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PubMed2005

Surimi wash water treatment for protein recovery: effect of chitosan-alginate complex concentration and treatment time on protein adsorption.

Chitosan (Chi), a protein recovery agent for the treatment of aqueous food processing streams, appears to work by mechanical entrapment and electrostatic interaction of chitosan amino groups with anionic groups on proteins. Chitosan effectiveness for recovering soluble proteins from surimi wash water (SWW) is increased by complexation with alginate (Alg) and by adjusting complex concentration and treatment time. Flocculation at 20 degrees C with Chi-Alg at a 0.2 mixing ratio added as 20, 40, 100 and 150 mg/L SWW was aided by 5 min agitation at 130 rpm and then held at the same temperature for 30 min, 1 and 24 h. Turbidity measurements, protein determinations and qualitative FTIR analysis confirmed SWW protein adsorption which depended on Chi-Alg concentration and reaction time while turbidity reduction was affected by concentration only. No differences (p < 0.05) in protein adsorption were found between 1 and 24 h. Using 100 mg Chi-Alg complex/L SWW for 1 h achieved 83% protein adsorption and 97% turbidity reduction.

Adsorption↗
PubMed2006

Effect of chitosan type on protein and water recovery efficiency from surimi wash water treated with chitosan-alginate complexes.

Previous research has shown that soluble protein recovery by chitosan (Chi) complexes with polyanions such as alginate (Alg) is more effective than using chitosan alone. In this study, Chi-Alg complexes were used to recover soluble proteins from surimi wash water (SWW) slightly acidified to pH 6. Six Chi samples differing in molecular weight (MW) and degree of deacetylation (DD) were used at 20, 40 and 100mg/L SWW Chi-Alg complexes prepared with a Chi:Alg mixing ratio previously optimized (MR=0.2). FTIR analysis of the solids recovered revealed the three characteristic amide bands observed in the same region for untreated SWW confirming protein adsorption by Chi-Alg. The superior effectiveness of Chi complexes was confirmed but differences among chitosan types could not be correlated to MW and DD. Experimental Chi samples with 94%, 93%, 75% and 93% DD and 22, 47, 225 and 3404 x 10(3)Da, respectively, showed 73-76% protein adsorption while a commercial chitosan sample with 84% DD and 3832 x 10(3)Da had 74-83% protein adsorption. An experimental chitosan, SY-1000 with 94% DD and 1.5 x 10(6)Da, showed the highest protein adsorption (79-86%) and turbidity reduction (85-92%) when used at 20mg/L SWW.

Alginates↗
PubMed2006

Optimization of culture variables for improving glucoamylase production by alginate-entrapped Thermomucor indicae-seudaticae using statistical methods.

Alginate-entrapped sporangiospores of Thermomucor indicae-seudaticae were used for the production of glucoamylase. The critical variables that affected glucoamylase production were identified by Plackett-Burman design (sucrose, yeast-extract, K(2)HPO(4) and asparagine) and further optimized by using a four factor central composite design (CCD) of response surface methodology (RSM). Immobilized sporangiospores secreted 41% and 60% higher glucoamylase titers in shake flasks and airlift fermenter, respectively, when the variables were used at their optimum levels (sucrose 3.0%, yeast-extract 0.2%, K(2)HPO(4) 0.1% and asparagine 0.35%). Glucoamylase production (26.3 U ml(-1)) in the optimized medium was in good agreement with the values predicted by the quadratic model (26.7 U ml(-1)), thereby confirming its validity. The enzyme production was sustainable in flasks of higher volume and also airlift fermenter, and attained a peak within 32 h in the fermenter as compared to that of 48 h in shake flasks.

Alginates↗
PubMed2005

Encapsulation of glucose oxidase and an oxygen-quenched fluorophore in polyelectrolyte-coated calcium alginate microspheres as optical glucose sensor systems.

Microspheres coated with polyelectrolyte multilayers (PEM's) are being investigated for potential use as implantable biosensors-so-called "smart tattoos." In this work, the feasibility of this approach for glucose sensors was demonstrated by glucose oxidase encapsulated within calcium alginate microspheres, followed by entrapment of an oxygen-quenched ruthenium compound in the same microstructure. A novel feature of these microdevices is the formation of multilayer nanofilms on the surface of the microspheres, used to stabilize enzyme entrapment and control substrate diffusion. Confocal microscopy was used to confirm the stable encapsulation of sensor chemistry. The reversible response of sensors to step changes in glucose was observed, and preliminary experimental data were compared to theoretical predictions produced by a computational model. These findings demonstrate the promise of the described nanoengineering approach for production of functional implantable glucose sensor materials.

