Showing papers on "Glutaraldehyde published in 2016"
TL;DR: In this paper, a purified laccase from the white rot fungus Trametes pubescens was entrapped onto chitosan beads with the crosslinker glutaraldehyde, in order to improve the stability and recovery rate of Tplac, and was applied in decolorization of various synthetic dyes.
153 citations
TL;DR: The changes in secondary structures revealed the enhancements in structural and conformational rigidity attributed by cross-linkers, and after five consecutive cycles dextran M-CLEAs retained 1.25 times higher initial activity than G- CLEAs.
114 citations
TL;DR: Cytotoxicity analysis showed the superior biocompatibility of the naturally occurring genipin in comparison with other synthetic crosslinking agents, in particular relative to GTA-crosslinked samples.
103 citations
TL;DR: Collagen hydrogels, which are comprised of fibrils and possess three-dimensional network structure, were prepared via self-assembly of collagen molecules and sequentially incubated in glutaraldehyde (GTA) solutions with different [CHO]/[NH 2 ] ratios, demonstrating the homogeneous reaction.
85 citations
TL;DR: In-vitro activity measurements indicated a sustained and controlled TCH time-release pattern and excellent antibacterial activity against E. coli, as assessed by UV-vis spectroscopy and viable cell counting.
83 citations
TL;DR: In this paper, porous nanofiber-microsphere mats of collagen (COL)/polyvinyl alcohol (PVA) containing salicylic acid (SA) as model drug were prepared by electrospinning for the assessment of drug delivery system.
82 citations
TL;DR: Although the hybrid hydrogels crosslinked with GEN presented a lower elastic modulus, the main advantage is that GEN is five to ten thousand times less cytotoxic than GA, which means that the structural and mechanical properties of hybrid hydrology can easily be tuned and could have potential applications in the tissue engineering, regenerative medicine, food, agriculture and environmental industries.
80 citations
TL;DR: Aminated starch coated iron oxide magnetic nanoparticles loaded with curcumin showed good internalization in HepG2 cells along with considerable ROS formation and the release of drug was dependent on time, crosslinker nature, cross linker concentration and pH of the medium.
65 citations
TL;DR: The key role of hydrophobic interactions for CGC materials was evidenced by the controlled sorptive uptake of carboxylate anions with variable molecular structure, which contributes to a greater understanding of the sorption properties of the two types of abundant biopolymers and their composites.
Abstract: Self-assembled and cross-linked chitosan/cellulose glutaraldehyde composite materials (CGC) were prepared with enhanced surface area and variable morphology. FTIR, CHN, and 13C solid state NMR studies provided support for the cross-linking reaction between the amine groups of chitosan and glutaraldehyde; whereas, XRD and TGA studies provided evidence of cellulose–chitosan interactions for the composites. SEM, equilibrium swelling, and nitrogen adsorption studies corroborate the enhanced surface area and variable morphology of the cross-linked biopolymers. Equilibrium sorption studies at alkaline conditions with phenolic dyes, along with single component and mixed naphthenates in aqueous solution revealed variable uptake properties with the composites. The Freundlich isotherm model revealed that the composite at the highest levels of cross-linker, CGC3, had the highest sorption affinity (KF; L mmol/g) for phenolphthalein (phth) followed by ortho-nitrophenyl acetic acid (ONPAA) and para-nitrophenol (PNP), a...
52 citations
TL;DR: In this article, a magnetic chitosan bead crosslinked with glutaraldehyde was used for Cs(I) removal from aqueous solution, and the maximum adsorption capacity was estimated at 3.86 µmg/g from the Langmuir isotherm.
50 citations
TL;DR: The results demonstrate that the enzyme activity and stability were greatly improved for the immobilization PFL, and highly pure enantiomers from racemic 1-PEOH were effectively achieved using the immobilized PFL.
Abstract: A porous polyurea (PPU) was prepared through a simple protocol by reacting toluene diisocyanate with water in binary solvent of water–acetone. Its amine group was determined through spectrophotometric absorbance based on its iminization with p-nitrobenzaldehyde amines. PPU was then used as a novel polymer support for enzyme immobilization, through activation by glutaraldehyde followed by immobilization of an enzyme, lipase from Pseudomonas fluorescens (PFL), via covalent bonding with the amine groups of lipase molecules. Influences of glutaraldehyde and enzyme concentration and pH in the process were studied. The results revealed that the activity of the immobilized PFL reached a maximum at GA concentration of 0.17 mol/L and at pH 8. Immobilization rate of 60% or higher for PFL was obtained under optimized condition with an enzyme activity of 283 U/mg. The porous structure of PPU, prior to and after GA activation and PFL immobilization, was characterized. The activity of the immobilized PFL at different t...
