Proteomic method for the quantification of methionine sulfoxide

Glycoxidation and lipoxidation reactions contribute to the chemical modification of proteins during the Maillard reaction. Reactive oxygen species, produced during the oxidation of sugars and lipids in these processes, irreversibly oxidize proteins. Methionine is particularly susceptible to oxidation, yielding the oxidation product methionine sulfoxide (MetSO). Here we describe a method for the analysis of MetSO using proteomic techniques. Using these techniques, we measured MetSO formation on the model protein RNase during aerobic incubations with glucose and arachidonate. We also evaluated the susceptibility of MetSO to reduction by NaBH4, a commonly used reductant in the analysis of Maillard reaction products.

Development of films based on blends of gelatin and poly(vinyl alcohol) cross linked with glutaraldehyde

Both gelatin and poly(vinyl alcohol) (PVA) can be cross linked with glutaraldehyde (GLU). In the case of gelatin, the GLU reacts with each e-NH2 functional group of adjacent lysine residues, while for PVA, the GLU reacts with two adjacent hydroxyl groups, forming acetal bridges. Thus it can be considered possible to cross link adjacent macromolecules of gelatin and PVA using GLU. In this context, the aims of this work were the development of biodegradable films based on blends of gelatin and poly(vinyl alcohol) cross linked with GLU, and the characterization of some of their main physical and functional properties. All the films were produced from film-forming solutions (FFS) containing 2 g macromolecules (PVA + gelatin)/100 g FFS, 25 g glycerol/100 g macromolecules, and 4 g GLU (25% solution)/100 g FFS. The FFS were prepared with two concentrations of PVA (20 or 50 g PVA/100 g macromolecules) and two reaction temperatures: 90 or 55 degrees C, applied for 30 min. The films were obtained after drying (30 degrees C/24 h) and conditioning at 25 degrees C and 58% of relative humidity for 7 days, and were then characterized. The results for the color parameters, mechanical properties, phase transitions and infrared spectra showed that some chemical modifications occurred, principally for the gelatin. However, in general, all the characteristics of the films were either typical of films based on blends of these macromolecules without cross linking, or slightly higher. A greater improvement in the properties of this material was probably not observed due to the crystallinity of the PVA, which has a melting point above 90 degrees C. The presence of microcrystals in the polymer chain probably reduced macromolecular mobility, hindering the reaction. Thus more research is necessary to produce biodegradable films with improved properties. (C) 2011 Elsevier Ltd. All rights reserved.

Design of a Modern Liposome and Bee Venom Formulation for the Traditional VIT-Venom Immunotherapy

Traditional venom immunotherapy uses injections of whole bee venom in buffer or adsorbed in Al (OH)(3) in an expensive, time-consuming way. New strategies to improve the safety and efficacy of this treatment with a reduction of injections would, therefore, be of general interest. It would improve patient compliance and provide socio-economic benefits. Liposomes have a long tradition in drug delivery because they increase the therapeutic index and avoid drug degradation and secondary effects. However, bee venom melittin (Mel) and phospholipase (PLA(2)) destroy the phospholipid membranes. Our central idea was to inhibit the PLA(2) and Mel activities through histidine alkylation and or tryptophan oxidation (with pbb, para-bromo-phenacyl bromide, and/or NBSN-bromosuccinimide, respectively) to make their encapsulations possible within stabilized liposomes. We strongly believe that this formulation will be nontoxic but immunogenic. In this paper, we present the whole bee venom conformation characterization during and after chemical modification and after interaction with liposome by ultraviolet, circular dichroism, and fluorescence spectroscopies. The PLA(2) and Mel activities were, measured indirectly by changes in turbidity at 400(nm), rhodamine leak-out, and hemolysis. The native whole bee venom (BV) presented 78.06% of alpha-helical content. The alkylation (A-BV) and succynilation (S-BV) of BV increased 0.44 and 0.20% of its alpha-helical content. The double-modified venom (S-A-BV) had a 0.74% increase of alpha-helical content. The BV chemical modification induced another change on protein conformations observed by Trp that became buried with respect to the native whole BV. It was demonstrated that the liposomal membranes must contain pbb (SPC:Cho:pbb, 26:7:1) as a component to protect them from aggregation and/or fusion. The membranes containing pbb maintained the same turbidity (100%) after incubation with modified venom, in contrast with pbb-free membranes that showed a 15% size decrease. This size decrease was interpreted as membrane degradation and was corroborated by a 50% rhodamine leak-out. Another fact that confirmed our interpretation was the observed 100% inhibition of the hemolytic activity after venom modification with pbb and NBS (S-A-BV). When S-A-BV interacted with liposomes, other protein conformational changes were observed and characterized by the increase of 1.93% on S-A-BV alpha-helical content and the presence of tryptophan residues in a more hydrophobic environment. In other words, the S-A-BV interacted with liposomal membranes, but this interaction was not effective to cause aggregation, leak-out, or fusion. A stable formulation composed by S-A-BV encapsulated within liposomes composed by SPC:Cho:pbb, at a ratio of 26:7:1, was devised. Large unilamellar vesicles of 202.5 nm with a negative surface charge (-24.29 mV) encapsulated 95% of S-A-BV. This formulation can, now, be assayed on VIT.

