Showing papers on "Glutaraldehyde published in 2000"

Formaldehyde, formalin, paraformaldehyde and glutaraldehyde: What they are and what they do.

Abstract: Aldehydes are the most commonly used fixatives. They serve to stabilize the fine structural details of cells and tissues prior to examination by light or electron microscopy. Research workers, technicians, pathologists and others who regularly use aldehyde fixatives frequently do not appreciate the nature and properties of these compounds or the reasons for choosing to fix a specimen in formaldehyde, glutaraldehyde or a mixture of the two. Misconceptions are widespread also about formalin and paraformaldehyde, the commercial products from which formaldehyde-containing solutions are made.

Palladium sorption on glutaraldehyde-crosslinked chitosan

Abstract: The high nitrogen content of chitosan is the main reason for its ability to sorb metal ions through several mechanisms including ion-exchange or chelation, depending on the metal and the pH of the solution. Glutaraldehyde is used to crosslink chitosan through imine linkage between amine groups of chitosan and aldehyde groups of the crosslinking agent. This modified biosorbent was studied for palladium recovery in acidic medium (around pH 2). The influence of several parameters such as pH and competitor anions were studied with respect to sorption equilibrium. Sorption isotherms were obtained and modeled using the Langmuir and the Freundlich model. This study also examines the effect of palladium concentration, particle size, sorbent dosage, and the extent of crosslinking on sorption kinetics. Kinetic curves are modeled using single diffusion model equations to evaluate the predominance of either external or intraparticle mass transfer resistance. The influence of the acid used to control the pH of the solution was examined in conjunction with the influence of competitor anions. Sulfuric acid proves to be unfavorable to palladium sorption, in comparison with hydrochloric acid. However, the addition of chloride anions in a palladium solution, whose pH is controlled with sulfuric acid, enhances metal anion sorption: results are interpreted with reference to chloropalladate speciation.

In vitro evaluation of the genotoxicity of a naturally occurring crosslinking agent (genipin) for biologic tissue fixation

Abstract: The objective of the present study was to evaluate in vitro, using Chinese hamster ovary (CHO-K1) cells, the genotoxicity of genipin, a naturally occurring crosslinking agent. Glutaraldehyde, the most commonly used crosslinking agent for biologic tissue fixation, was employed as a reference chemical. The selected procedures for this evaluation were the micronucleus (MN) and sister chromatid exchange (SCE) assays with or without the addition of a metabolic activation system (S9 mix). Before starting the genotoxicity assays, the maximum noncytotoxic amounts of glutaraldehyde and genipin were determined using the MTT assay. The results obtained in the MTT assay revealed that the cytotoxicity of genipin was significantly lower than that of glutaraldehyde with or without S9 mix. The frequencies of MN observed in the cases drugged with varying concentrations of glutaraldehyde or genipin were not statistically different from those seen in the negative controls (blank) in the presence or absence of S9 mix. However, it was noted that glutaraldehyde significantly inhibited the cell-cycle progression while the cells drugged with genipin did not result in cell-cycle delay. In the SCE assay, the numbers of SCE per cell observed in the cases drugged with varying concentrations of glutaraldehyde were significantly greater than those found in the negative controls with or without S9 mix. Nevertheless, these numbers were still low compared to the numbers of SCE induced by the strong mutagens used as our positive control substances. This suggests that glutaraldehyde may produce a weakly clastogenic response in CHO-K1 cells. In contrast, the numbers of SCE per cell obtained in the cases drugged with genipin were comparable to those observed in the negative controls in those that were except drugged with the highest dose (50 ppm). This suggests that genipin does not cause clastogenic response in CHO-K1 cells provided its concentration is lower than 50 ppm. In conclusion, as far as cytotoxicity and genotoxicity are concerned, genipin is a promising crosslinking agent for biologic tissue fixation.

Transmission electron microscopy of yeast.

