Showing papers on "Glutaraldehyde published in 2021"

Fabrication of Schiff’s Base Chitosan-Glutaraldehyde/Activated Charcoal Composite for Cationic Dye Removal: Optimization Using Response Surface Methodology

Abstract: In this work, a ternary composite containing a Schiff base adduct (chitosan-glutaraldehyde) along with activated charcoal (Ch-Glu/AC) was successfully prepared that contains activated charcoal with cross-linked chitosan. The Schiff base adduct was obtained by reaction of a dialdehyde bifunctional cross-linker agent (glutaraldehyde; Glu), where various methods were employed to study the morphology, material crystallinity, surface area, and surface functional group of the ternary composite (Ch-Glu/AC). Ch-Glu/AC was applied as an adsorbent to remove a cationic dye (thionine dye, TH) from aqueous media. The effect of various independent variables on the adsorption process including adsorbent dose (A: 0.02–0.1 g), solution pH (B: 4–10), temperature (C: 30–50 °C), and time (D: 30–180 min) were investigated and optimized using response surface methodology-Box–Behnken design (RSM-BBD). The results demonstrated that TH dye adsorption on the Ch-Glu/AC surface obeyed the pseudo-first order (PFO) kinetic model, and the Freundlich isotherm was obeyed at equilibrium. The maximum adsorption capacity (qm) of the TH dye was 30.8 mg/g at 50 °C. The TH dye adsorption mechanism onto the composite surface was attributed to the electrostatic interaction, π-π interaction, and H-bonding. The findings of this work reveal the feasibility of Ch-Glu/AC as a candidate adsorbent for effective removal of cationic dyes from aquatic media.

Impact of acid type and glutaraldehyde crosslinking in the physicochemical and mechanical properties and biodegradability of chitosan films

Abstract: Biodegradable chitosan films were produced using lactic and acetic acid solutions and glutaraldehyde as crosslinking agent by casting technique. The aim of this study was to evaluate the influence of different acids and the crosslinking on the characteristics and biodegradability of chitosan films. The films were analyzed through thickness, swelling degree, mechanical and thermal properties, chemical structure and biodegradability. The glutaraldehyde release was also evaluated. All films’ properties are deeply affected by the acid type and glutaraldehyde crosslinking. Crosslinking reduced the swelling degree of films, also increasing their fragility. The glutaraldehyde release from the films to the simulant solutions was not observed after the incubation period. Through biodegradation tests, it was observed that the crosslinking does not prevent films’ degradability but longer time is required. The qualitative analysis of ecotoxicity of the films suggests the possibility of composting the developed films. The films presented potential for application as membranes and in packaging, and different formulations can be used according to the desired final characteristics.

Immobilization of Pleurotus nebrodensis WC 850 laccase on glutaraldehyde cross-linked chitosan beads for enhanced biocatalytic degradation of textile dyes

Abstract: Immobilized laccases with aggrandized catalytic activity and stability have demonstrated potential applicability in wastewater treatment. Herein, a purified laccase from Pleurotus nebrodensis WC 850 was effectively immobilized onto high-quality spherical chitosan beads using the cross-linking method. The maximum immobilization yield was achieved by chitosan beads developed using a 2.5 % chitosan solution after 6 h of incubation in 1.0 % glutaraldehyde solution. The detection of copper by EDX analysis confirmed the occurrence of the enzyme in the laccase coupled beads. Chitosan-immobilized laccase (CTS-Lac) performed over wide working pH and temperatures with an optimum pH of 7.0 and 50 °C. Kinetic parameters Km and Vmax for CTS-Lac were calculated to be 120 μM and 597 U/mL, respectively. CTS-Lac achieved high decolorization efficiencies for different reactive and disperse dyes (83–90 %). Preservation of 84.19 % and 54.21 % of its initial activity after 3 and 8 consecutive dye removal cycles indicates a stable dye degradation performance in the repeated batches. After treatment with the enzymes, BOD, COD, and TOC levels were reduced to 92.25–96.55 %, 91.90–94.94, and 77.01–93.29 %, respectively, in the dye solutions. Conclusively, immobilized laccase treatment might appear a good choice for bioremediation of dye-laden industrial wastewater due to substantial degradation and appreciable improvement in water quality parameters.

