Showing papers on "Glutaraldehyde published in 1993"

Synthesis of porous-magnetic chitosan beads for removal of cadmium ions from wastewater

Abstract: Chitosan is a glucosamine biopolymer capable of adsorbing transition-metal ions from aqueous solution. Highly porous chitosan beads were prepared by dropwise addition of an acidic chitosan solution into a sodium hydroxide solution precipitation bath. The gelled chitosan beads were cross-linked with glutaraldehyde and then freeze dried. Beads of 1- and 3-mm diameter were prepared. Beads of 1-mm diameter possessed surface areas exceeding 150 m 2 /g and mean pore sizes of 560 A and were insoluble in acid media at pH 2. Well-mixed batch adsorption experiments revealed that both metal and hydronium ions compete for available adsorption sites by a chelation mechanism

Preparation of sub-100 nm human serum albumin nanospheres using a pH-coacervation method.

Abstract: Human serum albumin (HSA) nanospheres of about 100 nm diameter were prepared using a pH-coacervation method whereby acetone was added to an HSA solution (pH 9.0). The particles obtained were cross-linked by glutaraldehyde. Increasing the pH of the HSA solution resulted in a gradual rise in the particle size of the resultant nanospheres. A higher cross-linking efficiency was obtained with increased glutaraldehyde concentration and cross-linking time. No significant differences in surface properties, as determined by zeta potential measurements, were recorded between particles prepared from HSA solutions with different pH. The nanospheres were quite stable over 4 days in both phosphate buffer saline (PBS) solution (pH 7.4) and rat serum, but degraded rapidly over 6 hours when incubated in PBS solution containing trypsin.

Membrane formation by interfacial cross-linking of chitosan for microencapsulation of Lactococcus lactis.

Abstract: Lactic acid bacteria were microencapsulated within cross-linked chitosan membranes formed by emulsification/interfacial polymerization. The technique was modified and optimized to provide biocompatible conditions during encapsulation involving the use of mineral oils as the continuous phase and chitosan as the membrane material. Chitosan cross-linked with hexamethylene diisocyanate or glutaraldehyde resulted in strong membranes, with a narrow size distribution about a mean diameter of 150 mum. Cell viability and activity was demonstrated by the acidification of milk. Loss of acidification activity during microencapsulation was recovered in subsequent fermentations to levels similar to that of free cell fermentations.

Biocompatibility of solid surfaces

Abstract: An improved spacer material for improving the biocompatibility of a biomaterial and a method for making it in which a polyalkylimine is covalently attached to an aminated substrate and combined with a crosslinking agent which is at least difunctional in aldehyde groups. The polyalkylizine can be, for example, polyethyleneimine and the crosslinking agent can be, for example, glutaraldehyde. Preferably, the crosslinking agent is applied in dilute solution and at a pH suitable to accomplish light crosslinking of the polyalkylimine and also provide aldehyde linkages at the interface between the biomolecule and the spacer.

Surface modification of the biomedical polymer poly(ethylene terephthalate)

Abstract: X-ray photoelectron spectroscopy was used to characterize modified surfaces of a biomedically important polymer, poly(ethylene terephthalate). Several modification schemes were investigated and direct silanization with 3-aminopropyltriethoxysilane was found to be the optimum procedure, resulting in an aminated surface. Surface coverage of up to 100% was achieved with retention of the polymeric structural integrity. Further activation of the silanized surface was accomplished with two cross-linkers, glutaraldehyde and sebacoyl chloride. A simple biomolecule, L-cysteine, was successfully immobilized onto a surface pre-treated with 3-aminopropyltriethoxysilane and glutaraldehyde, with a coverage of 42%.

Release behaviour of 5-fluorouracil from chitosan-gel microspheres immobilizing 5-fluorouracil derivative coated with polysaccharides and their cell specific recognition.