Alginates↗
PubMed2006

The biofilm matrix of Pseudomonas sp. OX1 grown on phenol is mainly constituted by alginate oligosaccharides.

The structure of the major constituent of the biofilm matrix produced by Pseudomonas sp. OX1, when grown on phenol as the sole carbon source is described. This investigation, carried out by chemical analysis, NMR spectroscopy and MALDI-TOF MS spectrometry, showed the presence of an oligosaccharide blend with the typical alginate structure, namely (1-->4) substituted beta-D-mannuronic (ManA) and alpha-L-guluronic acid (GulA). GulA residues were non-acetylated whereas ManA was always O-acetylated at C-2 or C-3.

Alginates↗
PubMed2004

Interfacial and foaming properties of prolylenglycol alginates. Effect of degree of esterification and molecular weight.

In the present work we have studied the characteristics of propylene glycol alginates (PGA) adsorption at the air-water interface and the viscoelastic properties of the films in relation to its foaming properties. To evaluate the effect of the degree of PGA esterification and viscosity, different commercial samples were studied--Kelcoloid O (KO), Kelcoloid LVF (KLVF) and Manucol ester (MAN). The temperature (20 degrees C) and pH (7.0) were maintained constant. For time-dependent surface pressure measurements and surface dilatational properties of adsorbed PGA at the air-water interface an automatic drop tensiometer was used. The foam was generated by whipping and then the foam capacity and stability was determined. The results reveal a significant interfacial activity for PGA due to the hydrophobic character of the propylene glycol groups. The kinetics of adsorption at the air-water interface can be monitored by the diffusion and penetration of PGA at the interface. The adsorbed PGA film showed a high viscoelasticity. The surface dilatational modulus depends on the PGA and its concentration in the aqueous phase. Foam capacity of PGA solutions increased in the order KO > MAN > KLVF, which followed the increase in surface pressure and the decrease in the viscosities of PGA solutions. The stability of PGA foams monitored by the drainage rate and collapse time follows the order MAN > KLVF > KO. The foam stability depends on the combined effect of molecular weight/degree of esterification of PGA, solution viscosity and viscoelasticity of the adsorbed PGA film.

Adsorption↗
PubMed2006

Effect of preparation conditions on the nutrient release properties of alginate-whey protein granular microspheres.

The effect of preparation conditions on nutrient release from alginate (AL)-whey protein isolate (WPI) granular microspheres obtained by an emulsification/internal cold gelation method was studied by varying WPI/AL ratio, microsphere diameter, total polymer concentration and riboflavin loading. Microsphere size distribution and nutrient encapsulation efficiency (EE) were examined. Riboflavin release profiles were investigated in simulated gastric and intestinal fluids. Values for EE above 80% were obtained for most microspheres, with the notable exceptions of high AL or pure AL. Variations in WPI/AL ratio, granule size and nutrient loading have major impact on nutrient release. Microspheres prepared with a WPI/AL ratio of 8:2, a riboflavin concentration of 1% in the initial aqueous phase and diameters near 94 microm retained the vitamin in SGF and released it in SIF. By careful process design, granular microspheres with potential as oral delivery vehicles for bioactive compounds may be developed.

Administration, Oral↗
PubMed2004

N4-alkyloxycarbonyl derivatives of cytosine: physicochemical characterisation, and cytosine regeneration rates and release from alginic acid gels.

Nucleobase containing compounds might constitute a potential alternative to conventional antibiotics in the treatment of Helicobacter pylori infections. N4-alkyloxycarbonyl-cytosine derivatives were synthesized and subjected to basic physicochemical characterisation including assessment of hydrolytic stability in various matrices. pH-rate profiles of selected compounds (range 0-12) were constructed. Hydrolysis of the derivatives in slightly alkaline solution (60 degrees C) resulted in quantitative conversion to parent cytosine whereas at acidic pH (60 degrees C) liberation of cytosine was in most cases accompanied by the parallel formation of uracil. Interestingly the lipophilic N4-adamantyloxycarbonyl-cytosine prodrug exhibited a half-life of 41 min (pH 1.1 at 37 degrees C) with quantitative conversion to parent cytosine, the degradation rate being approximately 200 times faster than that of the non-cyclic aliphatic derivatives investigated. The presence of pig stomach homogenates, pepsin A and H. pylori did not have a noteworthy catalytic effect on the hydrolysis of the derivatives. The release of parent cytosine was markedly delayed from alginic acid gels loaded with the acid-labile and poorly soluble ADC prodrug as compared to gels loaded with parent cytosine.

