Showing papers on "Glutaraldehyde published in 1997"
TL;DR: In vivo toxicity tests indicated that chitosan is nontoxic, and the sterilized films were free of pyrogen, and autoclaving appeared to be an ideal sterilizing method as it caused least decrease in tensile strength and effected a negligible rate of hemolysis.
Abstract: Chitosan, a mucopolysaccharide of marine origin, was studied for its safety and hemostatic potential. Its surface was treated with glutaraldehyde, carbodiimide, and plasma glow discharge to elicit effects of enzyme degradation. Of the seven enzymes used, leucine amino peptidase caused maximum degradation. Autoclaving appeared to be an ideal sterilizing method as it caused least decrease in tensile strength and effected a negligible rate of hemolysis. Sterilizing with glutaraldehyde with a physiologic pH retained the maximum tensile strength of chitosan. In vivo toxicity tests indicated that it is nontoxic, and the sterilized films were free of pyrogen. Coagulation and hemagglutination tests showed that the hemostatic mechanism of chitosan seems to be independent of the classical coagulation cascade and appears to be an interaction between the cell membrane of erythrocytes and chitosan.
757 citations
TL;DR: Cytotoxicity towards B16F10 cells and ability to lyse rat erythrocytes was concentration-dependent and varied according to the salt used and polymer molecular weight, and polymers of higher molecular weight of each type were most toxic.
319 citations
TL;DR: Upon the study of crosslinking rate, DXR-loaded nanoparticles showed a greater number of free amino groups than the unloaded ones, which should be due to a competition between the amino group of DXR and the amino groups of the gelatin chains during the cross-linking process.
178 citations
TL;DR: Heterogeneous cross-linking was modeled as a shrinking core process where the molecular diffusion of glutaraldehyde through the cross-linked shell of the gel bead limited the overall rate of glutARaldehyde consumption.
Abstract: Chitosan, a linear biopolymer of glucosamine residues, selectively adsorbs transition-metal ions such as cadmium from dilute solution. In order to process chitosan into a more durable form, a 5 wt % chitosan solution was cast into spherical gel beads of 3 mm diameter and then reacted with glutaraldehyde at free amine sites to form imine cross-links between linear chitosan chains. The rate processes of the heterogeneous cross-linking reaction and the effect of cross-linking on the cadmium ion adsorption capacity were determined. The cross-linking reaction was complete within 48 h at 27 °C, and the final extent of cross-linking ranged from 0.07 to 2.40 mol of glutaraldehyde consumed/mol of amine. Heterogeneous cross-linking was modeled as a shrinking core process where the molecular diffusion of glutaraldehyde through the cross-linked shell of the gel bead limited the overall rate of glutaraldehyde consumption. The effective diffusion coefficient of glutaraldehyde through the cross-linked layer was 4.7 × 10...
156 citations
TL;DR: In this article, the authors used uncrosslinked hyaluronic acid (HA) films in acetone-water mixtures to produce water-insoluble films with water contents as low as 60 wt % when subjected to swelling with phosphate-buffered saline of pH 7.4 at 37°C.
Abstract: Hyaluronic acid (HA) was chemically crosslinked with glutaraldehyde (GA) to produce water-insoluble films having low water contents when brought into contact with water. The crosslinking reaction was performed using uncrosslinked HA films in acetone–water mixtures. This method could produce water-insoluble HA films with water contents as low as 60 wt % when subjected to swelling with phosphate-buffered saline of pH 7.4 at 37°C. This 60 wt % water content was lower than any values for HA ever reported. There was an optimal HCl concentration around 0.01N for the HA crosslinking with GA in acetone—water mixtures. To get information on the crosslinking mechanism, alginic acid, which possesses hydroxyl and carboxyl groups in one molecule, similar to HA, and poly(vinyl alcohol) (PVA) and amylopectin, which possess only hydroxyl groups, were subjected to crosslinking with GA. PVA and amylopectin were also found to become water-insoluble after reaction with GA. On the basis of the infrared spectra of these crosslinked films, it was concluded that intermolecular formation of hemiacetal bonds with GA between the hydroxyl groups belonging to different HA molecules led to crosslinking. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3553–3559, 1997
141 citations
TL;DR: Porcine pancreas lipase (triacylglycerol ester hydrolase, EC 3.1.3) was immobilized with the highest activity on polyacrylamide beads possessing carboxylic functional groups activated by a water-soluble carbodiimide to stabilized the enzyme against heat and urea treatment.
