Showing papers on "Glutaraldehyde published in 2018"
TL;DR: The potential use of conjugated biopolymers such as chitosan and lysozyme for water treatment applications is demonstrated by showing excellent removal of MO and Cr(VI) along with concurrent removal of other heavy metals such as Cd( II) and Ni(II) ions from aqueous mixtures.
81 citations
TL;DR: In this paper, a continuous adsorption study in a fixed-bed column was carried out using a chitosan-glutaraldehyde biosorbent for the removal of the textile dye Direct Blue 71 from an aqueous solution.
Abstract: A continuous adsorption study in a fixed-bed column was carried out using a chitosan–glutaraldehyde biosorbent for the removal of the textile dye Direct Blue 71 from an aqueous solution. The biosor...
80 citations
TL;DR: The new biocatalysts are significantly more stable and avoid enzyme subunit desorption, being the immobilization pH a key point in their design.
75 citations
TL;DR: Derivative obtained by sequentially activation with glycidol, ethylenediamine, and glutaraldehyde and subsequent TLL immobilization showed the best performance, with high hydrolytic activity value, and epichlorohydrin-activated chitosan derivative and both derivatives showed low immobilization yields.
Abstract: The aim of this paper was to evaluate different strategies of chitosan activation using cross-linking reagent like glycidol, epichlorohydrin, and glutaraldehyde for Thermomyces lanuginosus lipase (TLL) immobilization. Operational activity and stability by esterification of oleic acid with ethanol and thermal inactivation using these derivatives were investigated. Derivative obtained by sequentially activation with glycidol, ethylenediamine, and glutaraldehyde and subsequent TLL immobilization showed the best performance, with high hydrolytic activity value. Its stability was 15-fold higher than solubilized TLL in the evaluated inactivation conditions (60 °C, 25 mM sodium phosphate buffer pH 7). After 5 cycles of oleic acid esterification, only a few percentage of its conversion has reduced. On the other hand, glycidol-activated chitosan derivative showed very low hydrolytic activity value. Epichlorohydrin-activated chitosan derivative showed regular hydrolytic activity value. Both derivatives showed low immobilization yields. Operational stability of this last derivative was very low, where after the first cycle of oleic acid esterification, only 56% of its initial conversion was obtained.
70 citations
TL;DR: Ficin extract has been immobilized on different 4% aminated-agarose beads and the biocatalysts activity greatly decreased using more than 30 mg/g, suggesting that the near presence of other immobilized enzyme molecules may generate some steric hindrances for the casein hydrolysis.
Abstract: Ficin extract has been immobilized on different 4% aminated-agarose beads. Using just ion exchange, immobilization yield was poor and expressed activity did not surpass 10% of the offered enzyme, with no significant effects on enzyme stability. The treatment with glutaraldehyde of this ionically exchanged enzyme produced an almost full enzyme inactivation. Using aminated supports activated with glutaraldehyde, immobilization was optimal at pH 7 (at pH 5 immobilization yield was 80%, while at pH 9, the immobilized enzyme became inactivated). At pH 7, full immobilization was accomplished maintaining 40% activity versus a small synthetic substrate and 30% versus casein. Ficin stabilization upon immobilization could be observed but it depended on the inactivation pH and the substrate employed, suggesting the complexity of the mechanism of inactivation of the immobilized enzyme. The maximum enzyme loading on the support was determined to be around 70 mg/g. The loading has no significant effect on the enzyme stability or enzyme activity using the synthetic substrate but it had a significant effect on the activity using casein; the biocatalysts activity greatly decreased using more than 30 mg/g, suggesting that the near presence of other immobilized enzyme molecules may generate some steric hindrances for the casein hydrolysis.
65 citations
TL;DR: The combination of glutaraldehyde detoxification and a coating with chondroitin sulfate hydrogel promotes in situ mechanisms of endothelialization in fixed pericardium and offers a new solution for improving the long life of bioprosthetic valves and exploring the means of making valves suitable to endothelization.
63 citations
TL;DR: In this article, a facile method to immobilize trypsin on magnetic nanoparticles was developed by co-precipitating Fe2+and Fe3+in an ammonia solution and then coating by silicon dioxides.