Abstract: The challenges of sample preparation can limit a researcher's selection of transmission electron microcopy (TEM) for analysis of yeast. However, with the exception of thin sectioning, preparation of well-fixed and infiltrated samples of yeast cells is achievable by any reasonably equipped laboratory. This review presents a general overview of TEM sample preparation methods and detailed protocols for chemical fixation of yeast for ultrastructural analysis and immunolabeling. For ultrastructural analysis, the most commonly used chemical fixation involves treatment with glutaraldehyde followed by either potassium permanganate or osmium. Prior to osmium postfixation, the cell wall must be enzymatically digested to allow optimal fixation and embedding. Freeze substitution methods continue to provide the highest quality of fixation, but equipment needed for these protocols is not generally available to many labs. The low viscosity of Spurr's resin makes it the resin of choice for ultrastructure studies. Immunoelectron microscopy has enjoyed great success in analysis of yeast molecular organization. For immunoelectron microscopy, glutaraldehyde/formaldehyde-fixed cells are embedded in LR White resin. The thin sections are then treated in much the same way as an immunoblot: following blocking, they are incubated in primary antiserum, washed, and then incubated in gold-labeled secondary antiserum.

Mechanisms of killing of spores of Bacillus subtilis by iodine, glutaraldehyde and nitrous acid

Abstract: Treatment of wild-type spores of Bacillus subtilis with glutaraldehyde or an iodine-based disinfectant (Betadine) did not cause detectable mutagenesis, and spores (termed alpha-beta-) lacking the major DNA-protective alpha/beta-type, small, acid-soluble proteins (SASP) exhibited similar sensitivity to these agents. A recA mutation did not sensitize wild-type or alpha-beta- spores to Betadine or glutaraldehyde, nor did spore treatment with these agents result in significant expression of a recA-lacZ fusion when the treated spores germinated. Spore glutaraldehyde sensitivity was increased dramatically by removal of much spore coat protein, but this treatment had no effect on Betadine sensitivity. In contrast, nitrous acid treatment of wild-type and alpha-beta- spores caused significant mutagenesis, with alpha-beta- spores being much more sensitive to this agent. A recA mutation further sensitized both wild-type and alpha-beta- spores to nitrous acid, and there was significant expression of a recA-lacZ fusion when nitrous acid-treated spores germinated. These results indicate that: (a) nitrous acid kills B. subtilis spores at least in part by DNA damage, and alpha/beta-type SASP protect against this DNA damage; (b) killing of spores by glutaraldehyde or Betadine is not due to DNA damage; and (c) the spore coat protects spores against killing by glutaraldehyde but not Betadine. Further analysis also demonstrated that spores treated with nitrous acid still germinated normally, while those treated with glutaraldehyde or Betadine did not.

Amperometric hydrogen peroxide biosensor based on immobilization of peroxidase in chitosan matrix crosslinked with glutaraldehyde

Abstract: A new enzymatic amperometric biosensor for hydrogen peroxide (H2O2) was developed via an easy and effective enzyme immobilization method using chitosan film crosslinked with glutaraldehyde. Horseradish peroxidase was immobilized on the surface of a carbon paste electrode. Hexacyanoferrate(II) was present in the solution as a mediator. The biosensor exhibited a relatively fast response of less than 10 s and produced currents linearly related to the H2O2 concentration in the range of 4.7 × 10−5 to 2 × 10−3 M. The biosensor had very good stability as it retained ca. 85% activity after 30 d of storage in a phosphate buffer at 4 °C. The effect of the chitosan film thickness and various operational parameters were optimized. The applicability of this biosensor was demonstrated with the analysis of real samples and the results obtained by this biosensor corroborated well with the classical iodometric titration method.

Fixation of biological tissues with a naturally occurring crosslinking agent: fixation rate and effects of pH, temperature, and initial fixative concentration.

Abstract: In an attempt to overcome the cytotoxicity problem of the glutaraldehyde-fixed tissues, a naturally occurring crosslinking agent (genipin) was used by our group to fix biological tissues. The study was intended to investigate the rate of tissue fixation by genipin. Glutaraldehyde was used as a control. In addition, the degrees of tissue fixation by genipin at different pHs (pH 4.0, pH 7.4, pH 8.5, or pH 10.5), temperatures (4°C, 25°C, 37°C, or 45°C), and initial fixative concentrations (0.250%, 0.625%, or 1.000%) were examined. The results obtained revealed that the rate of tissue fixation by glutaraldehyde was significantly faster than that by genipin. The degree of tissue fixation by genipin may be controlled by adjusting its fixation duration or fixation conditions. The order in degree of tissue fixation by genipin at different pHs, from high to low, was: at nearly neutral pH (pH 7.4 or pH 8.5) > at basic pH (pH 10.5) > at acidic pH (pH 4.0). The degrees of tissue fixation by genipin at different temperatures were about the same, except for that at 4°C. In contrast, the initial fixative concentration did not seem to affect the degree of tissue fixation by genipin, if only the amount of genipin in the fixation solution was sufficient to complete tissue fixation. The concentrations of genipin in the aqueous solutions at different pHs, temperatures, and initial fixative concentrations tended to decrease with time with or without the occurrence of tissue fixation. This indicated that genipin was not stable in the aqueous solution. The instability of aqueous genipin was more remarkable with increasing pH or temperature. The results obtained in this study may be used to optimize the fixation process for developing bioprostheses fixed by genipin. © 2000 John Wiley & Sons, Inc. J Biomed Mater Res, 52, 77–87, 2000.

