Glutaraldehyde Cross-linked Chitosan Research Articles

Dissolution profiles of partially purified bromelain from pineapple cores [Ananas comosus (L.) Merr] encapsulated in glutaraldehyde-crosslinked chitosan

Dissolution profiles of partially purified bromelain from pineapple cores [Ananas comosus (L.) Merr] encapsulated in glutaraldehyde-crosslinked chitosan

Chemical cross-linking: A feasible approach to prolong doxylamine/pyridoxine release from spray-dried chitosan microspheres

Spray-dried chitosan microparticles have been widely exploited as vehicles for mucosal drug delivery. Despite their advantages as pharmaceutical formulations, one of the major challenges is achieving sustained drug release, which would diminish toxicity and dosage frequency. The aim of this study was to formulate mucoadhesive glutaraldehyde cross-linked chitosan microparticles loaded with doxylamine succinate and pyridoxine hydrochloride as potential nasal drug delivery systems with sustained release. Microparticle models were formulated via spray-drying technique, using glutaraldehyde in different concentrations (0.1–1.0 mg/mL) as a cross-linking agent for chitosan. The obtained particles were with spherical shape, smooth surface and median diameter of 4 μm. The drug entrapment efficiency was high (80.47%–94.25%), indicating a tendency to decrease at higher glutaraldehyde concentrations. FTIR data demonstrated that there were no chemical interactions between glutaraldehyde and the drugs. The in vitro studies showed that the cross-linking process substantially limited particles swelling. The cross-linked particles exhibited sustained drug release characteristics at pH 6.8 over a period of 5 h with an initial burst-effect in the first 30 min. Drug release followed Korsmeyer-Peppas kinetics. Although a decrease of the particles mucoadhesive properties was observed after modification, all cross-linked formulations demonstrated high in vitro adsorption of mucin. The proposed models of mucoadhesive microsphere with sustained drug release are a perspective ground for further development of a novel delivery system for nasal administration of doxylamine and pyridoxine.

Chitosan nanoparticles via high-pressure homogenization-assisted miniemulsion crosslinking for mixed-matrix membrane adsorbers

Glutaraldehyde-crosslinked chitosan nanoparticles (Chi-NPs) were prepared reproducibly via miniemulsion crosslinking for effective adsorption of the active pharmaceutical ingredient (API) Diclofenac (DCL). Three different molecular weights (MWs) of highly deacetylated (>90%) chitosans (low, medium and high MW) were used to vary the disperse phase viscosity. Particle formation was evaluated ranging from one to seven homogenization cycles at 40 MPa. Particles were prepared successfully with the low and medium MW chitosan in the range of 125 nm–250 nm (z-average). In HPLC assisted, static adsorption experiments, all particles showed a rapid sorption rate (<2 min) with an adsorption capacity of up to 256.2 mg g−1 DCL. Modelling of adsorption isotherms resulted in a qmax 358.3 mg g-1 for Langmuir and 502.5 mg g−1 for Sips, respectively. Membrane adsorbers were prepared by processing Chi-NPs into porous polyether sulfone microfiltration membranes via a casting and phase inversion process, resulting in an adsorption capacity of up to 3.6 mg m-2 DCL in dynamic adsorption experiments.

Selective Determination of Cr(VI) by Glutaraldehyde Cross-Linked Chitosan Polymer Fluorophores.

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 capable of selectively determining Cr(VI) within a concentration range up to 50 μM and a detection limit of 0.22 μM. The analytical performance of GCPF was also confirmed by analyzing real surface water and industrial samples.

Lignocellulose-Chitosan-Multiwalled Carbon Nanotube Composites with Improved Mechanical Strength, Dimensional Stability and Fire Retardancy.

