Showing papers on "Glutaraldehyde published in 2014"
TL;DR: Glutaraldehyde, an apparently old fashioned reactive, remains the most widely used and with broadest application possibilities among the compounds used for the design of biocatalyst.
Abstract: Glutaraldehyde is one of the most widely used reagents in the design of biocatalysts. It is a powerful crosslinker, able to react with itself, with the advantages that this may bring forth. In this review, we intend to give a general vision of its potential and the precautions that must be taken when using this effective reagent. First, the chemistry of the glutaraldehyde/amino reaction will be commented upon. This reaction is still not fully clarified, but it seems to be based on the formation of 6-membered heterocycles formed by 5 C and one O. Then, we will discuss the production of intra- and inter-molecular enzyme crosslinks (increasing enzyme rigidity or preventing subunit dissociation in multimeric enzymes). Special emphasis will be placed on the preparation of cross-linked enzyme aggregates (CLEAs), mainly in enzymes that have low density of surface reactive groups and, therefore, may be problematic to obtain a final solid catalyst. Next, we will comment on the uses of glutaraldehyde in enzymes previously immobilized on supports. First, the treatment of enzymes immobilized on supports that cannot react with glutaraldehyde (only inter and intramolecular cross-linkings will be possible) to prevent enzyme leakage and obtain some enzyme stabilization via cross-linking. Second, the cross-linking of enzymes adsorbed on aminated supports, where together with other reactions enzyme/support crosslinking is also possible; the enzyme is incorporated into the support. Finally, we will present the use of aminated supports preactivated with glutaraldehyde. Optimal glutaraldehyde modifications will be discussed in each specific case (one or two glutaraldehyde molecules for amino group in the support and/or the protein). Using preactivated supports, the heterofunctional nature of the supports will be highlighted, with the drawbacks and advantages that the heterofunctionality may have. Particular attention will be paid to the control of the first event that causes the immobilization depending on the experimental conditions to alter the enzyme orientation regarding the support surface. Thus, glutaraldehyde, an apparently old fashioned reactive, remains the most widely used and with broadest application possibilities among the compounds used for the design of biocatalyst.
639 citations
TL;DR: In this article, a series of cross-linked LVCS/PVA hydrogels with various feed compositions were prepared using glutaraldehyde as cross-linking agent, and the results showed that swelling increased by increasing PVA contents in the structure of hydrogel in solutions of higher pH values.
Abstract: In the present work, a series of cross-linked LVCS/PVA hydrogels with various feed compositions were prepared using glutaraldehyde as cross-linking agent. The prepared hydrogels were used for dynamic and equilibrium swelling studies. The swelling behavior of these hydrogels was investigated as functions of effect of pH, polymeric compositions and degree of cross-linking. Swelling studies were performed in 0.05 M USP phosphate buffer solutions of varying pH 1.2, 5.5, 6.5 and 7.5. Results showed that swelling increased by increasing PVA contents in the structure of hydrogels in solutions of higher pH values. This is due to the presence of more hydroxyl groups (–OH) in the PVA structure. On the other hand, by increasing LVCS contents, swelling increased in a solution of acidic pH and it is due to ionization of amino groups (–NH2), but this swelling was not significant. Swelling of hydrogels was decreased with increase in cross-linking ratio due to tighter hydrogel structure. Porosity and sol–gel fraction were also investigated. It was found that with increase in LVCS and PVA contents porosity and gel fraction increased, whereas by increasing glutaraldehyde content gel fraction increased and porosity decreased. Diffusion coefficient (D) and network parameters, i.e., the average molecular weight between cross-links (MC), solvent interaction parameters (χ), polymer volume fraction in swollen state (V2S) and cross-linked density (q) were calculated using Flory–Rehner theory. Selected samples were loaded with model drug diphenhydramine HCl. The release of diphenhydramine HCl was studied for 12 h period in 0.05 M USP phosphate buffer solutions of varying pH 1.2, 5.5 and 7.5. It was observed that drug release increased with increasing PVA contents in the hydrogels, while release of drug decreased as the ratio of cross-linking agent increased in the hydrogel structure owing to strong physical entanglements between polymers. The release mechanisms were studied by fitting experimental data to model equations like zero order, first order, Higuchi and Peppas. Results showed that the kinetics of drug release from hydrogels in buffer solutions of pH 1.2, 5.5 and 7.5 was mainly non-fickian diffusion. Hydrogels were characterized by Fourier transform infrared and X-ray diffraction to confirm the structure and study the crystallinity of hydrogel, respectively.