Raman evidence of the interaction between multiwalled carbon nanotubes and nanostructured TiO(2)

Nanocomposites of carbon nanotubes and titanium dioxide (TiO(2)) have attracted much attention due to their photocatalytic properties. Although many examples in the literature have visualized these nanocomposites by electron microscopic images, spectroscopic characterization is still lacking with regard to the interaction between the carbon nanotube and TiO(2). In this work, we show evidence of the attachment of nanostructured TiO(2) to multiwalled carbon nanotubes(MWNTs) by Raman spectroscopy. The nanostructured TiO(2) was characterized by both full-width at half-maximum (FWHM) and the Raman shift of the TiO(2) band at ca 144 cm(-1), whereas the average diameter of the crystallite was estimated as approximately 7 nm. Comparison of the Raman spectra of the MWNTs and MWNTs/TiO(2) shows a clear inversion of the relative intensities of the G and D bands, suggesting a substantial chemical modification of the outermost tubes due to the attachment of nanostructured TiO(2). To complement the nanocomposite characterization, scanning electronic microscopy and X-ray diffraction were performed. Copyright (C) 2011 John Wiley & Sons, Ltd.

Self-reinforced composites obtained by the partial oxypropylation of cellulose fibers. 1. Characterization of the materials obtained with different types of fibers

The in-depth oxypropylation of different types of cellulose fibers, namely Avicel, Rayon, Kraft, and Filter Paper, was investigated. New biphasic mono-component materials were obtained, which could be hot-pressed to form films of cellulose fibers dispersed into a thermoplastic matrix. The success of this chemical modification was assessed by FTIR spectroscopy, X-ray diffraction, scanning electron microscopy. differential scanning calorimetry, thermogravimetric analysis and contact angle measurements. The optimization of this process led to the establishment of the optimal molar ratio between the cellulose CH groups and propylene oxide, which varied as a function of the specific morphology of the fibers. (C) 2008 Elsevier Ltd. All rights reserved.

Self-reinforced composites obtained by the partial oxypropylation of cellulose fibers. 2. Effect of catalyst on the mechanical and dynamic mechanical properties

This work describes the partial oxypropylation of filter paper cellulose fibers, employing two different basic catalyst, viz., potassium hydroxide and 1,4-diazabicyclo [2.2.2] octane, to activate the hydroxyl groups of the polysaccharide and thus provide the anionic initiation sites for the ""grafting-from"" polymerization of propylene oxide. The success of this chemical modification was assessed by FTIR spectroscopy, X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, thermogravimetric analysis and contact angle measurements. The study of the role of the catalyst employed on the extent of the modification and on the mechanical properties of the ensuing composites, after hot pressing, showed that both the Bronsted and the Lewis base gave satisfactory results, without any marked difference.