A novel composite composed of lignocellulose (LC), glutaraldehyde crosslinked chitosan (GC) and multiwalled carbon nanotube (MWCNT) was fabricated by the hot-pressing process. The effect of the additional GC and MWCNT on the mechanical strength, dimensional stability and fire retardancy of lignocellulose composites was investigated. The results showed that LC/GC/MWCNT composite exhibited the maximum modulus of rupture (MOR) of 35.3 MPa, modulus of elasticity (MOE) of 2789.1 MPa and internal bonding (IB) strength of 1.2 MPa. Meanwhile, the LC/GC/MWCNT composite displayed improved dimensional stability with a thickness swelling (TS) value of 22.4%. Besides, the LC/GC/MWCNT composite exhibited improved fire retardancy with a limiting oxygen index of 29.0%. The peak heat release rate, the total heat release, the total smoke production and the maximum smoke production ratio of LC/GC/MWCNT composite decreased by 15.9%, 10.7%, 45.5% and 20.7% compared with those of LC composite, respectively. Therefore, the LC/GC/MWCNT composite may be a promising candidate for green wood based composites.

1,5 diphenyl carbazide immobilized cross-linked chitosan films: An integrated approach towards enhanced removal of Cr(VI)

Present study illustrates the significant enhancement in the adsorption capacity of glutaraldehyde cross-linked chitosan (C) films through immobilization of 1,5-diphenyl carbazide (D) towards Cr(VI). TGA studies reveal incorporation of about 11% D within the pores of the film while FESEM analysis further confirm thread like nature containing hydrophobic voids. Contact angle measurements suggest the appropriate balance of hydrophilic/hydrophobic nature of film through successive modifications with glutaraldehyde (G) and D. It is observed that Cr(VI) uptake by films is substantially improved by about 25% at pH2 that follows pseudo first order kinetics with a rate constant value of 0.085h−1. Adsorption studies suggest that removal of Cr(VI) is a spontaneous process occurring mainly through pore diffusion process with removal capacity of 166mgg−1. XPS analysis of Cr(VI) treated C+G+D film indicate formation of Cr-D complex on the surface of film as well as presence of predominantly adsorbed Cr(III) species. It is interesting to note that there exists strong binding of Cr(III) with D present within the pores of film in a quantitative manner. Thus, it can be argued that incorporation of a selective chelating agent like D has substantial effect on removal efficiency of C+G+D for Cr(VI); an approach possessing potential applications in membrane technology.

Magnetic nanoparticle-loaded alginate beads for local micro-actuation of in vitro tissue constructs

Magnetic nanoparticles (MNPs) self-align and transduce magnetic force, two properties which lead to promising applications in cell and tissue engineering. However, the toxicity of MNPs to cells which uptake them is a major impediment to applications in engineered tissue constructs. To address this problem, MNPs were embedded in millimeter-scale alginate beads, coated with glutaraldehyde cross-linked chitosan, and loaded in acellular and MDA-MB-231 cancer cell-seeded collagen hydrogels, providing local micro-actuation under an external magnetic field. Brightfield microscopy was used to assess nanoparticle diffusion from the bead. Phase contrast microscopy and digital image correlation were used to track collagen matrix displacement and estimate intratissue strain under magnetic actuation. Coating the magnetic alginate beads with glutaraldehyde-chitosan prevents bulk diffusion of nanoparticles into the surrounding microenvironment. Further, the beads exert force on the surrounding collagen gel and cells, resulting in intratissue strains of 0–10% tunable with bead dimensions, collagen density, and distance from the bead. Cells seeded adjacent to the embedded beads are subjected to strain gradients without loss of cell viability over two days culture. This study describes a simple way to fabricate crosslinked magnetic alginate beads to load in a collagen tissue construct without direct exposure of the construct to nanoparticles. The findings are significant to in vitro studies of mechanobiology in enabling precise control over dynamic mechanical loading of tissue constructs.