Glutaraldehyde-wheat gluten protein adhesives for wood bonding

Abstract: Wheat gluten protein hydrolysate was used as a biomass feedstock to prepare environmentally friendly protein-based adhesives, with hydrolyzed wheat protein as control. Glutaraldehyde was used to modify it to obtain a glutaraldehyde-wheat protein (GP) adhesive. Polyethylenimine (PEI) was also used as a crosslinking agent. Plywood has been prepared and tested, and its performance was used to measure the wheat gluten protein hydrolysate adhesive bonding performance. Differential scanning calorimetry (DSC) and thermomechanical analysis (TMA) were used to analyze the adhesive thermal properties and the microstructures of the cured adhesives by scanning electron microscopy (SEM). The results show that modification by glutaraldehyde can effectively improve the bonding performance of wheat protein adhesives, the plywood bonded strength having been improved by its addition. The effect of PEI as a crosslinking agent became evident. It can greatly improve the bonding properties of glutaraldehyde-modified wheat protein adhesives. TMA analysis indicates that the glutaraldehydemodified GP adhesive has a higher storage modulus than the unmodified one. The modulus of the adhesive increased after adding the PEI cross-linking agent.

Optimization of Chitosan Glutaraldehyde-Crosslinked Beads for Reactive Blue 4 Anionic Dye Removal Using a Surface Response Methodology.

Abstract: The use of dyes at an industrial level has become problematic, since the discharge of dye effluents into water disturbs the photosynthetic activity of numerous aquatic organisms by reducing the penetration of light and oxygen, in addition to causing carcinogenic diseases and mutagenic effects in humans, as well as alterations in different ecosystems. Chitosan (CS) is suitable for removing anionic dyes since it has favorable properties, such as acquiring a positive charge and a typical macromolecular structure of polysaccharides. In this study, the optimization of CS beads crosslinked with glutaraldehyde (GA) for the adsorption of reactive blue dye 4 (RB4) in an aqueous solution was carried out. In this sense, the response surface methodology (RSM) was applied to evaluate the concentration of CS, GA, and sodium hydroxide on the swelling degree in the GA-crosslinked CS beads. In the same way, RSM was applied to optimize the adsorption process of the RB4 dye as a function of the initial pH of the solution, initial concentration of the dye, and adsorbent dose. The crosslinking reaction was investigated by scanning electron microscopy (SEM), Fourier transformed infrared spectroscopy (FTIR), and X-ray diffractometry (XRD). The design described for the swelling degree showed an R2 (coefficient of determination) adjusted of 0.8634 and optimized concentrations (CS 3.3% w/v, GA 1.7% v/v, and NaOH 1.3 M) that were conveniently applied with a concentration of CS at 3.0% w/v to decrease the viscosity and facilitate the formation of the beads. In the RB4 dye adsorption design, an adjusted R2 (0.8280) with good correlation was observed, where the optimized conditions were: pH = 2, adsorbent dose 0.6 g, and initial concentration of RB4 dye 5 mg/L. The kinetic behavior and the adsorption isotherm allowed us to conclude that the GA-crosslinked CS beads' adsorption mechanism was controlled mainly by chemisorption interactions, demonstrating its applicability in systems that require the removal of contaminants with similar structures to the model presented.

Effect of glutaraldehyde/glycerol ratios on the properties of chitosan films

Abstract: Chitosan is a biodegradable polymer and could be applied as packaging. To make chitosan more competitive, plasticizers and cross‐linking agents are added in films. The aim of this paper was to obtain and characterize films of chitosan without or with glutaraldehyde (0; 0.99 mg/150 ml) in different concentrations of glycerol (0, 10, 20, and 30%w/w), for improving the properties like tensile resistance and the water vapor permeability. The films were homogeneous, without phase separation, and with a similar chemical structure. The glutaraldehyde makes the chitosan partly hydrophobic, leading to glycerol saturation in samples with glutaraldehyde and 20 or 30% of glycerol. The Principal Component Analysis for the film with glutaraldehyde and 10% of glycerol presented 3.60 g.mm/kPa.day.m² of water vapor permeability and 36.96 MPa of tensile resistance. The use of plasticizer and cross‐linking in combination is promising to make chitosan film more competitive on the market of packaging. PRACTICAL APPLICATIONS: The addition of glutaraldehyde and glycerol was efficient to improve film properties like water vapor permeability and mechanical properties. The chitosan films with glycerol and glutaraldehyde exhibited similar physical and chemical properties to non‐biodegradable polymers from the petrochemical origin and non‐renewable sources. Furthermore, chitosan films with these additives can be applied as packaging, improving the competitiveness of this biopolymer to the market. The technology described in the paper is important for application as secondary or tertiary packaging in the food industry.

