Search results for "Gels"
showing 10 items of 671 documents
Angels carrying crowns on the images of martyrs. Origin of the iconographic type
2013
Este artículo pretende explicar el origen de las imágenes de los ángeles portando coronas a los mártires, señalando para ello la relación de las coronas con los mártires desde la época paleocristiana, cómo éstas empezaron a ser portadas por ángeles, y los diferentes tipos de coronas que pueden portar según las distintas épocas. This article tries to explain the origin of the images of angels carrying crowns to the martyrs; to this end, it points out the relationship of the crowns with the martyrs from Early Christian period, the way these crowns began to be carried by angels, and the different types of crowns they could carry depending on different periods.
Xyloglucan-based hydrogel films for wound dressing: Structure-property relationships
2017
Thin xyloglucan-based hydrogel films have been synthetized and characterized in the prospect of producing wound dressings. Polyvinyl alcohol (PVA) and glycerol (Gro) were added to have an optimal combination of softness, conformability and resilience. Physical hydrogels have been transformed into permanent covalent hydrogels by reaction with glutaraldehyde (GA). Network structure-process-property relationships are discussed on the account of the results of several complementary characterizations: FTIR, rheology, thermal analysis, morphological analysis, moisture retention and swelling measurements. Selected formulations were also subjected to preliminary in vitro cytotoxicity tests. The phy…
Poly-l-Lactic Acid Nanofiber-Polyamidoamine Hydrogel Composites: Preparation, Properties, and Preliminary Evaluation as Scaffolds for Human Pluripote…
2016
Electrospun poly-l-lactic acid (PLLA) nanofiber mats carrying surface amine groups, previously introduced by nitrogen atmospheric pressure nonequilibrium plasma, are embedded into aqueous solutions of oligomeric acrylamide-end capped AGMA1, a biocompatible polyamidoamine with arg-gly-asp (RGD)-reminiscent repeating units. The resultant mixture is finally cured giving PLLA-AGMA1 hydrogel composites that absorb large amounts of water and, in the swollen state, are translucent, soft, and pliable, yet as strong as the parent PLLA mat. They do not split apart from each other when swollen in water and remain highly flexible and resistant, since the hydrogel portion is covalently grafted onto the …
Degradable poly(amidoamine) hydrogels as scaffolds for in vitro culturing of peripheral nervous system cells.
2012
This paper reports on the synthesis and physico-chemical, mechanical, and biological characterization of two sets of poly(amidoamine) (PAA) hydrogels with potential as scaffolds for in vivo peripheral nerve regeneration. They are obtained by polyaddition of piperazine with N,N′-methylenebis(acrylamide) or 1,4-bis(acryloyl)piperazine with 1,2-diaminoethane as cross-linking agent and exhibit a combination of relevant properties, such as mechanical strength, biocompatibility, biodegradability, ability to induce adhesion and proliferation of Schwann cells (SCs) preserving their viability. Moreover, the most promising hydrogels, that is those deriving from 1,4-bis(acryloyl)piperazine, allow the …
Synthesis and evaluation of thermo-rheological behaviour and ionotropic crosslinking of new gellan gum-alkyl derivatives.
2018
Abstract This paper reports the synthesis and the physicochemical characterization of two series of gellan gum (GG) derivatives functionalized with alkyl chains with different number of carbon, from 8 to 18. In particular, low molecular weight gellan gum samples with 52.6 or 96.7 kDa, respectively, were functionalized with octylamine (C8), dodecylamine (C12) and octadecylamine (C18) by using bis(4-nitrophenyl) carbonate (4-NPBC) as a coupling agent. Thermo-rheological and ionotropic crosslinking properties of these gellan gum-alkyl derivatives were evaluated and related to the degree of derivatization in alkyl chains. Results suggested as length and degree of derivatization differently infl…
Hyaluronic acid and beta cyclodextrins films for the release of corneal epithelial cells and dexamethasone
2016
In this work we prepared hydrogels based on hyaluronic acid and β-cyclodextrins to sustain the release of both corneal epithelial cells and dexamethasone. This steroid is administered as eye drops several times per day to reduce the risk of rejection in the post operative period after the cornea transplantation and cell release techniques. Hydrogels were produced by crosslinking an amino derivative of hyaluronic acid, with the divinyl sulfone derivative of β-cyclodextrins, this last employed as a crosslinker and solubilizing agent. Drug release studies revealed that dexamethasone containing samples are able to extend the release of this drug for at least five days. Biological studies, condu…
Temporal control of xyloglucan self-assembly into layered structures by radiation-induced degradation
2016
Partially degalactosylated xyloglucan from tamarind seeds (Deg-XG) is a very appealing biopolymer for the production of in situ gelling systems at physiological temperature. In this work, we observe that the morphology of hydrogels evolves towards high degrees of structural organization with time, yielding to dense stacks of thin membranes within 24 h of incubation at 37 °C. We also explore the possibility offered by gamma irradiation of controlling the time scale of this phenomenon, the final morphology and mechanical properties of the system. Structural and molecular modifications of Deg-XG with dose are investigated by FTIR, dynamic light scattering (DLS) and rotational viscosimetry. The…
Nanosized hydrophobic gels: Advanced supramolecules for use in electrochemical bio- and immunosensing
2018
Abstract Nanosized hydrogels have emerging as versatile supramolecules materials with application in various electrochemical biosensing devices. This review reports a systematic study of the usefulness of nano-sized hydrogels in the different steps of the process of development of electrochemical biosensing systems. The advantages offered by nano-sized hydrogels in detection of analytes are illustrated with representative recent examples that highlight the scientific interest in widening the use of hydrogel nanoparticles in electrochemical biosensing methods. In this review, different types of hydrogel nanoparticles-based electrochemical biosensors, such as enzyme, protein, and nucleic acid…
Dynamic Tuning of Viscoelastic Hydrogels with Carbonyl Iron Microparticles Reveals the Rapid Response of Cells to Three-Dimensional Substrate Mechani…
2021
Current methods to dynamically tune three-dimensional hydrogel mechanics require specific chemistries and substrates that make modest, slow, and often irreversible changes to their mechanical properties, exclude the use of protein-based scaffolds, or alter hydrogel microstructure and pore size. Here, we rapidly and reversibly alter the mechanical properties of hydrogels consisting of extracellular matrix proteins and proteoglycans by adding carbonyl iron microparticles (MP) and applying external magnetic fields. This approach drastically alters hydrogel mechanics: rheology reveals that application of a 4,000 Oe magnetic field to a 5 mg/mL collagen hydrogel containing 10 wt% MPs increases th…
Influence of different parameters on drug release from hydrogel systems to a biomembrane model. Evaluation by differential scanning calorimetry techn…
2000
A comparative study on the drug release capacity of four water swellable polymeric systems was carried out by differential scanning calorimetry (DSC). The polymeric systems chosen were alpha,beta-polyaspartahydrazide (PAHy) crosslinked by glutaraldehyde (GLU) (PAHy-GLU) or by ethyleneglycoldiglycidylether (EGDGE), (PAHy-EGDGE), polyvinylalcohol (PVA) crosslinked by glutaraldehyde (PVA-GLU) and alpha,beta-poly(N-hydroxyethyl)-DL-aspartamide (PHEA) by gamma irradiation (PHEA-gamma matrices). The degree of crosslinking for PAHy-GLU, PAHy-EGDGE and PVA-GLU samples was about 0.4 and 0.8. These hydrogels were characterized as free of drugs and were loaded with diflunisal (DFN) (approximately 2.5%…