94 citations
TL;DR: In this article, a modified polymethylmethacrylate (PMMA) microspheres with 1.5 μm diameter were produced by dispersion polymerization by using polyvinyl alcohol as a stabilizer.
94 citations
TL;DR: Results indicate that chitosan is a promising biopolymer as a scaffold of hepatocyte attachment, which can be applied to an effective bioartificial liver support system.
Abstract: The effectiveness of chitosan, a biocompatible polymer derived by the deacetylation of chitin, as a scaffold of hepatocyte attachment, was examined. Since chitosan gel was too fragile to use for cell culture, its free amino groups were crosslinked by glutaraldehyde to increase its strength. Rat hepatocytes seeded onto glutaraldehyde-crosslinked chitosan (GA-chitosan) gel could stably attach to the surface, retaining its spherical form, the same as in vivo, and then release a very small amount of lactate dehydrogenase during the 5 d culture period. By contrast, hepatocytes on a collagen-coated surface spread flat, and they released much more lactate dehydrogenase than those on the GA-chitosan gel. Hepatocytes on GA-chitosan also retained higher urea synthesis activity, a liver-specific function, than those on the collagen-coated surface. These results indicate that chitosan is a promising biopolymer as a scaffold of hepatocyte attachment, which can be applied to an effective bioartificial liver support system.
72 citations
TL;DR: Results suggest that glutaraldehyde crosslinking of collagen implants decreases the rate of biodegradation, and delayed degradation of crosslinked collagen may result clinically in reduced engraftment of skin substitutes.
Abstract: Collagen-based implants have been described as vehicles for transplantation of cultured skin cells for treatment of burn wounds. To optimize vascularization and repair of connective tissue, collagen solubility and glutaraldehyde crosslinking were evaluated. Cultured skin substitutes consisted of human keratinocytes and fibroblasts attached to collagen-glycosaminoglycan substrates that were prepared from acid-insoluble, or partially soluble collagen. Substrates were crosslinked with 0% or 0.25% glutaraldehyde, populated with cells, and grafted to full-thickness wounds on athymic mice (n = 6/condition). After 6 weeks, the wound area was measured by planimetry, and healed wounds were scored by histochemistry for immunoreactivity to HLA-ABC and bovine collagen. Data analysis shows that crosslinking of collagen implants with glutaraldehyde is associated (p < 0.001) with detection of the implant. No association was found between solubility of bovine collagen and immunodetection. Epidermis of all wounds was positive for HLA-ABC, and no differences in wound areas were found. These results suggest that glutaraldehyde crosslinking of collagen implants decreases the rate of biodegradation. Delayed degradation of crosslinked collagen may result clinically in reduced engraftment of skin substitutes.
72 citations
TL;DR: The elastic modulus increased with the reaction time, but reduction of elongation at breaking point and increased stiffness were observed, and this tendency was enhanced by ultraviolet irradiation.
Abstract: We examined the relationship between collagen crosslinking techniques and dentinum reinforcement. In the present study, the tensile tests, imbibition test and antienzyme test were performed on collagen films mainly composed of type I collagen after ultraviolet irradiation and immersion in tannic acid and glutaraldehyde. The elastic modulus increased with the reaction time, but reduction of elongation at breaking point and increased stiffness were observed. This tendency was enhanced by ultraviolet irradiation. Tannic acid treatment resulted in slower crosslinking than the other two techniques. Antienzyme activity was markedly increased by treatment with tannic acid and glutaraldehyde.