TL;DR: An initial characterization of a type of collagen protein revealed that the type I collagen protein used is considerably denatured, and increasing the protein content in the scaffold decreases the porosity, related to an increase in the elastic modulus producing an enhancement of its mechanical strength.
Abstract: Several studies have shown the influence of the physical properties of scaffolds on their mechanical properties. An initial characterization of a type of collagen protein was carried out by studying its composition andits solubility at different pH values and infrared spectroscopy. Subsequently, porosity and scaffold pore size were studied, assessing how varying the composition of the initial solution (increasing the protein concentration or adding glutaraldehyde) changed the properties of the final scaffolds obtained. Lastly, rheological measurements were performed to evaluate the mechanical strength of the scaffolds. The initial characterization revealed that the type I collagen protein used is considerably denatured. In addition, increasing the protein content in the scaffold decreases the porosity, related to an increase in the elastic modulus producing an enhancement of its mechanical strength, while adding glutaraldehyde to the scaffold increases its mechanical strength without lowering its pore size or porosity. The results obtained are useful in that they demonstrate that it is possible to design a scaffold with specific properties, by just controlling the collagen concentration or adding glutaraldehyde to the initial solution. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1462-1468, 2016.
TL;DR: A novel carbohydrate chain cross-linking method of sodium alginate (SA) is proposed in which glycogen with the branched-chain structure is utilized to cross-link with SA matrix by the bridging of glutaraldehyde (GA).
Abstract: A novel carbohydrate chain cross-linking method of sodium alginate (SA) is proposed in which glycogen with the branched-chain structure is utilized to cross-link with SA matrix by the bridging of glutaraldehyde (GA). The active layer of SA composite ceramic membrane modified by glycogen and GA for pervaporation (PV) demonstrates great advantages. The branched structure increases the chain density of the active layer, which compresses the free volume between the carbohydrate chains of SA. Large amounts of hydroxyl groups are consumed during the reaction with GA, which reduces the hydrogen bond formation between water molecules and the polysaccharide matrix. The two factors benefit the active layer with great improvement in swelling resistance, promoting the potential of the active layer for the dehydration of an ethanol–water solution containing high water content. Meanwhile, the modified active layer is loaded on the rigid α-Al2O3 ceramic membrane by dip-coating method with the enhancement of anti-deforma...
TL;DR: In this paper, a magnetically recoverable biocatalyst was successfully prepared through the immobilization of cellulase onto Fe 3 O 4 nanoparticles, which was synthesized by a hydrothermal method in an aqueous system.
TL;DR: The investigation of kinetic parameters of enzymatic reaction shows the decreasing of Km and vmax due to immobilization which represents the increasing of substrate affinity and decreasing of catalytic activity of immobilized enzyme.
TL;DR: The observed trends are in agreement with the greater surface accessibility and pore structure properties of cross-linked chitosan based on scanning electron microscopy studies, and further illustrate the rational design of chitOSan-based materials for the controlled uptake of urea in aquatic environments.
TL;DR: The immobilization of lipase onto PAMAM-dendrimer-grafted magnetic nanoparticles synthesized by a modified solvothermal reduction method was facile and eco-friendly for applications in lipase immobilization.
Abstract: This paper reported an immobilization of Candida rugosa lipase (CRL) onto PAMAM-dendrimer-grafted magnetic nanoparticles synthesized by a modified solvothermal reduction method. The dendritic magnetic nanoparticles were amply characterized by several instrumental measurements, and the CRL was covalently anchored on the three generation supports with glutaraldehyde as coupling reagent. The amount of immobilized enzyme was up to 150 mg/g support and the factors related with the enzyme activity were investigated. The immobilization of lipase improved their performance in wider ranges of pH and temperature. The immobilized lipase exhibited excellent thermal stability and reusability in comparison with free enzyme and can be reused 10 cycles with the enzymatic activity remained above 90 %. The properties of lipase improved obviously after being immobilized on the dendritic supports. The inactive immobilized lipase could be regenerated with glutaraldehyde and Cu2+, respectively. This synthetic strategy was facile and eco-friendly for applications in lipase immobilization.
