Mixture Of Alginate Research Articles

Interactions between bovine serum albumin and alginate: An evaluation of alginate as protein carrier

The intermolecular interactions between the model protein, bovine serum albumin (BSA) and a biocompatible polysaccharide, sodium alginate, have been investigated. Both the native BSA and the heat pre-denatured BSA were utilized to study, in parallel, the effect of protein conformational change during the protein–alginate complex formation. In this work, a comparison was performed between the native BSA and the heat-denatured BSA incubated sodium alginate mixtures by using zeta potential analyzer, dynamic light scattering (DLS) and turbidimetric analysis of the systems in combination with protein conformational tools, Fourier transform infrared spectroscopy (FT-IR) and size exclusion chromatography (SE-HPLC). The experimental results demonstrate that the intermolecular chain associations were formed between alginate chains and protein molecules in either the native form or the heat pre-denatured form, mainly driven by the electrostatic interactions between the oppositely charged amino acids and the anionic polysaccharide macromolecules. However, the majority of BSA was recovered from the dissociation of protein–alginate complexes and maintained its secondary structure and conformational property. Therefore, alginate is promising as a bioactive compound carrier.

Concurrent elution of calcium phosphate and macromolecules from alginate/chitosan hydrogel coatings

The concurrent release of calcium phosphate and biomacromolecules may improve wound healing responses at the interface with ceramic materials of orthopaedic and dental implants. Hydrogel coatings consisting of a mixture of alginate and chitosan were doped and applied onto solid carriers with the aim of investigating their use as local delivery vehicles. Coatings containing both the model macromolecule FITC-dextran 70 kDa (FD 70) and dispersed calcium phosphate carbonate (CPC) nanoparticles were coated onto a solid, nonporous model substrate to study the concurrent release of FD 70 and calcium and phosphate ions from within the hydrogel. Hydrogel coatings containing only FD 70 were cast onto porous calcium phosphate coatings, similar to hydroxyapatite, to study the release of FD 70 from, and calcium and phosphate ions through, the hydrogel coating. Transmission electron microscopy showed good dispersion of the CPC nanoparticles, and scanning electron microscopy and atomic force microscopy showed that increased CPC loading resulted in an increase in surface roughness but to extents well below those affecting cell responses. The release of FD 70 from CPC-loaded coatings was similar to release from the hydrogel alone, although higher CPC loadings resulted in small changes. The release of FD 70 was better described by double or triple phase zero order release kinetics; this complex time dependence indicates that in addition to outdiffusion, other, time-dependent factors apply, such as swelling of the gel, as expected from the known effects of calcium ions on alginate. Calcium and phosphate ions were also released, with similar release kinetics, through the hydrogel layer from the underlying CaP layer. In either case, release decreased to negligible levels after 3 days, suggesting that the systems of this study are suitable for short-term concurrent release of water-soluble biomacromolecules and calcium and phosphate ions.

Immobilization of Lipase by Entrapment in Ca-alginate Beads

The lipase-producing strain, Arthrobacter sp. (ABL), isolated was immobilized in Ca-alginate beads by entrapment. The alginate beads were prepared as an aqueous mixture of sodium alginate, the cells and CaCl2 to increase its reusability, and overall enzyme stability. Various parameters like alginate and CaCl2 concentration, lipase units loading and bead size were evaluated for optimum immobilization yield. It was observed that with the increase in alginate concentration, the yield of immobilized enzyme also increased up to a limit. A similar pattern was observed with CaCl2 addition; the optimum concentrations of alginate and CaCl2 observed were 1.5% (w/v) and 2%, respectively. The concentration of enzyme entrapped in the beads with an activity of 5 units per gram of wet beads was obtained by the addition of 100 units in 10 mL of slurry; beyond this amount a very little increase in activity was observed. The maximum immobilization yield was observed with a 1.2 mm bead size; increased bead sizes decreased the yield of immobilization. After optimization of all the parameters, a 40% yield of lipase (ABL) activity was observed in the Ca-alginate beads. These lipase beads were used for 10 cycles for the hydrolysis of triglycerides without any loss in activity. The entrapped lipase was more stable over a wide range of temperatures, pH, and storage time as compared to free enzyme.