65 citations
TL;DR: In this study, an optimal fixation protocol was developed and selected upon comparing seven different fixation procedures, using glutaraldehyde (GA) and the postfixatives ruthenium red, osmium tetroxide (OsO4) and rUThenium tetoxide (RuO 4) in combination with potassium ferrocyanide (K4Fe(CN)6) and potassium ferricyanide ( K3Fe( CN)6).
Abstract: The intercellular lipid bilayers of the stratum corneum provide the permeability barrier of the skin. To perform an electron microscopical examination of the ultrastructure of these bilayers, ruthenium tetroxide fixation is required. In this study an optimal fixation protocol was developed and selected upon comparing seven different fixation procedures, using glutaraldehyde (GA) and the postfixatives ruthenium red, osmium tetroxide (OsO4) and ruthenium tetroxide (RuO4) in combination with potassium ferrocyanide (K4Fe(CN)6) and potassium ferricyanide (K3Fe(CN)6). Instead of fixing skin with either OsO4 or RuO4, these two fixatives were combined in one protocol. In addition, the use of RuRed was introduced and the influence of both K4Fe(CN)6 and K3Fe(CN)6 in combination with RuO4 were examined. Furthermore, we compared two dehydration solvents, methanol and acetone. The most satisfying results were obtained when the skin was prefixed in GA and postfixed in OsO4 and RuO4 with K3Fe(CN)6, i.e. with Fe in its highest oxidation state (Fe3+). No differences were observed between dehydration in methanol and acetone.
TL;DR: The overall cell shrinkage and relative accentuation of the cell-cell borders was confirmed by SEM, which revealed that the 11 to 20% area shrinkage was also related to the number of cell sides.
Abstract: The purpose of this study was to quantitatively compare cell dimensions and cell layer organization of the corneal endothelium after chemical fixation. Rabbit corneas (9–10 weeks of age) were prepared immediately postmortem for transmission electron microscopy (TEM) and scanning electron microscopy (SEM) using either a widely used high osmolality fixative (glutaraldehyde-formaldehyde, after Karnovsky; 1% formaldehyde, 2.5% glutaraldehyde, 0.1 M cacodylate, pH 7.6, 850 mOsm/kg) or a glutaraldehyde fixative (2% glutaraldehyde in 80 mM cacodylate, pH 7.4, 330 mOsm/kg). With the glutaraldehyde-formaldehyde fixative, TEM revealed gross shrinkage (up to 40%) and distortion of the cytoplasm and organelles, while the regions of the cell-cell junctions were not attenuated but included dilated extracellular space. With the glutaraldehyde fixative, TEM also revealed shrinkage but the cytoplasm was less compact than with the high osmolality fixative. The overall cell shrinkage and relative accentuation of the cell-cell borders was confirmed by SEM, which also revealed that the 11 to 20% area shrinkage was also related to the number of cell sides.
TL;DR: In this paper, a comparison of the productive capacities of the various polyvinyl alcohol (PVA) crosslinked membrane has been conducted for the purpose of the separation of acetone/water and isopropanol (IPA)/water systems.
Abstract: Pervaporative separation of acetone/water and isopropanol (IPA)/water systems has been studied in the water-lean range of composition of the feed mixtures. Poly(vinyl alcohol) (PVA) membranes crosslinked with citric acid, adipic acid, maleic acid, glutaraldehyde, and glyoxal were used for this purpose. The sorption characteristics of all the membranes indicate that these membranes have a good sorption selectivity for water in view of the hydrophilic nature of PVA. The type of crosslinker used for crosslinking has been shown to have an important bearing on the permeation characteristics of the membranes. Thus, the trifunctional citric acid yields the highest selectivity but lowest flux. A comparison of the productive capacities of the various membranes indicates that the glutaraldehyde crosslinked membrane has the maximum productive capacity for IPA dehydration whereas maleic acid crosslinked membrane yields the highest productive capacity for acetone dehydration.
