Search results for "hydrogels"
showing 10 items of 299 documents
Two-Component Hydrogels Formed by Cyclodextrins and Dicationic Imidazolium Salts
2013
In the framework of our recent interest in studying the gelling behaviour of imidazolium salts, we took into account the possibility of obtaining two-component hydrogels by combining cyclodextrins and dicationic imidazolium salts. In particular, we used diimidazolium salts differing in the alkyl chain length and in the size, shape, and coordination ability of the anion, namely the 3,3′-di-n-decyl- and 3,3′-di-n-dodecyl-1,1′-(1,4-phenylenedimethylene)diimidazolium dibromide, and 3,3′-di-n-dodecyl-1,1′-(1,4-phenylenedimethylene)diimidazolium ditetrafluoroborate and dihexafluorophosphate. As far as cyclodextrins are concerned, to gain information on the effects of different sized cyclic oligos…
Chemical gels of scleroglucan obtained by cross-linking with 1,w-dicarboxylic acids: Synthesis and characterization
2005
Chemical gels obtained by cross-linking reaction between scleroglucan and I, omega-dicarboxylic acids having a number of carbon atoms from 4 to 8 in the chain, have been prepared and characterised. The networks show properties correlated with the number of carbon atoms of the acid and with the molar ratio carboxylic acid/glucose unit of the polymer (r) employed in the cross-linking reaction. The diffusion of theophylline, chosen as model drug, through the swelled cross-linked polymers has been also investigated and it has enabled the diffusion coefficients of the drug to be calculated under different environmental conditions. The release profiles of theophylline from tablets prepared with t…
Perfluorocarbon functionalized hyaluronic acid derivatives as oxygenating systems for cell culture
2014
A set of new hyaluronic acid (HA) derivatives was obtained by binding fluorinated oxadiazole (OXA) moieties to an amino derivative of the polysaccharide (HA-EDA). The obtained HA-EDA-OXA biomaterials are potentially able to improve oxygenation into a scaffold for tissue engineering purposes. The oxygen solubility in aqueous dispersions of the obtained derivatives showed that polymers were able to improve oxygen uptake and maintenance in the medium. The HA-EDA-OXA was employed to form a hydrogel in situ by reaction with a vinyl sulphone derivative of inulin, under physiological conditions. The influence of the presence of OXA moieties on the mechanical properties of the obtained hydrogels as…
Radiation synthesis of polyaspartamide functionalised hydrogels for sustained release of fragrances
2005
The aim of the present investigation is to assess the possibility of obtaining a biocompatible material device which is able to deliver oil-soluble fragrances in air over a length of time. Aqueous solutions of polyaspartamide functionalised with glycidyl methacrylate have been cross linked through gamma irradiation in the presence of a lipophilic model fragrance, emulsified prior to irradiation. Two emulsification conditions have been considered at two different concentrations of both fragrance and surfactant in water. Chemical hydrogels have been obtained in correspondence to two irradiation absorbed doses and have been characterised for their solubility properties and swelling ability in …
Injectable in situ forming hydrogels based on natural and synthetic polymers for potential application in cartilage repair
2015
In this work we prepared two new hyaluronic acid (HA) based in situ forming hydrogels for the potential treatment of articular cartilage damages. In particular the amino derivative of HA (HA-EDA) and its graft copolymer with α-elastin (HA-EDA-g-α-elastin) were crosslinked, in mild physiological conditions via Michael-type addition, with α,β-poly(N-2-hydroxyethyl)-dl-aspartamide (PHEA) derivatized with divinylsulfone (DV). The swelling and degradation profile of the obtained hydrogels as well as the metabolic activity of incorporated bovine articular chondrocytes were investigated. Histological analysis and scanning electron microscopy (SEM) were performed to analyze the morphology of cells …
In situ forming hydrogels of new amino hyaluronic acid/benzoyl-cysteine derivatives as potential scaffolds for cartilage regeneration
2012
A new chemical strategy is described to link ethylenediamino (EDA) groups to primary hydroxyl groups of hyaluronic acid (HA) and the obtained derivatives have been characterized by 1H-NMR and 13C-NMR analyses. Such HA–EDA derivatives have been exploited to control the functionalization degree in benzoyl-cysteine (BC) groups, chosen as moieties able to allow both self-assembling in aqueous media and an oxidative crosslinking. In particular, the kinetics of oxidation of thiol groups in HA–EDA–BC derivatives has been studied in Dulbecco's Phosphate Buffer Solution (DPBS) pH 7.4 by colorimetric assays and rheological measurements. Mechanical properties of chemical hydrogels obtained after oxida…
α,β-Poly(N-Hydroxyethyl)-DL-Aspartamide Hydrogels as Drug Delivery Devices
1996
α,β-poly(N-hydroxyethyl)-DL-aspartamide (PHEA) was exposed to gamma radiation to obtain micromatrices able to swell in an aqueous medium. Crosslinked PHEA was loaded with an anti-inflammatory drug, 4-biphenylacetic acid (BPAA) and the drug dispersion in the network was investigated by X-ray analysis. The BPAA loaded PHEA microparticles were also characterized by dimensional analysis, which showed the presence of quasispherical shapes. The drug release from PHEA hydrogel was studied in vitro in a pH 1.1 (simulated gastric juice) and in a pH 7.4 buffer solution, respectively. The experimental data indicate that an anomalous delivery occurs, but Fickian diffusion through swollen PHEA hydrogel…
Degradable cationic nanohydrogel particles for stimuli-responsive release of siRNA.
2014
Well-defined nanogels have become quite attractive as safe and stable carriers for siRNA delivery. However, to avoid nanoparticle accumulation, they need to provide a stimuli-responsive degradation mechanism that can be activated at the payload's site of action. In this work, the synthetic concept for generating well-defined nanohydrogel particles is extended to incorporate disulfide cross-linkers into a cationic nanonetwork for redox-triggered release of oligonucleotide payload as well as nanoparticle degradation under reductive conditions of the cytoplasm. Therefore, a novel disulfide-modified spermine cross-linker is designed that both allows disassembly of the nanogel as well as removal…
Magnetic Composite Thin Films of FexOy Nanoparticles and Photocrosslinked Dextran Hydrogels
2012
Abstract Magnetic hydrogel composites are promising candidates for a broad field of applications from medicine to mechanical engineering. Here, surface-attached composite films of magnetic nanoparticles (MNP) and a polymeric hydrogel (HG) were prepared from magnetic iron oxide nanoparticles and a carboxymethylated dextran with photoreactive benzophenone substituents. A blend of the MNP and the dextran polymer was prepared by mixing in solution, and after spin-coating and drying the blend film was converted into a stable MNP–HG composite by photocrosslinking through irradiation with UV light. The bulk composite material shows strong mobility in a magnetic field, imparted by the MNPs. By util…
Inulin vinyl sulfone derivative cross-linked with bis-amino PEG: new materials for biomedical applications
2009
In this work new hydrogels based on biocompatible polymers such as inulin (INU) and O,O'-bis(2-aminoethyl)polyethyleneglycol (PEGBa) have been prepared and charaterized. In particular, INU has been derivatized with divinyl sulfone (DV) thus obtaining the INUDV derivative, a copolymer bearing double bonds highly reactive towards the conjugate addition by nucleophilic molecules. INUDV has been characterized by FT-IR, 1 H-NMR and SEC analyses that have confirmed the success of the derivatization reaction. With the aim to obtain novel hydrogel systems, INUDV derivative has been cross-linked with PEGBa in phosphate buffer solution pH 7.4. The reaction has been carried out for 4 h at room tempera…