Abstract: In order to provide a device releasing drugs in a controlled manner and having targetability to specific organs or cells, chitosan-gel microspheres, CMS, crosslinked with glutaraldehyde, immobolizing 1-[N-(5-aminopentyl) carbamoyl]-5-fluorouracil, 1, coated with anionic polysaccharides, such as 6-O-carboxymethyl-N-acetyl-α-l,4-polygalactosamine (CM-NAPGA), 6-O-carboxymethyl-chitin, alginic acid and heparin, by polyelectrolyte complex membrane formation were prepared. When chitosan was crosslinked with glutaraldehyde, 1 was simultaneously immobilized into CMS by Schiff's base formation. Average diameter of CMS obtained was estimated to be about 0·5-1·0 μm by SEM observation. In physiological saline media, only free 5-FU was released from the CMS but 1 and any 5-FU derivative was not. Release rate of 5-FU from the CMS was reduced by coating with polyelectrolyte complex membrane of cationic chitosan and anionic polysaccharides. CMS coated with CM-NAPGA showed a lectin-mediated specific aggregation ph...

Inactivation of clostridium difficile spores by disinfectants

Abstract: OBJECTIVE The current study was designed to evaluate the activity of glutaraldehyde-based disinfectants against Clostridium difficile using the Association of Official Analytical Chemists' (AOAC) sporicidal test. This study was undertaken because gastrointestinal endoscopes that may be contaminated with C difficile spores are most commonly disinfected between patients using glutaraldehyde-based disinfectants. DESIGN Using the AOAC test, the following disinfectants were tested: 2% alkaline glutaraldehyde, 2% acid glutaraldehyde, a 1:16 dilution of a 2% glutaraldehyde-7.05% phenol-1.20% sodium phenate, and a 1:20 dilution of a 10% glutaraldehyde-0.5% phenylphenol-0.1% amylphenol. RESULTS Test results of the four disinfectants against C difficile spores at exposure times of 10, 20, and 60 minutes were as follows (number of positive penicylinders per 30 replicates): 0, 0, and 0 for 2% alkaline glutaraldehyde; 6, 3, and 0 for 2% acid glutaraldehyde; 30, 29, and 30 for a 1:16 dilution of glutaraldehyde-7.05% phenol-1.20% sodium phenate; and 30, 30, and 30 for a 1:20 dilution of glutaraldehyde-0.5% phenylphenol-0.1% amylphenol. CONCLUSIONS C difficile spores are more susceptible to inactivation by glutaraldehyde-based disinfectants than the spore-forming organisms recommended in the AOAC sporicidal test (i.e., Bacillus subtilis and Clostridium sporogenes). Diluting glutaraldehyde-based disinfectants below 2% led to the inability to inactivate spores of C difficile using exposure times commonly employed to disinfect semicritical items such as gastrointestinal endoscopes.

Pharmaceutically acceptable fixed-dried human blood platelets.

Abstract: Fixed-dried human blood platelets and processes for preparing the same are disclosed. The platelets, upon reconstitution: adhere to thrombogenic surfaces; do not adhere to non-thrombogenic surfaces; undergo shape change (spreading) upon adhering to a thrombogenic surface; adhere to one another to form a hemostatic plug upon adhering to a thrombogenic surface; and release their granular contents. Pharmaceutical formulations containing the same are also disclosed. The platelets are preferably fixed by means of a fixative such as formaldehyde, paraformaldehyde, or glutaraldehyde, or fixed by means of a permanganate fixate. The platelets are preferably dried by lyophilization.

A critical review of the toxicology of glutaraldehyde

Abstract: Glutaraldehyde, a low molecular weight aldehyde, has been investigated for toxicity in humans and animals. Examination of this dialdehyde was indicated from previous studies with other aldehydes in which carcinogenicity of formaldehyde and toxicity of acetaldehyde and malonaldehyde have been disclosed. Information gaps concerning the actions of glutaraldehyde have been identified in this review and recommendations are suggested for additional short- and long-term studies. In particular, information regarding irritation of the respiratory tract, potential neurotoxicity, and developmental effects would assist in a complete hazard evaluation of glutaraldehyde. Further study related to disposition, metabolism, and reactions of glutaraldehyde may elucidate the mechanism of action.

