Effect Of Glutaraldehyde Concentration Research Articles

FORMULATION AND EVALUATION OF RACECADOTRIL MUCOADHESIVE MICROSPHERES

Objective: To develop and evaluate the mucoadhesive microsphere using combinations of natural polymers chitosan and xanthan gum for sustained release.
 Methods: In the present work mucoadhesive microspheres were prepared by using natural polymers like chitosan and xanthan gum by using the emulsion chemical cross-linking method. Chemical cross-linking was done by using glutaraldehyde. The 22 factorial design was employed to show the effect of cross-linking agent and processing factor-like stirring and speed. Prepared microspheres were evaluated for their particle size, surface morphology, drug entrapment efficiency, in vitro drug release, swelling index, and mucoadhesive strength.
 Results: The size of microspheres of factorial batches were in the range of 26-46 µm. The swelling index was showed in the range of 1.51-1.66 percentage. The equation of multiple regression revealed that there was significant interaction among factors. The glutaraldehyde concentration had a positive effect on % entrapment efficiency, % cumulative drug release and % mucoadhesion. Stirring speed showed a negative impact on % entrapment efficiency, % cumulative drug release and % mucoadhesion. The interactive effect of glutaraldehyde concentration and the stirring speed was found to be positive for % entrapment efficiency and % cumulative drug release. In vitro drug release study of optimized formulation F2 show 96 % of drug release with 6 h indicating sustained release behavior with diffusion mechanism. The SEM image of the optimized batch was spherical with a porous surface.
 Conclusion: The results obtained in this research work indicated that a promising potential of chitosan and xanthan gum combination for the preparation of the mucoadhesive microsphere of Racecadotril.

Effect of Glutaraldehyde Concentration on Catalytic Efficacy of <i>Candida rugosa</i> Lipase Immobilized onto Silica from Oil Palm Leaves

Till date, studies that investigated the effect of glutaraldehyde concentration on catalytic efficacy of biocatalyst developed with silica-derived from oil palm leaves (OPL) as support, are unknown. The study presents the preparation of a support consisting of silica extracted from OPL coated over magnetite (G/A/SiO2-M) for the immobilization of Candida rugosa lipase (CRL). Herein, the effect of glutaraldehyde concentration on the catalytic efficacy of immobilized CRL was assessed by the enzymatic production of butyl butyrate as a model. Fourier transform infrared (FTIR) spectra and immobilization parameters indicated that covalent bound CRL on functionalized OPL-derived silica-magnetite composite activated with 4% (v/v) glutaraldehyde solution (100 mM, pH 7.0) (CRL/G/A/SiO2-M) and pretreated in toluene, resulted in a protein loading and an immobilization yield of 68.3 mg/g and 74.3%, respectively. The resultant CRL/G/A/SiO2-M biocatalyst which specific activity was 61.9 U/g catalyzed the esterification production of 76.5% butyl butyrate in just 3 h, as confirmed by analyses of the purified ester using FTIR and 1H NMR spectroscopy. Hence, the finding envisages the promising use of G/A/SiO2-M support fabricated from discarded OPL as a carrier for immobilization and activation of CRL, in conjunction to being a good alternative source of renewable silica.

Influence of Laponite RD on the properties of poly(vinyl alcohol) hydrogels

ABSTRACTPoly(vinyl alcohol) (PVA) hydrogels were prepared in the presence/absence of Laponite RD (LRD) by using glutaraldehyde (GL) as chemical crosslinker. The effect of GL concentration (CHO/OH ratio between 0.02 and 0.38) and of clay addition on the PVA hydrogel properties was investigated. The swollen hydrogels showed good transparency and flexibility. LRD incorporation into the PVA hydrogel, revealed by Fourier transform infrared spectroscopy, led to a significant increase of the roughness of the dried hydrogel surface (about two times), as established by atomic force microscopy. The swelling ability was affected in a small extent by the clay addition. The elastic modulus decreased from 4680 to 3340 Pa and from 2195 to 1603 Pa by addition of 0.5% LRD into PVA hydrogels obtained with CHO/OH ratio of 0.02 and 0.06, respectively. The LRD addition reduced the gelation time determined by in situ rheological monitoring of PVA crosslinking reaction. The experimental investigations showed that there is an optimum CHO/OH ratio of 0.02 for which the PVA/LRD hybrid hydrogel presents the properties required by a targeted application, as for example support material for wound dressings. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46661.