Carbon‐Nanotube–Alginate Composite Modified Electrode Fabricated by In Situ Gelation for Capillary Electrophoresis

This report describes the development and the application of a novel carbon-nanotube (CNT)-alginate composite modified electrode as a sensitive amperometric detector for capillary electrophoresis (CE). The composite electrode was fabricated on the basis of in situ gelation of a mixture of CNTs and sodium alginate on the surface of a carbon disc electrode in aqueous calcium chloride solution. SEM, energy-dispersive spectroscopy, XRD, and FTIR spectroscopy offered insights into the nature of the novel composite. The results indicated that the CNTs were well dispersed and embedded throughout the alginate matrix to form an interconnected carbon-nanotube network on the base electrode. The performance of this unique CNT-based detector has been demonstrated, in conjunction with CE, by separating and detecting five caffeic acid derivatives. The new CNT-based CE detector offered significantly lower operating potentials, substantially enhanced signal-to-noise characteristics, and a lower expense of operation. The simplicity and significant performance exhibited by the CNT-alginate composite modified electrode also indicate great promise for the use of this electrode in microchip CE, flowing-injection analysis, and other microfluidic analysis systems.

Gelation behaviour of gelatin and alginate mixtures

Mixtures of alginate and gelatin were studied by rheology as a function of different parameters, such as temperature, biopolymer concentrations, calcium concentration and ionic strength. In particular conditions, the formation of a mixed gel of alginate and gelatin is obtained. A slow release of calcium ions leads first to an irreversible alginate gel and cooling results in a reversible gelatin gel. Depending on experimental conditions, non-linear behaviours upon gelation of alginate occur and a collapse of alginate gel is directly observable by rheology. These trends are favoured between 35 and 45 °C, by a high total biopolymer concentration or a high calcium concentration and ionic strength. Different mechanisms could be responsible for this collapse, such as a competition between alginate gelation and phase separation in the biopolymer mixture or an over-association of alginate chains at high Ca 2+ concentration, favoured by the presence of gelatin.

Preparation and evaluation of buccoadhesive films of atenolol

This paper describes the preparation of new bilayered device comprising a drug containing mucoadhesive layer and a drug free backing layer. Bilaminated films were produced by a casting/ solvent evaporation technique. The mucoadhesive layer was composed of mixture of drug and sodium alginate with or without carbopol 934 P, and backing layer was made of ethyl cellulose. The double layer structure design was expected to provide drug delivery in a unidirectional fashion to the mucosa and avoid loss of drug due to wash out with saliva. The fabricated films were subjected to in vitro drug release, in vitro permeation through porcine buccal mucosa. The bilayered films were also evaluated for mucoadhesive strength, mucoadhesive time, folding endurance, hydration studies and tensile strength.

Development of Clindamycin-Loaded Wound Dressing with Polyvinyl Alcohol and Sodium Alginate

To develop a clindamycin-loaded wound dressing, cross-linked hydrogel films were prepared using freeze-thawing method with various mixtures of polyvinyl alcohol (PVA) and sodium alginate (SA). The physicochemical properties such as swelling ratio, tensile strength and elongation of hydrogels were evaluated. The drug release from this clindamycin-loaded hydrogel, in vitro protein adsorption test and in vivo wound healing observations in rats were then performed. Increased SA concentration decreased the gelation %, maximum strength and break elongation, but it resulted into an increment in the swelling ability, elasticity and thermal stability of hydrogel film. However, SA had insignificant effect on the release of clindamycin. This hydrogel improved the healing rate of artificial wounds in rats. Thus, a clindamycin-loaded wound dressing with PVA and SA hydrogel should be a candidate for wound care.

Preparation of Calcium Alginate Microgel Beads in an Electrodispersion Reactor Using an Internal Source of Calcium Carbonate Nanoparticles

An electrodispersion reactor has been used to prepare calcium alginate (Ca-alginate) microgel beads in this study. In the electrodispersion reactor, pulsed electric fields are utilized to atomize aqueous mixtures of sodium alginate and CaCO3 nanoparticles (dispersed phase) from a nozzle into an immiscible, insulating second liquid (continuous phase) containing a soluble organic acid. This technique combines the features of the electrohydrodynamic force driven emulsion processes and externally triggered gelations in microreactors (the droplets) ultimately to yield soft gel beads. The average particle size of the Ca-alginate gels generated by this method changed from 412 +/- 90 to 10 +/- 3 microm as the applied peak voltage was increased. A diagram depicting structural information for the Ca-alginate was constructed as a function of the concentrations of sodium alginate and CaCO3 nanoparticles. From this diagram, a critical concentration of sodium alginate required for sol-gel transformation was observed. The characteristic highly porous structure of Ca-alginate particles made by this technique appears suitable for microencapsulation applications. Finally, time scale analysis was performed for the electrodispersion processes that include reactions in the microreactor droplets to provide guidelines for the future employment of this technique. This electrodispersion reactor can be used potentially in the formation of many reaction-based microencapsulation systems.