Chitosan microspheres and sponges: Preparation and characterization

Abstract: In this study, chitosan microspheres and sponges were prepared and characterized for diverse biomedical applications successfully. The chitosan microspheres were obtained with a “suspension crosslinking technique” in the size range of 30–700 μm. The stirring rate of the suspension medium and the chitosan/acetic acid ratio, emulsifier, and crosslinker, that is, the glutaraldehyde concentration in the suspension medium, were evaluated as the effective parameters on the size/size distributions of the microspheres. The microsphere size/size distributions were increased with the decreasing of all effective parameters except the chitosan/acetic acid ratio. In the second part of the study, chitosan sponges were prepared with a solvent-evaporation technique and sponges were cross-linked either during the formation or after the formation of sponges by using a cross-linker, that is, glutaraldehyde. When the sponges were crosslinked during the formation, fibrillar structures were obtained, while the leaflet structures were obtained in the case of crosslinking after the formation of sponges. In the last part of the study, the swelling behavior of both the chitosan microspheres and sponges were evaluated using different amounts of the crosslinker. The swelling ratio was increased in both types of structures, that is, microspheres and sponges, by decreasing the amount of the crosslinker. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1637–1643, 2000

Allergic contact dermatitis from glutaraldehyde in health-care workers.

Abstract: Glutaraldehyde is considered the disinfectant of choice for sterilizing medical and dental equipment. Unfortunately, glutaraldehyde has many toxic side-effects, including the ability to induce allergic contact dermatitis. In a 5-year study at the University of Kansas, 468 patients were patch tested to glutaraldehyde. A comparison of results was made between those employed in a healthcare related field and those who were not. Health-care workers (HCWs) were more than 8x more likely to be allergic to glutaraldehyde than their non-health-care working peers (NHCWs). Statistically significant differences between HCWs and NHCWs were seen in their reactivity to glutaraldehyde, thimerosal, benzalkonium chloride and methyl methacrylate. A higher than expected co-reactivity between glutaraldehyde and formaldehyde was also noted among HCWs and NHCWs, which cannot fully be explained by concomitant exposure. Allergic contact dermatitis from glutaraldehyde often causes persistent dermatitis, which frequently forces patients to leave their jobs. Although the National Institute of Occupational Safety and Health has published guidelines for safe handling of glutaraldehyde, allergy appears to continue to rise, especially among those employed in health-care professions. Until a less sensitizing disinfectant is developed, it is in the best interest of those in health-care professions, and other professions exposed to glutaraldehyde, to heighten occupational safety standards and to improve methods of barrier protection.

Synthesis and characterization of a thiourea derivative of chitosan for platinum recovery

Abstract: Chitosan is effective at removing platinum from dilute solutions, but sorption properties are significantly affected by the presence of competitor anions, such as chloride and, especially, sulfate anions. Sorption capacities in such complex solutions are enhanced by grafting thiourea through glutaraldehyde linkage. The influence of the amount of glutaraldehyde and thiourea in the impregnation bath was investigated and optimized with special attention to the composition of the solution and the type of acid used for pH control. This modification involves a change in the sorption mechanism: While glutaraldehyde-crosslinked chitosan adsorbs platinum through an ion-exchange mechanism, the thiourea derivative of chitosan acts as a chelating resin, less sensitive to ionic strength and competitor anions. Platinum sorption is also less sensitive to pH, and increasing the sulfate anion concentration has a limited effect on platinum sorption in comparison with the crosslinked sorbent. Thiourea grafting seems to increase sorption kinetics, especially in solutions controlled with sulfuric acid. SEM–EDAX techniques as well as FTIR analyses were used to characterize chemical modifications of the sorbent. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 119–134, 2000