TL;DR: There was a suppression in enzymatic activity when the microspheres were placed in reaction media with an increasing concentration of organic solvent such as ethanol, acetonitrile or isopropanol, but when returned to a totally aqueous environment, the enzyme resumed its initial tryptic capability.
Abstract: Trypsin microencapsulated in a calcium alginate matrix was lost quickly through diffusion when the microspheres were placed in an aqueous medium. This problem was overcome by first reacting trypsin with glutaraldehyde to form cross-linkages and then incorporating the enzyme in the alginate micro-spheres. The performance of the cross-linked trypsin remained optimal at pH 8 while it was found to be more heat-stable and remained highly active even at 80°C. Esters and amides of L-arginine were preferentially hydrolysed by the enzyme indicating that cross-linking did not adversely affect the conformation of the active site. There was a suppression in enzymatic activity when the microspheres were placed in reaction media with an increasing concentration of organic solvent such as ethanol, acetonitrile or isopropanol. However, when returned to a totally aqueous environment, the enzyme resumed its initial tryptic capability. Such a microencapsulated form of cross-linked enzyme may find application in enzy...
TL;DR: The goal of the new method is to make possible the use of a great number of available glutaraldehyde-raised antisera for immunofluorescence techniques, a useful tool in both basic and clinical research.
TL;DR: In this article, the propylethylenediamine moiety was anchored on silica in acid medium by using sol−gel methodology, and a sequence of reactions was carried out with glutaraldehyde followed by EDE in order to increase the organic chain pendant groups covalently bonded to the inorganic support.
Abstract: The propylethylenediamine moiety was anchored on silica in acid medium by using sol−gel methodology. A sequence of reactions was carried out with glutaraldehyde followed by ethylenediamine in order to increase the organic chain pendant groups covalently bonded to the inorganic support. All synthesized silicas were characterized by carbon and nitrogen elemental analyses, thermogravimetry, differential scanning calorimetry, solid state 13C and 29Si NMR, and calorimetry. These analyses and techniques quantitatively confirmed all reaction steps. The results found strongly indicated that some silanol groups are converted to siloxane, which presented a great stability toward ring opening in aqueous medium.
TL;DR: A sensitive and reproductible HPLC method to determine the reactive lysine content of films made from cottonseed flour was developed in this article, which is applied to follow the cross-linking of cottonseed proteins by formaldehyde, glutaraldehyde, or glyoxal.
Abstract: A sensitive and reproductible HPLC method to determine the reactive lysine content of films made from cottonseed flour was developed. This method is applied to follow the cross-linking of cottonseed proteins by formaldehyde, glutaraldehyde, or glyoxal. The cross-linking of these proteins resulted in the decrease of reactive lysine content within the film. The maximum puncture force of the films is correlated with the modified reactive lysine content after cross-linking treatments. Of the three cross-linking agents, formaldehyde was the most effective to enhance the maximum puncture force of the films despite its moderate reaction with only 50% of reactive lysine in the films. By contrast, glutaraldehyde, which reacted with nearly 100% of lysine, led to less resistant films. The results were interpreted as the impact of the molecular structure of the cross-link bridges on the mobility between protein chains. Keywords: Cross-linking; HPLC; cottonseed proteins; films; reactive lysine
TL;DR: A reduced calcification of BT-PEO-SO3 can be explained by decreases of residual glutaraldehyde groups, a space filling effect and, therefore, improved biostability and synergistic blood-compatible effects of PEO and SO3 groups after the covalent binding of PEL3 to tissue.