Fouling mechanisms of model polymeric substances

AbstractExtracellular polymeric substances (EPS) and soluble microbial products (SMP) have been identified as the main foulants in membrane bioreactor (MBR) operation. For a better understanding of the fouling mechanisms of these substances, filtration of model solutions with submerged membranes was carried out. Filtration was conducted following the flux‐stepping method. In this work alginate was used as a model for polysaccharide, bovine serum albumin (BSA) as a model for protein, and yeast (washed and unwashed) and bentonite were used for suspended solid contents. Fouling behaviours and rejection propensities were also assessed for one‐component and two‐component solutions and provided explanations for fouling mechanisms of carbohydrate and its interaction with protein and membrane in MBR systems. During the filtration of most foulants (except BSA), introducing the alginate increased the reversible fouling more than the irreversible one. In addition, a different behaviour was observed for the mixture of BSA and alginate. Fouling rate was also affected by the introduction of alginate. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd.

Stomach-specific drug delivery of 5-fluorouracil using floating alginate beads

A multiple-unit-type oral floating dosage form (FDF) of 5-fluorouracil (5-FU) was developed to prolong gastric residence time, target stomach cancer, and increase drug bioavailability. The floating bead formulations were prepared by dispersing 5-FU together with calcium carbonate into a mixture of sodium alginate and hydroxypropyl methylcellulose solution and then dripping the dispersion into an acidified solution of calcium chloride. Calcium alginate beads were formed, as alginate undergoes ionotropic gelation by calcium ions and carbon dioxide develops from the reaction of carbonate salts with acid. The evolving gas permeated through the alginate matrix, leaving gas bubbles or pores, which provided the beads buoyancy. The prepared beads were evaluated for percent drug loading, drug entrapment efficiency, image, surface topography, buoyancy, and in vitro release. The formulations were optimized for different weight ratios of gas-forming agent and sodium alginate. The beads containing higher amounts of calcium carbonate demonstrated instantaneous, complete, and excellent floating ability over a period of 24 hours. The optimized formulation was subjected to in vivo antitumor studies to check the therapeutic efficacy of the floating dosage forms containing 5-FU against benzo(a)pyrene-induced stomach tumors in albino female mice (Balb/C strain). The multiple-bead FDF was found to reduce the tumor incidence in mice by 74%, while the conventional tablet dosage form reduced this incidence by only 25%. Results indicate that FDF performed significantly better than the simple tablet dosage form.

Synergistic Effects in Semidilute Mixed Solutions of Alginate and Lactose-Modified Chitosan (Chitlac)

The present study specifically aimed at preparing and characterizing semidilute binary polymer mixtures of alginate and chitlac which might find an application in the field of cell encapsulation. A polyanion, alginate, and a polycation, a lactose-modified chitosan, were mixed under physiological conditions (pH 7.4 and NaCl 0.15) and at a semidilute concentration avoiding associative phase separation. The mutual solubility was found to be dependent on the charge screening effect of the added NaCl salt, being prevented below 0.05 M NaCl. A comparison with the behavior of the polyanion (alginate) under the same experimental conditions revealed that both the viscosity and the relaxation times of the binary polymer solutions are strongly affected by the presence of the polycation. In particular, the occurrence of electrostatic interactions between the two oppositely charged polysaccharides led to a synergistic effect on the zero-shear viscosity of the solution, which showed a 4.2-fold increase with respect to that of the main component of the solution, i.e., alginate. Moreover, the relaxation time, calculated as the reciprocal of the critical share rate, markedly increased upon reducing the alginate fraction in the binary polysaccharide solution. However, the formation of the soluble complexes and the synergistic effect are reduced upon increasing the concentration of the 1:1 electrolyte. By containing a gel-forming polyanion (alginate, e.g., with Ca(2+) ions) and a bioactive polycation (chitlac, bearing a beta-linked D-galactose), the present system can be regarded as a first step toward the development of biologically active scaffold from polysaccharide mixtures.