159 citations
TL;DR: In this article, a cross-linked modification of magnetic chitosan nanoparticles (GMCNs) using glutaraldehyde as crosslinker was presented, which not only exhibited excellent food dyes adsorption performance, but also showed low cytotoxicity.
146 citations
TL;DR: This study reports the preparation of chitosan-glutaraldehyde (Chi-Glu) copolymers at modified reaction conditions such as the temperature prior to gelation, pH, and reagent ratios, with evidence of self-polymerized glutaraldehyde.
135 citations
TL;DR: The resin was chemically modified through the reaction with tetraethylenepentamine (TEPA) to produce amine bearing chitosan to show higher affinity towards the uptake of UO2(2+) ions from aqueous medium and desorption yield as high as 98% was obtained.
127 citations
TL;DR: In this article, a novel poly(vinyl alcohol)/sodium alginate membranes (PVASA) are prepared and the PVASA membranes are further treated by chemical cross-linking with glutaraldehyde as a crosslinking agent to get the crosslinked PVA-GA.
98 citations
TL;DR: In this paper, a review of the potential of glutaraldehyde and the precautions that must be taken when using this effective reagent is presented, with an emphasis on the use of aminated supports preactivated with glutaraldehyde.
Abstract: Glutaraldehyde is one of the most widely used reagents in the design of biocatalysts. It is a powerful crosslinker, able to react with itself, with the advantages that this may bring forth. In this review, we intend to give a general vision of its potential and the precautions that must be taken when using this effective reagent. First, the chemistry of the glutaraldehyde/amino reaction will be commented upon. This reaction is still not fully clarified, but it seems to be based on the formation of 6-membered heterocycles formed by 5 C and one O. Then, we will discuss the production of intra- and inter-molecular enzyme crosslinks (increasing enzyme rigidity or preventing subunit dissociation in multimeric enzymes). Special emphasis will be placed on the preparation of cross-linked enzyme aggregates (CLEAs), mainly in enzymes that have low density of surface reactive groups and, therefore, may be problematic to obtain a final solid catalyst. Next, we will comment on the uses of glutaraldehyde in enzymes previously immobilized on supports. First, the treatment of enzymes immobilized on supports that cannot react with glutaraldehyde (only inter and intramolecular cross-linkings will be possible) to prevent enzyme leakage and obtain some enzyme stabilization via cross-linking. Second, the cross-linking of enzymes adsorbed on aminated supports, where together with other reactions enzyme/support crosslinking is also possible; the enzyme is incorporated into the support. Finally, we will present the use of aminated supports preactivated with glutaraldehyde. Optimal glutaraldehyde modifications will be discussed in each specific case (one or two glutaraldehyde molecules for amino group in the support and/or the protein). Using preactivated supports, the heterofunctional nature of the supports will be highlighted, with the drawbacks and advantages that the heterofunctionality may have. Particular attention will be paid to the control of the first event that causes the immobilization depending on the experimental conditions to alter the enzyme orientation regarding the support surface. Thus, glutaraldehyde, an apparently old fashioned reactive, remains the most widely used and with broadest application possibilities among the compounds used for the design of biocatalyst.
89 citations
TL;DR: Cross-linked enzyme aggregates of lipase Candida sp.
Abstract: With the aim to provide a highly stable and active biocatalyst, cross-linked enzyme aggregates (CLEAs) of lipase Candida sp. 99-125 were prepared in three-dimensionally ordered macroporous silica materials (CLEAs-LP@3DOM-SiO2). Lipase Candida sp. 99-125 was first precipitated in the pores of 3DOM SiO2 (named EAs-LP@3DOM-SiO2), and further cross-linked by glutaraldehyde to form CLEAs-LP@3DOM-SiO2. Saturated ammonium sulfate was used as a precipitant and glutaraldehyde with a concentration of 0.25% (w/w) was employed as a cross-linker. Compared with EAs-LP@3DOM-SiO2 and native lipase, CLEAs-LP@3DOM-SiO2 exhibited excellent thermal and mechanical stability, and could maintain more than 85% of initial activity after 16 days of shaking in organic and aqueous phase. When CLEAs-LP@3DOM-SiO2 was applied in esterification and transesterification reactions, improved activity and reusability were achieved. This method can be used for the immobilization of other enzymes of interest.