62 citations
TL;DR: Lipase from Rhizomucor miehei was immobilized onto chitosan support in the presence of some surfactants added at low levels using two different strategies and the derivatives obtained showed high catalytic activity and excellent thermal stability at 60° and 37 °C.
Abstract: Lipase from Rhizomucor miehei (RML) was immobilized onto chitosan support in the presence of some surfactants added at low levels using two different strategies. In the first approach, the enzyme was immobilized in the presence of surfactants on chitosan supports previously functionalized with glutaraldehyde. In the second one, after prior enzyme adsorption on chitosan beads in the presence of surfactants, the complex chitosan beads-enzyme was then cross-linked with glutaraldehyde. The effects of surfactant concentrations on the activities of free and immobilized RML were evaluated. Hexadecyltrimethylammonium bromide (CTAB) promoted an inhibition of enzyme activity while the nonionic surfactant Triton X-100 caused a slight increase in the catalytic activity of the free enzyme and the derivatives produced in both methods of immobilization. The best derivatives were achieved when the lipase was firstly adsorbed on chitosan beads at 4 °C for 1 h, 220 rpm followed by cross-link the complex chitosan beads-enzyme with glutaraldehyde 0.6% v.v−1 at pH 7. The derivatives obtained under these conditions showed high catalytic activity and excellent thermal stability at 60° and 37 °C. The best derivative was also evaluated in the synthesis of two flavor esters namely methyl and ethyl butyrate. At non-optimized conditions, the maximum conversion yield for methyl butyrate was 89%, and for ethyl butyrate, the esterification yield was 92%. The results for both esterifications were similar to those obtained when the commercial enzyme Lipozyme® and free enzyme were used in the same reaction conditions and higher than the one achieved in the absence of the selected surfactant.
57 citations
TL;DR: The synthesized nonconjugated polymer fluorophore (GCPF) synthesized by cross-linking chitosan with glutaraldehyde via Schiff base reactions and systematically investigated for selective determination of Cr(VI) exhibited excellent photostability and water solubility and possessed dramatically enhanced fluorescence intensity.
Abstract: Selective determination of aquatic chromium is critically important because of the dramatic differences in health and environment impacts by trivalent and hexavalent forms of chromium; however, it is challenging. In this work, for the first time, a nonconjugated polymer fluorophore (GCPF) was synthesized by cross-linking chitosan with glutaraldehyde via Schiff base reactions and systematically investigated for selective determination of Cr(VI). The results revealed that the synthesized GCPF exhibited excellent photostability and water solubility. More importantly, GCPF possessed dramatically enhanced fluorescence intensity originated from the n−π* transitions of the Schiff base subfluorophore groups (e.g., C═N) that can be selectively and sensitively quenched by Cr(VI) through oxidative damages to C═N group. An effective EDTA masking agent approach was employed to minimize ionic interferences. In the presence of high concentration of interference ions including Cr(III), the quenching GCPF fluorescence is ...
57 citations
TL;DR: While co-immobilization was successfully performed with both materials, the specific activities of enzymes were found to be higher for the enzymes co- immobilized with glutaraldehyde-activated chitosan beads.
Abstract: In this study, two different materials—alginate and glutaraldehyde-activated chitosan beads—were used for the co-immobilization of α-amylase, protease, and pectinase. Firstly, optimization of multienzyme immobilization with Na alginate beads was carried out. Optimum Na alginate and CaCl2 concentration were found to be 2.5% and 0.1 M, respectively, and optimal enzyme loading ratio was determined as 2:1:0.02 for pectinase, protease, and α-amylase, respectively. Next, the immobilization of multiple enzymes on glutaraldehyde-activated chitosan beads was optimized (3% chitosan concentration, 0.25% glutaraldehyde with 3 h of activation and 3 h of coupling time). While co-immobilization was successfully performed with both materials, the specific activities of enzymes were found to be higher for the enzymes co-immobilized with glutaraldehyde-activated chitosan beads. In this process, glutaraldehyde was acting as a spacer arm. SEM and FTIR were used for the characterization of activated chitosan beads. Moreover, pectinase and α-amylase enzymes immobilized with chitosan beads were also found to have higher activity than their free forms. Three different enzymes were co-immobilized with these two materials for the first time in this study.