Sucrose hydrolysis by invertase immobilized on Duolite A-568 employing a packed-bed reactor

ABSTRACTThe conversion of sucrose to a highly concentrated commercial syrup by immobilized invertase by combining the processes of adsorption and cross-linking using Duolite A-568 as the carrier was studied. Central Composite Design (CCD) was used to assess the effect of glutaraldehyde concentration and cross-linking reaction time on immobilized enzyme activity throughout the hydrolysis of sucrose in a batch reactor. Cross-linking optimization allowed us to find the optimum conditions for activity with a glutaraldehyde concentration of 0.6 g · L−1 and a cross-linking time of 6 h. The temperature and pH that maximized the activity of the immobilized biocatalyst in the cross-linking process were 50°C and 4.0, respectively. Cross-linking allows the biocatalyst to be active at higher temperatures and lower pH. High-sucrose conversions to invert sugar using a continuous fixed-bed reactor were obtained. The immobilized biocatalyst also demonstrated greater thermal stability at low temperatures.

Improvement of starch digestion using α-amylase entrapped in pectin-polyvinyl alcohol blend.

Polyvinyl alcohol (PVA) and pectin blends were used to entrap α-amylase (Termamyl) using glutaraldehyde as a cross-linker. The effect of glutaraldehyde concentration (0.25, 0.5, 0.75, 1.0, and 1.25%) on the activity of the immobilized enzyme and rate of enzyme released was tested during a 24 h period. Characteristics of the material, such as scanning electron microscopy (SEM), tensile strength (TS), elongation, and rate of dissolution in water (pH 5.7), ruminal buffering solution (pH 7.0), and reactor containing 0.1 mol L−1 sodium phosphate buffer (pH 6.5), were also analyzed. SEM results showed that the surfaces of the pectin/PVA/amylase films were highly irregular and rough. TS values increased as a function of glutaraldehyde concentration, whereas percentage of elongation (%E) decreased. Pectin/PVA/amylase films presented similar values of solubility in the tested solvents. The material obtained with 0.25% glutaraldehyde performed best with repeated use (active for 24 h), in a phosphate buffer reactor. By contrast, the material obtained with 1.25% glutaraldehyde presented higher performance during in vitro testing using an artificial rumen. The results suggest that pectin/PVA/amylase is a highly promising material for biotechnological applications.

Mechanical, swelling and adsorptive properties of dry–wet spun chitosan hollow fibers crosslinked with glutaraldehyde

Chitosan (CS) hollow fiber (HF) membranes were successfully prepared according to the dry–wet spinning technique. A post-treatment with glutaraldehyde (GA) aqueous solution was carried out to perform the cross-linking reaction. The effect of GA concentration in the range 50–1000mgl−1 on the swelling, mechanical and adsorptive properties was investigated. The morphology and chemical structure of the fibers were examined by means of SEM and FTIR. The degree of swelling and adsorption capacity decreased as the GA concentration increased. CS hollow fibers swelled the most in acidic solution as compared with distilled water and saline solution. The adsorption capacity of CS HFs increased while decreasing of initial pH from 7.5 to 3.5. Desorption experiments showed that CS HFs were reusable as adsorbent. Mechanical properties were strongly affected by GA post-treatment: tensile strength and elastic modulus increased at low GA concentration (50mgl−1), to sharply decrease when concentration was ⩾500mgl−1. Breaking elongation decreased with increasing GA concentration.

