Correlations on the Structure and Properties of Collagen Hydrogels Produced by E-Beam Crosslinking (original) (raw)
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Journal of Functional Biomaterials
Herein, three different recipes of multi-component hydrogels were synthesized by e-beam irradiation. These hydrogels were obtained from aqueous polymer mixtures in which different proportions of bovine collagen gel, sodium carboxymethylcellulose (CMC), poly(vinylpyrrolidone), chitosan, and poly(ethylene oxide) were used. The cross-linking reaction was carried out exclusively by e-beam cross-linking at 25 kGy, a dose of irradiation sufficient both to complete the cross-linking reaction and effective for hydrogel sterilization. The hydrogels developed in this study were tested in terms of physical and chemical stability, mechanical, structural, morphological, and biological properties. They are transparent, maintain their structure, are non-adhesive when handling, and most importantly, especially from the application point of view, have an elastic structure. Likewise, these hydrogels possessed different swelling degrees and expressed rheological behavior characteristic of soft solids ...
Electron beam irradiation modification of collagen membrane
Biomaterials, 2006
A critical observation of reconstituted collagen membrane radiated by electron beam (EB) indicated that these collagenous fibers become cross-linked network when the irradiation is carried out in greater than melt temperature and nitrogen atmosphere. Studies on the membrane properties showed that glass transformation temperature (T g ) and melt point (T m ) of reconstituted collagen have no changes, but thermal gravity curves and infrared (IR) spectra become obviously different before and after irradiation. Crosslinking density calculated by the equation based on the theory of Flory-Rehner proved further that the densities increase with radiation doses increasing. Resistance to enzymatic digestions in vitro and implantation in vivo were determined to evaluate the physicochemical properties of cross-linked matrices. Based on the above results, it was concluded that EB radiation inducing crosslinking in greater than melt temperature and nitrogen atmosphere condition is an attractive, effective method, which introduce into intermolecular covalent cross-linkings. r
Non-destructive mechanical characterisation of UVA/riboflavin crosslinked collagen hydrogels
British Journal of Ophthalmology, 2008
Aims: To establish a non-destructive method of characterising the mechanical properties of collagen hydrogels to model corneal tissue and to examine the effect of photochemical crosslinking on their mechanical properties. Methods: Collagen hydrogels were manufactured, submerged in 0.1% riboflavin solution and crosslinked using two UVA tube bulbs with an intensity of between 2.8 and 3.2 mW/cm 2. The hydrogels were clamped around their outer edge and deformed using a sphere. The deformation was measured in situ using a long-working-distance microscope connected to a CCD camera, and the deformation displacement was used with a theoretical model to calculate the Young modulus of the hydrogels. Collagen hydrogels seeded with human corneal fibroblasts were used to examine cell viability after UVA irradiation. Results: There was an increase in Young modulus of the collagen hydrogels after UVA/riboflavin treatment that was dependent on the exposure time. UVA irradiation without riboflavin showed decreased mechanical integrity and strength. Cell viability was reduced with increased UVA exposure time. Conclusion: The non-destructive technique demonstrated a new methodology comparable with strip extensiometry for cornea or corneal model specimens but with more convenient features. This approach could be used as an initial step in developing new crosslinking treatments for patients with keratoconus.
Gels
In the present study, we report on the complex hydrogels formulations based on collagen-poly(vinyl pyrrolidone) (PVP)-poly(ethylene oxide) (PEO) cross-linked by e-beam irradiation in an aqueous polymeric solution, aiming to investigate the influence of different PEO concentrations on the hydrogel properties. The hydrogel networks’ structure and their composition were investigated using equilibrium swelling degree, complex rheological analysis, and FT-IR spectroscopy. Rheological analysis was performed to determine the elastic (G′) and viscous (G″) moduli, the average molecular weight between cross-linking points (Mc), cross-link density (Ve), and the mesh size (ξ). The effect of the PEO concentration on the properties of the hydrogel was investigated as well. Depending on the PEO concentration added in their composition, the hydrogels swelling degree depends on the absorbed dose, being lower at low PEO concentrations. All hydrogel formulations showed higher G′ values (9.8 kPa) compa...