56 citations
TL;DR: The infrared spectra and morphological analyses demonstrated that the gelatin-zein composite film was successfully crosslinked after the addition of glutaraldehyde, with the formation of crosslinked networks between proteins and a denser packed organization of proteins.
TL;DR: The tri-enzyme co-immobilized MNPs were successfully utilized for extraction of piperine from black pepper, preparation of sugarcane cell protoplasts, and clarification of papaya juice with prominent yield and reusability vis-à-vis traditional methods.
TL;DR: Electrospun chitosan mats functionalized with glucose oxidase (GOX) to implement an in-situ hydrogen peroxide (H2O2) generation system did not show an influence on the viability of the cells which proved it a functional biomaterial of great potential for biomedical applications.
Journal Article•
TL;DR: The results showed that the enzyme immobilization increased the enzyme activity in different pHs and temperatures, without any changes in the optimum pH and temperature for enzyme activity.
TL;DR: In this article, a new magnetic composite hydrogel (Mag-H) based on gelatin/bacterial cellulose (BC), was synthesized and incorporated into the gelatin/BC matrices, followed by chemical crosslinking with glutaraldehyde.
TL;DR: Recyclability studies indicated that the membranes still maintained a high BPA removal of up to 79% even after four filtration cycles, while contact-angle analyses, pure water flux measurements and rejection analyses were carried out.
Abstract: Laccase enzymes from Rhus vernificera were covalently bound on hyperbranched polyethyleneimine/polyethersulfone (HPEI/PES) electrospun nanofibrous membranes and used for the removal of bisphenol A (BPA) from water. The laccase enzyme was anchored on the dendritic membranes through the abundant peripheral amine groups on the HPEI using glutaraldehyde as a crosslinker. The membranes were characterized with attenuated total reflectance-Fourier transform infrared spectroscopy, scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) and ultraviolet–visible spectroscopy and correlative light and electron microscopy (CLEM). Furthermore, contact-angle analyses, pure water flux measurements and rejection analyses were carried out. CLEM showed that the enzymes were uniformly dispersed on the nanofibres while SEM analysis revealed that the nanofibres had an average diameter of 354 ± 37 nm. EDS showed the presence of Cu, which is the active entity in laccase enzymes. The lacca...
TL;DR: In this article, the preparation and evaluation of two kinds of polyvinyl alcohol/chitosan polymer electrolyte membranes, PVA/CS solution casting membrane and composite electrospun nanofiber membranes, are reported.
TL;DR: In this paper, the influence of glutaraldehyde crosslinking and an alkaline post-treatment with NaOH on the characteristics of chitosan-based films was evaluated.
Abstract: Depending on the modifications proposed, chitosan films present different characteristics, for instance correlated to hydrophilicity, chemical and mechanical properties. The aim of this study was to evaluate the influence of glutaraldehyde crosslinking and an alkaline post-treatment with NaOH on the characteristics of chitosan based films. Films were obtained by casting and characterized by thickness, swelling degree, mechanical and thermal properties and chemical structure. The water vapor permeability (WVP) was also evaluated for food packaging application. It was observed that crosslinking and NaOH post-treatment have great influence on the chitosan films characteristics. Crosslinking reduced the swelling degree of films and increased its fragility, whereas NaOH treatment also reduces the swelling degree and changes mechanical properties, acting in the same way as a crosslinker. The WVP analyses showed that the basic treatment could substitute the glutaraldehyde crosslinking for film water stability, without greatly compromising the barrier properties of chitosan based films.
TL;DR: This research provides a promising approach for expanding the use of NC from OPFL for enhancing enzyme activity in favour of an alternative eco-friendly means to synthesize butyl butyrate.
TL;DR: Enhanced α-amylase stabilities upon immobilization make it suitable for industrial application as well as improve the storage stability and reusability of the immobilized enzyme.
TL;DR: In this paper, composite alginate membranes filled with various amount of iron ferroferric oxides (Fe3O4) and crosslinked by four different agents were prepared.
TL;DR: The genipin obtained in this work proved to be an excellent alternative to the use of glutaraldehyde in chitosan crosslinking applications and was applied for the first time in liquid-liquid two-phase aqueous system.