TL;DR: In this article, a self-healing soy protein isolate (SPI)-based "green" thermoset resin is developed using poly(d,l-lactide-co-glycolide)(PLGA) microcapsules containing SPI, as crack healant.
Abstract: Self-healing soy protein isolate (SPI)-based “green” thermoset resin is developed using poly(d,l-lactide-co-glycolide)(PLGA) microcapsules containing SPI, as crack healant. The SPI–PLGA microcapsules with an average diameter of 778 nm that contain sub-capsules are prepared using a water-in-oil-in-water double-emulsion solvent evaporation technique. The encapsulation efficiency is found to be high, up to 89%. Thermoset green SPI resin containing the SPI–PLGA microcapsules successfully arrests and retards the microcracks. The healing efficiency is investigated using mode I fracture toughness test for resins containing different concentrations of microcapsules from 5 to 20 wt% and glutaraldehyde as a crosslinker at 9 or 12 wt%. The SPI resin containing 12 wt% glutaraldehyde and 15 wt% microcapsules shows self-healing efficiency of up to 48%. It is observed that the SPI released from SPI–PLGA microcapsules can react with the excess glutaraldehyde present in the resin when the two come in contact within the microcracks and bridge the two fracture surfaces. The results of this study show for the first time that SPI–PLGA microcapsules can self-heal protein-based green resins. The same method can be extended to self-heal other proteins as well as protein-based green composites resulting in higher fracture toughness and longer useful life.
TL;DR: The activated partial thromboplastin time and thrombin time results indicated that both of the HLCSs and their hydrogels exhibited excellent thrombus inhibition property, and the contact activation and complement activation results proved that the hydrogel possessed good blood compatibility and had the potential to be used as blood-contacting materials.
TL;DR: In this paper, porine pancreas lipase was immobilized on mesoporous chitosan beads, and the characteristics of the immobilized lipases such as immobilization efficiency, enzyme activity, pH stability, thermal stability, reusability, storage stability and enzyme leakage were evaluated.
Abstract: Porcine pancreas lipase was immobilized on mesoporous chitosan beads. Glutaraldehyde as coupling agent was used through several immobilization techniques. With the aid of FESEM, BET and BJH analysis, the effect of glutaraldehyde on porosity of chitosan was evaluated. It was observed that the total surface area and pore volume of the carrier were significantly improved by addition of glutaraldehyde as cross-linking agent. The surface area exposure and pore volume were substantially increased (both by 4.4 folds). In addition, distribution of enzyme on the carrier was illustrated by fluorescence image. The characteristics of the immobilized lipases such as immobilization efficiency, enzyme activity, pH stability, thermal stability, reusability, storage stability and enzyme leakage were evaluated. In kinetic studies of enzyme, Michaelis–Menten kinetic coefficients of the hydrolytic activity for the immobilized lipase were defined using Lineweaver–Burk plot. The low value of ionization constant, Km (∼0.008 mM) and high value of specific rate, Vmax(∼200 μM/ml.min) indicate strong affinity and high activity of enzyme. The obtained results demonstrate that use of glutaraldehyde has an excellent impact on expansion of the porosity of chitosan and enzyme distribution. The immobilization efficiency increased by1.6 folds and enzyme leakage was minimized (17% reduced to zero); while, glutaraldehyde has improved pH stability (in acidic range), thermal stability, reusability and storage stability of immobilized lipase.
TL;DR: Chitosan provides an excellent immobilization environment for AChE biosensors designed to operate in environments containing high amounts of organic solvents and can enable future selection of the immobilization matrix and solvent type for the development of organic phase enzyme based systems.
TL;DR: In this paper, a nano-thin coatings of glutaraldehyde (GA)-crosslinked polyethyleneimine (PEI) are demonstrated to be highly stable under acidic conditions and retained their copper-binding selectivity after repeated cycles of binding and acid-mediated elution.
Abstract: Nano-thin coatings of glutaraldehyde (GA)-crosslinked polyethyleneimine (PEI) are extremely selective and effective in binding copper from seawater. Here it was demonstrated that GA-PEI performs significantly different from PEI. The copper-selectivity of self-assembled PEI coatings on silicon substrates was greatly improved by GA-crosslinking. After submersion in artificial seawater containing 200 ppb copper and equimolar amounts of 11 competing ions only copper and trace amounts of Zn were detected in the GA-crosslinked coatings, while for non-crosslinked PEI there was about 30% Zn present relative to copper. The coatings were demonstrated to be highly stable under acidic conditions and retained their copper-binding selectivity after repeated cycles of binding and acid-mediated elution. After self-assembly of the GA-crosslinked coating on mesoporous diatomaceous earth particles, significant amounts of copper could be extracted from 200 ppb in artificial seawater and eluted under acidic pH.
