Search results for "self-healing"
showing 10 items of 222 documents
Biodegradable hydrogels obtained by photocrosslinking of dextran and polyaspartamide derivatives
2003
The functionalization of dextran with glycidyl methacrylate (GMA) leads to the formation of a derivative that generates hydrogels for irradiation at 365nm. The effects of various polymer concentrations and irradiation times on the yield and the properties of the obtained hydrogels are reported. The networks have been characterized by FT-IR spectra, dimensional analysis and swelling measurements carried out at different pH values. In vitro studies suggest that all samples undergo a partial chemical hydrolysis, whereas the incubation with dextranases causes a total degradation whose rate depends on the degree of crosslinking. In addition, aqueous solutions of functionalized dextran have been …
DRUG DELIVERY FROM MUCOADHESIVE DISKS BASED ON A PHOTO-CROSS-LINKABLE POLYASPARTAMIDE DERIVATIVE
2005
Disks for local delivery of amoxicillin to the buccal or gastric cavity were prepared using as starting polymer a polyaspartamide derivative. In particular, α,β-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) was derivatized with glycidyl methacrylate (GMA) in order to synthesize PHG, a photo-cross-linkable and biodegradable polymer that gives rise to the formation of a chemical hydrogel (PHG-UV) by UV irradiation. This hydrogel was shaped as disks whose mucoadhesive properties have been confirmed by swelling measurements in phosphate buffer/citric acid solution at pH 7.0 in the presence of various concentrations of mucin. Swelling ability of PHG-UV disks was also evaluated in simulated saliva…
Synthesis of fluorinated oxadiazoles with gelation and oxygen storage ability
2012
A new family of fluorinated low molecular weight (LMW) gelators has been synthesized through SNAr substitution of 5-polyfluoroaryl-3-perfluoroheptyl-1,2,4-oxadiazoles with glycine ester. The obtained compounds give thermal and pH-sensitive hydrogels or thermo-reversible organogels in DMSO. Oxygen solubility studies showed the ability to maintain high oxygen levels in solution and in gel blend with plate counter agar (PCA).
Designed biodegradable hydrogel structures prepared by stereolithography using poly(ethylene glycol)/poly(D,L-lactide)-based resins
2010
Designed three-dimensional biodegradable poly(ethylene glycol)/poly(D,L-lactide) hydrogel structures were prepared for the first time by stereolithography at high resolutions. A photo-polymerisable aqueous resin comprising PDLLA-PEG-PDLLA-based macromer, visible light photo-initiator, dye and inhibitor in DMSO/water was used to build the structures. Porous and non-porous hydrogels with well-defined architectures and good mechanical properties were prepared. Porous hydrogel structures with a gyroid pore network architecture showed narrow pore size distributions, excellent pore interconnectivity and good mechanical properties. The structures showed good cell seeding characteristics, and human…
Timing effect of intramyocardial hydrogel injection for positively impacting left ventricular remodeling after myocardial infarction
2015
Intramyocardial injection of various injectable hydrogel materials has shown benefit in positively impacting the course of left ventricular (LV) remodeling after myocardial infarction (MI). However, since LV remodeling is a complex, time dependent process, the most efficacious time of hydrogel injection is not clear. In this study, we injected a relatively stiff, thermoresponsive and bioabsorbable hydrogel in rat hearts at 3 different time points - immediately after MI (IM), 3 d post-MI (3D), and 2 w post-MI (2W), corresponding to the beginnings of the necrotic, fibrotic and chronic remodeling phases. The employed left anterior descending coronary artery ligation model showed expected infar…
Tunable and Large-Scale Model Network StarPEG-DNA Hydrogels
2021
The use of DNA as a building block in synthetic polymer hydrogels promises high levels of programmability regarding sol/gel temperatures, tunable bond lifetimes, biocompatibility, and interaction w...
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…
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 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…