Positively Charged Gelatin Microspheres as Gastric Mucoadhesive Drug Delivery System for Eradication of H. pylori

Abstract: Gastric mucoadhesive drug delivery systems are very promising for eradication of Helicobacter pylori (H. pylori), a spiral bacterium that resides in the gastric mucus layer and at the mucus-epithelial cell interface. New positively charged biodegradable microspheres were prepared using aminated gelatin by surfactant-free emulsification in olive oil, followed by a cross-linking reaction with glutaraldehyde. The amino group contents of the modified gelatin and the microspheres were determined using a 2,4,6-trinitrobenzenesulfonic acid method. With the increase of glutaraldehyde concentration, the amino group content of the microspheres decreased accordingly. The influence of glutaraldehyde concentration, cross-linking reaction time, drug-loading patterns, and type of release media on the in vitro release characteristics of amoxicillin from the microspheres was investigated. Amoxicillin release rate from the modified gelatin microspheres was significantly reduced compared with that from gelatin microspheres. Furthermore, the release was decreased with the increase of glutaraldehyde concentration and/or cross-linking time. On the other hand, a faster release was observed in a lower pH release medium and/or using a lower pH solution for amoxicillin loading. The gastric mucoadhesive properties of the microspheres were evaluated using RITC-labeled microspheres in an isolated rat stomach. The gastric mucoadhesion of the modified gelatin microspheres was markedly improved compared with that of gelatin microspheres. The modified gelatin microsphere proves to be a possible candidate delivery system for the effective eradication of H. pylori.

Solvent and pH resistance of surface crosslinked chitosan/poly(acrylonitrile) composite nanofiltration membranes

Abstract: The resistance of novel surface crosslinked Chitosan/poly(acrylonitrile) (PAN) composite nanofiltration (NF) membranes to pH and organic solvents was studied with respect to the effects of crosslinking parameters, namely, glutaraldehyde concentration and crosslinking time. The pH resistance was determined by permeation of aqueous acidic (pH 2.5) and basic (pH 11) solutions as well as swelling studies in the pH range of 2.5–11. The solvent resistance was determined by swelling, immersion, and permeation studies with several industrially important organic solvents, namely methanol, ethanol, iso-propanol, methyl ethyl ketone, ethyl acetate and hexane. It was observed that the crosslinked composite membranes maintain the permeate fluxes for test solvents for 2 h of continuous operation without any significant change in flux. SEM studies on membrane samples after immersion as well as permeation with the above-mentioned solvents indicated that the membrane morphology was maintained. The results are explained in terms of solvent–membrane polar and hydrophobic interactions, using solubility parameters of membrane and solvents and dielectric constants of solvents. Pure water flux and polyethylene glycol transmission data indicated that at pH 2.5 and 11, the membrane stability increased with increasing glutaraldehyde concentration and was much better at pH 11 than at pH 2.5. All surface crosslinked membranes showed reduced swelling between pH 4–10. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1782–1793, 2000

Preparation, characterization and release profiles of pH‐sensitive chitosan beads

Abstract: Spherical crosslinked beads using chitosan, glycine and glutaraldehyde were prepared for controlled release formulations. Structural investigation of the beads was made with IR analysis. Morphological study of the beads was carried out by scanning electron microscopy. The swelling behaviour of the beads was monitored as a function of time in solutions of different pH. The release experiments were performed using thiamine hydrochloride (Thi-HCl) as a model drug. These preliminary results suggest the possibility of modifying the formulations to obtain the desired controlled release of drug in an oral sustained delivery system. © 2000 Society of Chemical Industry

Preparation and properties of alginate superabsorbent filament fibers crosslinked with glutaraldehyde

Abstract: Superabsorbent filament fibers based on sodium alginate were prepared using glutaraldehyde as a crosslinking agent. Alginate was extruded into an aqueous hydrochloric acid coagulation bath to form continuous alginic acid gel fibers via a wet-spinning method. The alginic acid gel fibers were dehydrated by exchanging water with dioxane, crosslinked, then neutralized for better absorbency. Crosslinked alginate filaments exhibited a high saline solution and synthetic urine absorbencies, maintaining the integrity of the fiber structure. Maximum synthetic urine absorbency was obtained with the fiber crosslinked at a lower glutaraldehyde concentration compared with that required for maximum saline solution absorbency. This appears to be due to the crosslinking effect of calcium ions in the synthetic urine solution being absorbed. Strain and tenacity of the crosslinked alginate fibers decreased with an increasing amount of glutaraldehyde used in the crosslinking reaction. The decrease in tenacity was not significant while the strain showed an extensive decrease. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1797–1804, 2000

L-DOPA production by immobilized tyrosinase.