84 citations
TL;DR: In this article, the effect of various factors including pH value, core/wall ratio, wall material concentration, stirring speed, cross-linkers and homogenization rate on the appearance, mean particle size, yield, loading capacity and encapsulation efficiency were investigated.
Abstract: The aim of this work was to encapsulate lavender oil by complex coacervation using gelatin and gum Arabic as encapsulants. The effects of various factors including pH value, the core/wall ratio, wall material concentration, stirring speed, cross-linkers and homogenization rate on the appearance, mean particle size, yield, loading capacity (LC) and encapsulation efficiency (EE) were investigated. The optimal conditions (pH 3.5, core/wall 3:2, wall material concentration 1%, stirring speed 450 rpm, homogenization rate 19 000 rpm and glutaraldehyde as cross-linker) for preparing spherical multinuclear microcapsules were obtained. At the optimal conditions, the highest yield is 65.8 ± 1.0%; the maximum LC is 61.3 ± 0.7%; the highest EE is 66.0 ± 0.3%. The effect of three different cross-linkers on the hardening effectiveness of multinuclear microcapsules containing lavender oil was investigated. Glutaraldehyde and transglutaminase exhibit similar microcapsule hardening effectiveness. When tannic acid was used instead of glutaraldehyde and transglutaminase, the mean particle size and EE remained the same as that when hardening with glutaraldehyde or transglutaminase, but the morphology obviously changes, while the yield and LC significantly decrease. Copyright © 2013 John Wiley & Sons, Ltd.
77 citations
TL;DR: A novel adhesive hydrogel consisting of dextran and epsilon-poly(L-lysine) (dextran-PL) with multiple biomedical applications was developed and showed considerably low cytotoxicity and high reactivity with amine species when compared with glutaraldehyde.
Abstract: A novel adhesive hydrogel consisting of dextran and epsilon-poly(L-lysine) (dextran-PL) with multiple biomedical applications was developed. Periodate oxidation in aqueous media almost stoichiometrically introduces aldehyde groups in dextran molecules, and aldehyde dextran can react with the primary amino groups in epsilon-PL (ɛ-PL) at neutral pH to form a hydrogel. The gelation time of the hydrogel can be easily controlled by the extent of oxidation in dextran and of the acylation in ɛ-PL by anhydrides. The shear adhesion strength of dextran-PL was 10 times higher than that of fibrin glue, when wet collagen sheets were selected as test specimens. The cytotoxicity of aldehyde dextran and ɛ-PL were 1000 times lower than that of glutaraldehyde and poly(allylamine). The considerably low cytotoxicity of aldehyde dextran could be ascribed to its low reactivity with amine species when compared with glutaraldehyde. In contrast, a high reactivity of amino groups in ɛ-PL was observed when compared with glycine, L-lysine, and gelatin, which could be explained by their poor dissociation at neutral pH, thus leading to low cytotoxicity.
68 citations
TL;DR: The immobilization strongly affects the enzyme catalytic features: octyl-Lecitase was more active versus p-nitrophenylbutyrate but less active versus methyl phenylacetate than the covalent preparations.
TL;DR: In this article, the cross-linking of diethanolamine (DEA) impregnated polyvinyl alcohol (PVA) on polytetrafluoroethylene (PTFE) by glutaraldehyde (GA) with different blend compositions (GA/PVA: 0.5, 1, 3, 5, 7 ratio%) was performed in the absence of an acid catalyst and organic solvents in order to avoid any interference in CO2 facilitation reaction with DEA.
TL;DR: Several semi and full IPN type hydrogels were prepared by varying initiator and crosslinker concentration and also monomer to chitosan mass ratio and were characterized and used for removal of methyl violet and congo red dye from water.
TL;DR: High glucose yields were obtained by one round of enzymatic hydrolysis of hydrothermally pretreated barley straw during a 72 h reaction with immobilized BG and free BG, verifying a significant stabilization of the BG by immobilization.
