Showing papers on "Glutaraldehyde published in 2012"
TL;DR: 5 different CALB biocatalysts were prepared following the previous described protocols, and its stability and activity, pH/activity profile and specificity versus R and S methyl mandelate were analyzed, suggesting that the immobilization protocol may greatly affect the final effect of a chemical modification on the enzyme properties.
192 citations
TL;DR: The results suggest that the nano-insulin-loaded hydrogels are a promising non-invasive TDD system for diabetes chemotherapy.
141 citations
TL;DR: Candida antarctica lipase B immobilization by covalent attachment on chitosan and on ch itosan–alginate complex previously activated by different strategies was studied.
130 citations
TL;DR: Investigation of the tensile and compression properties of the scaffolds found that the mechanical property of S2-0.04% is closest to that of S1, which indicates that it is a feasible method to prepare the GA cross-linked collagen/chitosan scaffold.
112 citations
TL;DR: In this paper, a polyvinyl alcohol/chitosan, PCS, blended membrane is prepared by direct blend process and solution casting method, in order to reduce the swelling ratio and enhance the chemical and thermal stabilities of the PCS.
112 citations
TL;DR: In this article, the crosslinking of polyvinyl alcohol (PVA) using glutaraldehyde as the crosslink agent was investigated. And the cross-link time was shown to have an effect on the pore size distribution.
92 citations
TL;DR: The glutaraldehyde activated PVA- co -PE nanofibrous membrane is a promising solid support media for enzyme immobilization, and the immobilized enzymes could have broad biocatalytic applications.
Abstract: Poly(vinyl alcohol- co -ethylene) (PVA- co -PE) nanofibrous membranes were successfully fabricated and activated with glutaraldehyde (GA) to interact with enzyme molecules. A lipase isolated from Candida rugosa was employed as a model biocatalyst and successfully immobilized onto the membrane surfaces via covalent bonds with the aldehyde groups. Scanning electron microscopy images revealed that the membranes retained uniform nanofibrous and open porous structures after the treatments. The results indicated that the increment of the initial glutaraldehyde concentration induced an increase of the enzyme loading on the membrane surfaces but a decrease in the activity of the immobilized enzyme. Under an optimum condition, the glutaraldehyde activated PVA- co -PE nanofibrous membrane reached the highest enzyme activity at 676.19 U/g of the membrane. The pH tolerance, thermal and storage stability of the immobilized lipase were significantly improved. In addition, the immobilized lipase can be easily recovered and retained at 67% of its initial activity after 10 time uses. Therefore, the glutaraldehyde activated PVA- co -PE nanofibrous membrane is a promising solid support media for enzyme immobilization, and the immobilized enzymes could have broad biocatalytic applications.
91 citations
TL;DR: The morphology of gelatin nanoparticles loaded with three different drugs (Tizanidine hydrochloride, Gatifloxacin and Fluconazole) and their characteristics of entrapment and release from gelatin nanop articles were investigated by the analysis on nanoparticle size distribution, SEM and FT-IR in this study.
