymer layer. The current findings open up perspectives for regeneration and multiple application of gold chips for SPR measurements.

Immobilization of cytochrome c on cysteamine-modified gold electrodes with EDC as coupling agent.

Cyclic voltammetry has been applied for the characterization of cross-linked horse heart cytochrome c (HHC) on cysteamine-modified gold electrodes. The cross-linking, i.e.

Comparison between the electrocatalytic properties of different metal ion phthalocyanines and porphyrins towards the oxidation of hydroxide.

This work reports on the electrocatalytic oxidation of hydroxide using different central metal ion phthalocyanines and porphyrins immobilized on gold electrodes. The apparent electrocatalytic activity of cobalt phthalocyanine or porphyrin modified electrodes was found to be the greatest among the present series of metal ion macrocycles investigated. Copper and unmetallated phthalocyanine or porphyrin modified electrodes show no electrocatalytic behaviour towards hydroxide, such as bare gold.

Assessment of the uncertainty budget for the amperometric measurement of dissolved oxygen.

This work aimed at identifying the main sources of uncertainty for the measurement of dissolved oxygen concentration in aqueous solutions. The experimental apparatus consists of an amperometric cell based on the Clark-type sensor. The corresponding uncertainty budget was assessed, this being a fundamental step for the validation of a measurement method.

Insights into electrolytic stabilization with weak polarization as treatment for archaeological copper objects.

Immersion of corroded copper artefacts in dilute sodium sesquicarbonate solution is a well-recognized stabilization technique--especially in the conservation of objects recovered from marine environments and therefore saturated with chlorides. Here we describe three linked experiments performed to investigate a variation on this treatment, involving the application of a low potential to the artefact in order to drive the chloride extraction process. This includes a new spectroelectrochemical approach which allows 2-D pseudorandom X-ray reflection diffraction patterns to be obtained without interrupting the reaction in solution.

Cell for simultaneous synchrotron radiation X-ray and electrochemical corrosion measurements on cultural heritage metals and other materials.

We describe the construction of an electrochemical cell of the Bragg type suitable for in situ synchrotron X-ray measurements on rough, heterogeneous metals such as cultural heritage alloys and simulants with corroding or passivated surfaces. The cell features a working electrode, which may be moved under remote control from a position close to an X-ray window to full immersion in the electrolyte. A pocket of electrolyte in contact with the bulk can be maintained on the working electrode surface at all times.

Evaluation of corrosion potential measurements as a means to monitor the storage and stabilization processes of archaeological copper-based artifacts.

The focus of this study consists of examining how corrosion potential measurements can contribute in providing information on the effectiveness of storage and stabilization treatments of copper alloys in aqueous solutions. We report on the electrochemical behavior of artificial copper alloy coupons (covered or not with corrosion layers), simulating the behavior of real artifacts, immersed in sodium sesquicarbonate solutions. Particular attention is given to the transformation of the corrosion layer as a function of time.

Feasibility of analyzing molecular pigments in paint layers using TOF S-SIMS.

A first attempt to measure the molecular compositions of pigments in paintings using static SIMS was made. An investigation of pellets of pure pigments such as auripigment and verdigris allowed the detection of numerous high m/z ions useful for molecular identification. Analysis of pigments in embedded paint fragments, on the other hand, only yielded elemental information because of charge build-up and contamination problems.