Abstract: The high cellulase enzyme dosages required for hydrolysis of cellulose is a major cost challenge in lignocellulosic ethanol production. One method to decrease the enzyme dosage and increase biocatalytic productivity is to re-use β-glucosidase (BG) via immobilization. In the present research, glutaraldehyde cross-linked BG was entrapped in calcium alginate gel particles. More than 60% of the enzyme activity could be recovered under optimized conditions, and glutaraldehyde cross-linking decreased leakage of BG from the calcium alginate particles. The immobilized BG aggregates were visualized by confocal laser scanning microscopy (CLSM). The CLSM images, which we believe are the first to be published, corroborate that more BG aggregates were entrapped in the matrix when the enzymes were cross-linked by glutaraldehyde as opposed to when they are not cross-linked. The particles with the immobilized BG were recycled for cellulase catalyzed hydrolysis of Avicel. No significant loss in BG activity was observed for up to 20 rounds of reaction recycle steps of the BG particles of 48 h each, verifying a significant stabilization of the BG by immobilization. Similar high glucose yields were obtained by one round of enzymatic hydrolysis of hydrothermally pretreated barley straw during a 72 h reaction with immobilized BG and free BG.
TL;DR: In this article, a polyelectrolyte complex (PEC) membrane of cationic chitosan and anionic sodium alginate with fiber structure was prepared by freeze-drying method.
Abstract: Polyelectrolyte complex (PEC) membrane of cationic chitosan and anionic sodium alginate with fiber structure were prepared by freeze-drying method. Chitosan and sodium alginate were blended in different concentrations and frozen at different temperatures. Freeze-dried fiber membranes were extensively characterized for their inter-molecular interaction, the solution property, morphology and biocompatibility by using FTIR, XRD, zeta (ζ) potentials, SEM and cytotoxicity assay. The study of swelling property showed that PEC membrane with the fiber structure cross-linked with glutaraldehyde exhibited pH and ionic strength-dependent swelling in aqueous media, which might have a potential application in tissue engineering or drug controlled release. Furthermore, chitosan–sodium alginate samples showed better cell adhesion and proliferation than pure chitosan. The results indicated that two natural polyelectrolyte complex nanofibers were prepared by freeze-drying method and fitted for tissue engineering or as drug carriers.
TL;DR: In this paper, the influence of cross-linking agents and iron oxide powder content on the transport properties of composite chitosan membranes was discussed, and the difference between permeation coefficients for ethanol and water was observed.
TL;DR: Pervaporation membranes made by solution blending of polyvinyl alcohol (PVA) and sodium alginate (SA) were characterized by mechanical properties, FTIR, SEM, DTA-TGA and XRD, and showed the best results for flux and selectivity.
TL;DR: In this article, the adsorption characteristics of the obtained chitosan toward As(V) at different experimental conditions were investigated by means of batch and column methods, where the resin showed high affinity and fast kinetics for the adaption of As (V) where an uptake value of 1.30 mmol g−1 was reported in 6 min at 25 °C.
Abstract: Chitosan was cross-linked using glutaraldehyde in the presence of magnetite. The resin obtained was chemically modified through the reaction with tetraethylenepentamine ligand. The obtained resin was loaded with Mo(VI) and investigated. The adsorption characteristics of the obtained resin toward As(V) at different experimental conditions were investigated by means of batch and column methods. The resin showed high affinity and fast kinetics for the adsorption of As(V) where an uptake value of 1.30 mmol g−1 was reported in 6 min at 25 °C. Various parameters such as pH, agitation time, As(V) concentration and temperature had been studied. The kinetics and thermodynamic behavior of the adsorption reaction were defined. These data indicated an endothermic and spontaneous adsorption process and kinetically followed pseudo-second-order model, Fickian diffusion low and Elovich equation. Breakthrough curves for the removal of As(V) were studied at different flow rates and bed heights. The critical bed height for the studied resin column was found to be 0.656 cm at flow rate of 4 mL min−1. The mechanism of interaction between As(V) and resin’s active sites was discussed. Regeneration and durability of the loaded resin toward the successive cycles were also clarified.
TL;DR: A new glutaraldehyde activated support without a net charge is presented and characterized in immobilizations of trypsin, penicillin acylase G, lipase and E. coli BL21 cell extract, promoting initially a reversible immobilization, converting into irreversible after incubation of the enzyme-support for several days or after a reduction step.