Abstract: The morphology of gelatin nanoparticles loaded with three different drugs (Tizanidine hydrochloride, Gatifloxacin and Fluconazole) and their characteristics of entrapment and release from gelatin nanoparticles were investigated by the analysis on nanoparticle size distribution, SEM and FT-IR in this study. The particles were prepared by nanoprecipitation using water and ethanol as a solvent and a nonsolvent, respectively. The exclusion of a crosslinking agent from the procedure led the system to have an irregularly-shaped morphology. Nonetheless, the uncrosslinked case of Gatifloxacin loading generally led to a more homogeneous population of nanoparticles than the uncrosslinked case of Tizanidine hydrochloride loading. No loading was achieved in the case of Fluconazole, whereas both Tizanidine hydrochloride and Gatifloxacin are observed of being capable of being loaded by nanoprecipitation. Tizanidine hydrochloride-loaded, blank and Gatifloxacin-loaded nanoparticles yielded, under crosslinked condition, 59.3, 23.1 and 10.6% of the used dried mass. The crosslinked Tizanidine hydrochloride-loaded particles showed the loading efficiency of 13.8%, which was decreased to 1.1% without crosslinking. A crosslinker such as glutaraldehyde is indispensable to enhance the Tizanidine hydrochloride-loading efficiency. To the contrary, the Gatifloxacin-loading efficiency for crosslinked ones was lower by a factor of 2–3 times than that for uncrosslinked ones. This is due to the carboxylic groups of Gatifloxacin and the aldehyde groups of glutaraldehyde competing with each other during the crosslinking process, to react with the amino groups of gelatin molecules. The loading efficiency of gelatin nanoparticles reported by other investigators greatly varies. Nevertheless, the loading efficiency reported by us is in good agreement with the drug-loading data of gelatin nanoparticles reported by other investigators. The 80% of loaded Tizanidine hydrochloride was released around 15 h after start-up of the release experiment, while the 20% of loaded Gatifloxacin was released more rapidly, as free Gatifloxacin, than the loaded Tizanidine hydrochloride and it showed the trend of sustained slow release during the remaining period of its release experiment. Furthermore, the result of comparative FT-IR analysis is consistent to that of the corresponding drug release study.
87 citations
TL;DR: In vivo studies revealed a significant reduction in blood glucose level after administration of the optimized formulation, in comparison to a subcutaneous insulin injection, and chitosan microspheres were superior in terms of sustaining protein release over conventional insulin therapy.
86 citations
TL;DR: The Hb entrapment efficiency ranged from 8 to 50% corresponding to a hemoglobin quantity per Hb-MP of at least one-third of that in one erythrocyte, and phagocytosis assays showed low immunogenicity of HB-MPs if the particles were cross-linked with low concentration of GA and treated with sodium borohydride.
76 citations
TL;DR: Genipin fixation is a novel alternative to conventional GA fixation in vitro material assessment and in vivo anticalcification effect and GA groups are superior to genipin groups in tissue cross-linking without difference according to addition of decellularization, organic solvent treatment, and detoxification by resistance toward pronase degradation.
Abstract: OBJECTIVE: Calcification plays a major role in the failure of bioprosthetic and other tissue heart valve substitutes. The objective of this study was to evaluate the anticalcification effect of decellularization and detoxification in glutaraldehyde (GA)/genipin- and solventfixed bovine pericardium using a rabbit intramuscular model which is effective for assessing calcification in bioprosthetic tissue. METHODS: Bovine pericardial tissues were fixed with 0.5% GA/0.4% genipin in organic solvent (75% ethanol + 5% octanol, 75% ethanol + 5% octanediol, or 70% ethanol + 10% isopropanol) and post-treated with glycine, glutamic acid, or sodium bisulfite. Decellularization was performed with 0.25% sodium dodecylsulfate prior to fixation. The material characteristics of the treated tissues were assessed by thermal stability test, uniaxial mechanical test, and light microscopy. Stability of the treated tissue was measured by the resistance to enzymatic degradation using protease. The tissues were intramuscularly implanted into 4-week-old rabbits for 8 weeks, and the anti-αGal(Gal[alpha]1,3-Gal[beta]1,4GlcNAc-R) antibodies (immunoglobulin G) were measured at various time intervals after implantation. Explanted tissues were examined by light microscopy and calcium contents of the explanted tissues were measured. RESULTS: Differently treated tissues resulted in no significant alterations in material characteristics and morphology. GA groups are superior to genipin groups in tissue cross-linking without difference according to addition of decellularization, organic solvent treatment, and detoxification by resistance toward pronase degradation. The titer of anti-α-Gal antibodies gradually increased after implantation in all study groups. The titer of anti-α-Gal antibodies increased less in genipin groups than in GA groups, and less with decellularization than without decellularization. The calcium contents of genipin groups (n= 75) were significantly lower than those of GA groups (n= 118) (28.55 ± 11.22 μ gm g �1 vs 37.16 ± 7.75 μ gm g �1 , p < 0.001). Calcium contents decreased with decellularization, organic solvent treatment, and detoxification, irrespective of the type of organic solvent and amino acids. Inorganic phosphorus contents of genipin groups (n= 66) were significantly lower than those of GA groups (n= 103) (55.36 ± 26.98 μ gm g �1 vs 75.67 ± 23.44 μ gm g �1 , p= 0.000). CONCLUSIONS: Genipin fixation is a novel alternative to conventional GA fixation in vitro material assessment and in vivo anticalcification effect. The addition of decellularization, organic solvent treatment, and detoxification prevented calcification of GA/genipin-fixed bovine pericardium in the rabbit intramuscular implantation model, irrespective of the type of organic solvent and amino acids.