Interpenetrating polymeric network hydrogel for stomach-specific drug delivery of clarithromycin: Preparation and evaluation

The aim of this study was to develop a controlled release system targeting antibiotic delivery to the stomach. The hydrogels were synthesized by using chitosan, poly (acrylic acid) and poly (vinyl pyrrolidone) polymers crosslinked with glutaraldehyde and N,N’-methylenebisacrylamide. Interpenetrating polymeric network (IPN) hydrogels were prepared by varying the concentration of crosslinking agent (glutaraldehyde). The amount of chitosan, poly (acrylic acid), poly (vinyl pyrrolidone) and N,N’-methylenebisacrylamide were kept constant in all formulations. The effect of glutaraldehyde concentration on the swelling and release characteristics were evaluated. Modalities used to assess the most optimal hydrogel formulation included high liquid chromatography, FTIR analysis, differential scanning calorimetry, swelling studies, in vitro drug release study, mucoadhesive study and scanning electron microscopy. The result showed that IPN hydrogels were greater in swelling, more mucoadhesive and released more drug at lower pH values. Thus, it is believed that the antibiotic concentration in the stomach might be sustained through this formulation.

Interpenetrating polymeric network hydrogel for stomach-specific drug delivery of clarithromycin: Preparation and evaluation

The aim of this study was to develop a controlled release system targeting antibiotic delivery to the stomach. The hydrogels were synthesized by using chitosan, poly (acrylic acid) and poly (vinyl pyrrolidone) polymers crosslinked with glutaraldehyde and N,N’-methylenebisacrylamide. Interpenetrating polymeric network (IPN) hydrogels were prepared by varying the concentration of crosslinking agent (glutaraldehyde). The amount of chitosan, poly (acrylic acid), poly (vinyl pyrrolidone) and N,N’-methylenebisacrylamide were kept constant in all formulations. The effect of glutaraldehyde concentration on the swelling and release characteristics were evaluated. Modalities used to assess the most optimal hydrogel formulation included high liquid chromatography, FTIR analysis, differential scanning calorimetry, swelling studies, in vitro drug release study, mucoadhesive study and scanning electron microscopy. The result showed that IPN hydrogels were greater in swelling, more mucoadhesive and released more drug at lower pH values. Thus, it is believed that the antibiotic concentration in the stomach might be sustained through this formulation.

Effect of glutaraldehyde concentration on the physical properties of polymerized hemoglobin-based oxygen carriers.

Artificial blood substitutes based on glutaraldehyde cross-linked hemoglobin (PolyHb) are currently being developed for use in human subjects needing blood transfusions. Despite the commercial development of PolyHb dispersions, a systematic study of the effect of varying the glutaraldehyde to hemoglobin (G-Hb) molar ratio on the resulting PolyHb physical properties (molecular weight distribution and oxygen binding parameters) has not been conducted to date. The results of this study show that increasing the G-Hb molar ratio elicits a general decrease in the P50 (partial pressure of oxygen at which Hb is half saturated with oxygen) and cooperativity and a simultaneous increase in the weight averaged molecular weight (Mw) of the PolyHb dispersion and methemoglobin (MetHb) level. Three PolyHb dispersions (20:1, 30:1, and 40:1 G-Hb molar ratios) displayed potential as artificial blood substitutes. The 20:1 PolyHb dispersion resulted in the presence of more intramolecularly cross-linked and non-cross-linked tetramers versus cross-linked species that were larger than a tetramer ( approximately 75% tetrameric and approximately 25% higher-order species), lower MetHb level (8%), and P50 (20.1 mmHg) similar in magnitude to that of non-cross-linked Hb. The 30:1 PolyHb dispersion consisted of more higher-order species ( approximately 76%), higher MetHb level (28%), and lower P50 (13.3 mmHg). The 40:1 PolyHb dispersion resulted in a similar P50 of 13.0 mmHg and similar MetHb level (30%); however, this PolyHb dispersion only consisted of species larger than a tetramer. The molecular weight distribution of PolyHb dispersions was determined using asymmetric flow field-flow fractionator (AFFF) coupled with multiangle static light scattering (MASLS). This is the first time that AFFF-MASLS has been used to characterize the molecular weight distribution of PolyHb dispersions.