TL;DR: Analysis of the immobilization of CAL-B enzyme on different magnetic nanoparticles synthesized by the coprecipitation method inside inverse micelles made of zwitterionic surfactants confirmed the potential of immobilized CAL- B enzyme in microbial production of biodiesel.
Abstract: Lipase B from Candida antarctica (CAL-B) is largely employed as a biocatalyst for hydrolysis, esterification, and transesterification reactions. CAL-B is a good model enzyme to study factors affecting the enzymatic structure, activity and/or stability after an immobilization process. In this study, we analyzed the immobilization of CAL-B enzyme on different magnetic nanoparticles, synthesized by the coprecipitation method inside inverse micelles made of zwitterionic surfactants, with distinct carbon chain length: 4 (ImS4), 10 (ImS10) and 18 (ImS18) carbons. Magnetic nanoparticles ImS4 and ImS10 were shown to cross-link to CAL-B enzyme via a Michael-type addition, whereas particles with ImS18 were bond via pyridine formation after glutaraldehyde cross-coupling. Interestingly, the Michael-type cross-linking generated less stable immobilized CAL-B, revealing the influence of a cross-linking mode on the resulting biocatalyst behavior. Curiously, a direct correlation between nanoparticle agglomerate sizes and CAL-B enzyme reuse stability was observed. Moreover, free CAL-B enzyme was not able to catalyze transesterification due to the high methanol concentration; however, the immobilized CAL-B enzyme reached yields from 79.7 to 90% at the same conditions. In addition, the transesterification of lipids isolated from oleaginous yeasts achieved 89% yield, which confirmed the potential of immobilized CAL-B enzyme in microbial production of biodiesel.
TL;DR: Even after 28 days after solution preparation, DAC exhibited the capability to act as an efficient crosslinker for PVA, with exceptional crosslinking potential in comparison to glutaraldehyde, which is likely related to DAC macromolecular character.
TL;DR: In this paper, a green synthesis of 2,4,5-trisubsituted and 1,2,4-5-tetrasubstituted imidazoles was developed using a novel MCS-GT@Co(II) magnetically recoverable and recyclable catalyst under refluxing conditions with ethanol as a solvent.
Abstract: A simple, highly efficient and green synthesis of 2,4,5-trisubsituted and 1,2,4,5-tetrasubstituted imidazoles was developed using a novel MCS-GT@Co(II) magnetically recoverable and recyclable catalyst under refluxing conditions with ethanol as a solvent. The catalyst was prepared by immobilization of chitosan onto Fe3O4 using glutaraldehyde as crosslinker followed by Co(II) ion immobilization via cobalt acetate. The catalyst was characterized using various techniques. For organic products determination, 1H NMR, 13C NMR and Fourier transform infrared spectroscopies were used. The reaction was also tried with individual components of the catalyst, but the synergistic effect of the components in the prepared catalyst showed the highest yield and shortest reaction time.
TL;DR: In this paper, a modified chitosan hydrogel was used to recover beryllium ion from their solution by modifying chitosa with glutaraldehyde to prevent its dissolution in aqueous acidic solutions.
Abstract: The goal of the present work is the recovery of beryllium ion from their solution by modified chitosan hydrogel. Chitosan was chemically cross-linked with glutaraldehyde to prevent its dissolution in aqueous acidic solutions. The obtained chitosan/glutaraldehyde adsorbent was reacted with chloroacetic acid to produce carboxymethyl chitosan (CMC), which was converted into sodium form by reaction with sodium hydroxide solution to increase its hydrophilic properties. The chemically synthesized chitosan adsorbent contains carboxylate group that expected to have a strong affinity to beryllium ions according to the hard-soft acid-base concept by Pearson because that beryllium ion is a hard acid and has smaller ionic radii. The synthesized adsorbent was characterized and its affinity towards beryllium ions was tested. The different experimental parameters including pH, beryllium concentration, agitation period and temperature were studied to optimize the biosorption process. The maximum biosorption value...
TL;DR: The obtained results suggested that these nanoparticles can serve as potential carriers for the pH-triggered delivery of an anticancer drug.