TL;DR: In this article, the CLEA technique was used to immobilize the lipase B from Candida antarctica (CALB) using BSA-CLEA and bovine serum albumin was used as a feeder to improve the crosslinking.
Abstract: Lipase B from Candida antarctica (CALB) has been immobilized using the CLEA technique. Due to the low content of surface Lys on the enzyme and the purity of the commercial preparation, CALB crosslinking did not work properly, and it was always possible to find some CALB (as molecules or soluble aggregates) when analyzing the CLEA using SDS-PAGE. To improve the crosslinking, bovine serum albumin was used as a feeder, and after optimization using response surface methodology, the glutaraldehyde crosslinking step was effective, and permitted to greatly stabilize the enzyme (no activity decrease was observed after a time where the free enzyme was almost fully inactivated). After two experimental designs, the best conditions for preparation of CALB–BSA-CLEA were: protein concentration (3 mg/mL), tert-butylalcohol as precipitant, precipitation for 60 min; precipitant concentration, 50% v/v; and glutaraldehyde concentration (1.5% w/v).
TL;DR: G gelatin nanofibers are electrospun from phosphate buffer saline/ethanol binary mixtures as a benign solvent at ambient temperature and 3T3 fibroblasts displayed spindle-like morphology, similar to the cell's normal morphology in a 3D extracellular matrix.
Abstract: Electrospinning of natural polymer nanofibers useful for biomedical applications often requires the use of cytotoxic organic solvents. In this study, gelatin nanofibers are electrospun from phosphate buffer saline/ethanol binary mixtures as a benign solvent at ambient temperature. The influences of ionic strength, ethanol concentration, and gelatin concentration on the electrospinnability of gelatin solutions and the fiber microarchitectures are analyzed. The electrospun scaffolds retain their morphologies during vapor-phase crosslinking with glutaraldehyde in ethanol and the subsequent removal of salts contained in the nanofibers via water rinsing. When fully hydrated, the mechanically preconditioned scaffolds display a Young's modulus of 25.5 ± 5.3 kPa, tensile strength of 55.5 ± 13.9 kPa, deformability of 160 ± 15%, and resilience of 89.9 ± 1.8%. When cultured on the gelatin scaffolds, 3T3 fibroblasts displayed spindle-like morphology, similar to the cell's normal morphology in a 3D extracellular matrix.
TL;DR: The cationic demand and pitch deposits in whitewater were reduced by 58% and 74%, respectively, when treating whitewater with immobilized dual-enzymes for 15min at 55°C and pH 7.5.
TL;DR: In this article, a high flux thin film nanofibrous composite (TFNC) membrane consisting of a nonwoven non-woven supporting layer and a thin hydrophilic barrier layer was developed and used as an ultrafiltration media to separate an oil/water emulsion at low feeding pressure.
TL;DR: Covalent bonding between BC and fibrin occurred via glutaraldehyde, affording mechanical properties comparable to that of the native small blood vessel.