Nonglutaraldehyde crosslinked bioprosthetic heart valves based on 2-isocyanatoethyl methacrylate crosslinked porcine pericardium with improved properties of stability, cytocompatibility and anti-calcification

Abstract: Valvular heart diseases (VHD) have a high incidence in the elderly, and the morbidity and fatality rate of VHD increase gradually. To save the lives of patients at the end stage of VHD, valve replacement is the most effective treatment. Owning to the good hydrodynamic performance and application of transcatheter aortic valve replacement (TAVR), bioprosthetic heart valves (BHVs) fabricated from glutaraldehyde crosslinked porcine or bovine pericardium have become a popular choice for patients. However, BHVs fail within 10–15 years of implantation due to the structural degradation and calcification which are greatly attributed to glutaraldehyde crosslinking. In this work, 2-isocyanatoethyl methacrylate (ICM) was used as crosslinking agent for the first time to stabilize porcine pericardium by radical polymerization crosslinking. The ICM-crosslinked pericardium (PICM10-PP) was demonstrated to exhibit better cytocompatibility, mechanical property, and milder immune responses compared with glutaraldehyde crosslinked porcine pericardium (GA-PP). In addition, the PICM10-PP was less calcific than GA-PP after 30 and 90 days of subcutaneous implantation. Following the guidance of ISO5840-3, the hydrodynamic performance and durability of PICM10-PP were evaluated and demonstrated to conform the requirements for BHVs. These results indicate that ICM is a potential alternative of glutaraldehyde in crosslinking BHVs.

A Novel Superabsorbent Polymer from Crosslinked Carboxymethyl Tragacanth Gum with Glutaraldehyde: Synthesis, Characterization, and Swelling Properties.

Abstract: Nowadays, current global environmental problems include measures to eliminate or reduce the negative impact of chemicals from petroleum sources and, therefore, the use of materials from natural resources is increasingly recommended. In this context, natural-based superabsorbent polymers derived from polypeptides and polysaccharides have undergone chemical and biochemical modifications to improve their ability to absorb and retain large amounts of liquids. In the present paper, a new process has been used to overcome the side effects of radical polymerization in the manufacture of conventional polyacrylate superabsorbents (SAPs). Tragacanth gum (TG) was selected to prepare a new superabsorbent material (CMTG-GA) based on carboxymethyl tragacanth (CMTG) crosslinked with glutaraldehyde (GA). The characterization of the polymer was carried out by FTIR, TGA, XRD, and SEM. The effect of the amount of crosslinking agent and the pH on the water absorption capacity was also examined. Subsequently, swelling studies were performed using free swelling capacity (FSC) and centrifuge retention capacity (CRC) techniques in distilled water, tap water, and saline solution. The results showed that the CRC of the new material is not less than 42.1 g/g, which was observed for a ratio of 20% by weight of GA to CMTG. Likewise, the maximum absorption results were 43.9 and 32.14 g/g, respectively, for FSC and CRC at pH 8.0. In addition, a comparison of the swelling capacities of the synthesized product with a commercial SAP extracted from a baby diaper, well known in the Moroccan market, showed that the performances were very similar.

Gelatin supports with immobilized laccase as sustainable biocatalysts for water treatment

Abstract: Millimeter-size beads of gelatin are manufactured by dripping process to give enzyme supports qualified for micropollutants biodegradation in alternative wastewater treatment. The bead diameter is dependent on the tip diameter, the gelatin solution viscosity and the swelling of polymer chains in the collecting bath. Chemical crosslinking was performed with glutaraldehyde using optimal concentration to give mechanical and thermal properties suitable for application in stirred reactor in aqueous medium. Laccases from Trametes versicolor are grafted on the gelatin beads with glutaraldehyde. Sixty percentage of the initial enzymatic activity, evaluated by the oxidation of 2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)diammonium salt (ABTS) is maintained after 10 successive cycles of reaction. Thermal stability at 60°C of immobilized biocatalysts is improved when compared to free enzymes (45% vs 10% of relative activity after 6 h of incubation). The simplicity of the procedure to form gelatin beads and their properties make them promising bio-based and biodegradable support for enzyme immobilization.