Cellulose and chitosan derivatives for enhanced sorption of erbium(III)

Cellulose (Cell) was chemically modified by grafting thiourea (Thio-Cell) and glutaraldehyde cross-linked chitosan (GLA-Chit) was functionalized by poly(aminocarboxymethylation) (PCM-Chit); material was also prepared as a composite material that incorporates a magnetic core (Magn PCM-Chit). The sorption properties of these materials have been compared to non-modified cellulose and GLA-Chit for Er(III) uptake. Sorption increases with progressive deprotonation of reactive groups, such as ROH, RSH, amine and carboxylic acid groups. The chemical modification significantly increases sorption performance and more specifically the poly(aminocarboxymethylation): sorption capacities increase up to 117–145mgEr(III)g−1. Sorption capacities also increase with temperature: the sorption is endothermic and spontaneous. The spontaneity of the reaction significantly increases with chemical modification of chitosan-based sorbent. The entropy of the system is negative for GLA-Chit, Cell and Thio-Cell and positive for PCM-Chit materials. Acidic solutions of thiourea efficiently desorb Er(III) and allows the recycling of the sorbents for a minimum of 5 sorption/desorption cycles. FT-IR spectrometry, XRD, TGA, elemental analyses and SEM observations have been used for characterizing the materials. The magnetic properties of Magn PCM-Chit were also characterized by VSM.

Application of Glutaraldehyde-Crosslinked Chitosan Membranes from Shrimp Shellwaste on Production of Biodiesel from Calophyllum Inophyllum Oil

Для поліпшення якості і зниження вартості виробництва біодизельного палива проведено його очищення з використанням глутаральдегід-зшитих хітозанових мембран. Біодизель одержано перестерифікацією калофілевої олії з вико- ристанням кислотного каталізатора. Показано, що кількість гліцерину в біодизельному паливі перед процесом очищення ста- новить 0,3014 ± 0,05 %. Після проведення очищення протягом 1 год. вміст гліцерину в біодизелі зменшується до 0,1429 ± 0,09 %.

The Adsorption of Pb, Zn, Cu, Ni, and Cd by Modified Ligand in a Single Component Aqueous Solution: Equilibrium, Kinetic, Thermodynamic, and Desorption Studies.

In this investigation, an amino functionalized adsorbent was developed by grafting 4-aminobenzoic acid onto the backbone of cross-linked chitosan beads. The 3 sets of beads including chitosan (CX), glutaraldehyde cross-linked chitosan (CCX), and 4-aminobenzoic acid grafted cross-linked chitosan (FGCX) were characterized by FTIR, XRD, SEM, and TGA. The water content and amine concentration of FGCX were determined. The effect of adsorption parameters was studied and the optimum was used for further studies. Equilibrium data was obtained from the adsorption experiment carried out at different initial concentration; the data were applied in isotherm, thermodynamics, and kinetic studies. The Langmuir and Dubinin-Kaganer-Radushkevich (DKR) models were successful in describing the isotherm data for the considered metal ions while the Freundlich and Temkin model fit some of the considered metal ions. Pseudo-second-order and intraparticle model described the kinetic data quite well. Thermodynamic parameters such as Gibb's free energy change (ΔGo), enthalpy change (ΔHo), and entropy change (ΔSo) were calculated and the results showed that the adsorption of Pb, Cu, Ni, Zn, and Cd ions onto FGCX is spontaneous and endothermic in nature. Regeneration of the spent adsorbent was efficient for the considered metal ions.

Synthesis and Characterization of 5-Fluorouracil-Loaded Glutaraldehyde Crosslinked Chitosan Hydrogels

In this work, the characterization and drug release behavior of 5-fluorouracil-loaded glutaraldehyde-crosslinked chitosan hydrogels have been studied. The structure of the hydrogels were investigated by Fourier transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction, also their properties were compared with those of the drug-unloaded hydrogels. The equilibrium swelling studies and drug release profiles were determined at 37°C in two different pHs (2.1 and 7.4). The results indicated that increased chitosan concentration in the hydrogel decreased the swelling and drug release values and the hydrogels released nearly the same amount of 5-fluorouracil in both acidic (~59%) and basic medium (~50%).

