Search results for "GELS"

Radiation synthesis of nanogels as therapeutic agent vectors

2015

Nanogels (NGs) are physically or chemically crosslinked polymer networks and are promising candidates in the development of therapeutic agent vectors. In fact, thanks to their tunable size and properties, they offer unique advantages, including a large and flexible surface for multivalent bio-conjugation, an internal 3D aqueous environment for incorporation and protection of (bio)molecular drugs, stimuliresponsiveness to achieve temporal and/or site control of the release function and biocompatibility. In order to develop effective NGs-based biomedical devices an inexpensive, robust and versatile synthetic methodology is required. In this perspective, we have produced NGs with high yields a…

New insights on the mechanism of PVP nanogels radiation synthesis

2017

In this work, the H2O2 build-up for several system compositions and irradiation conditions was investigated, by using the Ghormley triiodide method. Interestingly, the application of the method has revealed the occurrence of two concurrent reactions, the expected one responsible for the I3 - production (by reaction with the H2O2 formed upon irradiation) and one that is responsible for I3 - consumption. Both the concentrations of I3 - -forming and I3 - -consuming species are dose-dependent and polymer concentration-dependent. The kinetic study of the two reactions and some further experiments carried out with model molecules will be described. We believe that the results of this study can of…

Ionogels: Multifaced Materials

Bridging rigidity and flexibility : modulation of supramolecular hydrogels by metal complexation

2021

The combination of complementary, noncovalent interactions is a key principle for the design of multistimuli responsive hydrogels. In this work, an amphiphilic peptide, supramacromolecular hydrogelator which combines metal-ligand coordination induced gelation and thermoresponsive toughening is reported. Following a modular approach, the incorporation of the triphenylalanine sequence FFF into a structural (C3EG ) and a terpyridine-functionalized (C3Tpy ) C3 -symmetric monomer enables their statistical copolymerization into self-assembled, 1D nanorods in water, as investigated by circular dichroism (CD) spectroscopy and transmission electron microscopy (TEM). In the presence of a terpyridine …

Biomimetic Alginate/Gelatin Cross-Linked Hydrogels Supplemented with Polyphosphate for Wound Healing Applications

2020

In the present study, the fabrication of a biomimetic wound dressing that mimics the extracellular matrix, consisting of a hydrogel matrix composed of non-oxidized and periodate-oxidized marine alginate, was prepared to which gelatin was bound via Schiff base formation. Into this alginate/oxidized-alginate-gelatin hydrogel, polyP was stably but reversibly integrated by ionic cross-linking with Zn2+ ions. Thereby, a soft hybrid material is obtained, consisting of a more rigid alginate scaffold and porous structures formed by the oxidized-alginate-gelatin hydrogel with ionically cross-linked polyP. Two forms of the Zn-polyP-containing matrices were obtained based on the property of polyP to f…

Relation between structural and release properties in a polysaccharide gel system.

2007

Abstract The potential utility of κ-carrageenan gels for preparing drug release devices is here shown. Structural properties of κ-carrageenan gels prepared with different salt composition and containing Ketoprofen sodium salt, as model drug, have been evaluated with static light scattering and rheological measurements. These properties have been correlated with release profiles in vitro at pH 5.5. Release properties from gelled matrices have been compared with those obtained by two commercial products containing the same drug. Results show that: i) in this system it is possible to easily control the gel texture by using different cationic concentration; ii) the kinetics of drug release by κ…

Polymerization reactions and modifications of polymers by ionizing radiation

2020

International audience; Ionizing radiation has become the most effective way to modify natural and synthetic polymers through crosslinking, degradation, and graft polymerization. This review will include an in-depth analysis of radiation chemistry mechanisms and the kinetics of the radiation-induced C-centered free radical, anion, and cation polymerization, and grafting. It also presents sections on radiation modifications of synthetic and natural polymers. For decades, low linear energy transfer (LLET) ionizing radiation, such as gamma rays, X-rays, and up to 10 MeV electron beams, has been the primary tool to produce many products through polymerization reactions. Photons and electrons in…

Structural Organization of Poly(vinyl alcohol) Hydrogels Obtained by Freezing and Thawing Techniques:  A SANS Study

2005

The structural organization of matter in poly(vinyl alcohol) (PVA) hydrogels obtained by repeatedly freezing and thawing dilute solutions of PVA in D2O is investigated by use of small-angle neutron scattering measurements (SANS). This study is the first systematic and quantitative investigation in the medium range of length scales on PVA hydrogels obtained by freezing and thawing techniques. The studied gels have a complex hierarchical structure, extending over a wide range of length scales. The structural organization on the micron length scale originates from the presence of two separated phases constituted by polymer-rich and polymer-poor regions. The network structure may be interpreted…

Effect of 15% carbamide peroxide bleaching gel on color stability of giomer and microfilled composite resin: an in vitro comparison

2011

Objectives: The effect of 15% carbamide peroxide bleaching gel on color stability and surface topography of a giomer and a microfilled composite resin was evaluated in the present in vitro study. Study design: Forty discs measuring 10 mm in diameter and 1 mm in thickness were prepared from a giomer and a microfilled composite resin. Each material yielded 20 discs with completely smooth surfaces. Then a spectrophotometer was used to measure L* (lightness), a* (redness, greenness) and b* (blueness, yellowness) color coordinates of all the discs. Subsequently, the specimens were subjected to 15% carbamide peroxide bleaching gel. After measuring the color coordinates once again, color changes (…

Effect of pH on the transfer kinetics of an anti-inflammatory drug from polyaspartamide hydrogels to a lipid model membrane

1997

Abstract The release of a nonsteroidal anti-inflammatory drug (NSAID), 4-biphenylacetic acid (BPAA), from α,β-poly( N -hydroxyethyl)- dl -aspartamide (PHEA) hydrogels was tested at different pHs (4 and 7.4) by measuring the drug transfer from loaded hydrogel to dimyristoylphosphatidylcholine (DMPC) liposomes (multilamellar vesicles, MLV), chosen as a biomembrane model. This drug transfer was compared with the transfer from powdered drug and with drug classical. The perturbing effect of pure BPAA on the thermotropic behaviour of DMPC liposomes, in terms of transition temperature shift (Δ T m ) and enthalpy changes (Δ H ), was analysed at different pHs (4 and 7.4) by differential scanning cal…