Indonesian Journal of Chemistry, 2014
The aim of this research is to explore the possibility of methylcellulose polymer to be used as wound dressing material prepared using electron beam technique. The methylcellulose paste solution with various of molecular weight (SM-4, SM-100, SM-400, SM-4000 and SM-8000) at different concentration (15-30% w/v) were irradiated by using electron beam on the dose range of 10 kGy up to 40 kGy. Gel fraction and swelling ratio of hydrogels were determined gravimetrically. Tensile strength and elasticity of hydrogels were measured using a universal testing machine. It was found that with the increasing of irradiation dose from 10 up to 40 kGy, gel fraction and tensile strength were increased for all of hydrogels with various of molecular weight. On contrary, the swelling ratio of hydrogels decreased with increasing of irradiation dose. The optimum hydrogels elasticity were obtained from methylcellulose solution with the concentration range of 15-20% with irradiation dose of 20 kGy and showed excellent performance. The hydrogels based on methylcellulose prepared by electron beam irradiation can be considered for wound dressing material.
Network structure studies on γ–irradiated collagen–PVP superabsorbent hydrogels
Radiation Physics and Chemistry, 2017
Collagen-polyvinylpyrrolidone (PVP) superabsorbent hydrogels were synthesized by γirradiation in the absence of oxygen, using high molecular weight PVP and acidic collagen Type I. Sol-gel analysis and swelling experiments were performed in order to determine the gel fraction, network parameters, the yield of cross-linking, respectively scission, as well as to establish the diffusion characteristics of water. Rheological experiments and characterization of the chemical structure before and after irradiation were conducted in order to evaluate the gel character and its stability upon irradiation. The relationship between these parameters and radiation dose was also established. Gel fraction reached up to 90 %, and the p 0 /q 0 ratio (degradation vs. cross-linking ratio) shows a negligible degradation process. The collagen-PVP hydrogels present swelling in the range 1000-2000 %, the diffusion exponent (n) was found to be between 0.59-0.68. The network parameters as the molecular weights between two successive cross links (), the cross-linking density () and the mesh size () are ranged between 3.39 8.08 , 1.24 2.95 , respectively 75-134 nm.
Electron Beam Effects on Gelatin Polymer
2002
The main field of electron-beam radiation processing applications is the modification of polymeric material. Polymer development includes new pathways to produce natural polymers with better mechanical and barrier properties and thermal stability. The aim of this paper was to investigate the behavior of a gelatin/acrylamide polymer treated by electron-beam radiation. Gelatin is a heterogeneous mixture of water-soluble proteins of high average molecular mass derived by hydrolytic action from animal collagen, a fibrous insoluble protein, which is widely found in nature as the major constituent of skin, bones and connective tissue. Hydrolyzed collagen is composed of a unique sequence of amino acids, characterized particularly by the high content of glycine, proline and hydroxyproline. Among biomaterials, gelatin is an interesting material because is a partially crystalline polymer and has a relatively low melting point. Samples of gelatin together with glycerin as plasticizer and acrylamide as copolymer were irradiated with doses of 10 kGy and 40 kGy, using an electron beam accelerator, dose rate 22.41kGy/s, at room temperature in presence of air. After irradiation, some preliminary analyses were done like viscometry, texture analyses and colorimetry. The results of the diverse tests showed changes that can be ascribed to radiation-induced crosslinking. The electron-beam processed acrylamide-gelatin polymer using glycerin as plasticizer must be first extensively characterized before to be used for general applications.