Technological aspects for restructuring concentrated pineapple pulp

This study investigated how different concentrations of alginate, low methoxy pectin and glycerol could be used to obtain restructured concentrated pineapple pulp, with the aid of response surface methodology. The results of a central composite design show that changes in pectin and alginate levels have statistically significant effects on the firmness of restructured pineapple fruit. Products with the highest values for firmness resulted from using 16 g/kg of both alginate and pectin independent of the concentration of glycerol used. Glycerol, used at the concentration of 100 g/kg, reduced the water activity of the restructured product to an intermediate moisture level (0.880), besides substituting part of the sucrose incorporated into the fruit pulp. A mixture of low methoxy pectin and alginate made it possible to obtain very firm structured fruits using acid pulps. The restructured fruit formulated with a high content of concentrated pineapple pulp (735 g/kg), low sugar content (210 g/kg) and a combination of alginate (20 g/kg), pectin (10 g/kg) and glycerol (100 g/kg), partially dehydrated to 20% moisture content (w.b.), was evaluated by a group of panelists and received a mean score of 5.45, between “liked slightly” and “liked moderately” on the seven-point hedonic scale.

Interaction of unmodified and hydrophobically modified alginate with sodium dodecyl sulfate in dilute aqueous solution: Calorimetric, rheological, and turbidity studies

Interactions between hydrophobically modified alginate (HM-alginate) and the anionic surfactant sodium dodecyl sulfate (SDS) have been investigated by microcalorimetry, rheology and turbidimetry. Significant polymer–surfactant interactions were observed between HM-alginate and SDS, whereas for mixtures of unmodified alginate and SDS only a weak synergism was detected. The intrinsic viscosity of HM-alginate solutions with added SDS showed a strong upturn at low SDS concentrations, indicating a polyelectrolyte effect. The zero-shear viscosity of the semidilute HM-alginate solution was found to increase at a low level of SDS addition, and then decrease with increasing SDS concentration. The turbidity curves exhibit the same profile as those of the viscosity. The maximum of the turbidity is located at the same SDS concentration as the viscosity maximum for the semidilute solution. This picture is consistent with the conjecture of the formation and breakup of the associations as the SDS concentration increases.

PREPARATION PROCEDURE OF BARIUM HYDROXYAPATITE WITH SOL CONSISTING OF SODIUM ALGINATE AND SODIUM DIPHOSPHATE

Barium hydroxyapatite (Ba10(PO4)6(OH)2; BaHAp) was successfully prepared with a sol obtained from the addition of sodium alginate ((C5H7O4 · COONa)n) to the aqueous mixture of sodium diphosphate (Na4P2O7) and barium nitrate (Ba(NO3)2) although it has been already reported that calcium hydroxyapatite, typical hydroxyapatite, was prepared with a sol obtained from the addition of the corresponding nitrate to the aqueous mixture of sodium diphosphate and sodium alginate.

Microbiological aspects of thermally processed foods

The knowledge requirements of the food microbiologist working with thermally processed products are very challenging; particularly in relation to minimally processed foods. In the past, the minimum criteria for sterilized canned foods was very well-defined, however, the diversity of food products, packages and related heat processes are now very difficult to summarize in terms of minimum requirements. The overall heating characteristics of these products can be complex, particularly for mixed particulate products or multicompartment packages. Similarly, the death kinetics of the contaminating micro-organisms can be markedly different dependent on the composition of the food product. These factors combined with the consumer demands for 'fresher' foods has resulted in product, process and package development and innovation progressing at a much faster rate than in the past. While food safety is the most important factor, there are also other issues such as shelf-life and visual quality that have strong market influences and must therefore also be considered by the microbiologist.

Evaluation of modified leather dyeing technique using black dyestuffs from the economical view

From the economical point of view, this work illustrates the effect of compact dyeing technique of chrome tanned leather on the final quality of wet-finished leather in which all wet-finishing steps are in one drum, using black dyestuffs (Acid Black 210 and Remazol black B), with low concentrations, this was done alternative to that used in leather industry. In case of soft leather dyed with Acid Black 210 and top dyed with Remazol Black B the colour strength of both grain and flesh sides increases when using a mixture of (chitosan/non-ionic surfactant, after storing for five days), while the dye penetration decreases compared with heavily retanned leather impregnated with a mixture of (sodium alginate/non-ionic surfactant, after storing for five days) under the same condition without affecting the exhaustion percentage of the dye bath. Using Remazol Black B, the colour strength and the dye bath exhaustion were not affected, while the total dye penetration through cross-section of the dyed leather was improved under the action of either sodium alginate mixture or the natural tanning materials. In addition, the effect of this new technology on the final properties of wet-finished chrome tanned leather such as light and rubbing fastness, mechanical properties and thermal stability were studied.

