Pyrite oxidation inhibition by a cross-linked lipid coating

The effect of a diacetylene-containing phospholipid on the oxidation of pyrite, FeS(2), was investigated. Earlier work reported by our research group showed that the adsorption of l,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine on pyrite suppressed the extent of its oxidation by about 75% over a specific time period. Results presented here show that the pre-exposure to UV radiation of this lipid after sorption onto pyrite results in a 90% suppression. Attenuated total reflection (ATR) Fourier transform infra-red spectroscopy (FTIR) suggests that the UV irradiation of the lipid does not result in degradation of the adsorbed layer. It is believed that the UV exposure results in the cross-linking and polymerization of the adsorbed phospholipid into a relatively impermeable barrier that separates the pyrite from the aqueous phase. The results of this study might have implications for the protection of pyrite from oxidation in the environment

Electroanalysis may be used in the Vanillin Biotechnological Production

This study shows that electroanalysis may be used in vanillin biotechnological production. As a matter of fact, vanillin and some molecules implicated in the process like eugenol, ferulic acid, and vanillic acid may be oxidized on electrodes made of different materials (gold, platinum, glassy carbon). By a judicious choice of the electrochemical method and the experimental conditions the current intensity is directly proportional to the molecule concentrations in a range suitable for the biotechnological process. So, it is possible to imagine some analytical strategies to control some steps in the vanillin biotechnological production: by sampling in the batch reactor during the process, it is possible to determine out of line the concentration of vanillin, eugenol, ferulic acid, and vanillic acid with a gold rotating disk electrode, and low concentration of vanillin with addition of hydrazine at an amalgamated electrode. Two other possibilities consist in the introduction of electrodes directly in the batch during the process; the first one with a gold rotating disk electrode using linear sweep voltammetry and the second one requires three gold rotating disk electrodes held at different potentials for chronoamperometry. The last proposal is the use of ultramicroelectrodes in the case when stirring is not possible

Cyanide ion minisensor based on methemoglobin incorporated in metal supported self-assembled bilayer lipid membranes and modified with platelet- activating factor

The present paper reports the development of an electrochemical minisensor for the detection of cyanide ions based on methemoglobin, which is incorporated into self-assembled bilayer lipid membranes (s-BLMs) on a metal support. The presence of cyanide in solution was found to modulate the ion permeability of BLMs containing methemoglobin, when using a lipid composition containing egg phosphatidylcholine (egg PC) and semisynthetic platelet- activating factor (PAF; 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine, AGEPC). The cyanide ion sensor exhibited good mechanical stability and longevity (routinely over 48 h) and constant sensitivity and response to a given concentration of cyanide ion in solution. Incorporation of hemoglobin or methemoglobin into s-BLMs was examined, and methemoglobin was found to provide lower (by five-fold) detection limit for cyanide ion determination. The effects of protein concentration and composition of BLMs on sensitivity of response were examined. Selectivity studies of cyanide detection were done in the presence of oxygen, carbon monoxide and dioxide, and other anions. The present cyanide ion sensor based on thin lipid film technology provides advantages of fast response times (in the order of 10 s) to alterations of cyanide ion concentration, low detection limits (ca. 4.9 nM, 0.317 μg l- 1), and the capability of analyzing small volumes of samples. Furthermore, a device can now simply and reliably be fabricated at low cost, and therefore can be used as a disposable sensor

Cyanide ion minisensor based on methemoglobin incorporated in metal supported self-assembled bilayer lipid membranes and modified with platelet- activating factor

The present paper reports the development of an electrochemical minisensor for the detection of cyanide ions based on methemoglobin, which is incorporated into self-assembled bilayer lipid membranes (s-BLMs) on a metal support. The presence of cyanide in solution was found to modulate the ion permeability of BLMs containing methemoglobin, when using a lipid composition containing egg phosphatidylcholine (egg PC) and semisynthetic platelet- activating factor (PAF; 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine, AGEPC). The cyanide ion sensor exhibited good mechanical stability and longevity (routinely over 48 h) and constant sensitivity and response to a given concentration of cyanide ion in solution. Incorporation of hemoglobin or methemoglobin into s-BLMs was examined, and methemoglobin was found to provide lower (by five-fold) detection limit for cyanide ion determination. The effects of protein concentration and composition of BLMs on sensitivity of response were examined. Selectivity studies of cyanide detection were done in the presence of oxygen, carbon monoxide and dioxide, and other anions. The present cyanide ion sensor based on thin lipid film technology provides advantages of fast response times (in the order of 10 s) to alterations of cyanide ion concentration, low detection limits (ca. 4.9 nM, 0.317 μg l- 1), and the capability of analyzing small volumes of samples. Furthermore, a device can now simply and reliably be fabricated at low cost, and therefore can be used as a disposable sensor

Study of calix[4]resorcinarene-dopamine complextion in mixed phospholipid monolayers formed at the air-water interface

We have studied the physical properties of monolayers formed by calix[4]resorcinarene and in mixtures with dipalmitoyl phosphatidylcholine (DPPC) in various molar ratios formed at the air-water interface and at presence of dopamine in water subphase by means of measurements of surface pressure and dipole potential. We showed that both calix[4]resorcinarene as well as its mixture with DPPC form stable monolayers at the water subphase. The presence of dopamine resulted in an increase of the mean molecular area and in a decrease of the compressibility modulus of the monolayers. For mixed monolayers at higher content of calix[4]resorcinarene (> 0.2 molar fraction) a deviation from ideal miscibility took place especially for monolayers in a solid state. This can be connected with formation of aggregates of calix[4] resorcinarene. Lowest miscibility and weakest interaction of dopamine with a monolayer was observed for calix[4]resorcinarene molar fraction of 0.33 in the monolayer. (c) 2006 Elsevier B.V. All rights reserved

Nano-enabled medical devices based on biosensing principles: technology basis and new concepts

Research and development in the biosensors for medical applications remain a focused area benefiting industry, society and knowledge production alike. The framework established is conducive to innovation and rapid assimilation of technological change. At the advent of nanotechnology, the various biosensor classes have been benefited in different ways, scales and rates. This paper studies the nanotechnology-driven shifting of the biosensor innovation system towards new concepts and the broadening, in depth and extent, of its science base. The scientific domain of (nano)biosensors has been studied using a roadmapping framework, especially developed to handle the dynamics and scopes of academic research. The results indicate that the sector seized the opportunities that nanotools offered to solve technology problems and revisit old concepts for optimizing the traditional platforms. Yet, the ability to control nanoeffects fuels a new transition towards bioelectronic integration that sets entirely new horizons for future trajectories