Abstract: Immobilization of enzymes on glutaraldehyde-activated supports has been largely used on supports previously activated with amine groups. Therefore, the supports are positively charged hence usually the immobilization is promoted through a two step mechanism: in a first step the enzyme is adsorbed on the support via an anionic exchange mechanism and then, the covalent immobilization occurs. In this paper a new glutaraldehyde activated support without a net charge is presented and characterized in immobilizations of trypsin, penicillin acylase G, lipase and E. coli BL21 cell extract. Immobilization mechanism was studied and this was produced without an adsorption step. This support promoted initially a reversible immobilization, converting into irreversible after incubation of the enzyme-support for several days or after a reduction step. In addition the stability of glutaraldehyde groups was studied retaining around 50 and 25% of its immobilization capacity for 24 h at pH 7 and 10 respectively. This fact allows the incubation of the enzyme with the support even at alkaline pH promoting an extra stabilization factor for trypsin on this support.
TL;DR: In this paper, the authors showed that the addition of gelatin significantly influences the yield of BC/GEL composites and that the increase in the crosslinking degree also descreased the composite's strain at break in elongation but increased the compressive and tensile strength.
Abstract: Bacterial cellulose (BC)/GEL composites were prepared in situ by adding gelatin into BC-producing culture medium. The addition of gelatin interfered with the formation of the BC pellicle structure and thus made the BC yield and growth rate quite different from that of pure BC. Scanning electron microscope images showed that the width of cellulose ribbons became narrower than that of pure BC and the gelatin filled in the pores of BC to form a dense structure. The addition level of gelatin significantly influences the yield of BC/GEL composites. An optimum value of 0.5 wt/v% gelatin was attained, with which the highest yield of 0.0541 g/100 mL was achieved. Under this condition, the weight percentage of gelatin in BC/GEL composite was 65 wt%. BC/GEL composites were treated with glutaraldehyde to crosslink BC fibrils and gelatin. The crosslinking degree, determined by the concentration of glutaraldehyde and crosslinking time, could affect the swelling behavior, thermal stability and mechanical properties of composites. With increasing of the crosslinking degree, the crystallinity index and swelling behavior of the composites decreased. The increase in the crosslinking degree also descreased the composite’s strain at break in elongation but increased the compressive and tensile strength. Covalent bonding between BC and gelatin provides good strength retention to the glutaraldehyde-treated composites with a high crosslinking degree. Considering the cytocompatibility and properties of composites, the most appropriate concentration of glutaraldehyde and crosslinking time were 1.0 wt/v% and 24 h, respectively.
TL;DR: In this paper, a semi-interpenetrating polymer network (semi-IPN) in the form of microspheres prepared by water-in-oil emulsion method was used to investigate the controlled release of theophylline (THP), an antiasthmatic drug.
Abstract: Carboxymethyl guar gum (CMGG) was synthesized by carboxymethylation of guar gum (GG), which was blended with gelatin (GE) to obtain a novel semi-interpenetrating polymer network (semi-IPN) in the form of microspheres prepared by water-in-oil emulsion method to investigate the controlled release of theophylline (THP), an antiasthmatic drug. Electronic spectroscopy revealed the drug encapsulation ranging from 56 to 74 %. Fourier Transform infrared spectroscopy confirmed the carboxymethylation of GG as well as the semi-IPN structure of the blend polymer. Scanning electron microscopy indicated the smooth surfaces with spherical microspheres. Differential scanning calorimetric and X-ray diffraction studies showed the molecular level dispersion of drug in the microspheres. The in vitro drug release profiles were analyzed to study the effect of polymer blend composition, % drug loading and amount of glutaraldehyde added as a crosslinker. The drug release was extended up to 26 h. The in vitro release data performed in acidic and alkaline media were analyzed using the empirical equations to understand the release profiles of THP.
TL;DR: In this paper, polyvinyl alcohol (PVA) thin films were reinforced by glutaraldehyde and multiwalled carbon nanotubes (MWCNTs) and then mechanical, water solubility, water swelling, water uptake, water vapor permeability, and antibacterial properties of the films were examined.
