Search results for "alginate"

Influence de l'état protéique sur la dynamique de séparation de phase et de gélification dans un système ternaire aqueux à base de protéines de pois …

2012

Two aqueous systems at 20°C in 0.1 M NaCl and pH 7.2 containing globular pea proteins and sodium alginate were investigated in this study. First, phase behavior of (i) either low-denatured mixed globulins or (ii) their thermally pre-aggregated counterparts - alginate mixtures was compared using a multi-scale approach, by means of phase diagram and microstructure analysis by confocal microscopy. Thermodynamic incompatibility was the main driving force leading to phase separation within the mixtures, which presented according to their initial biopolymer composition both different morphological and time-evolution features of coexisting phases. Thereafter, a cold-set gelation for each system wa…

Protection of yeast cells in micro-organized shells of natural polyelectrolytes during drying process

2016

The encapsulation techniques are applied in various fields and for various applications. The layer-by-layer self-assembly (LbL), one of the encapsulation techniques, is built by the electrostatic attraction between oppositely charged polyelectrolytes, and the topmost layer determines essentially the sur-face properties of the edifice. This technique offers several advantages (low cost, simplicity of process and equipment, biocompatibility and biodegra-dation, etc.). In this present paper, results of the protection of Saccharomyces cerevisiae yeast cells in microorganized shell of natural polyelectrolytes during dehydration process are reported. To apply the LbL method to individually encaps…

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 …

Biopolymer-Based Hybrid Hydrogels for Biomedical Applications: From Macroscopic to Nanosized Systems

2021

Les partícules portadores basades en biopolímers són biocompatibles i ofereixen la capacitat d’incorporar agents actius hidròfils i hidròfobs. La incorporació d’un fàrmac en una matriu polimèrica pot millorar-ne la protecció contra la degradació en mitjans fisiològics severs. A més, pot controlar-ne l’alliberament al lloc d’acció específic, amb una biodisponibilitat terapèutica augmentada i efectes secundaris o toxicitat minimitzats. Aquesta tesi presenta la preparació de diferents sistemes híbrids de polisacàrids per a encapsular substàncies hidròfiles, que posteriorment són alliberades. Es preparen portadors que varien de mida macroscòpica a nanomètrica mitjançant diferents mètodes: gelif…

2003

Resting cells of the yeast Rhodosporidium toruloides (UOFS Y-0471) were immobilised in calcium alginate beads for the enantioselective kinetic resolution of racemic-1,2-epoxyoctane. The initial activity exhibited by immobilised cells was almost 50% lower than that of the free counterpart but was extremely stable when compared to the free cells. The concentration of the immobilised biomass had no effect on apparent enzyme activity but did lead to a decrease in single cell activity. An increase in both the alginate and CaCl2 concentrations used for bead preparation led to a decrease in enzyme stability. An increase in the alginate concentration led to an increase in bead diameter. The stoichi…

Current Trends in Advanced Alginate-Based Wound Dressings for Chronic Wounds

2021

Chronic wounds represent a major public health issue, with an extremely high cost worldwide. In healthy individuals, the wound healing process takes place in different stages: inflammation, cell proliferation (fibroblasts and keratinocytes of the dermis), and finally remodeling of the extracellular matrix (equilibrium between metalloproteinases and their inhibitors). In chronic wounds, the chronic inflammation favors exudate persistence and bacterial film has a special importance in the dynamics of chronic inflammation in wounds that do not heal. Recent advances in biopolymer-based materials for wound healing highlight the performance of specific alginate forms. An ideal wound dressing shou…

Long-term function of porcine islets and single cells embedded in barium-alginate matrix.

1993

The influence of alginate-embedding on the maintenance of functioning and morphological integrity in long-term culture of isolated porcine islets and islet cells was studied. Free-floating islets and islet cells served for control. Function was tested after the 1st, 2nd and 4th week. Basal and glucose-stimulated insulin secretion of embedded islets decreased slightly, but significantly after the first week (from 4.39 +/- 0.64 to 2.87 +/- 0.47 at normal and from 11.96 +/- 1.44 to 4.76 +/- 0.78 microU pro 24 h pro islet at elevated glucose concentration, p < 0.05 and < 0.01, resp.) and remained unchanged thereafter. Glucose-stimulation resulted in significant increases in insulin secretion at…

Modular Small Diameter Vascular Grafts with Bioactive Functionalities.

2015

We report the fabrication of a novel type of artificial small diameter blood vessels, termed biomimetic tissue-engineered blood vessels (bTEBV), with a modular composition. They are composed of a hydrogel scaffold consisting of two negatively charged natural polymers, alginate and a modified chitosan, N,O-carboxymethyl chitosan (N,O-CMC). Into this biologically inert scaffold two biofunctionally active biopolymers are embedded, inorganic polyphosphate (polyP) and silica, as well as gelatin which exposes the cell recognition signal, Arg-Gly-Asp (RGD). These materials can be hardened by exposure to Ca(2+) through formation of Ca(2+) bridges between the polyanions, alginate, N,O-CMC, and polyP…

Structural behaviour differences in low methoxy pectin solutions in the presence of divalent cations (Ca 2+ and Zn 2+ ): a process driven by the bind…

2014

International audience; In this paper, we compare the interactions between low methoxy pectin (LMP) and either Ca2+ or Zn2+ in semi-dilute solutions. Intrinsic viscosity and turbidity measurements reveal that pectin-calcium solutions are more viscous, but yet less turbid, than pectin-zinc ones. To get a molecular understanding on the origin of this rather unexpected behavior, we further performed isothermal titration calorimetry, small angle neutron scattering experiments, as well as molecular dynamics simulations. Our results suggest that calcium cations induce the formation of a more homogeneous network of pectin than zinc cations do. The molecular dynamics simulations indicate that this …

Engineering a morphogenetically active hydrogel for bioprinting of bioartificial tissue derived from human osteoblast-like SaOS-2 cells.

2014

Abstract Sodium alginate hydrogel, stabilized with gelatin, is a suitable, biologically inert matrix that can be used for encapsulating and 3D bioprinting of bone-related SaOS-2 cells. However, the cells, embedded in this matrix, remain in a non-proliferating state. Here we show that addition of an overlay onto the bioprinted alginate/gelatine/SaOS-2 cell scaffold, consisting of agarose and the calcium salt of polyphosphate [polyP·Ca 2+ -complex], resulted in a marked increase in cell proliferation . In the presence of 100 μ m polyP·Ca2+ -complex, the cells proliferate with a generation time of approximately 47–55 h. In addition, the hardness of the alginate/gelatin hydrogel substantially i…