Abstract: Bacterial cellulose/fibrin composites were treated with glutaraldehyde in order to crosslink the polymers and allow better match of the mechanical properties with those of native small-diameter blood vessels. Tensile and viscoelastic properties of the glutaraldehyde treated composites were determined from tensile static tests and cyclic creep tests, respectively. Glutaraldehyde-treated (bacterial cellulose) BC/fibrin composites exhibited tensile strength and modulus comparable to a reference small-diameter blood vessel; namely a bovine coronary artery. However, the breaking strain of the glutaraldehyde-treated composites was still well below that of the native blood vessel. Yet a long strain hardening plateau was induced by glutaraldehyde treatment which resembled the stress–strain response of the native blood vessel. Tensile cyclic creep test indicated that the time-dependent viscoelastic behavior of glutaraldehyde-treated BC/fibrin composites was comparable to that of the native blood vessel. Covalent bonding between BC and fibrin occurred via glutaraldehyde, affording mechanical properties comparable to that of the native small blood vessel.
TL;DR: Ultraviolet spectrum analysis showed that the largest loading efficiency and encapsulation efficiency could be 8.55% and 94.01%, respectively, among blank chitosan nanoparticles prepared by emulsification-crosslinking method in a W/O emulsion system.
TL;DR: The addition of glutaraldehyde and nanoclay has been found to improve the thermal stability, flame retardancy, dimensional stability and mechanical strength of the prepared composite.
TL;DR: Results show that the addition of ethanol permits to have a distance between enzyme molecules that did not allow intermolecular crosslinking, and this has permitted to distinguish between the effects of intramolecular glutaraldehyde modifications and intermolescular glutARaldehyde crossl linking.
TL;DR: The regeneration of support was investigated by reactivating the deactivated immobilized lipase with glutaraldehyde and the results indicated that these regenerated supports remained to be efficient for lipase immobilization.
Abstract: Superparamagnetic sodium alginate nanoparticles with diameter around 25–30 nm were prepared with a water-in-oil emulsion method. The resulted magnetic SA nanoparticle was activated with glutaraldehyde and epichlorohydrin to form nanoscale support. Candida rugosa lipase (CRL), hereby chosen as a model enzyme, was covalently immobilized on the resulted magnetic support. The structure and magnetic behavior of the magnetic nanoparticles were confirmed by transmission electron microscopy, Fourier transform infrared spectroscopy, and vibrating sample magnetometer. Based on the structural character of enzyme (containing functional residues that are ideal reaction sites for the immobilization of enzyme repeatedly), the regeneration of support was investigated by reactivating the deactivated immobilized lipase with glutaraldehyde. And the results indicated that these regenerated supports remained to be efficient for lipase immobilization. Finally, all of the immobilized CRL prepared by different generations of supports displayed excellent reusability and applicability.
TL;DR: The results support the idea that controlling hydrophobic interactions is a means to control the size of α-LA nanoparticles, which are very stable at pH values >4.8, based on their ζ-potential, although their antioxidant activity is weak.
TL;DR: Unless they had been treated with a sodium metabisulfite aqueous solution, these hydrogels were proven, based on the indirect cytotoxicity evaluation, to be toxic to human's normal skin fibroblasts.