Application of Poly (Agar-Co-Glycerol-Co-Sweet Almond Oil) Based Organo-Hydrogels as a Drug Delivery Material

Abstract: In this study, it was aimed to investigate the synthesis, characterization and drug release behaviors of organo-hydrogels containing pH-sensitive Agar (A), Glycerol (G), Sweet Almond oil (Wu et al. in J Mol Struct 882:107–115, 2008). Organo-hydrogels, which contained Agar, Glycerol and different amounts of Sweet Almond oil, were synthesized via the free-radical polymerization reaction with emulsion technique using glutaraldehyde or methylene bis acrylamide crosslinkers. Then, the degree of swelling, bond structures, blood compatibility and antioxidant properties of the synthesized organo-hydrogels were examined. In addition, Organo-hydrogels which loaded with Ceftriaxone and Oxaliplatin were synthesized with the same polymerization reaction and release kinetics were investigated. In vitro release studies were performed at media similar pH to gastric fluid (pH 2.0), skin surface (pH 5.5), blood fluid (pH 7.4) and intestinal fluid (pH 8.0), at 37 °C. The effects on release of crosslinker type and sweet almond oil amount were investigated. Kinetic parameters were determined using release results and these results were applied to zero and first-order equations and Korsmeyer-Peppas and Higuchi equations. Diffusion exponential was calculated for drug diffusion of organo-hydrogels and values consistent with release results were found.

Tailoring the Effects of Titanium Dioxide (TiO2) and Polyvinyl Alcohol (PVA) in the Separation and Antifouling Performance of Thin-Film Composite Polyvinylidene Fluoride (PVDF) Membrane.

Abstract: In this study, thin-film composite (TFC) polyvinylidene fluoride (PVDF) membranes were synthesized by coating with titanium dioxide (TiO2)/polyvinyl alcohol (PVA) solution by a dip coating method and cross-linked with glutaraldehyde. Glutaraldehyde (GA) acted as a cross-linking agent to improve the thermal and chemical stability of the thin film coating. The incorporation of TiO2 in the film enhanced the hydrophilicity of the membrane and the rejection of dyes during filtration. The layer of TiO2 nanoparticles on the PVDF membranes have mitigated the fouling effects compared to the plain PVDF membrane. The photocatalytic performance was studied at different TiO2 loading for the photodegradation of dyes (reactive blue (RB) and methyl orange (MO)). The results indicated that the thin film coating of TiO2/PVA enhanced photocatalytic performance and showed good reusability under UV irradiation. This study showed that nearly 78% MO and 47% RB were removed using the TFC membrane. This work provides a new vision in the fabrication of TFC polymeric membranes as an efficient wastewater treatment tool.

The study of dry biological valve crosslinked with a combination of carbodiimide and polyphenol.

Abstract: The glutaraldehyde crosslinked pericardium has been used in bioprosthetic valves for about 50 years. However, problems such as glutaraldehyde residue and calcification still exist in current commercial products. Non-glutaraldehyde crosslinked dry valve is an important strategy to solve those problems. In this study, a non-glutaraldehyde crosslinked dry biological valve material was obtained by the combined crosslinking of carbodiimide (EDC) and polyphenol. The results showed that the comprehensive properties of EDC and curcumin crosslinked pericardium were superior to glutaraldehyde crosslinked pericardium, including unfolding property, anti-calcification, cytotoxicity, anticoagulant properties, mechanical properties, enzyme degradation resistance and thermal shrinkage temperature. EDC and curcumin crosslinked dry pericardium could flatten after being folded at 40°C for 3 days while glutaraldehyde crosslinked pericardium could not. The calcification of pericardium treated with EDC and curcumin was 1.21 ± 0.36 mg/g in rats after 60 days' subdermal implantation, much lower than that of glutaraldehyde treated control group (22.06 ± 3.17 mg/g).

Decellularized nerve extracellular matrix/chitosan crosslinked by genipin to prepare a moldable nerve repair material.

Abstract: Decellularized nerve extracellular matrix (NECM) composited with chitosan are moldable materials suitable for spinal cord repair. But the rapid biodegradation of the materials may interrupt neural tissue reconstruction in vivo. To improve the stability of the materials, the materials produced by NECM and chitosan hydrogels were crosslinked by genipine, glutaraldehyde or ultraviolet ray. Physicochemical property, degradation and biocompatibility of materials crosslinked by genipin, glutaraldehyde or ultraviolet ray were evaluated. The scaffold crosslinked by genipin possessed a porous structure, and the porosity ratio was 89.07 + 4.90%, the average diameter of pore was 85.32 + 5.34 μm. The crosslinked degree of the scaffold crosslinked by genipin and glutaraldehyde was 75.13 ± 4.87%, 71.25 ± 5.06% respectively; Uncrosslinked scaffold disintegrated when immerged in distilled water while the scaffold crosslinked by genipin and glutaraldehyde group retained their integrity. The scaffold crosslinked by genipin has better water absorption, water retention and anti-enzymatic hydrolysis ability than the other three groups. Cell cytotoxicity showed that the cytotoxicity of scaffold crosslinked by genipin was lower than that crosslinked by glutaraldehyde. The histocompatibility of scaffold crosslinked by genipin was also better than glutaraldehyde group. More cells grew well in the scaffold crosslinked by genipin when co-cultured with L929 cells. The decellularized nerve extracellular matrix/chitosan scaffold crosslinked by the genipin has good mechanical properties, micro structure and biocompatibility, which is an ideal scaffold for the spinal cord tissue engineering.

