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Hydrogel Matrix (hydrogel + matrix)

Distribution by Scientific Domains

Polymers and Materials Science	50%
Life Sciences	50%

Selected Abstracts

Mass transfer from theophylline hydrogels of a -PVA/H2O and a -PVA/NaCl/H2O system on heating

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10 2003
Sharif M. Shaheen
Abstract Theophylline hydrogels of atactic -poly(vinyl alcohol) (a -PVA)/H2O and a -PVA/NaCl/H2O systems were prepared followed by cyclic freezing (,30°C for 16,hr),thawing (at room temperature for 8,hr) and one cycle gelation (at ,20°C for 24,hr) processes, respectively. In order to prepare xerogels (dried hydrogels) of these hydogel systems, an apparently first-order mass transfer phenomenon of water as evaporation was observed for a -PVA/H2O hydrogel system, while heating at 60°C. The rate of evaporation decreased with increasing time in hyperbolic fashion. The total surface area (both lateral and two end surfaces of hydrogel matrix disc) decreased linearly for the first 90,min and thereafter had a tendency towards the steady-state. The total mass flux showed time dependent linear reduction phenomenon, which is a characteristic physical behavior for these hydrogel systems on heat treatment. When NaCl was included in a -PVA/H2O system mass transfer of water followed fourth-order polynomial. But in consideration of a comparative study, sustained mass transfer was found from the hydrogel matrices of a -PVA/H2O/NaCl system (gelation at ,20°C). Copyright © 2003 John Wiley & Sons, Ltd. [source]

Cell-mediated Delivery and Targeted Erosion of Vascular Endothelial Growth Factor-Crosslinked Hydrogels

MACROMOLECULAR RAPID COMMUNICATIONS, Issue 14 2010
Sung Hye Kim
Abstract We have previously reported a novel polymeric delivery vehicle that is assembled via interaction between heparin and the vascular endothelial growth factor (VEGF). Here, the cell-responsiveness of this hydrogel,including the delivery of VEGF in response to VEGFR-2 overexpressing PAE/KDR cells (porcine aortic endothelial cells (PAE) equipped with the transcript for the kinase insert domain receptor (KDR)), consequent erosion of the hydrogel matrix, and cellular response,are highlighted. The release of VEGF and hydrogel erosion reached 100% only in the presence of PAE/KDR. The [PEG-LMWH/VEGF] hydrogel (PEG,=,poly(ethylene glycol), LMWH,=,low molecular weight heparin) correspondingly prompted increases in VEGFR-2 phosphorylation and proliferation of PAE/KDR cells. This study proves that growth factor-crosslinked hydrogels can liberate VEGF in response to specific receptors, causing gel erosion and desired cell responses. The promise of these approaches in therapeutic applications, including targeted delivery, is suggested. [source]

Peptide-dominated membranes preceding the genetic takeover by RNA: latest thinking on a classic controversy

BIOESSAYS, Issue 10 2009
Richard Egel
Abstract It is commonly presumed that abiotic membranes were colonized by proteins later on. Yet, hydrophobic peptides could have formed primordial protein-dominated membranes on their own. In a metabolism-first context, "autocatalytically closed" sets of statistical peptides could organize a self-maintaining protometabolism, assisted by an unfolding set of ribotide-related cofactors. Pairwise complementary ribotide cofactors may have formed docking guides for stochastic peptide formation, before replicating RNA emerged from this subset. Tidally recurring wet-drying cycles and an early onset of photosynthetic activities are considered most likely to meet the thermodynamic requirements. Conceivably, the earliest peptide-dominated vesicles were engaged in light harvesting, together with isoprenoid-tethered pigments, rather than providing an external boundary. Early on, the bulk of prebiotic organic matter can have formed a contiguous layer covering the mineral sediment, held in place by colloidal coherence of a hydrogel matrix. This unconventional scenario assumes a late onset of cellular individualization , perhaps from within, resembling endosporogenesis. [source]

An alginate hydrogel matrix for the localised delivery of a fibroblast/keratinocyte co-culture

BIOTECHNOLOGY JOURNAL, Issue 5 2009
Nicola C. Hunt
Abstract There is significant interest in the development of tissue-engineered skin analogues, which replace both the dermal and the epidermal layer, without the use of animal or human derived products such as collagen or de-epidermalised dermis. In this study, we proposed that alginate hydrogel could be used to encapsulate fibroblasts and that keratinocytes could be cultured on the surface to form a bilayered structure, which could be used to deliver the co-culture to a wound bed, initially providing wound closure and eventually expediting the healing process. Encapsulation of fibroblasts in 2 and 5% w/v alginate hydrogel effectively inhibited their proliferation, whilst maintaining cell viability allowing keratinocytes to grow uninhibited by fibroblast overgrowth to produce a stratified epidermal layer. It was shown that the alginate degradation process was not influenced by the presence of fibroblasts within the hydrogel and that lowering the alginate concentration from 5 to 2% w/v increased the rate of degradation. Fibroblasts released from the scaffold were able to secrete extracellular matrix (ECM) and thus should replace the degrading scaffold with normal ECM following application to the wound site. These findings demonstrate that alginate hydrogel may be an effective delivery vehicle and scaffold for the healing of full-thickness skin wounds. [source]