Search results for " gelation"

Physics of agarose fluid gels: Rheological properties and microstructure

2021

Agarose, a strongly gelling polysaccharide, is a common ingredient used to optimize the viscoelastic properties of a multitude of food products. Through aggregation of double helices via hydrogen bonds while cooling under quiescent conditions it forms firm and brittle gels. However, this behavior can be altered by manipulating the processing conditions viz shear. For example, gelation under shear leads to microgel particles with large surface area, which in turn leads to completely different rheological properties and texture. Such fluid gels are shown to play an important role in texture modification of foods and beverages for dysphagia patients. In this study, different concentration of a…

Spectroscopic and microscopic characterization of BSA hydrogels: towards new biomaterials

2014

In situ formation of steroidal supramolecular gels designed for drug release

2013

In this work, a steroidal gelator containing an imine bond was synthesized, and its gelation behavior as well as a sensitivity of its gels towards acids was investigated. It was shown that the gels were acid-responsive, and that the gelator molecules could be prepared either by a conventional synthesis or directly in situ during the gel forming process. The gels prepared by both methods were studied and it was found that they had very similar macroand microscopic properties. Furthermore, the possibility to use the gels as carriers for aromatic drugs such as 5-chloro-8-hydroxyquinoline, pyrazinecarboxamide, and antipyrine was investigated and the prepared two-component gels were studied with…

Physico-chemical state influences in vitro release profile of curcumin from pectin beads

2014

International audience; Curcumin is a polyphenolic compound with diverse effects interesting to develop health benefit products but its formulation in functional foods or in food supplement is hampered by its poor water solubility and susceptibility to alkaline conditions, light, oxidation and heat. Encapsulation of curcumin could be a mean to overcome these difficulties. In this paper, curcumin was encapsulated by ionotropic gelation method in low methoxyl pectin beads associated with different surfactants: Solutol®, Transcutol® and sodium caseinate. After encapsulation, physico-chemical properties of encapsulated curcumin such as its solubility, physical state, tautomeric forms and encaps…

Bipyridine based metallogels: an unprecedented difference in photochemical and chemical reduction in the in situ nanoparticle formation

2017

Metal co-ordination induced supramolecular gelation of low molecular weight organic ligands is a rapidly expanding area of research due to the potential in creating hierarchically self-assembled multi-stimuli responsive materials. In this context, structurally simple O-methylpyridine derivatives of 4,4′-dihydroxy-2,2′-bipyridine ligands are reported. Upon complexation with Ag(I) ions in aqueous dimethyl sulfoxide (DMSO) solutions the ligands spontaneously form metallosupramolecular gels at concentrations as low as 0.6 w/v%. The metal ions induce the self-assembly of three dimensional (3D) fibrillar networks followed by the spontaneous in situ reduction of the Ag-centers to silver nanopartic…

Subcomponent Self-Assembly A Quick Way to New Metallogels

2013

Subcomponent self-assembly, introduced by the Nitschke group,[1] is a process which allow complex structures to be generated from simple building blocks (generally aldehydes and amines). In this bottom-up approach, the building blocks spontaneously self-assemble around templates (usually metal ions) leading to a simultaneous covalent (C=N) and dative (N– metal) bonds formation. The method has been successfully used to construct well-defined metal-organic macrocycles, helicates, catenanes, rotaxanes, grids,[2] and cages.[3] Our field of interest lies not in building-up of defined structures but in designing gelator molecules for a formation of supramolecular gels as functional nanomaterials.…

TEMPERATURE-TRIGGERED MACROSCOPIC GELATION OF IRRADIATED XYLOGLUCANS FOR BIOMEDICAL APPLICATIONS

2014

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…

Gelation of degalactosylated xyloglucan from nano to macroscopic scale

2016

Partially degalactosylated xyloglucans are able to form thermo-reversible gels in aqueous solution at physiological temperature. This property makes them very promising materials for tissue engineering. Moreover, due to a highly branched, hydroxyl group-rich molecular structure, xyloglucans are particularly interesting for manufacturing of micro/nanoparticles to be used as nano-scalar delivery devices of active ingredients in cosmetic and pharmaceutical formulations. Here we present results on the temperature-induced self-assembly of degalactosylated xyloglucan at varying polymer concentration from dilute to semi-dilute regime. Our aim is to investigate the gelation mechanism for gaining in…

Pellets based on polyuronates: Relationship between gelation and release properties

2017

International audience; Three polyuronates: amidated low methoxyl pectin (ALMP), low methoxyl pectin (LMP) and polygalacturonic acid (PGA) were used to encapsulate rutin in pellets, and they were characterized by different techniques (macroscopic properties, Calcium and rutin release). The ability of the three polyuronates to bind calcium ions and the viscoelastic properties of gels were performed to relate the properties of the pellets to the gel structures. The pellets size, the water content, the water uptake, the release of calcium and rutin varied depending on the polyuronate used. The pellets size of ALMP were smaller than LMP and PGA with a lower water content, but this matrix was mo…