Abstract: Polyvinyl alcohol (PVA) thin films were reinforced by glutaraldehyde and multiwalled carbon nanotubes (MWCNTs) and then mechanical, water solubility, water swelling, water uptake, water vapor permeability, and antibacterial properties of the films were examined. Cross-linking by glutaraldehyde or incorporation of MWCNT caused a significant increase in tensile strength, decrease in elongation at break, and increase in Young’s modulus of the PVA films, while MWCNTs were more effective rather than that of glutaraldehyde. Cross-linking by glutaraldehyde or incorporation of MWCNT caused a significant decrease in water solubility, water swelling and water uptake, with a similar manner. Cross-linking by glutaraldehyde or incorporation of MWCNT caused a significant increase in the light absorbance, while maximum absorbance was at 400 nm. Only PVA/MWCNT films but no PVA/glutaraldehyde showed significant antibacterial activities in a dose-dependent manner against both Gram-positive and Gram-negative bacteria. Thus, noncovalent improvement by MWCNT was more effective on the PVA thin films rather than covalent cross-linking by glutaraldehyde. Our results suggest that the PVA/ MWCNT composites films could be used as a very attractive alternative to traditional materials for different biomedical and food applications. POLYM. COMPOS., 00:000–000, 2014. V C 2014 Society of Plastics Engineers
TL;DR: In this paper, a crosslinked polyvinyl alcohol/glutaraldehyde (PVA/GA) and β-cyclodexrin (β-CD) membranes were synthesized for dye adsorption in textile liquid waste processing.
Abstract: Crosslinked polyvinyl alcohol/glutaraldehyde (PVA/GA) membranes were prepared, and attempts to obtain hydrophilic crosslinked PVA membranes were made by adding various amounts of β-cyclodexrin (β-CD), which is a typical cyclic oligosaccharide able to form inclusion complexes with organic host molecules (host-guest complexes). Thus, membranes of PVA/GA/β-CD were synthesized. The membranes were characterized by infrared spectroscopy (FTIR) and swelling measurements. The ability of cyclodextrin to include a wide variety of chemicals was also exploited for the dye adsorption to show the potentialities of the membranes in textile liquid waste processing. Adsorption of reactive methyl orange, and methylene blue dyes on PVA/GA/β-CD membranes was consequently studied using UV-Vis spectroscopy at wavelengths of 547, 463, and 660 nm. Adsorption reached equilibrium after 24 h. Results indicated that there is no covalent bond formation between PVA and β-CD; the β-CD is completely mixed into the PVA matrix polymer. The adsorption capacity increases with increasing amounts of cyclodextrin; the maximum adsorption capacity was obtained with 8% β-CD. Therefore, the change in adsorption capacities may be due to the dye structure effect, and the negative value of free energy indicated the spontaneous nature of adsorption.
TL;DR: In this paper, a crosslinking enzyme aggregate (CLEA) of alginate lyase (AL) from Sphingobacterium multivorum was proposed, which showed 100% precipitation yield.
Abstract: Alginate lyase (AL) from Sphingobacterium multivorum is unsuitable for oral delivery because of its rapid inactivation under acidic conditions. The synthesis of a novel crosslinking enzyme aggregate (CLEA) of AL (AL-CLEA) is proposed. AL precipitation with 95% ammonium sulfate and combined with low methoxylated pectin (LMP), showed 100% precipitation yield. Crosslinking with glutaraldehyde reduced the AL-CLEA activity to less than 1%, but addition of bovine serum albumin (BSA) and LMP during AL-CLEA synthesis increased the activity yield to 14.7%. AL-CLEA exposed to simulated gastric conditions (pH 1.2 to 3.0) showed more than 70% retention of enzymatic activity. Moreover, AL-CLEA showed thermal stability at temperatures over 37 °C. Stability against chemical denaturants (ethanol, acetone and propylene glycol) showed that AL-CLEA was 14 times more stable than free AL in all cases. Finally, a 25% viscosity reduction of alginate solution was achieved with AL-CLEA. This is the first report of AL-CLEA synthesis and evaluation.
TL;DR: Lipases immobilized on MNPs were evaluated for biotransformation reactions including synthesis of ethyl acetate and transesterification of vegetable oil for producing biodiesel and the MNP immobilized esterase had prolonged shelf life and there was no loss in enzyme activity.
TL;DR: In this article, the effects of citric acid and glutaraldehyde on the mechanical properties, thermal properties and swelling degree of potato starch and polyvinyl alcohol were investigated by solution casting method.