Patent•
30 Oct 1997
TL;DR: In this paper, a method of using sodium or potassium borohydride to reduce dehydrated, aldehyde treated biological tissues is disclosed, which comprises the steps of: providing the tissue, such as porcine heart valves or bovine pericardium; treating the tissue with an aldehydes,such as glutaraldehyde; dehydrating the tissue by treatment with an anhydrous polar organic solvent such as ethanol.
Abstract: A method of using sodium or potassium borohydride to reduce dehydrated, aldehyde treated biological tissues is disclosed. The method comprises the steps of: providing the tissue, such as porcine heart valves or bovine pericardium; treating the tissue with an aldehyde, such as glutaraldehyde; dehydrating the tissue, for example by treatment with an anhydrous polar organic solvent such as ethanol; and, treating the tissue with sodium or potassium borohydride. Following reduction, the sodium borohydride may be extracted from the tissue with an organic solvent, such as ethanol. The tissue may be rehydrated for use in bioprosthetic implants such as heart valves and pericardial patches.
TL;DR: There was limited recovery and repeated drops in capacity with adsorption of human serum albumin (HSA), and the total amount of irreversible HSA binding decreased with greater crosslinking and there were large differences in HSA adsorptive characteristics between differing dye types.
TL;DR: The use of fish protein (FP) in the manufacture of a superabsorbent hydrogel was investigated in this paper, where proteins were crosslinked by sulfhydryl-disulfide interchange reaction between the endogenous sulf hydryl groups and disulfide bonds to produce an insoluble gel structure.
Abstract: The novel use of fish protein (FP) in the manufacture of a superabsorbent hydrogel was investigated. Following the introduction of a large number of hydrophilic groups into fish protein by modification with ethylenediaminetetraacetic dianhydride (EDTAD), proteins were cross-linked by sulfhydryl-disulfide interchange reaction between the endogenous sulfhydryl groups and disulfide bonds to produce an insoluble gel structure. The water uptake of 76% EDTAD-modified FP hydrogel was 540 g water/g dry gel at 214 × g, and it depended on pH and ionic strength of the solution. The structural changes in proteins consequent to modification were also investigated. EDTAD-FP hydrogels had increased rigidity after glutaraldehyde treatment but displayed diminished water uptake characteristics.
TL;DR: The cell wall structure of the Gram-positive Corynebacterium glutamicum was evaluated by electron microscopy of thin sections after freeze-substitution and conventional fixation with glutaraldehyde, detecting knob-like surface structures previously observed in freeze-fracture experiments.
Abstract: The cell wall structure of the Gram-positive Corynebacterium glutamicum was evaluated by electron microscopy of thin sections after freeze-substitution and conventional fixation with glutaraldehyde. For the cell wall an overall thickness of approximately 32 nm was determined, with 8.5 nm corresponding to an outer layer, 6.5 nm to an electron translucent region (ETR) as found in mycobacteria and 17 nm to the peptidoglycan. Knob-like surface structures previously observed in freeze-fracture experiments were detected when cells were conventionally processed with a fixation using glutaraldehyde. By mild treatment with detergents approximately 20 proteins were extracted from the cell wall. From seven of these N-terminal amino acid sequences were determined.
TL;DR: Sodium hypochlorite was the agent most sensitive to protein, with its sporicidal activity nearly disappearing in the presence of 2% serum or an equivalent amount of purified protein, and cupric ascorbate and peracetic acid were inhibited by serum, but this effect was linked to a rise in pH.
Abstract: This study compares the effects of various concentrations of salt or serum in the killing of Bacillus subtilis spores by either glutaraldehyde, sodium hypochlorite, cupric ascorbate, hydrogen peroxide, peracetic acid, formaldehyde, or phenol. Salt affected only glutaraldehyde, its sporicidal activity increasing with an increase in concentration of sodium bicarbonate or sodium chloride. The sporicidal activity of glutaraldehyde was minimal when the concentrations of aldehyde groups and lysine residues from protein were similar. We present an equation describing the effect of serum on spore survival as a function of glutaraldehyde concentration that fits the data with a regression coefficient of 0.9. Cupric ascorbate and peracetic acid were inhibited by serum, but this effect was linked to a rise in pH. Sodium hypochlorite was the agent most sensitive to protein, with its sporicidal activity nearly disappearing in the presence of 2% serum or an equivalent amount of purified protein.