Biosensors for determination of glucose with glucose oxidase immobilized on an eggshell membrane

A glucose biosensor using an enzyme-immobilized eggshell membrane and oxygen electrode for glucose determination has been fabricated. Glucose oxidase was covalently immobilized on an eggshell membrane with glutaraldehyde as a cross-linking agent. The glucose biosensor was fabricated by positioning the enzyme-immobilized eggshell membrane on the surface of a dissolved oxygen sensor. The detection scheme was based on the depletion of dissolved oxygen content upon exposure to glucose solution and the decrease in the oxygen level was monitored and related to the glucose concentration. The effect of glutaraldehyde concentration, pH, phosphate buffer concentration and temperature on the response of the glucose biosensor has been studied in detail. Common matrix interferents such as ethanol, d-fructose, citric acid, sodium benzoate, sucrose and l-ascorbic acid did not give significant interference. The resulting sensor exhibited a fast response (100 s), high sensitivity (8.3409 mg L −1 oxygen depletion/mmol L −1 glucose) and good storage stability (85.2% of its initial sensitivity after 4 months). The linear response is 1.0×10 −5 to 1.3×10 −3 mol L −1 glucose. The glucose content in real samples such as commercial glucose injection preparations and wines was determined, and the results were comparable to the values obtained from a commercial glucose assay kit based on a spectrophotometric method.

Biosensors for determination of glucose with glucose oxidase immobilized on an eggshell membrane

A glucose biosensor using an enzyme-immobilized eggshell membrane and oxygen electrode for glucose determination has been fabricated. Glucose oxidase was covalently immobilized on an eggshell membrane with glutaraldehyde as a cross-linking agent. The glucose biosensor was fabricated by positioning the enzyme-immobilized eggshell membrane on the surface of a dissolved oxygen sensor. The detection scheme was based on the depletion of dissolved oxygen content upon exposure to glucose solution and the decrease in the oxygen level was monitored and related to the glucose concentration. The effect of glutaraldehyde concentration, pH, phosphate buffer concentration and temperature on the response of the glucose biosensor has been studied in detail. Common matrix interferents such as ethanol, d-fructose, citric acid, sodium benzoate, sucrose and l-ascorbic acid did not give significant interference. The resulting sensor exhibited a fast response (100 s), high sensitivity (8.3409 mg L−1 oxygen depletion/mmol L−1 glucose) and good storage stability (85.2% of its initial sensitivity after 4 months). The linear response is 1.0×10−5 to 1.3×10−3 mol L−1 glucose. The glucose content in real samples such as commercial glucose injection preparations and wines was determined, and the results were comparable to the values obtained from a commercial glucose assay kit based on a spectrophotometric method.

Viscoelasticity of dynamically fixed bioprosthetic valves. II. Effect of glutaraldehyde concentration

Objectives: We have previously shown the benefits of dynamic fixation over conventional static fixation of bioprosthetic valves. In an attempt to increase the durability of bioprosthetic heart valves, we explored the benefit of low-concentration glutaraldehyde dynamic fixation. Methods: Pig aortic valves obtained fresh from the abattoir and excised with the entire root were dynamically fixed in glutaraldehyde phosphate buffer solutions varying in concentration from 0.05% to 2.5%. Denaturation temperatures were measured and mechanical testing was performed at low (3 mm/sec) to high physiologic rates (30 mm/sec) at 37° C in isotonic modified Hanks solution. Results: When fixed dynamically in 0.05% glutaraldehyde solution for 24 hours, the tissue reached a degree of cross-linking (denaturation temperature = 82.8° ± 0.6° C) significantly higher than that obtained for 0.05% static fixation (denaturation temperature = 79.3° ± 0.9° C) ( p < 0.05) but similar to that for conventional static fixation in 0.5% glutaraldehyde solution (denaturation temperature = 83.5° ± 0.3° C). After fixation in low-concentration glutaraldehyde (0.05%), final relaxation slopes and moduli in the circumferential direction were significantly higher than those for the statically fixed tissue but similar to those for the fresh tissue. However, both dynamic and static fixation had the effect of increasing tissue extensibility to similar extents in both directions, irrespective of glutaraldehyde concentration. Conclusion: Dynamic glutaraldehyde fixation of a porcine aortic valve at lower concentrations resulted in a better degree of cross-linking and a material with biomechanical properties that more closely mimic those of natural heart valve tissue. (J thorac Cardiovasc Surg 1997;113:302-10)

Laboratory validation of a diffusive sampler for the determination of glutaraldehyde in air

A diffusive sampling method has been validated for determination of glutaraldehyde in air. The sampler consists of a filter impregnated with 2,4-dinitrophenylhydrazine, mounted in a polypropylene housing. The uptake rate was determined to be 11.8 ml/min, with a relative standard deviation of 13%. The effect of glutaraldehyde concentration, sampling time and relative humidity on uptake rate was undetectable or small. The temperature effect was significant, about 1.5%/°C. The samplers are stable for at least two weeks at 22°C. The detection limit is about 0.03 mg/m 3 for a 15-min sample.