Abstract: The production of L-DOPA using L-tyrosine as substrate, the enzyme tyrosinase (EC 1.14.18.1) as biocatalyst, and L-ascorbate as reducing agent for the o-quinones produced by the enzymatic oxidation of the substrates was studied. Tyrosinase immobilization was investigated on different supports and chemical agents: chitin flakes activated with hexamethylenediamine and glutaraldehyde as crosslinking agent, chitosan gel beads, chitosan gel beads in the presence of glutaraldehyde, chitosan gel beads in the presence of polyvinylpyrrolidone, and chitosan flakes using glutaraldehyde as crosslinking agent. The last support was considered the best using as performance indexes the following set of immobilization parameters: efficiency (90.52%), yield (11.65%), retention (12.87%), and instability factor (0.00). The conditions of immobilization on chitosan flakes were optimized using a two-level full factorial experimental design. The independent variables were enzyme-support contact time (t), glutaraldehyde concentration (G), and the amount of enzyme units initially offered (U C). The response variable was the total units of enzymatic activity shown by the immobilized enzyme (U IMO). The optimal conditions were t = 24 h, G = 2% (v/v), and U C = 163.7 U. Under these conditions the total units of enzymatic activity shown by the immobilized enzyme (U IMO) was 23.3 U and the rate of L-DOPA production rate was 53.97 mg/(L·h).

A note: ortho-phthalaldehyde: proposed mechanism of action of a new antimicrobial agent.

Abstract: Ortho-phthalaldehyde (OPA) is a new aromatic dialdehyde antimicrobial agent, the mechanism of action of which has been little studied. The aims of this paper are to examine what is currently known about its mechanism of action, to compare the action with that of a widely investigated aliphatic dialdehyde, glutaraldehyde (GTA), and to put forward a hypothesis that would, in the light of current knowledge, explain how OPA inactivates micro-organisms, including GTA-resistant Mycobacterium chelonae.

Immobilization of penicillin G acylase onto chemically grafted nylon particles

Abstract: Nylon particles, grafted with diethylene glycol dimethacrylate (DGDA) using potassium persulphate as initiator, were treated with hexamethylene diamine (HMDA). The aminoalkylated particles were activated with glutaraldehyde and finally, penicillin G acylase (PA) was immobilized to these activated particles. Both the conditions of the aminoalkylation- and the immobilization process were optimized. The hydrolysis of cephalexin was used as model conversion. The retention of activity of the immobilized enzyme was 12%. This value improved to 30% by adding phenyl acetic acid (PAA), as active-site protecting agent, to the enzyme solution. The results suggest formation of multi-point attachment between the enzyme and the matrix.

Detection of intracellular nitric oxide using a combination of aldehyde fixatives with 4,5-diaminofluorescein diacetate

Abstract: Using 4,5-diaminofluorescein diacetate (DAF-2DA), which was recently developed for the detection of intracellular nitric oxide (NO) in living cells, we examined the sensitivity of intracellular NO in cells treated with some fixatives Cultured human umbilical vein endothelial cells loaded with DAF-2DA in the presence of 10(-6) M acetylcholine showed intense fluorescence when fixed in paraformaldehyde or glutaraldehyde, but no fluorescence could be detected after fixation in ethanol or acetone Fluorescence generation depended on the combination of each aldehyde fixative with DAF-2, which is produced enzymatically from DAF-2DA within the cells Subtracting the fluorescence intensity of non-activated controls from that of cells activated by acetylcholine indicated the NO produced in the stimulated cells, since the control cells that took up DAF-2DA also generated fluorescence when treated with aldehyde fixatives Thus, detection of intracellular NO by combining aldehyde fixatives with DAF-2DA is useful for examining the functions of NO in cells both in situ and in vivo

Prevention of glutaraldehyde-fixed bioprosthetic heart valve calcification by alcohol pretreatment: further mechanistic studies.