Abstract: The silver nanoparticle (nAg)-loaded gelatin hydrogel pads were prepared from 10 wt % gelatin aqueous solution containing silver nitrate (AgNO3) at 0.75, 1.0, 1.5, 2.0, or 2.5 wt % by solvent-casting technique. These AgNO3-containing gelatin solutions, that had been aged for 15, 12, 8, 8, and 8 h, respectively, showed noticeable amounts of the as-formed nAgs, the size of which increased with an increase in the AgNO3 concentration (i.e., from 7.7 to 10.8 nm, on average). The hydrogels were crosslinked with a glutaraldehyde aqueous solution (50 wt %, at 1 μL mL−1). At 24 h of submersion in phosphate buffer saline (PBS) or simulated body fluid buffer (SBF) solution, about 40.5–56.4% or 44.4–79.6% of the as-loaded amounts of silver was released. Based on the colony count method, these nAg-loaded hydrogels were effective against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, with at least about 99.7% of bacterial growth inhibition. Unless they had been treated with a sodium metabisulfite aqueous solution, these hydrogels were proven, based on the indirect cytotoxicity evaluation, to be toxic to human's normal skin fibroblasts. Lastly, only the hydrogels that contained AgNO3 at 0.75 and 1.0 wt % were not detrimental to the skin cells that had been cultured directly on them. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
TL;DR: In this article, six different methods used for EPS extraction, including ultrasonication, heating, formaldehyde + NaOH, H2SO4, glutaraldehyde, and EDTA, from Bacillus megaterium TF10, a bacterium with a high EPS-producing capacity isolated from a soil sample, are investigated.
TL;DR: In this article, the polysulfone membrane (PS) and β-cyclodextrin glutaraldehyde (XβCD) crosslinked polySulfone membranes (β-CDXM) were prepared by phase inversion technique from the solutions prepared by solubilizing poly sulfone polymer, β-cycle in N, N-dimethyl formamide (DMF) and adding glutaraaldehyde.
Journal Article•
TL;DR: Alpha amylase from Bacillus amyloliquefaciens was immobilized as cross-linked enzyme aggregates (CLEAs) and Scanning electron microscopy analysis showed that morphology of CLEAs substantially changed after 4 reuses, and substrate affinity of the enzyme increased.
Abstract: Stabilization of enzymes is one of the major challenges in biocatalytic processes. Alpha amylase from Bacillus amyloliquefaciens was immobilized as cross-linked enzyme aggregates (CLEAs). Alpha amylase was aggregated using ammonium sulfate. The resultant aggregates on cross-linking with glutaraldehyde produced insoluble catalytically active cross-linked enzyme aggregates. The effects of precipitation and cross-linking were studied and immobilized alpha amylase was characterized. Seventy percent ammonium sulfate saturation, 2% (v/v) glutaraldehyde, were used; 6 h cross-linking reaction at room temperature was performed and 100% activity recovery was achieved in CLEAs with enhanced thermal and acidic condition stabilities. The cross-linked enzyme aggregates exhibited pH optima of 6.0 and higher temperature optima of 60°C. Although after immobilization maximum velocity of enzyme reaction did not change, substrate affinity of the enzyme increased. Alpha amylase CLEAs retained 65% activity after 4 reuses with 30 min of each reaction time. The Scanning electron microscopy analysis showed that morphology of CLEAs substantially changed after 4 reuses.
TL;DR: In this paper, a homogeneous α-amylase was extracted and purified from soybean seeds to apparent homogeneity by affinity precipitation, and the homogeneous enzyme preparation was immobilized on gelatin matrix using glutaraldehyde as an organic hardener.
TL;DR: Electrodes prepared by crosslinking using glutaraldehyde vapour, without and with a NaBH(4) reduction, provide higher glucose oxidation current than those prepared using a well-established diepoxide method and potential application to implantable enzymatic biofuel cells is demonstrated.
Abstract: Co-immobilisation approaches for preparation of glucose-oxidising films of [Os(2,2′-bipyridine)2(poly-vinylimidazole)10Cl] and glucose oxidase on glassy carbon electrodes are compared. Electrodes prepared by crosslinking using glutaraldehyde vapour, without and with a NaBH4 reduction, provide higher glucose oxidation current than those prepared using a well-established diepoxide method. Addition of multi walled carbon nanotubes to the film deposition solutions produces an enhanced glucose oxidation current density of 5 mA cm−2 at 0.35 V vs. Ag/AgCl, whilst improving the operational stability of the current signal. Carbon nanotube, glutaraldehyde vapour crosslinked, films on electrodes, reduced by NaBH4, retain 77% of initial catalytic current over 24 hours of continuous amperometric testing in a 37 °C, 50 mM phosphate buffer solution containing 150 mM NaCl and 100 mM glucose. Potential application of this approach to implantable enzymatic biofuel cells is demonstrated by production of glucose oxidation currents, under pseudo-physiological conditions, using mediating films with lower redox potentials.