Tissue Engineering, 2007
Hydrogels (hylans AU1 c ) containing divinyl sulfone (DVS)-crosslinked hyaluronan (HA) are potentially useful implant biomaterials because of their non-cytotoxicity and -antigenicity. However, to successfully fulfill their intended role in vivo, their properties (e.g., mechanics, pore size, surface topography, hydrophilicity, swelling) must be modulated to match the demands of the target application. This study explored whether controlled irradiation with gamma (c) can strengthen hylans and modulate their physical and biologic properties, as has previously been shown to be possible with other natural and synthetic polymers. Hydrated hylans containing two different amounts of DVS were irradiated in vacuum to increasing doses of c (0-13.5 kGy). The properties of the irradiated gels were compared with those of non-irradiated controls. Changes to bulk structure were evaluated using swelling tests, surface topography and pore structure were evaluated using scanning electron microscopy, mechanics were evaluated using unconfined compression tests, and surface hydrophilicity was evaluated by measuring contact angle changes AU2 c . Irradiated gels exhibited lower swelling capacity, structural weakening, increase in elasticity, surface texturing, increased pore size, and decreased surface hydrophilicity in direct correlation with received dose. Cells adhered and proliferated readily on the irradiated gel surfaces but not on control gels. The irradiated gels, however, deteriorated during long-term (<60 days) storage. Irradiation of hylans in a lyophilized state instead resulted in gels that were more compact, swelled less, and exhibited smaller pores than their hydrated counterparts. The results show that c-irradiation, although useful to modulate hylan gel properties, presents challenges of degradation that may be associated with its generation of free-radicals, HA chain fragmentation, and disruption of DVS crosslinks, particularly when the gels are irradiated in their native hydrated state (>98% water content). Future studies will optimize parameters for c-mediated modulation of hylan properties through irradiation under water-free conditions.
Macromolecular Research, 2018
Collagen (C)-poly(N-vinyl-2-pyrrolidone) (PVP) double-network superabsorbent hydrogels were synthesized by e-beam (electron beam) radiation processing, both with the addition of water-soluble cross-linking agents (CA), as well as without CA. The aim of the study was to develop a hydrogel for future application as wound dressings via e-beam radiation cross-linking of two biocompatible polymers. The formation of C-PVP hydrogels was confirmed by Fourier transform infrared (FTIR) spectroscopy and their performance was determined from morphological and rheological experiments, such as sol-gel analysis, swelling capacity, storage (G') and viscous (G'') moduli, cross-linking density, and pore size. Sol-gel analysis was performed in order to determine the gel properties as function of absorbed dose and it was found that the degradation density (p 0)/cross-linking density (q 0) ratio indicates a negligible contribution of chain scission processes. The rheological data confirmed that the elastic properties were predominant: G' moduli were larger than G'' moduli, as is specific to elastic solids and indicate the formation of a permanent hydrogel network were cross-links are present. Moreover, the swelling studies indicated that the hydrogels have good stability both in deionized water and phosphate-buffered saline (PBS) solution at 37 o C, and superabsorbent properties. The hydrogels network parameters obtained with lower content of CA, could be controlled by changing the absorbed dose.
Materials Proceedings
Semi-synthetic hydrogels made of carboxymethyl hyaluronic acid (CMHA) and polyacrylic acid (PAA) were synthesized using electron beam irradiation. CMHA, with a degree of substitution of 0.87 and a molecular weight of 149 kDa, was mixed with linear PAA and slightly crosslinked PAA (Carbopol). The equal weight ratio of the CMHA-Carbopol blends (10% CMHA, 10% Carbopol) was successfully crosslinked, even at a low irradiation dose of 20 kGy, producing a hydrogel with 60% gel fraction and 430 g/g degrees of swelling. The gel properties of this formulation showed good stability when exposed in PBS (pH 7.4) at 37 °C. Furthermore, the FT-IR spectra of the 10% CMHA, 10% Carbopol blends showed an increase in peak intensity at 1405 cm−1 due to the neutralization reaction between the COOH and COO- groups of PAA and CMHA polymers. The interaction effects between the concentration of CMHA and PAA and varying irradiation doses in the gel properties in CMHA-PAA hydrogels will be explored in a future...