Surface esterification of cellulose fibres: Processing and characterisation of low-density polyethylene/cellulose fibres composites

Low-density polyethylene was filled with cellulose fibres from sugar cane bagasse obtained from organosolv/supercritical carbon dioxide pulping process. The fibres were also used after chemical modification with octadecanoyl and dodecanoyl chloride acids. The morphology, thermal properties, mechanical properties in both the linear and nonlinear range, and the water absorption behaviour of ensuing composites were tested. The evidence of occurrence of the chemical modification was checked by X-ray photoelectron spectrometry. The degree of polymerisation of the fibres and their intrinsic properties (zero tensile strength) were determined. It clearly appeared that the surface chemical modification of cellulose fibres resulted in improved interfacial adhesion with the matrix and higher dispersion level. However, composites did not show improved mechanical performances when compared to unmodified fibres. This surprising result was ascribed to the strong lowering of the degree of polymerisation of cellulose fibres (as confirmed by the drastic decrease of their zero tensile strength) after chemical treatment despite the mild conditions used. (c) 2007 Elsevier Ltd. All rights reserved.

Extrusion and characterization of functionalized cellulose whiskers reinforced polyethylene nanocomposites

The surface of ramie cellulose whiskers has been chemically modified by grafting organic acid chlorides presenting different lengths of the aliphatic chain by an esterification reaction. The occurrence of the chemical modification was evaluated by FTIR and X-ray photoelectron spectroscopies, elemental analysis and contact angle measurements. The crystallinity of the particles was not altered by the chain grafting, but it was shown that covalently grafted chains were able to crystallize at the cellulose surface when using C18. Both unmodified and functionalized nanoparticles were extruded with low density polyethylene to prepare nanocomposite materials. The homogeneity of the ensuing nanocomposites was found to increase with the length of the grafted chains. The thermomechanical properties of processed nanocomposites were studied by differential scanning calorimetry (DSC), dynamical mechanical analysis (DMA) and tensile tests. A significant improvement in terms of elongation at break was observed when sufficiently long chains were grafted on the surface of the nanoparticles. It was ascribed to improved dispersion of the nanoparticles within the LDPE matrix. (C) 2009 Elsevier Ltd. All rights reserved.

Removal of Zn(2+) from Electroplating Wastewater Using Modified Wood Sawdust and Sugarcane Bagasse

This paper describes the preparation of new adsorbents derived from sugarcane bagasse and wood sawdust (Manilkara sp.) to remove zinc (II) ions from electroplating wastewater. The first part deals with the chemical modification of sugarcane bagasse and wood sawdust, using succinic anhydride to introduce carboxylic acid functions into the material. The obtained materials (modified sugarcane bagasse MB2 and modified wood sawdust MS2) were then characterized by infrared spectroscopy (IR) and used in adsorption experiments. The adsorption experiments evaluates Zn(2+) removal from aqueous single metal solution and real electroplating wastewater on both batch and continuous experiments using fixed-bed columns prepared in laboratorial scale with the obtained adsorbents. Adsorption isotherms were then developed using Langmuir model and the Thomas kinetic model. The calculated Zn(2+) adsorption capacities were found to be 145 mg/g for MS2 and 125 mg/g for MB2 in single metal aqueous solution, whereas for the industrial wastewater these values were 61 mg/g for MS2 and 55 mg/g for MB2.

Chemistry of carbon nanotubes

Judicious application of site-selective reactions to non-aligned and aligned carbon nanotubes has opened a rich field of carbon nanotube chemistry. In order to meet specific requirements demanded by particular applications (e.g. biocompatibility for nanotube biosensors and interfacial strength for blending with polymers), chemical modification of carbon nanotubes is essential. The tips of carbon nanotubes are more reactive than their sidewalls, allowing a variety of chemical reagents to be attached at the nanotube tips. Recently, some interesting reactions have also been devised for chemical modification of both the inner and outer nanotube walls, though the seamless arrangement of hexagon rings renders the sidewalls relatively unreactive. This review provides a brief summary of very recent progress in the research on chemistry of carbon nanotubes.

