Search results for "chitosan"
showing 10 items of 195 documents
Halloysite nanotubes sandwiched between chitosan layers: novel bionanocomposites with multilayer structures
2018
This work is a contribution to the design of multilayer biocomposites based on halloysite nanotubes (HNTs) and chitosan. Both the polymer and nanotubular inorganic additive have been selected among easily available green materials. An innovative preparation procedure based on the sequential casting of chitosan and HNTs has been proposed in order to obtain multilayer composite biofilms. A physico-chemical investigation (contact angle measurements, differential scanning calorimetry, thermogravimetry) has been conducted to characterize the bionanocomposites. As evidenced by scanning electron microscopy, the nanocomposites possess an intermediate halloysite layer between the chitosan ones. The …
An approach to rheological and electrokinetic behaviour of lipidic vesicles covered with chitosan biopolymer
2008
The rheological and electrokinetic properties of soybean lecithin vesicles prepared from concentrated soy lecithin dispersions (250 g/L) obtained by slow swelling under shear conditions and mixed with chitosan biopolymer solutions were studied. The rheological behaviour of lecithin-chitosan vesicles was determined by shear stress against shear rate measurements, as well as by the variation on the hysteresis loop area. The results were compared with the rheopectic behaviour of soy lecithin dispersions without chitosan. An important change on the rheological properties of the complex dispersion was observed, depicting in a thixotropic behaviour with a plastic character in the presence of chit…
Synthesis and characterization of modified sulfonated chitosan for beryllium recovery
2019
Abstract A new adsorbent, sulfated crosslinked chitosan (SGCH), has been synthesized for the effective extraction of beryllium ions from their aqueous solutions. In recent times, beryllium extraction has been of great importance because beryllium can be used in many applications such as in nuclear reactor, heat shields, high-technology ceramics, alloys and electronic heat sinks. SGCH has been synthesized by two successive phases. The first is the conversion of chitosan (CH) into non-soluble cross-linked chitosan (GCH) through the interaction between chitosan and glutaraldehyde. The second step is the formation of functional sulfonate groups onto the adsorbent material through the interactio…
Treatment of recurrent aphtous stomatitis: A systematic review
2022
Background: Recurrent Aphtous Stomatitis (RAS) is the most common process affecting the oral mucosa. It is painful, multifactorial and generally recurrent. The aim of this systematic review is to know the last treatment approaches and their effectivity.Material and Methods: we compared the outcome of different kind of treatments in terms of the improvement of the lesions, reduction of the size of those lesions and the time needed for their healing. Inclusion criteria were: clinical trials, articles written in English or Spanish and published less than 5 years ago.Results: we used the following keywords: treatment, aphtous stomatitis, canker sores; combined with Bool-ean operators AND y OR. …
Crosslinked chitosan/poly(vinyl alcohol)-based polyelectrolytes for proton exchange membranes
2019
[EN] The preparation polyelectrolytes based on crosslinked poly(vinyl alcohol) (PVA) and chitosan (CS) was considered as a feasible alternative to develop highly functionalised, cost-effective and eco-friendly membranes for proton exchange fuel cell technologies. CS/PVA-based membranes were combined with sulfosuccinic acid (SSA) as crosslinking and sulfonating agent, and glycerol (GL) to promote flexibility and favour their manageability. The chemical structure, the thermo-oxidative behaviour, the ethanol uptake, the electric, the proton conductivity, and the performance in direct ethanol fuel cell (DEFC) were assessed. In general, all the CS/PVA-based polyelectrolytes showed a synergetic i…
E-beam crosslinked, biocompatible functional hydrogels incorporating polyaniline nanoparticles
2012
Abstract PANI aqueous nanocolloids in their acid-doped, inherently conductive form were synthesised by means of suitable water soluble polymers used as stabilisers. In particular, poly(vinyl alcohol) (PVA) or chitosan (CT) was used to stabilise PANI nanoparticles, thus preventing PANI precipitation during synthesis and upon storage. Subsequently, e-beam irradiation of the PANI dispersions has been performed with a 12 MeV Linac accelerator. PVA-PANI nanocolloid has been transformed into a PVA-PANI hydrogel nanocomposite by radiation induced crosslinking of PVA. CT-PANI nanoparticles dispersion, in turn, was added to PVA to obtain wall-to-wall gels, as chitosan mainly undergoes chain scission…
Combined effect of natural antioxidants and antimicrobial compounds during refrigerated storage of nitrite-free frankfurter-type sausage.
2019
Abstract The effects of nisin (200 and 400 ppm), e-polylysine (0.1 and 0.2%) and chitosan (0.5 and 1%) in combination with a Mixed Extract (green tea, stinging nettle and olive leaves extracts) on the physicochemical, microbiological characteristics, fatty acid composition and sensory attributes of the nitrite-free frankfurter-type sausages were assessed during 45 days of storage. The results revealed no significant differences on moisture, fat, protein, ash, salt and water activity (aw) among treatments. 1% Chitosan + Mixed Extract sausages displayed the lowest thiobarbituric acid reactive substances (TBARS) and total volatile nitrogen (TVN) values compared to Control after 45 days of refr…
Contribution à la compréhension de l'influence des paramètres de formulation et de procédé sur la structure et les propriétés fonctionnelle de films …
2012
The aim of this study is the analysis of structure and transfer mechanisms through chitosan based food packaging materials with incorporated carvacrol as a model of antimicrobial active substance. Integration of composition parameters, structure, processing and drying of chitosan systems is correlated to its physico chemical and functional properties. Understanding and detailed analyses of processing parameters is crucial in production of active chitosan coatings applied on conventional materials such as polyethylene. So, the knowledge of composition and microstructure in association to environmental conditions, control the retention and the release kinetics of carvacrol from chitosan film.…
Acetone Vapor-Sensing Properties of Chitosan-Polyethylene Glycol Using Surface Plasmon Resonance Technique
2020
To non-invasively monitor and screen for diabetes in patients, there is need to detect low concentration of acetone vapor in the range from 1.8 ppm to 5 ppm, which is the concentration range of acetone vapor in diabetic patients. This work presents an investigation for the utilization of chitosan-polyethylene glycol (PEG)-based surface plasmon resonance (SPR) sensor in the detection of trace concentration acetone vapor in the range of breath acetone in diabetic subjects. The structure, morphology, and elemental composition of the chitosan-PEG sensing layer were characterized using FTIR, UV-VIS, FESEM, EDX, AFM, and XPS methods. Response testing was conducted using low concentration of aceto…
Efecto del quitosán de alto peso molecular y del alginato de sodio sobre la hidrofobicidad y adhesión de Candida albicans a células
2006
Objetivo: Evaluar el efecto del quitosán de alto peso molecular (QAPM) y del alginato de sodio (NaAL) sobre la hidrofobicidad superficial de Candida albicans y la adhesión de esta levadura a células epiteliales y fibroblastos de distinto origen. Diseño del estudio: Para el estudio de la hidrofobicidad, las levaduras (n=7) se hicieron crecer en agar glucosado de Sabouraud suplementado con QAPM o NaAL o en ausencia de los mismos (controles). La determinación de la hidrofobicidad se realizó por el método de adhesión a hidrocarburos utilizando dos solventes orgánicos (xileno y cloroformo). En los estudios de adhesión, las levaduras se pusieron en contacto con soluciones de biopolímeros y luego …