Preparation of alginate-polymethacrylate hybrid material by radical polymerization of cationic methacrylate monomer in the presence of sodium alginate

An alginate-polymethacrylate hybrid material was prepared by radical polymerization of a cationic methacrylate monomer, i.e. 2-aminoethyl methacrylate hydrochloride in the presence of sodium alginate in water. The insoluble material was formed with progress of the polymerization. The structure of the product was confirmed by the IR spectrum and elemental analysis, as well as the acid hydrolysis experiment to be composed of alginate and polymethacrylate. The TG and DSC data of product were different from those of a mixture of sodium alginate with poly(2-aminoethyl methacrylate hydrochloride). Furthermore, the films of the hybrid materials could be formed by means of the polymerization of the methacrylate monomer in the presence of sodium alginate, followed by the evaporation of the solvent.

Morphology and metabolism of hepatocytes microencapsulated with acrylic terpolymer-alginate using gelatin and poly(vinyl alcohol) as extracellular matrices

Microcapsules with good mechanical stability were prepared using an appropriate mixture of alginate and acrylic terpolymer. It was found from the microscopic observation that the microcapsules had a porous structure with interconnected pores, with a size of 50–150 nm. The results of the permeability experiment of microcapsules using FITC-dextrans showed that the capsule had a molecular mass cut-off of 120 kDa. The hepatocytes encapsulated in both alginate and acrylic terpolymer with gelatin and PVA rapidly aggregated in the core. The aggregated cells showed high albumin synthesis and ammonia removal, suggesting good metabolic function.

A correlation for the mass transfer coefficients during the biodegradation of phenolic effluents in a packed bed reactor

The biological methods of treatment in continuous reactors using immobilized microorganisms have gained wide recognition due to their high degradation efficiency and their usage at high dilution rates. The present study in a cocurrent upflow packed bed reactor involves the treatment of phenolic effluents obtained from petrochemical, leather and polymer industries, using a microorganism Pseudomonas pictorum (NCIM 2077) immobilized on alginate and activated carbon–alginate mixtures. Based on the results of the present investigation on the degradation of phenolic effluents, the mass transfer coefficients were determined. Further, the characteristics of the phenolic effluents namely their pH, colour, odour, total dissolved solid (TDS), total suspended solid (TSS), phenol content, biochemical oxygen demand (BOD) and chemical oxygen demand (COD) were also determined. A mass transfer model of the form j D = K( Re′) n−1 was developed with the values of ‘ K’ as 1.59, 1.07 and 1.42 for petrochemical, leather and polymer effluents treated with P. pictorum-alginate beads and 2.26, 1.75 and 1.92 for petrochemical, leather and polymer effluents treated with activated carbon– P. pictorum-alginate beads. For both the cases, the value of ‘( n − 1)’ was found to be –0.28.

Survival of Freeze-DriedLactobacillus bulgaricusKFRI 673 in Chitosan-Coated Calcium Alginate Microparticles

The aim of this study was to investigate the effect of alginate microparticles coated with three kinds of chitosans of different molecular weights on the survival of Lactobacillus bulgaricus KFRI 673 in simulated gastric (SGJ) and intestinal juices (SIJ) and on their stability during storage at 4 and 22 degrees C. L. bulgaricus KFRI 673 loaded in alginate microparticles was prepared by spraying the mixture of sodium alginate and cell culture into the calcium chloride solution using an air-atomizing device. When L. bulgaricus KFRI 673 was exposed to SGJ of pH 2.0 for 60 min, none of the microorganism survived. Contrary to this result, microbiological analysis indicated that microencapsulation in alginate microparticles improved the survival of acid-sensitive L. bulgaricus KFRI 673 in SGJ and that high molecular weight chitosan coating resulted in the highest survival in SGJ. To study storage stability of free and microencapsulated cells, in vitro studies were conducted at 4 and 22 degrees C during a 4 week period. Both free and microencapsulated cells showed similar stabilities during 4 weeks of storage at 4 degrees C. However, the stability of Lactobacillus at 22 degrees C was appreciably improved when loaded in high molecular weight chitosan-coated alginate microparticles. In conclusion, microencapsulation of lactic acid bacteria with alginate and chitosan coating offers an effective way of delivering viable bacterial cells to the colon and maintaining their survival during refrigerated storage.