Abstract: Background and aim of the study Calcification is a major cause of failure of bioprosthetic heart valves derived from glutaraldehyde-crosslinked bovine pericardium or porcine aortic valve (PAV) cusps. Recently, we have shown that ethanol pretreatment of PAV cusps prevents calcification in animal models. Methods and results In this study we showed that ethanol pretreatment was equally effective in preventing calcification of glutaraldehyde-crosslinked bovine pericardium (control Ca2+ = 121.16+/-7.49 microg/mg tissue; ethanol-pretreated Ca2+ = 2.95+/-0.78 microg/mg). Furthermore, other low-molecular weight alcohols such as methanol and isopropanol were also effective in mitigating calcification of PAV cusps. Storage of ethanol-pretreated cusps in glutaraldehyde before implantation allowed partial return of calcification, suggesting a role for ethanol-glutaraldehyde interactions in preventing calcification. However, when ethanol-pretreated cusps were stored in ethanolic glutaraldehyde up to one month, the anti-calcification effect of ethanol persisted. The conditions whereby PAV cusps were crosslinked in pure, non-aqueous, alcoholic glutaraldehyde solutions were also examined. The crosslinking was equivalent to the standard aqueous glutaraldehyde crosslinking as indicated by thermal denaturation temperatures (Td) obtained by differential scanning calorimetry (DSC) and resistance to collagenase digestion. However, these cusps had lower water content and showed a marked decrease in spin-lattice relaxation times (T1) obtained by solid-state proton nuclear magnetic resonance (NMR). Moreover, these cusps calcified heavily in the 21-day rat subdermal implants. Thus, alcohol treatment during glutaraldehyde crosslinking was not useful. Conclusion Glutaraldehyde storage after ethanol pretreatment aggravates calcification; moreover, alcoholic-glutaraldehyde crosslinking solutions are not beneficial for anti-calcification. Ethanol pretreatment of glutaraldehyde-pretreated bovine pericardium prevents its calcification.

Evaluating Glutaraldehyde as a Nonformaldehyde Durable Press Finishing Agent for Cotton Fabrics

Abstract: In recent years, extensive efforts have been made to find nonformaldehyde durable press finishes to replace the traditional formaldehyde-based reagents. In this research, glutaraldehyde is evaluated as a nonformaldehyde durable press finish for cotton fabrics. The infrared spectroscopy data show that the two aldehyde groups of glutaraldehyde react with cotton at elevated temperatures. There is a linear correlation between the fabric wrinkle recovery angle and the reduction in the carbonyl band intensity of the treated cotton cured at increasing temperatures. We have compared glutaraldehyde with low- formaldehyde DMDHEU and nonformaldehyde DHDMI as crosslinking agents for cotton. The fabric finished with glutaraldehyde shows adequate wrinkle resistance, sufficient white ness, and high strength retention. As a nonformaldehyde durable press finishing agent, the performance of glutaraldehyde is superior to that of DHDMI.

Preparation of Cross-Linked Sodium Alginate Microparticles Using Glutaraldehyde in Methanol

Abstract: Polymeric sodium alginate microparticles were prepared by precipitating sodium alginate in methanol, followed by cross-linking with glutaraldehyde. The extent of cross-linking was controlled by the time of exposure to glutaraldehyde. The topology of microparticles was characterized by scanning electron microscopy (SEM), which indicated smooth surfaces. The equilibrium swelling experiments were carried out in water to observe the effect of cross-linking and drug loading for better utility of microparticles. It was found that swelling decreased, but drug loading increased, with an increase in cross-linking of the matrix.

Characterization of the activity of penicillin G acylase immobilized onto nylon membranes grafted with different acrylic monomers by means of γ-radiation

Abstract: Penicillin G acylase (PGA) has been immobilized onto nylon membranes grafted with methylmethacrylate (MMA) or diethyleneglycoldimethacrylate (DGDA) monomers by means of γ-radiation. Hexamethylenediamine (HMDA) has been used as spacer between the grafted membranes and the enzyme. Glutaraldehyde (GA) was used as crosslinking to couple the enzyme to the HMDA. The catalytic membranes so prepared were studied as a function of pH and temperature of the solution containing the substrate. The membranes showing the best characteristics were the ones grafted with DGDA. The dependence of the behavior of these membranes on several experimental conditions was studied, i.e., the temperature and duration of the aminoalkylation process, spacer concentration, the glutaraldehyde concentration and the enzyme concentration. The experimental conditions giving the best performance of the catalytic membranes have been deduced. The time requested to obtain 50% of substrate conversion, i.e., hydrolysis of cephalexin, has been studied as a function of its initial concentration.