1,721,020 research outputs found
Cartilage replacement implants using hydrogels
No full textArticular cartilage (AC), a highly specialised tissue that provides low friction and allows for efficient load bearing and distribution, can undergo disruption for traumatic or degenerative processes. Conservative treatment with various medications gives only temporary relief of symptoms rather than cure. Since 1960 several surgical procedures have been tested without significant improvement of AC regeneration. Actually, third generation tissue engineering applied to the cartilage tissue regeneration is giving promising results. The right combination of cell types, scaffolds and culture media can represent the only way to cure degenerated cartilage tissue. However, several critical issues need to be overcome
Formation of defined microporous 3D-structures starting from cross-linked hydrogels
No full textA new and simple technique was developed to obtain polysaccharide (hyaluronane, alginate and carboxymethylcellulose) -based hydrogels with a defined porous morphology. The technique consists of stratifying a cross-linked hydrogel on a filter with known pore diameter. CO2 bubbles, produced by the addition of HCl to a porogen salt NaHCO3, are forced to pass through the filter, and they induce the hydrogel to assume a porous morphology. The presence and distribution of pores was confirmed by scanning-electron microscopy (SEM). A strict correspondence was found between the porosity of the filter and the pore diameter in the hydrogels. Water uptake measurements showed a decreased amount of water taken up by the porous hydrogels compared with the native hydrogels, due to a compacting of the material. An explanation of the porous material properties of Hyal hydrogel was given on the basis of FTIR spectra.
The effects of spacer arms in cross-linked hyaluronic hydrogel on Fbg and HSA adsorption and conformation
No full textFour hyaluronan based hydrogels with different cross-linking agents were synthesised. Compounds with an increasing hydrophobic character and length as spacer arms were chosen, i.e. O,O'-bis (2 aminopropyl) polyethylen glicol, 1.3 diaminopropane, 1.6 diamino hexane and 1.12 diamine dodecane. The cross-linking reaction involved 50% of the carboxylate groups present in the hyaluronan macromolecule chain. Hydrogels were characterised by water-uptake measurements and SEM analysis. The adsorption of two plasma proteins (HSA and Fbg) was analysed onto the four hydrogels in flow conditions by ATR-FTIR, evaluating the adsorption kinetics and the eventual protein conformational changes. The increasing hydrophobic character of the surface imposes a clear trend to the protein adsorption kinetics. The influence of the spacer arms on the protein conformation is evident on HSA, whereas Fbg does not seem to be significantly influenced by the change of the substrate hydrophobic properties
Novel carboxymethylcellulose-based microporous hydrogels suitable for drug delivery
No full textSeveral materials capable of acting as structures for controlled release were analysed for the fabrication of matrices. Among those used, hydrophilic polysaccharides appeared to be the most suitable materials. Carboxymethylcellulose (a semi-synthetic polysaccharide) was chemically cross-linked with a 60% and 90% cross-linking degree in order to obtain hydrogels and utilised as matrix for the realisation of controlled drug release systems. The morphology of the gels was changed in order to obtain a microporous structure with different porosity (14, 30 and 40 μm). The obtained porous matrices were characterised in terms of pore density, dimension and swelling behaviour. The influence of both the pore dimension and technique of loading on the release kinetics was analysed. By increasing the pore dimension the release of ibuprofen-lysin was slower. Inducing the microporous structure after the loading of the hydrogel with the drug resulted in a slower release. © VSP 2004
Thixotropic gel properties in the osteoarthritis treatment and for cell scaffolding
No full textThe use of polysaccharide hydrogels with thixotropic properties in the osteoarthritis treatment and for cell scaffolding was investigated. The hydrogels which were synthesized by crosslinking the hyaluronane, alginate or carboxymethylcellulose chains with an alkylic diamine exhibited the thixotropic properties. The hydrogel were modified to obtain a microporous structure by stratifying the crosslinked polysaccharide gel on filter with pores of known diameter and forcing CO2 bubbles through the filter. The microporous hydrogels showed a lower water uptake and increased the mechanical properties. The results show that the alginate and carboxymethylcellulose gels are good scaffolds for the cells which adhere and spread into the hydrogels
States of water, surface and rheological characterisation of a new biohydrogel as articular cartilage substitute
No full textPVA based hydrogel was synthesised using, as crosslinking agent, trisodium trimetaphosphate (STMP) and its morphology was modified inducing a microporous structure to obtain potential substitutes for cartilage tissue. The hydrogel was characterised by Infrared Spectroscopy combined with Time of flight mass spectrometry (ToF-SIMS) that confirmed the successful occurrence of crosslinking reaction, the hyphotised crosslinking arm and its homogeneous distribution. The mechanical spectra of the fully hydrated samples confirmed covalently crosslinked systems with a rheological behaviour similar to that of tibial cartilage. Further analysis in terms of water content measurements, thermal stability and cytotoxicity confirmed the applicability of such a hydrogel as cartilage substitute
A new Phosphorylated Polysaccharide for Biomedical Applications: Generation of 3D Scaffolds with Osteogenic Activity and Coating of Titanium Oxide Surfaces
No full textA new phosphorylated derivative of carboxymethylcellulose and amidic carboxymethylcellulose containing one phosphate group for each disaccharide unit was synthesized using sodium trimetaphospahte (STMP) as the phosphating agent. The new polysaccharide was characterized by infrared spectroscopy (FT-IR) and the amount of phosphate groups was determined by elemental analysis. These modified polysaccharides were used both to prepare 3D scaffolds and functionalize titanium oxide surfaces with the aim to improve the osseointegration with the host tissue. The presence of phosphate groups modify the physical-chemical properties of the hydrogels with respect to the native ones. The evaluation of the bioactivity of the phosphorylated carboxymethylcellulose hydrogels towards osteoblast-like cells showed a significant increase in the osteocalcin production. The modified surfaces were chemically characterized by means of X-ray photoelectron spectroscopy (XPS) and FT-IR, whereas the surface topography was analysed by Atomic Force Measurements (AFM) measurements before and after the polysaccharide coating. In vitro biological tests using osteoblast-like cells demonstrated that phosphorylated carboxymethylcellulose functionalized TiO2 surfaces promoted better cell adhesion and significantly enhanced their proliferation. These findings suggest that the phosphate polysaccharide both as a 3D scaffold and as a surface coating promotes osteoblast growth potentially improving the biomaterial osseointegration rate
New hyaluroran derivative with prolonged half-life for ophthalmogical formulation
No full textTwo new hyaluronan derivatives containing phosphate or cystamine groups have been synthesised to obtain tear drops with improved rheological properties and prolonged half-life. Rheological analysis, in terms of apparent viscosity, pointed out that phosphorylated hyaluronan showed promising characteristics for the foreseen application. The presence of phosphate groups along the chains, confirmed by infrared analysis, induced a strengthening in hyaluronan hydrogen bond capability thus modifying its thermal behaviour and prolonging its resistance against hyaluronidase attack. Finally, in vitro cytoxicity tests excluded any adverse effect of the developed hyaluronan derivative. © 2012 Elsevier Ltd. All rights reserved
- …