TL;DR: In this paper, Aspergillus niger beads from a microbial source, i.e., shellfish derived chitosan with three different molecular weights (low, medium and high), were used as enzyme carriers to be applied in a continuous packed-bed reactor (PBR) for white wine protein stabilization.
TL;DR: Enterococcus faecalis Esawy dextransucrase was immobilized in Fe(3+)-cross-linked alginate/carboxymethyl cellulose (AC) beads and immobilized enzyme was applied successfully in the synthesis of oligosaccharides and different molecular weights of dextran.
TL;DR: The functionalization of carrageenan with amine terminal functional group for the covalent immobilization of cellulase showed better stability for the immobilized enzyme.
Abstract: Cellulase was immobilized on the surface of carrageenan beads activated by using polyethyleneimine and glutaraldehyde, then immobilized cellulase was used to transform ginsenoside Rb1. In this work, we studied the functionalization of carrageenan with amine terminal functional group for the covalent immobilization of cellulase. The process of immobilization was performed by amination process on the surface of the carrageenan gel beads with polyethylenimine followed by activation with glutaraldehyde to finally immobilize the enzyme. Different factors affecting the amination and activation processes were studied and their effects on the catalytic activity of the immobilized cellulase were followed, then Fourier transform infrared spectroscopy and scanning electron microscopy were applied to verify the process. Furthermore, the optimum conditions of transformation of ginsenoside Rb1 were also studied and showed better stability for the immobilized enzyme. The best results were obtained using carrageenan as support and covalent binding method, which consisted of amination process (0.5% PEI (pH 8))) for 3 h and 3% GA in activation process for 3 h. These experiments gave optimum reaction condition of temperature at 60° C and pH 5.0. Enzyme after immobilization exhibited high activity with broader pH and temperature range. Full conversion and kinetic parameters Km and Vmax for them were also studied. The Km of immobilized enzyme, 3.64 mM, is lower than free one, 4.82 mM; and the Vmax of immobilized enzyme, 0.04 mM, is lower than free one, 0.06 mM. Results detected also show after using for 5 consecutive times, the immobilized enzyme can retain 60% of its initial activity.
16 Feb 2016
TL;DR: In this article, a series of novel cross-linked highly quaternized chitosan and poly (vinyl alcohol) membranes were successfully synthesized to be applied in alkaline direct ethanol fuel cells.
Abstract: A series of novel cross-linked highly quaternized chitosan and quaternized poly (vinyl alcohol) membranes were successfully synthesized to be applied in alkaline direct ethanol fuel cells. Cross-linking was accomplished using two different cross-linking agents and an additional thermal process to improve both chemical and thermal properties. Equivalent blends of chitosan and poly (vinyl alcohol) membranes with various degrees of cross-linking were prepared by using different amounts of glutaraldehyde and ethylene glycol diglycidyl ether as cross-linkers. To investigate their applicability in direct ethanol fuel cells, the membranes were characterized in terms of their structural properties, chemical, thermal and alkaline stability, ion transport and ionic properties using following methods: Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, scanning electron microscopy, thermogravimetric analysis, water uptake by mass change, ethanol permeability in the diffusion cell, back titration method (ion exchange capacity) and electrochemical impedance spectroscopy (anion conductivity). Despite the high degree of quaternization of the applied materials and regardless of the thin film thickness of the blend membranes, the novel cross-linked products displayed outstanding mechanical stability. The lower cross-linked membranes exhibited the best transport and ionic properties with a high anion conductivity of 0.016 S cm-1 and a high ion exchange capacity of 1.75 meq g-1, whereas membranes with a higher degree of cross-linking performed superior in terms of reduced ethanol permeability of 3.30âÂÂ10-7 cm2 s-1 at 60°C. The blend membranes - chemically and thermally cross-linked - provide excellent thermal stability with an onset degradation temperature above 280°C and superb alkaline stability in 1.0 M KOH at 60°C for 650 h. Therefore, these composite membranes exhibit high potential for application as alkaline electrolytes in fuel cells.