Alginates↗
PubMed2005

Azo dye biodegradation by microbial cultures immobilized in alginate beads.

Microbial degradation of azo dyes usually starts in anaerobic conditions with a reductive cleavage of the azo bond, followed by an aerobic step necessary for the degradation of the aromatic amines formed. Because some reductive processes take place also in presence of molecular oxygen, a one-step azo dye degrading process has been investigated. A microbial consortium able to degrade ethyl orange in aerobic conditions has been selected and immobilized in alginate beads coated with polyacrylamide resin. Different concentrations of ethyl orange have been completely degraded in the presence of 1% glucose or starch as cosubstrates, and different beads preparation procedures have been studied to determine the best condition for microbial degradation. The catalytic activity of the immobilized consortium improved during five serial processes carried out for 30 days at room temperature. Three pure cultures were then isolated from the consortium. The one with the greatest degrading activity, a filamentous fungus, had a degradative capacity similar to that of the whole consortium.

Alginates↗
PubMed2006

Microencapsulation of alpha-tocopherol using sodium alginate and its controlled release properties.

Response surface methodology (RSM) was used to optimize microencapsulation yield (MY) using three independent variables; the ratio of coating material to core material (w/w, X1), the emulsifier concentration (%, v/v, X2), and the CaCl2 concentration (%, w/v, X3). In the preparation of sodium alginate (SA) microcapsule, the regression model equation for the MY was predicted as follows; MY(%) = 56.02 + 3.64X2 + 3.18X1X2 - 3.74X2(2). The optimal conditions for the SA microcapsule were obtained at the [SA]/[alpha-TP] ratio of 6.6:3.4 (w/w), [emulsifier] of 1.35% (v/v), and [CaCl2] of 4.3% (w/v), and the predicted MY in this condition was of 57.2%. In vitro alpha-TP releasing test of the SA-based microcapsules was performed. The SA microcapsule released 28.8% of alpha-TP when exposed in the simulated gastric fluid (SGF, pH 1.2) for 24 h. In the simulated intestinal fluid (SIF, pH 7.4), the amount of released alpha-TP (81.5%) was significantly greater than that in the SGF. The duration time required for releasing 50 (T50%) and 70% (T70%) of alpha-TP from the SA-microcapsule were calculated to be 3.8 and 12.3 h, respectively. From these results, it was suggested that SA microcapsule would be structurally resistant against acidic environment, and it would rapidly release core material under mild alkali condition.

Alginates↗
PubMed2005

Characteristics of interpolyelectrolyte complexes of Eudragit E 100 with sodium alginate.

With a view to the application in oral drug delivery formulations, the possibility to form interpolyelectrolyte complexes (IPEC) of Eudragit E 100 (EE) with sodium alginate (AL) was investigated, employing turbidimetry, apparent viscosity measurements, FT-IR and elementary analysis. The interaction or binding ratio of a unit molecule of AL with EE was largely affected by the pH value of the media, showing a change from 1.5:1 to 1:1.25 (0.66<Z<1.25) with increase in pH value from 2.5 to 6.0. Based on the results of elementary analysis and FT-IR, the interaction ratio of each component in the solid complexes was very close to that observed in turbidity and apparent viscosity measurements thus proving that the synthesized products actually can be considered as IPEC.

Acrylates↗
PubMed2005

Two new plate nozzles for the production of alginate microspheres.

Combining the Rayleigh-type jet break-up and two new plate nozzles, the alginate microsphere was produced. Spray generators made of syringe needle and laser-drilling nozzle plate and synthetic red stone nozzle plate were fabricated and contrasted. The above two plate nozzles provided lower liquid resistance and yield well. Furthermore, the more uniform microsphere was produced within a wider range of frequency by plate nozzles. Experiments using multiple-nozzle synthetic red stone plate was easy to feasible.

Alginates↗
PubMed2006

Alginate-magnesium aluminum silicate films: effect of plasticizers on film properties, drug permeation and drug release from coated tablets.