Effect of glutaraldehyde concentration and fixative temperature on the number of spermatozoa with normal acrosomes in goat semen

Two experiments were conducted to determine the best fixative solution and the most suitable temperature for fixing sperm cells from goat ejaculates. In Experiment 1, a 6×3 factorial design was used to test 4 glutaraldehyde concentrations (0.5, 1, 2 and 4%) plus 1 treatment that did not contain a fixative (0%) but to which 0.3% sodium fluoride (NaF) had been added to immobilize the spermatozoa; the control treatment contained no fixative or NaF. The 6 treatments were tested with 3 different solvents: PBS, Na citrate and BL-1, representing a total of 18 samples per replicate. The fixed samples always provided a significantly higher (P<0.01) percentage of normal acrosomes than the unfixed samples, whether immobilized with NaF or observed inmediately after dilution. In Experiment 2, a 3×3 factorial design was used to determine the effect of the temperature of the glutaraldehyde fixative solution on the number of morphologically normal acrosomes from goat semen samples kept at 3 different temperatures. Our findings indicated that at all 3 fixative solution temperatures (5, 20 and 37°C) there was a significant difference (P<0.01) in the percentage of normal acrosomes. At 5°C, glutarhaldehyde yielded a general mean number of 53.6 normal acrosomes vs 75.1 at 20°C and 83.05 at 37°C. Based on these results, we recommend that the temperature of a fixative solution be established when designing an experiment using goat semen, since the temperature has a significant effect on the number of the normal acrosomes found in a semen sample.

Collagen Cross‐Linking and Resorption: Effect of Glutaraldehyde Concentration

Cross-linked collagen bioprostheses usually are designed to be inert and nonresorbable, resulting in fatigue and wear failure in high-stress environments. Eventual replacement of the implant, although minimizing strength loss during resorption, would result in a graft with reparative ability. Kangaroo tail tendon (KTT) partially cross-linked with glutaraldehyde (GA) was evaluated in vitro for resistance to bacterial collagenase digestion and in vivo for biocompatibility and resorbability in an intramuscular implant assay. Cross-linking was quantified by thermal denaturation studies. Incomplete cross-linking was achieved with concentrations of GA less than 0.1% (w/v). KTT cross-linked in greater than or equal to 0.05% GA were collagenase resistant being incompletely digested after 240 h. Cross-linking of KTT with low concentrations of GA resulted in partial collagenase resistance and slowed resorption.

Urease bound to chitin with glutaraldehyde.

The enzyme urease (urea amidohydrolase, EC 3.5.1.5) prepared from Cajanus indicus, has been immobilized with glutaraldehyde-treated chitin as the solid support. The immobilized enzyme was characterized by determining the pH profiles and optimum temperature. Effect of glutaraldehyde concentration on the binding of enzyme to chitin was studied. The storage stability of the chitin-urease system was determined.

PREPARATION AND CHARACTERIZATION OF α‐AMYLASE IMMOBILIZED ON COLLAGEN MEMBRANES

Crystalline pancreatic α‐amylase was codispersed with hide collagen at pH 4.0 and tanned to form a membrane which degraded starch. The optimum pH for the codispersed membrane preparation was at pH 7.0 in contrast to the soluble enzyme which was as active at pH 8.0 as at pH 7.0. The immobilized enzyme responded maximally to 0.22M chloride whereas 0.02M chloride gave optimum rates for the soluble enzyme. The immobilized enzyme resisted thermal inactivation better than the soluble α‐amylase. Raising the temperatures from 30 ° to 50 °C produced a 500% increase in rate for the bound enzyme. It was also demonstrated that membranes retained greater activity when stored in starch solution than in water. The effect of glutaraldehyde concentration on membrane activity was also studied.