Abstract: In this study, amino acid (glycine) functionalized hydroxyapatite nanoparticles (Gly-HANPs) were synthesized in situ by a simple co-precipitation method. The structural and morphological properties of the synthesized nanoparticles were evaluated using various characterization techniques including powder X-ray diffraction and electron microscopy. The presence of glycine functionalities on the surface of the nanoparticles was ascertained from infrared spectroscopy, thermal analysis, CHN analysis and zeta potential measurements. Doxorubicin (DOX), an anthracycline antibiotic commonly used in cancer chemotherapy, was covalently bound to Gly-HANPs via a pH sensitive imine linkage using glutaraldehyde as a cross-linker. The DOX loaded nanoparticles (DOX-Glut-Gly-HANPs) showed pH-responsive controlled and sustained release of the drug. In particular, the drug release rate from nanoparticles was higher under acidic pH conditions, characteristic of tumour tissues, than at physiological pH, typical for normal tissues. The higher release of DOX at acidic pH is indicative of the cleavage of the imine (–CN–) linkage at acidic pH. The cell uptake and therapeutic efficacy of DOX conjugated nanoparticles were investigated in WEHI-164 mouse fibrosarcoma cancer cells. The in vitro cytotoxicity studies suggested that glutaraldehyde treated nanoparticles (Glut-Gly-HANPs) have insignificant cytotoxicity towards WEHI-164 cancer cells, however the DOX loaded nanoparticles exhibited significant dose and time dependent cytotoxicity towards WEHI-164 cells. Furthermore, the confocal laser scanning microscopy studies demonstrated good cellular uptake of the DOX loaded nanoparticles into the WEHI-164 cells. The obtained results suggested that these nanoparticles can serve as potential carriers for the pH-triggered delivery of an anticancer drug.
TL;DR: In this paper, three-dimensional polypyrrole/chitosan nanocomposite aerogel monoliths are fabricated by polymerization of pyrrole in chitosans aqueous solution.
Abstract: Three-dimensional polypyrrole/chitosan nanocomposite monoliths are fabricated by polymerization of pyrrole in chitosan aqueous solution. The static polymerization of pyrrole monomer and the cross-linking of chitosan by glutaraldehyde occur simultaneously, resulting in the self-assembly of polypyrrole/chitosan nanocomposite aerogel monolith. The addition of methyl orange and glutaraldehyde and the static reaction play key roles in the formation of the self-standing aerogel monolith. The as-prepared monolith with larger specific surface area exhibits much better adsorption capability for Cr(VI) removal in comparison with that prepared without the addition of glutaraldehyde. The adsorption process and adsorption isotherms are found to well follow the pseudo-second-order and Langmuir models, respectively. Furthermore, this polypyrrole/chitosan nanocomposite monolith is stable and recyclable. About 73.5% of the initial adsorption capability is kept after eight adsorption–desorption cycles. The polypyrrole/chitosan nanocomposite monolith can be a promising candidate for the efficient removal of Cr(VI).
TL;DR: Immobilization of the A. awamori β-glucosidase on glutaraldehyde cross-linked commercial gelatin is an efficient and cheap method allowing the reuse of the enzyme by at least 10 times, and was able to hydrolyze cellobiose more extensively.
TL;DR: It was found that nonhydraulic fracturing-impacted microcosms biodegraded glutaraldehyde faster than the hydraulic fracturing-Impactedmicrocosms, showing a decrease in degradation potential after exposure to hydraulic fracturing activity.
Abstract: The environmental impacts of hydraulic fracturing, particularly those of surface spills in aquatic ecosystems, are not fully understood. The goals of this study were to (1) understand the effect of previous exposure to hydraulic fracturing fluids on aquatic microbial community structure and (2) examine the impacts exposure has on biodegradation potential of the biocide glutaraldehyde. Microcosms were constructed from hydraulic fracturing-impacted and nonhydraulic fracturing-impacted streamwater within the Marcellus shale region in Pennsylvania. Microcosms were amended with glutaraldehyde and incubated aerobically for 56 days. Microbial community adaptation to glutaraldehyde was monitored using 16S rRNA gene amplicon sequencing and quantification by qPCR. Abiotic and biotic glutaraldehyde degradation was measured using ultra-performance liquid chromatography--high resolution mass spectrometry and total organic carbon. It was found that nonhydraulic fracturing-impacted microcosms biodegraded glutaraldehyde ...