The effect of hydrophilic plasticizers, namely glycerin and polyethylene glycol 400 (PEG400), on physicochemical properties of sodium alginate-magnesium aluminum silicate (SA-MAS) microcomposite films was characterized and application of the films for controlling drug release from tablets was evaluated as well. The plasticizers could possibly interact with SA or MAS by formation of hydrogen bonding, as revealed using FTIR spectroscopy. PXRD studies presented that glycerin or PEG400 could intercalate into the silicate layers of MAS and higher crystallinity of the films with PEG400 was obtained. This led to a different thermal behavior of the films. Glycerin gave more flexibility of the films than PEG400. Incorporation of plasticizers into the films did not affect water uptake in acid medium, but increasing an erosion of the films because of the leaching of the plasticizers. Water vapor permeability of the films decreased with increasing amount of plasticizers in the range of 10-30% (w/w). Diffusion coefficient (D) of acetaminophen (ACT) across the films in acid medium increased with addition of the plasticizers because the leaching of plasticizers could reduce tortuosity of aqueous pore channels of the films. The tablets coated with plasticized films had a quite smooth surface without defect as shown by SEM. The ACT release profiles from the coated tablets showed a zero-order release kinetic with drug diffusion mechanism across in situ insoluble composite films in acid medium, and coating film swelling and erosion mechanism in pH 6.8 phosphate buffer. Moreover, neither the release rate nor the release pattern of the ACT coated tablets was obviously changed. The findings show that glycerin or PEG400 could improve physicochemical properties of the SA-MAS films and the plasticized films could control the drug release from tablets in gastro-intestinal condition.

Acetaminophen↗
PubMed2004

In vivo determination of tumor oxygenation during growth and in response to carbogen breathing using 15C5-loaded alginate capsules as fluorine-19 magnetic resonance imaging oxygen sensors.

PURPOSE: The objective was to present a method for the repeated noninvasive measurement of tumor oxygenation (Po(2)) over the whole period of tumor growth. METHODS AND MATERIALS: A mixture of tumor homogenate (GH3 prolactinoma) and alginate capsules loaded with perfluoro-15-crown-5-ether (15C5) was injected into the flanks of Wistar Furth rats. The temporal behavior of tumor Po(2) was monitored between Day 1 and 26 after injection using fluorine-19 ((19)F) magnetic resonance imaging (MRI). In addition, the response of tumor Po(2) to modifiers of the tumor microenvironment (carbogen [95% O(2)/5% CO(2)], nicotinamide, and hydralazine) was investigated. RESULTS: An initial increase of tumor Po(2), probably reflecting neovascularization, followed by a decrease after Week 2, probably indicating tumor hypoxia or necrosis, were observed. The minimum and maximum average Po(2) +/- SEM observed were 3.3 +/- 2.0 mm Hg on Day 2 and 25.7 +/- 3.8 mm Hg on Day 13, respectively. Carbogen increased the tumor Po(2), whereas nicotinamide caused no significant change and hydralazine induced a significant decrease in tumor oxygenation. CONCLUSIONS: A preclinical method for the repeated noninvasive determination of tumor Po(2) was presented. It might help to investigate tumor physiology and the mechanisms of modifiers of the tumor microenvironment and their role in different therapeutic approaches.

Alginates↗
PubMed2004

Kluyveromyces lactis cells entrapped in Ca-alginate beads for the continuous production of a heterologous glucoamylase.

Viable cells of Kluyveromyces lactis, transformed with the glucoamylase gene from Arxula adeninivorans, were entrapped in beads of Ca-alginate and employed on a lab scale in a continuous stirred and a fluidised bed reactor (FBR), both fed with a rich medium (YEP) containing lactose as carbon source. Experiments with freely suspended cells in batch and chemostat had demonstrated that glucoamylase production was favoured in the presence of lactose and YEP medium. Employing controlled-sized beads having a 2.13 mm diameter, specific glucoamylase productivity was higher in the stirred reactor (CSTR) than in the FBR; in the latter a higher volumetric productivity was achieved, due to the lower void degree. The performance of the immobilised cell systems, in terms of specific glucoamylase productivity, was strongly affected by mass transfer limitations occurring throughout the gel due to the high molecular weight of the product. In the perspective to improve and scale-up the immobilised cell system proposed, a mathematical model, which takes into account substrate transfer limitations throughout the gel, has been developed. The effective lactose diffusivity was related to the bead reactive efficiency by means of the Thiele modulus. The regression of the model parameters on the experimental data of substrate consumption obtained both in the CSTR and in the FBR allowed to estimate lactose diffusivity and the kinetic parameters of the immobilised yeast.