Abstract: Biodegradable blends of potato starch and polyvinyl alcohol were prepared by solution casting method. Citric acid was employed to introduce the plasticizing effect into the starch materials. Glutaraldehyde as cross-linker was used to enhance the properties of the blend films. Cross-linking is a common method to improve the strength and stability of starch products. The effects of citric acid and glutaraldehyde on the mechanical properties, thermal properties and swelling degree were investigated. The prepared films were measured for their antibacterial activities and biodegradability. The blend samples were characterized by the thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and FTIR analysis techniques. From the mechanical properties study, it was analyzed that the blend films showed improvement in their tensile strength after cross-linking with glutaraldehyde. The SEM micrographs indicated that the blend films were smooth without any cracks, pores and were well cross-linked. The TGA curves showed that there was an increase in the thermal stability of the blend films after cross-linking as compared to uncross-linked blend films. The prepared films showed good antibacterial properties against Gam-positive and Gram-negative bacteria. The biodegradability of the blends was determined by placing the samples in compost soil for different time intervals and were found to be biodegradable in nature.
TL;DR: It was proved that the collagen solutions possessed strikingly different physicochemical properties depending on the amount of GTA, with a clear loss of flow and a sudden rise of the Td value compared to the uncross-linked collagen solution, probably illustrating thatThe collagen solution was converted into a gel with mature network structure-containing nuclei observed in AFM image.
Abstract: The physicochemical properties of collagen solutions (5 mg/ml) cross-linked by various amounts of glutaraldehyde (GTA) [GTA/collagen (w/w) = 0–0.5] under acidic condition (pH 4.00) were examined. Based on the results of the determination of residual amino group content, sodium dodecyl sulphate–polyacrylamide gel electrophoresis, dynamic rheological measurements, differential scanning calorimetry and atomic force microscopy (AFM), it was proved that the collagen solutions possessed strikingly different physicochemical properties depending on the amount of GTA. At low GTA amounts [GTA/collagen (w/w) ≤ 0.1], the residual amino group contents of the cross-linked collagens decreased largely from 100% to 32.76%, accompanied by an increase in the molecular weight. Additionally, increases of the fiber diameter and the values of G′, G″ and η* were measured, while the thermal denaturation temperature (Td) did not change visibly and the fluidity of collagen samples was still retained with increasing the GTA ...
TL;DR: The immobilization on chitosan beads enhanced the shelf life of acid phosphatase and immobilized enzyme retained its more than 50% hydrolytic activity for approximately two months.
TL;DR: Synthesized hydrogel was evaluated as a device for colon-specific controlled drug delivery and results indicated that higher drug release was found at pH 9.2 followed by pH 7.0 and 2.0.
Abstract: In this work, natural polymer was used as matrix for preparing hydrogel to improve the performance of the material in biomedical sector. Gum tragacanth and acrylic acid [Gt-cl-poly(AA)] based hydrogel was prepared by graft copolymerization of natural Gum tragacanth with acrylic acid using ascorbic acid–potassium persulfate as an initiator and glutaraldehyde as cross-linker. Synthesized hydrogel was evaluated as a device for colon-specific controlled drug delivery. The results indicated that higher drug release was found at pH 9.2 followed by pH 7.0 and 2.0. Non-Fickian diffusion mechanism was exhibited at pH 9.2 and Case II diffusion mechanism was found in the case of pH 2.0 and 7.0.
TL;DR: The adequate adherence, proliferation, and morphology of HaCaT type cells on the scaffolds showed that these scaffolds can be used as carriers for culturing HaCaTs and could be promising candidates for engineering skin tissue.
Abstract: Chitosan-gelatin (CG) scaffolds were fabricated with glutaraldehyde as a cross-linker by vacuum freeze-drying. Mixtures of different volumes of chitosan and glutaraldehyde were considered. Morphology, porosity, density, and water absorbency of the scaffolds were studied. Both tensile and compressive properties of the scaffolds were tested. In addition, cellular adherence, proliferation, and morphology on the scaffolds were tested to evaluate the compatibility. It was found that porosity, density, water absorbency, and mechanical properties of CG scaffolds changed with the variation of chitosan or GA content. The adequate adherence, proliferation, and morphology of HaCaT type cells on the scaffolds showed that these scaffolds can be used as carriers for culturing HaCaT. The CG scaffolds, particularly those with chitosan-gelatin volume ratios of 1:1 and adding 6% or 8% volume of 0.25 wt% GA solution, were more suitable than the others through comparing the above properties and could be promising candidates ...