Comparison of the cross-linking characteristics of porcine heart valves fixed with glutaraldehyde or epoxy compounds

Abstract: The concerns about currently available bioprosthetic heart valves are calcification, long-term durability, and functional and hemodynamic performance. These concerns are all more or less related to the cross-linking reagents, glutaraldehyde or formaldehyde, used in fixing bioprostheses. To address these concerns, the authors undertook the development of a porcine heart valve cross-linked with an epoxy compound. This study compared the cross-linking characteristics, shrink temperature, and moisture content of porcine heart valves fixed with epoxy compounds or glutaraldehyde. Two types of epoxy compounds, Denacol EX-313 and EX-810, or a 0.625% glutaraldehyde were used to fix the porcine aortic valves procured from a slaughter house. Samples of each group were removed at various elapsed fixation times. The shrink temperature and moisture content of the valvular leaflet and distinct layers of aortic wall of each sample were measured. Fresh porcine aortic valve was used as a control. It was found that the shrink temperature of the glutaraldehyde leaflet was the highest, whereas the moisture content of the EX-313 leaflet was the greatest among the three test groups. No significant difference in shrink temperature was observed among the epoxy compound fixed inner, middle, outer, and entire aortic walls. This implied that the cross-linking density of the epoxy compound valve was uniform throughout the entire aortic wall. The same also was observed for the glutaraldehyde fixed aortic wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Improvements in the technique of vascular perfusion‐fixation employing a fluorocarbon‐containing perfusate and a peristaltic pump controlled by pressure feedback

Abstract: Summary A new, improved technique for whole-body perfusion-fixation of rats and other small animals is described. The driving force is a peristaltic pump which is feedback regulated by a pressure transducer that monitors the blood/perfusion pressure in the left ventricle of the heart. The primary perfusate-fixative is composed of a blood substitute—13·3% oxygenated fluorocarbon FC-75—in 0·05 M cacodylate buffer (pH 7·4) with 2% glutaraldehyde. The secondary perfusate-fixative is composed of 2% glutaraldehyde in 0·05 M cacodylate buffer (pH 7·4) with 20 mM CaCl2. A double-barrelled, self-holding cannula is used to cannulate the heart; the outer and inner barrels of the cannula are connected to the peristaltic pump and to the pressure transducer, respectively. The tissue oxygen tension in the rat is monitored by a subcutaneous oxygen electrode. Measurements showed that tissue hypoxia/anoxia did not develop before or during the perfusion-fixation. Thus, the technique permits study of specimens which do not exhibit fixation gradients and do not contain cells fixed in a state of asphyxia. This is substantiated by electron micrographs of cells from different organs, revealing new fine structural elements. By adding oxygenated fluorocarbon to glutaraldehyde perfusate-fixatives, enough oxygen is made accessible for cellular respiration as well as for the oxygen-consuming chemical reactions of glutaraldehyde with the tissue. Data on anaesthesia, operative manoeuvres, mechanical components of the system, preparation of fixatives and flow of the perfusate-fixatives are furnished and discussed.

Enzyme electrodes for the determination of carbohydrates in food

Abstract: Characteristic features of screen-printed enzyme electrodes for glucose, lactose and sucrose are described. Glucose oxidase was immobilized on a screen-printed Pt electrode either by crosslinking with glutaraldehyde or by adsorption in an enzyme paste which incorporated either platinized graphite or graphite modified with the mediator tetrathiafulvalene. Thus, detection was based on either H2O2 oxidation or mediator oxidation. The highest reproducibility was obtained with sensors based on the enzyme crosslinked with glutaraldehyde. Hence, this immobilization procedure was also used for the preparation of lactose and sucrose sensors. These sensors are based on co-immobilized β-galactosidase and glucose oxidase and invertase, mutarotase and glucose oxidase, respectively. Adding mutarotase to the enzyme mixture of the sucrose sensor enhanced sensitivity approximately 100 times. The linear range of the sensors could be increased by additional membranes fixed over the electrode surface. The greatest effect was observed using membranes with a reduced number of pores. This also led to a decrease in the sensitivity of the sensor. Additionally, these sensors showed a reduced response to ascorbic acid, the main electrochemically interfering compound in food. Hence, no interference was observed in juices without added ascorbic acid.