TL;DR: Four different methods were investigated to immobilize the carbohydrate N-acetyl-d-glucosamine (d-GlcNAc) on the surface of supermacroporous cryogels made for lectin purification, and results showed that the activation methods did not affect the macroporous structure.
TL;DR: The results showed the enhancement of the stability of the crosslinking interactions between the proteases and nanoparticles, which contributes to the residual activity of both immobilised proteases on MNPs retaining more than 60% of their initial values after seven hydrolytic cycles.
Abstract: Alkaline proteases produced from protein-rich waste (hair waste and soya residues) by solid state fermentation (SSF) were immobilised onto functionalized magnetic iron oxide nanoparticles (MNPs) using glutaraldehyde as a crosslinking agent. The covalent binding method had a better immobilisation yield compared to simple adsorption, retaining 93%–96% (459 ± 106 U/mg nanoparticles, 319 ± 34 U/mg nanoparticles) of hair waste and soya residues proteases, respectively after crosslinking with 5% glutaraldehyde for 6 h. However, the adsorption immobilisation yield was 47%–54% after 8 h for both proteases. MNPs and immobilised proteases were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and electron diffraction. Our results indicated successful crosslinking between the proteases and amino-functionalized MNPs. The operational stability (pH and temperature) and storage stability of free and immobilised enzyme were also analysed. Despite the fact that the optimum pH of free and immobilised proteases was identical in the alkaline region, the immobilised proteases reached their optimum condition at higher temperatures (40 °C–60 °C). After 2 months of storage at 4 °C, the immobilised proteases showed good stability, retaining more than 85% of their initial activity. The high magnetic response of MNPs render an ease of separation and reusability, which contributes to the residual activity of both immobilised proteases on MNPs retaining more than 60% of their initial values after seven hydrolytic cycles. These results showed the enhancement of the stability of the crosslinking interactions between the proteases and nanoparticles. The immobilised proteases were capable of hydrolysing selected proteins (casein, oat bran protein isolate, and egg white albumin). However, differences in the degree of hydrolysis were observed, depending on the combination of the protease and type of substrate used.
TL;DR: In this paper, a polyvinyl alcohol (PVA) and triethylenetetramine (TETA) nanofiber was crosslinked using glutaraldehyde (GA).
Abstract: In this paper, poly(vinyl alcohol) (PVA)–triethylenetetramine (TETA) nanofiber was prepared and crosslinked using glutaraldehyde (GA). Dye removal ability of the modified nanofiber (PVA–TETA–GA) from colored wastewater was studied. Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscopy (SEM) were used to investigate the characteristics of the modified nanofiber. The effect of operational parameters (adsorbent dosage, pH, and the initial dye concentration) on dye removal was studied. The dye adsorption isotherm and kinetics on the nanofiber follows the Langmuir isotherm and pseudo-second-order kinetics, respectively. The results showed that the PVA–TETA–GA nanofiber is a suitable adsorbent with high dye adsorption capacity.
TL;DR: It can be concluded that the real number of crosslinks needed to cause gelation of chitosan chains may be less than 1% and the remarkable difference in the crosslinking properties of nucleoside and nucleotide dialdehydes can be clearly attributed to the presence of the phosphate group in nucleotides that participates in the gelation process through ionic interactions with the amino groups of chitsan.
Abstract: In medical and pharmaceutical applications, chitosan is used as a component of hydrogels-macromolecular networks swollen in water. Chemical hydrogels are formed by covalent links between the crosslinking reagents and amino functionalities of chitosan. To date, the most commonly used chitosan crosslinkers are dialdehydes, such as glutaraldehyde (GA). We have developed novel GA like crosslinkers with additional functional groups-dialdehyde derivatives of uridine (oUrd) and nucleotides (oUMP and oAMP)-leading to chitosan-based biomaterials with new properties. The process of chitosan crosslinking was investigated in details and compared to crosslinking with GA. The rates of crosslinking with oUMP, oAMP, and GA were essentially the same, though much higher than in the case of oUrd. The remarkable difference in the crosslinking properties of nucleoside and nucleotide dialdehydes can be clearly attributed to the presence of the phosphate group in nucleotides that participates in the gelation process through ionic interactions with the amino groups of chitosan. Using NMR spectroscopy, we have not observed the formation of aldimine bonds. It can be concluded that the real number of crosslinks needed to cause gelation of chitosan chains may be less than 1%.