TL;DR: In this paper, a novel nanofiber membrane was fabricated by electrospinning composed of polyvinyl phosphonic acid (PVPA) and PVA to stabilize the high dissolvability of the membrane when in contact with water.
Abstract: A novel nanofiber membrane was fabricated by electrospinning composed of polyvinyl phosphonic acid (PVPA) and polyvinyl alcohol (PVA). Stabilization was done due to the high dissolvability of the membrane when in contact with water. Physical treatment was done by exposure to heat at 150°C in a vacuum environment at different periods of time. Chemical crosslinking was done by immersion inmethanol and methanol/ glutaraldehyde. A heat-exposed membrane was also further crosslinked chemically. All conditions were compared with regards to its effect on the material properties of the membranes and its biological response in vitro with MG-63 osteoblast-like cell line. Visual examination and dimensional analyses showed that heat treatment produced discoloration on the membrane surface and chemical crosslinking reduced membrane dimensions. Tensile strength and strain improved in crosslinked membranes compared to noncrosslinked counterpart. Swelling and degradation was also investigated and was seen to vary depending on the crosslinking condition. Biocompatibility was observed to be more favorable in heat-treated membranes.
TL;DR: In this article, the synthesis, characterization, preliminary cytocompatibility, and degradation behavior of the hybrids based on 70% Poly(vinyl alcohol) and 30% bioactive glass (58SiO2-33CaO-9P2O5, BaG) with macroporous tridimensional structure is reported for the first time.
Abstract: The synthesis, characterization, preliminary cytocompatibility, and degradation behavior of the hybrids based on 70% Poly(vinyl alcohol) and 30% bioactive glass (58SiO2-33CaO-9P2O5, BaG) with macroporous tridimensional structure is reported for the first time. The effect of glutaraldehyde covalent crosslinker in the organic-inorganic nanostructures produced and, as a consequence, tailoring the hybrids properties was investigated. The PVA/BaG hybrids scaffolds are characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray Microcomputed tomography analysis (µCT). Cytotoxicity assessment is performed by the MTT method with VERO cell culture. Additionally, the hybrid in vitro degradation assay is conducted by measuring the mass loss by soaking in deionized water at 37°C for up to 21 days. The results have clearly shown that it is possible to modify the PVA/BaG hybrids properties and degradation behavior by engineering the structure using different concentrations of the chemical crosslinker. Moreover, these hybrid crosslinked nanostructures have presented 3D hierarchical pore size architecture varying within 10-450 µm and a suitable cytocompatibility for potential use in bone tissue engineering applications.
TL;DR: In this paper, the effects of cross-linker, including crosslinker concentration and cross-linking time, on the diameter, swelling ratio and cytotoxicity in-vitro of the microspheres were investigated.
Abstract: Gelatin/chitosan (Gel/Cs) microspheres were prepared by water/oil (W/O) elusion with the use of chemical cross–linking agent of glutaraldehyde. The effects of cross-linking, including cross-linker concentration and cross-linking time, on the diameter, swelling ratio and cytotoxicity in-vitro of the microspheres were investigated. The results showed that the diameter of Gel/Cs microspheres decreased with increasing cross-linker content and cross-linking time period. Further, the swelling ratio of microspheres also decreased as increasing cross-linker content and cross-linking time. This indicated that the diameter and swelling ratio of the Gel/Cs microspheres can be achieved by controlling the amount of the cross-linking agent and the cross-linking time. The microsphere extracts with lower contents of glutaraldehyde (0.5 wt% and 1 wt%) were no toxic; however, the extract with 2.5 wt% of glutaraldehyde showed potential cytotoxicity.