TL;DR: In this article, the reaction rate of formation of covalent bonds between PVA and glutaraldehyde in acidic saline water solutions was found to be of first order with respect to both the H 1 concentration and the formal dialdehyde concentration.
TL;DR: Although the catalytic activity of the cross-linked cellulases was 85% smaller than that of the free counterparts, they resisted thermal inactivation to a greater extent and their thermal stability was enhanced by their complexation to the colloids.
TL;DR: It is hypothesize that CNBr differentially degraded the elastin-associated microfibrillar proteins in aortic elastic tissue, thus producing the observed differences in mechanical behavior, and the increases in both stiffness and time-dependent behavior observed after treatment may be explained.
Abstract: The extent to which elastic tissue can be crosslinked in aldehydes and the mechanism of such action is unresolved in the literature. We have used glutaraldehyde/solvent solutions of decreasing dielectric constant (phosphate buffer, methanol, 95% ethanol, n-propanol, n-butanol) to alter the mechanical properties of aortic elastic tissue obtained from autoclaved and CNBr-purified bovine aortae. Treated and untreated hoop samples were examined for stress-strain and stress relaxation behavior and for residual stress using opening angle experiments as per Fung. The extent of exogenous crosslinking was analyzed through amino acid analysis. Mechanical properties of autoclaved elastic tissue varied with dielectric constant in glutaraldehyde/solvent treatments; however, solvent treatment alone produced no effect. Extensibility decreased with decreasing dielectric constant while tensile modulus changed over a range from -2.4% (-0.86 kPa) for glutaraldehyde/buffer to +35.3% (+14.3 kPa) for glutaraldehyde/n-propanol (untreated-treated). Residual stress experiments similarly showed a systematic decrease in opening angle with decreasing dielectric constant. Differences ranged from 10.5 degrees for glutaraldehyde/buffer to 22.2 degrees for glutaraldehyde/n-butanol. Interestingly, purification of aortae with CNBr reduced the effects of glutaraldehyde/n-butanol treatment. We hypothesize that CNBr differentially degraded the elastin-associated microfibrillar proteins in aortic elastic tissue, thus producing the observed differences in mechanical behavior. The observed phenomena in this study may be attributed to the composite structure of elastic tissue: elastin and microfibrillar protein. During treatment, conformational changes in elastin facilitated by polar/nonpolar interactions occurred which then were "locked" in by glutaraldehyde crosslinking of the microfibrillar proteins. By this mechanism the increases in both stiffness and time-dependent behavior observed after treatment may be explained.
TL;DR: Sterilization of the epoxy-fixed tissue with EtOH may increase its denaturation temperature and tensile strength, while neither masking nor crosslinking of free amino groups within the tissue took place, and the resistance to degradation of the EtOH sterilized tissue did not improve as compared to its nonsterilized counterpart.