Comprehensive study of serratia peptidase immobilization from Serratia sp. ZF03 onto chitosan nanogels

Abstract Objective In the present work, we have extended the study and immobilized the metalloprotease enzyme in glutaraldehyde cross-linked chitosan nanogels to scrutinize the enzyme’s features including stability over its soluble free form. Method The immobilized metalloprotease was characterized using scanning electron microscopy (SEM), followed by Fourier transform infrared (FTIR) spectroscopy. The enzyme is optimally active at 50°C and pH range of 8.0–10. Results Thermal stability of the enzyme enhanced when immobilized on the nanogel. After 5 min of incubation at 50°C, immobilized enzymes retained 60% of their original activity, while negligible activity (23%) was observed in the case of the free enzyme. Conclusion The results obtained here provide a powerful demonstration of the benefits of taking the glutaraldehyde cross-linked chitosan matrices to enhance metalloprotease stability. The high stability of the immobilized enzyme serves to improve its performance for possible application on the industrial scale.

Synthesis, characterization, and biological activity of cross-linked chitosan biguanidine loaded with silver nanoparticles

Chitosan biguanidine hydrochloride (ChG) and glutaraldehyde cross-linked chitosan biguanidine (CChG) were synthesized and characterized by Fourier transform infrared spectroscopy, 1H NMR and 13C NMR, X-ray diffraction, scanning electron microscopy (SEM) and thermal analyses (TGA and DTA). The results showed that ChG and CChG had a more amorphous structure than that of chitosan, and their thermal stability were slightly lower than that of chitosan. Colloidal silver nanoparticles (AgNPs) were prepared using borohydride reduction method and then investigated as fillers in partially cross-linked chitosan biguanidine. The obtained nanoparticles were uniform and spherical with average size of 9.6 ± 0.5 nm. The prepared CChG/AgNPs composites were characterized for their morphology, thermal properties, cytotoxicity and antimicrobial activity. The SEM images showed that the AgNPs are well imbedded in the CChG matrix. The thermal stability of CChG was improved with incorporation of AgNPs. The CChG and CChG/AgNPs showed less cytotoxicity to breast cancer cells (MCF-7). Compared with chitosan and CChG, the ChG and CChG/AgNPs showed better antimicrobial activity against Streptococcus pneumoniae and Bacillus subtilis as Gram-positive bacteria, Escherichia coli as Gram-negative bacteria and Aspergillus fumigatus, Geotricum candidum and Syncephalastrum recemosum as fungi.

Pd(II) adsorption characteristics of glutaraldehyde cross-linked chitosan copolymer resin

Deliberating upon the role of solution chemistry in influencing the Pd(II) adsorption and desorption characteristics using chitosan based resins, this work addresses the competence of glutaraldehyde cross-linked chitosan (GCC) co-polymer resin for the removal and recovery of Pd(II) from synthetic electroless plating solutions. GCC copolymer adsorbent was prepared by grafting of fixed weight ratio (1/17) of medium molecular weight chitosan and glutaraldehyde (25% in H2O). Within the adsorption parametric range of 2–10pH, 60–300min contact time, 10–50mg adsorbent dosage and 50–500mg/L initial Pd(II) concentration, the solution chemistry associated to synthetic ELP solution has been evaluated to strongly reduce the adsorption capacity of the GCC resin. Batch equilibrium adsorption studies inferred upon the fitness of Langmuir isotherm with a monolayer adsorption capacity of 166.67mg/g. Adsorption kinetics and thermodynamic parametric evaluations affirmed pseudo-second-order kinetics and spontaneous exothermic Pd(II) adsorption on the resin. Further, speciation analysis provided valuable insights by indicating greater favourability of Pd(NH3)42+ species (at pH=8) than PdEDTA−2 (at lower pH) to foster chemisorption with the GCC resin. In summary, the observations affirmed that solution chemistry needs to be addressed in laboratory investigations to further industrial application and competitiveness of alternate resins.