A preliminary study of the fixation mechanism of collagen reaction with a polyepoxy fixative.

Abstract: A new biomaterial has been developed by fixing native collagens with a polyepoxy compound (PC) fixative. Prior studies have shown that this biomaterial has comparable properties as compared to collagen fixed with glutaraldehyde (GA) and thus has a great promise for use as an implantable bioprosthesis. The purpose of this study was to understand the mechanism of the amino acids-PC reactions in the fixation process. Bovine arteries were fixed with PC under various pH, concentration and temperature conditions as a function of fixation time. Individual amino acid components in the fresh and the fixed arteries were assayed using a Beckman amino acid analyzer to determine the degree of tanning. The denaturation temperature (Td) was also measured on each sample. Since the denaturation temperature is a direct indication of cross-linking of individual amino acids with the fixative, the difference in the degree of tanning for the same increase in Td may be indicative of the quantity of the masked, non-cross-linked amino acids. The fixation reaction data indicated that not all amino acids were cross-linked upon contacting the PC fixative. Masking appeared to be more substantial with a fixation at higher pH values.

Production of submicron-size monodisperse polymer particles having aldehyde groups by seeded aldol condensation polymerization

Abstract: Submicron-size monodisperse polystyrene/polyglutaraldehyde composite particles having aldehyde groups at the surfaces were produced by seeded aldol condensation polymerization of glutaraldehyde in the presence of polystyrene particles prepared by emulsifier-free emulsion polymerization. This technique is expected to be useful for the production of size-controlled polymer particles having aldehyde groups.

Microbubble-based contrast agents with crosslinked and reduced proteinaceous shells

Abstract: The present invention pertains to proteinaceous gas- or gas precursor-containing microbubble contrast agents for use in ultrasound and/or MR imaging, in which the protein matrix is crosslinked by reaction with a bifunctional aldehyde (e.g., a dialdehyde such as glutaraldehyde or an α,β-unsaturated aldehyde such as acrolein) in an aqueous medium at substantially neutral pH. The contrast agents exhibit improved in vivo and storage stabilities, particularly if the matrix is also reacted with a Schiff's base reducing agent such as a borohydride. Modification of the size distribution of such crosslinked proteinaceous gas-containing contrast agents, e.g. to reduce the mean size of the microbubbles, further enhances their stability and permits preparation of novel contrast agents having a particularly narrow microbubble size distribution.

A fixative suitable for in situ hybridization histochemistry.

Abstract: We compared the morphology and stability of hybridization signals between paraffin sections of rat retina fixed with commonly used 4% paraformaldehyde/PBS and those fixed with a fixative containing glutaraldehyde in in situ hybridization histochemistry, using a digoxigenin-labeled RNA probe complementary for beta-galactoside alpha 2,6-sialyltransferase mRNA. Retinal detachment was frequently observed in the sections fixed with 4% paraformaldehyde-PBS, whereas the morphology was satisfactorily preserved in those fixed with either 0.5% glutaraldehyde, 4% paraformaldehyde-PBS, or 2.5% glutaraldehyde-PBS. Without glutaraldehyde, it was difficult to determine the most appropriate length of proteinase K digestion of tissue sections for facilitating probe penetration, since the optimal time for definite hybridization was variable among the retinal cells in heterogeneous layers. By addition of glutaraldehyde to paraformaldehyde or with glutaraldehyde alone, it was easy to establish the appropriate time for the unmasking procedure, since intense mRNA signals were constant throughout the retina by proteinase K digestion for more than 30-40 min. Using a fixative that causes stronger cross-linking (e.g., glutaraldehyde) is recommended to improve not only the morphology but also the stability of hybridization signals in in situ hybridization histochemistry with paraffin embedding and digoxigenin-labeled RNA probes.

The silver staining procedure of sodium dodecyl sulfate-gels may be accelerated by shortening fixation time.