Preparation of cross-linked enzyme aggregates of lipase from Aspergillus niger: process optimization, characterization, stability, and application for epoxidation of lemongrass oil

Abstract: Cross-linked enzyme aggregates (CLEAs) of lipase were prepared after fractional precipitation with 40–50% ammonium sulfate and then cross-linking with glutaraldehyde. The process variables for the preparation of lipase-CLEAs such as glutaraldehyde concentration, cross-linking period, and initial pH of medium were optimized. The optimized conditions for the preparation of lipase-CLEAs were 25 mM/80 min/pH 7.0, and 31.62 mM/90 min/pH 6.0 with one factor at a time approach and numerical optimization with central composite design, respectively. Lipase-CLEAs were characterized by particle size analysis, SEM, and FTIR. Cross-linking not only shifted the optimal pH and temperature from 7.0 to 7.5 and 40–45 to 45–50 °C, but also altered the secondary structure. Lipase-CLEAs showed an increase in Km by 7.70%, and a decrease in Vmax by 16.63%. Lipase-CLEAs presented better thermostability than free lipase as evident from thermal inactivation constants (t1/2, D and Ed value), and thermodynamic parameters (Ed, ΔH°, ΔG°, and ΔS°) in the range of 50–70 °C. Lipase-CLEAs retained more than 65% activity up to four cycles and showed good storage stability for 12 days when stored at 4 ± 2 °C. They were successfully utilized for the epoxidation of lemongrass oil which was confirmed by changes in iodine value, epoxide value, and FTIR spectra.

Gelatin-derived honeycomb like porous carbon for high mass loading supercapacitors

Abstract: Using gelatin as the carbon source and glutaraldehyde as the cross linking agent, a novel honeycomb like porous carbon has been successfully prepared through simple cross linking reaction and KOH activation at high temperature. Compact and uniform honeycomb morphology has been formed in Gel/G-1.0 (Gel represents gelatin, G represents glutaraldehyde, and 1.0 represents the amount of glutaraldehyde) which brings micropores and high specific surface area (SSA). Heteroatoms including O and N have been introduced into carbon material which contribute pseudo-capacitance. Higher degree of graphitization for Gel/G-1.0 has improved the conductivity of the carbon material which exhibits good electrochemical performances under high mass loading. When the active carbon material mass loading is about 10 mg, the specific capacitance (Csp) of Gel/G-1.0 is 392 F g−1 at current density of 1 A g−1 in 2 M H2SO4, with high retention of 64% at current density of 10 A g−1. More importantly, the carbon material exhibits a high energy density of 6.39 W h kg−1 with the power density of 50.03 W kg−1, even at the power density of 502.79 W kg−1, the energy density remains 5.00 W h kg−1. This simple synthesis strategy and outstanding electrochemical performances of carbon materials with high mass loading are great significance in the application of supercapacitors.

Molecular Docking and Antibacterial Studies of Pyranopyrazole Derivatives Synthesized Using [Pap-Glu@Chi] Biocatalyst Through a Greener Approach

Abstract: In the present work, papain enzyme was immobilized on a polymer support chitosan through a linkage of glutaraldehyde to form the [Pap-Glu@Chi] biocatalyst through the covalent bonding method The immobilization of papain on Chitosan was confirmed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) which revealed the change in morphology of chitosan due to immobilization of papain through glutaraldehyde Thus prepared heterogeneous biocatalyst was used for the four-component synthesis of pyranopyrazole derivatives by the reaction of substituted aromatic aldehydes, malononitrile, ethylacetoacetate and hydrazine hydrate affording excellent yields within short reaction times at moderate temperature The catalyst exhibited significant activity up to six cycles Synthesized compounds were checked for their molecular docking activity using AutoDock Vina against the bacterial protein receptors (PDB code 2VF5 and 1BAG) obtained from the RCSB Protein Data Bank Significant binding energy values obtained from docking studies revealed good interaction between synthesized compounds and bacterial protein receptor Synthesized compounds were tested against human pathogenic bacterial strains Escherichia coli, Salmonella typhi, Bacillus subtilis, Pseudomonas aeruginosa along with Gentamicine as a reference antibiotic using disk diffusion method The compounds were found to exhibit moderate-to-high antibacterial activity