Hierarchically porous carbon foams for electric double layer capacitors

The growing demand for portable electronic devices means that lightweight power sources are increasingly sought after. Electric double layer capacitors (EDLCs) are promising candidates for use in lightweight power sources due to their high power densities and outstanding charge/discharge cycling stabilities. Three-dimensional (3D) self-supporting carbon-based materials have been extensively studied for use in lightweight EDLCs. Yet, a major challenge for 3D carbon electrodes is the limited ion diffusion rate in their internal spaces. To address this limitation, hierarchically porous 3D structures that provide additional channels for internal ion diffusion have been proposed. Herein, we report a new chemical method for the synthesis of an ultralight (9.92 mg/cm3) 3D porous carbon foam (PCF) involving carbonization of a glutaraldehydecross-linked chitosan aerogel in the presence of potassium carbonate. Electron microscopy images reveal that the carbon foam is an interconnected network of carbon sheets containing uniformly dispersed macropores. In addition, Brunauer–Emmett–Teller measurements confirm the hierarchically porous structure. Electrochemical data show that the PCF electrode can achieve an outstanding gravimetric capacitance of 246.5 F/g at a current density of 0.5 A/g, and a remarkable capacity retention of 67.5% was observed when the current density was increased from 0.5 to 100 A/g. A quasi-solid-state symmetric supercapacitor was fabricated via assembly of two pieces of the new PCF and was found to deliver an ultra-high power density of 25 kW/kg at an energy density of 2.8 Wh/kg. This study demonstrates the synthesis of an ultralight and hierarchically porous carbon foam with high capacitive performance.

Effective removal of sulfur dyes from water by biosorption and subsequent immobilized laccase degradation on crosslinked chitosan beads

In this study, sulfur dyes were effectively removed from water samples through biosorption and subsequent immobilized laccase degradation on glutaraldehyde-crosslinked chitosan beads (GA-CBs). The Langmuir equation described the biosorption isotherms of the single dyes, sulfur blue 15 (SB15) and sulfur brown GD (SBGD), well. The decreased biosorption of one dye was found in binary mixtures by increasing the concentration of the second dye, and the extended Freundlich equation could reasonably describe such isotherms. Laccase immobilized on GA-CBs showed a high catalytic ability and provided reusability even at low laccase concentrations. In the treatment of single dyes at an initial concentration of 200mgL−1, for example, over 81.6% and 70.8% of SB15 and SBGD, respectively, were removed at a pH of 6.5 after the successive biosorption and enzymatic degradation with a biosorbent dose of 3.6gL−1, an initial laccase activity of 2.24UL−1, and 2.66×10−4mg(gsupport)−1 of immobilized laccase. In the treatment of binary mixtures under the same conditions, the efficiency of each dye decreased. The overall removals of SB15 and SBGD from binary mixtures containing 100mgL−1 of SB15 and 100mgL−1 of SBGD became 78.2% and 52.6%, respectively.

Preparation of a Crosslinked Chitosan Coated Calcium Sulfate Whisker and Its Reinforcement in Polyvinyl Chloride

A calcium sulfate whisker (CSW) coated with glutaraldehyde crosslinked chitosan (GACS) was prepared to reinforce polyvinyl chloride (PVC) in this study. The results show that the optimum concentration of both chitosan (CS) and glutaraldehyde (GA) is 0.05 wt%. The tensile strength, impact strength, flexural modulus and vicat softening temperature of the PVC composite with 12 wt% of modified CSW are increased by 17.5%, 40.4%, 0.8% and 3.8% compared with those of the PVC composite with 12 wt% of unmodified CSW, and by 2.9%, 42.4%, 27.1% and 6.8% compared with those of pure PVC, respectively. The dynamic mechanical analysis results indicate that the modified CSW/PVC composite exhibits much higher storage modulus and glass transition temperature than those of unmodified CSW/PVC composite and pure PVC. In addition, the modified CSW/PVC composite also demonstrates good thermal properties with a high rapidest decomposition temperature (Trpd) and char residue. The scanning electron microscopy images of tensile-fractured surfaces show that the modified CSW has a strong interfacial adhesion with PVC matrix.