Abstract: In most silver staining methods the first step in the staining of proteins separated after sodium dodecyl sulfate-polyacrylamide gel electrophoresis is a rather protracted fixation of the gels. Optimum fixation should be short, cause no background staining and effectively immobilize the proteins in the gel without masking the proteins for reaction with the staining solution. Further, the concentration of the fixing compounds should be as low as possible due to the potentional toxicity of fixatives. Fixation for only 5 min with mixtures of very low concentrations of formaldehyde and glutaraldehyde in ethanol, or a solution of formaldehyde or glutaraldehyde in picric acid and ethanol, fulfill these demands, provided that the gels were prefixed in ethanol-acetic acid for 10 min. As a consequence of these results a fast and sensitive silver staining procedure is proposed.

Process for the elimination of hydrogen sulfide by using water-in-oil emulsions

Abstract: A process for the removal of hydrogen sulfide present in a composition comprising treating the composition with a water-in-oil emulsion wherein said water-in-oil emulsion containing by weight about: 20 to 80% of a dispersed aqueous phase containing about 20 to 70% of one or more aldehydes chosen from the group constituted by formaldehyde, glyoxal, glutaraldehyde, glycolaldehyde or glyoxylic acid and 80 to 30% of an aqueous solution containing 90 to 100% water and 10 to 0% of a buffer agent pH=5.5±1.5; and 80 to 20% of a continuous oil phase containing about 90 to 99% of one or more saturated and liquid C6 -C16 hydrocarbons, and 10 to 1% of an emulsifying system constituted by one or more water-in-oil emulsifying agents.

Evaluation of collagen modification and surface properties of a bovine artery via polyepoxy compound fixation.

Abstract: Collagen of bovine internal thoracic artery (BITA) was treated with glutaraldehyde (GA) or polyepoxy compounds (PC). This study was to evaluate the surface properties as a result of tissue tanning reaction with PC. The fixation resulted in a significant reduction of available lysine, histidine, and other amino acid residues in PC fixed grafts as compared to fresh pre-fixed arteries. Among them, the lysine (Lys) content was reduced by about 80%, indicating that PC reactions mainly involve with Lys residues. Both PC and GA treatment led to crosslinking as evidenced by the increase in the denaturation temperature. The critical surface tension and the Fourier Transform Infrared Spectrum (FTIR) on a pre-implant and its 96 days explant were evaluated and found to be similar. The FTIR analysis of a pre-implant and the 96 day explant indicated that there was no lipid deposition.

Characteristics of permeation and separation of aqueous alcoholic solutions with chitosan derivative membranes

Abstract: Permeation and separation characteristics for the feed vapours from aqueous alcoholic solutions through chitosan derivative membranes such as chitosan acetate (GA-ChitoA), chitosan (GA-Chito), and carboxymethyl chitosan acetate (GA-CM-ChitoA) membrane crosslinked with glutaraldehyde were investigated by evapomeation. The GA-Chito and GA-CM-ChitoA membranes prepared from casting solutions containing an optimum amount of glutaraldehyde showed a high permeation rate and high water permselectivity for an azeotropic composition in an aqueous ethanol solution. The permselectivity for water through the GA-CM-ChitoA membrane in evapomeation was in the order of aqueous solutions of methanol < ethanol < 1-propanol. The effect of the chemical and physical structure of these hydrophilic membranes on the permeation and separation characteristics is discussed.

Glutaraldehyde: Species Comparisons of in Vitro Skin Penetration

Abstract: It has been reported that the major portion of the applied dose was recovered from skin at the application site in previously conducted in vivo rat and rabbit pharmacokinetic studies with 14C-labeled glutaraldehyde. To investigate this finding further, and to compare penetration of glutaraldehyde through human skin with absorption data for animal skin preparations, the potential for in vitro skin penetration of [1,5-14C]glutaraldehyde (CAS #111-30-8) was evaluated with samples of excised skin from Fischer 344 rats, CD-1 mice, Hartley guinea pigs, New Zealand White rabbits, and humans (women undergoing reconstructive mammoplasty). A flow-through skin penetration chamber design was used and the aqueous glutaraldehyde concentrations of 0.75% and 7.5% used in the previous in vivo rat and rabbit percutaneous study were applied. The in vitro results indicated that glutaraldehyde did not penetrate human or animal skin to any substantial degree following application of either a 0.75% or a 7.5% aqueous sol...