Abstract: Due to the nature of bioprostheses, which are mainly biological tissues that cannot be sterilized with heat or irradiation, the sterilization method by choice is generally liquid chemicals. It is known that a number of liquid chemicals can have rapid germicidal effect and can be used to sterilize bioprostheses. The study was to evaluate the effects of various chemical sterilization methods on the crosslinking and enzymatic degradation characteristics of an epoxy-fixed biological tissue. The chemical sterilants employed were: a 70% ethanol solution (EtOH), a 2% epoxy compound + 20% ethanol solution (EX-810), a 2% propylene oxide + 20% ethanol solution (PO), and a 0.625% glutaraldehyde + 20% ethanol + 0.2% polysorbate solution (GA). Both masking and crosslinking of the free amino groups within the epoxy-fixed tissue were observed subsequent to sterilization with GA or EX-810. This improved the resistance of the GA or EX-810 sterilized tissues against collagenase degradation as compared to its nonsterilized counterpart. However, subsequent to sterilization with PO, only masking of the free amino groups within the epoxy-fixed tissue was noted. The inhibition of the collagenase degradation by masking of the free amino groups was traded off by the more random molecular packing of the PO sterilized sample due to the introduction of the side branches. Sterilization of the epoxy-fixed tissue with EtOH may increase its denaturation temperature and tensile strength, while neither masking nor crosslinking of free amino groups within the tissue took place. The resistance to degradation of the EtOH sterilized tissue, however, did not improve as compared to its nonsterilized counterpart.
Patent•
19 Jun 1997TL;DR: In this paper, the authors used a carboxyl activating agent to convert the free COOH (COOH) groups of the collagen molecules to activated carboxy-carboxyl moieties (e.g., o-acylisourea).
Abstract: Methods for treating glutaraldehyde-fixed collagenous tissues to mitigate their propensity for subsequent calcification and to improve durability. Collagenous tissues which have been harvested and cross-linked by glutaraldehyde are exposed to a carboxyl activating agent to convert the free carboxyl (COOH) groups of the collagen molecules to activated carboxyl moieties (e.g., o-acylisourea). Thereafter, the collagenous tissue is exposed to a compound capable of reacting with the activated carboxyl moieties (e.g., o-acylisourea) to form non-carboxyl side groups. Monofunctional and multi-functional amines are examples of compounds which may be utilized to react with the activated carboxyl moieties to form such non-carboxyl side groups. Thereafter, the collagenous tissue is again exposed to glutaraldehyde. If the non-carboxyl side groups have functional amino groups (NH2), such additional exposure to glutaraldehyde will result in additional glutaraldehyde cross-linking of the collagen molecules and resultant improvement of durability.
TL;DR: Drug release from gelatin/poly(acrylic acid) oxprenolol-loaded microspheres has been evaluated using an in situ sink immersion method and a wetting method and the influence of glutaraldehyde cross-linking agent concentration, the poly(ac acrylic acid) content, the pH of the release medium and the particle size of the beads on the drug release kinetics were evaluated and discussed.
Abstract: Drug release from gelatin/poly(acrylic acid) oxprenolol-loaded microspheres has been evaluated using an in situ sink immersion method and a wetting method The kinetics of drug release were analysed by applying the empirical exponential equation and by the calculation of the approximate contribution of the diffusional and relaxational mechanisms to the anomalous release process by fitting the data to the coupled Fickian/Case II equation The influence of glutaraldehyde cross-linking agent concentration, the poly(acrylic acid) content, the pH of the release medium and the particle size of the beads on the drug release kinetics were evaluated and discussed
TL;DR: With nearly all dentin-bonding agents, the marginal contraction gap could be significantly reduced if Gluma was used after conditioning of the dentin, but this improvement may be that glutaraldehyde cross-links the collagen fibers and thereby strengthens the organic part of the hybrid layer.
Abstract: Dentin cavities, prepared in extracted human teeth, were treated with various proprietary dentin-bonding agents and then filled with a light-cured restorative resin for posterior use. All bonding agents were either treated in accordance with the manufacturers' instructions or combined with Gluma, which is an aqueous solution of glutaraldehyde and HEMA, a hydrophilic monomer. 10 min after polymerization, the width and the extent of the marginal contraction gap was measured approximately 0.1 mm below the free surface of the filling, using a light microscope. With nearly all dentin-bonding agents, the marginal contraction gap could be significantly reduced if Gluma was used after conditioning of the dentin. The reason for this improvement may be that glutaraldehyde cross-links the collagen fibers and thereby strengthens the organic part of the hybrid layer, however, other mechanisms might also play a role in the improvement found.