DESIGN, IN VITRO AND IN VIVO EVALUATION OF CHRONOMODULATED DELIVERY SYSTEMS OF TERBUTALINE SULPHATE FOR NOCTURNAL ASTHAMA

The present study deals with the design and evaluation of chronomodulated delivery of terbutaline sulphate as a chronotherapeutic approach in the treatment of nocturnal asthma. The basic design is based on the Pulsincap technology and consisted of formaldehyde treated insoluble hard gelatin capsule body filled with glutaraldehyde cross-linked carboxymethyl chitosan microspheres of terbutaline sulphate and sealed with a hydrogel tablet plug. The entire device was enteric coated, so as to prevent the variable gastric emptying time. The glutaraldehyde cross-linked carboxymethyl chitosan microspheres appeared to be roughly spherical with the size range of 4.63±0.48 to 11.75±0.92µm. The prepared microspheres possessed good yield and high encapsulation efficiency. Particle size, encapsulation efficiency and release rate are dependent on the fabrication conditions of the microspheres. Drug release from the microspheres depended on the core: coat ratio, reaction time and the rotational speed used in the preparation of microspheres. Formaldehyde treatment efficiently rendered the hard gelatine capsule bodies water insoluble. The ejection of the plug from the chrnomodulated delivery system depended on the nature and concentration of polymer used in the preparation of table plug. A lag time of 3-8hrs was observed for the chronomodulated delivery systems prepared with different hydrogel plugging materials. Among the different polymers studied, HPC showed highest lag time compared to HPMC K4 M and sodium alginate. The Roentgenographic studies revealed the predicted in vivo performance of the developed chronomodulated delivery systems of terbutaline sulphate. Pharmacokinetic analysis revealed the significant increase in tmax, AUC and MRT of optimized chronomodulated system of terbutaline sulphate compared to that of pure drug. The results of the study conclusively proved the suitability of carboxymethyl chitosan microspheres and the adopted Pulsincap technology in the development of chronomodulated delivery systems for terbutaline sulphate in the treatment of nocturnal asthma. Key words: Nocturnal asthma; Terbutaline sulphate; Chronomodulated systems; Lag time; Roentgenography; In vivo pharmacokinetics

Nitrate decontamination through functionalized chitosan in brackish water

N, N, N-Triethyl ammonium functionalized cross-linked chitosan beads (TEACCB) was prepared by alkylation of glutaraldehyde cross-linked chitosan beads to remove nitrate from brackish water. Physico-chemical characteristics of TEACCB were analyzed using FTIR, SEM, EDAX, TGA, DTA, BET surface area, swelling ratio and pHzpc. The maximum nitrate removal capacity of TEACCB was 2.26meq/g and is higher than other reported chitosan based adsorbents. Nitrate removal ratio in the presence and absence of common anions like chloride and sulphate demonstrated the selectively of TEACCB towards nitrate. The kinetic data of nitrate removal fitted well with the pseudo-second-order kinetic model. The thermodynamic parameters indicated that nitrate removal could be spontaneous and exothermic in nature. TEACCB was reused with 100% efficiency after regenerating with 0.05N HCl. Column study was carried out to remove nitrate from brackish water. These results are very significant to develop TEACCB based nitrate removal technology with great efficiency.

Glutaraldehyde Cross-Linked Chitosan Nanofibers: Preparation, Characterization and Application in Adsorption of Cu (II).

Chitosan nanofibers were prepared via electrospinning and cross-linked by a treatment with glutaraldehyde (GA) in order to obtain insoluble adsorbents in aqueous acidic and basic solutions. Then, the prepared nanofiber was investigated for its adsorption of Cu (II) in aqueous solution. The effects of the viscosity, conductivity of chitosan-TFA spinning solution and the properties of the nanofibers related to the molecular weight of chitosan were studied. The scanning electron microscope (SEM) images demonstrated a smooth and inter-connected morphology comprising fibers with diameters between 70 nm and 350 nm. An amount of 72 mg/g of Cu (II) adsorption was achieved and its mechanism was elucidated. After removing the adsorbed Cu (II), the cross-linked chitosan nanofibers were regenerated and could be reused.