Alginates↗
PubMed2005

Deposition temperature effect on release rate of indomethacin microcrystals from microcapsules of layer-by-layer assembled chitosan and alginate multilayer films.

Indomethacin (IDM) microcrystals sized 5 approximately 10 microm were directly encapsulated with nature polysaccharides chitosan (CHI) and sodium alginate (ALG) through layer-by-layer (LbL) self-assembly. Due to partial dissolution of IDM in the deposition solution, the retention of the IDM microcrystals gradually decreased with increasing deposition times and became 47.7% as 10 layers of polysaccharides formed. The release rate of the IDM from the microcapsules was monitored with UV absorbance. The half release time t(1/2) of IDM in the microcapsule increased with the layer number and the initial burst phenomenon was relieved after encapsulation. It was found that added NaCl did not affect the release rate even up to 0.5 M of its concentration, while increasing the release temperature remarkably speeded up the release process. The prolonged release of the encapsulated IDM was still observed when the aqueous release solution containing 20 vol.% ethanol. It was very significant that increasing deposition temperature from 20 to 60 degrees C reduced the release rate efficiently, owing to the increase in multilayer thickness and formation of a more perfect multilayer film. This finding provides a new and simple method to control the permeability of the LbL assembled multilayer films. Because of the biodegradability of CHI and ALG and various methods to tune the release rate, the LbL self-assembly on drug microcrystals promises high potential for encapsulation used in controlled release.

Alginates↗
PubMed2005

Investigation of novel alginate-magnesium aluminum silicate microcomposite films for modified-release tablets.

Physicochemical properties of sodium alginate-magnesium aluminum silicate (SA-MAS) composite films were investigated and a potential as a film former of SA-MAS dispersion for modifying drug release from tablets was evaluated as well. Interaction between SA and MAS in the composite films was revealed using FTIR spectroscopy. Thermal behavior of the composite films was changed due to the complexation of SA and MAS. Powder X-ray diffractometry data suggested that a higher crystallinity of the composite film and a phase-separated microcomposite were formed. The composite films in the ratios of 1:0.5 and 1:1 showed the increases of tensile strength and percentage of elongation when compared with SA films. Water vapor permeability of the composite films tended to increase with increasing ratio of MAS. The decreases in water uptake and drug permeability in 0.1 M HCl were found in the composite films. A positive charge drug, propranolol HCl, provided a higher affinity on the composite films than a weakly acidic nonelectrolyte, acetaminophen, resulting in a longer lag time and a higher partition coefficient depending on the content of MAS in the composite films. This was due to the complex formation of propranolol HCl and MAS. Using SEM, the tablets coated with SA-MAS dispersion had a smooth surface, while those with SA dispersion showed a pinholing on the surface, resulting in a faster drug release. The drug release profiles of the tablets could be modified by coating with the composite film at different coating levels. This finding suggests that MAS could improve physicochemical properties of the SA films, leading to a novel coating material of the SA-MAS dispersion for modifying drug release from tablets.

Absorption↗
PubMed2005

Triggered release of proteins from emulsan-alginate beads.

Emulsan/alginate beads were studied for protein adsorption and stability in the context of controlled release. The beads, 400 +/- 80 microm diameter with approximately 10% emulsan content, offer unusual opportunities for delivery of proteins due to the natural ability of emulsan to bind proteins, coupled with the selective biological activation features of this complex lipoheteropolysaccharide. The binding capacity of azo-bovine serum albumin by the emulsan/alginate beads was 0.637 +/- 0.004 vs. 0.170 +/- 0.007 microg/mg for beads formed from alginate alone. In additional protein adsorption experiments, the lipase and subtilisin maintained activity when adsorbed to the emulsan/alginate beads albeit with lower specific activity when compared to the enzyme free in solution. However, the half life of the adsorbed enzyme was significantly higher than the free forms. To explore functional utility of this system, two types of triggered release were studied in the context of these bead systems. First, azo-BSA as a model protein was physically bound to emulsan/alginate beads and then selectively released by triggering with subtilisin, a serine protease, which cleaves the azo dye, sulfanilic acid, from the bound protein. In absence of subtilisin no triggered release was observed. Second, azo-BSA as a prodrug model, was adsorbed to the emulsan/alginate beads and then release of the dye was demonstrated by lipase treatment which cleaves the fatty acid esters from the emulsan structure to release the bound protein. The results establish the versatility and utility of emulsan-based beads for protein binding and triggered release.

Acinetobacter↗