Developing a stakeholder analysis to aid bio-based product innovation

Purpose – The results which that study seeks to report are the first part of a larger research programme funded by the New Zealand Foundation for Research, Science & Technology (FRST) aimed at gaining a better understanding of stakeholder perceptions in relation to bio-based products.

Design/methodology/approach – Utilising three chemically modified wood products, data were collected from focus groups and questionnaires and centred primarily on perceptions surrounding the acceptability of building materials that have been bio-modified. Irrespective of the type of chemical modification, family health and durability were the most important factors identified.

Findings – The study finds that product cost rated lower in the 16 factors evaluated, and energy used in production was of little concern. When comparing the three products to one another, two distinct groups with quite differing purchasing philosophies were identified and these perspectives significantly influenced perceptions of product acceptability and willingness to purchase. Utilising a paired comparison technique, an investigation of trade-offs indicated preference for performance over cost and product familiarity. Similarly, low chemical emissions were also preferred over cost considerations. Among the findings, there was scepticism regarding trust in manufacturers to adequately safeguard health and safety and to have a minimum impact on the environment. Low levels of trust were expressed in regard to manufacturers' concern for future generations.

Originality/value – The paper develops an investigative framework which could be applied to the evaluation of products arising from bio-material technology innovation and recommendations for future research directions.

Carbon nanotubes for biological and biomedical applications

Ever since the discovery of carbon nanotubes, researchers have been exploring their potential in biological and biomedical applications. The recent expansion and availability of chemical modification and bio-functionalization methods have made it possible to generate a new class of bioactive carbon nanotubes which are conjugated with proteins, carbohydrates, or nucleic acids. The modification of a carbon nanotube on a molecular level using biological molecules is essentially an example of the 'bottom-up' fabrication principle of bionanotechnology. The availability of these biomodified carbon nanotube constructs opens up an entire new and exciting research direction in the field of chemical biology, finally aiming to target and to alter the cell's behaviour at the subcellular or molecular level. This review covers the latest advances of bio-functionalized carbon nanotubes with an emphasis on the development of functional biological nano-interfaces. Topics that are discussed herewith include methods for biomodification of carbon nanotubes, the development of hybrid systems of carbon nanotubes and biomolecules for bioelectronics, and carbon nanotubes as transporters for a specific delivery of peptides and/or genetic material to cells. All of these current research topics aim at translating these biotechnology modified nanotubes into potential novel therapeutic approaches.

Preparation of nanoparticles by crosslinking folate conjugated chitosan with vanillin and its characterization

Functionalized chitosan (CS) were widely used as drug delivery system in the chemotherapy of various disease. In this work, folate (FA) was conjugated into chitosan molecular as targeting ligand based on Schiff reaction between –NH₂ group of CS and –COOH group of FA. And nanoparticles were made by emulsion method with vanillin novel cross-linking agent. The FA modified CS and its nanoparticles were characterized by Fourier transform spectroscopy (FT-IR), scanning electron microscope (SEM) and Zeta potential. SEM results confirmed the nanoparticles made from FA-CS conjugate were spherical in shape and were about 100 nm in size. Zeta potential analysis revealed that the nanoparticles were negatively charged with charge density of -7.73mV.

Novel dithiolene complexes incorporating conjugated electroactive ligands

A series of new metal (M) dithiolene complexes bearing terthiophene (3, 12, M = Ni; 4, M = Pd; 5, 6, M = Au) and 2,5-bis(para-methoxyphenyl)thiophene units (14, M = Ni; 15, 16, M = Au; 17, M = Pd) have been synthesised in 38–99% yield. The electrochemical properties of the materials have been characterised by cyclic voltammetry and UV-vis spectroelectrochemistry. The nickel complexes possess low oxidation potentials (−0.12 to −0.25 V vs Ag/AgCl) due to the electron-rich dithiolene centres and all complexes display ligand-based redox activity. The terthiophene derivatives have been polymerised by electrochemical oxidation to give stable films with, in the case of poly(3), broad absorption characteristics. Charge transfer materials have been isolated from 14 and 16 with conductivities in the range 9 × 10⁻⁶ to 7 × 10⁻⁸ S cm⁻¹.