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ca-alginate spheres behavior in presence of some solvents and water-solvent mixtures

Advances in Bioscience and Biotechnology 2011年第1期2卷 8-12页

作者： Luis G. Torres Angelica Velasquez Marco A. Brito-Arias 不详

Immobilization systems more frequently used are calcium alginate spheres. These biocatalysts have many potential applications in the immobilization of enzymes, prokaryotic cells, vegetal and animal cells, algae, organelles and mixtures of these living components. Other applications of immobilized cells imply the use of non aqueous systems. Some bioconversions are carried out in the presence of solvents such as hexane acetone or acetonitrile, or mixtures water-solvents. The aim of this work was to investigate the behaviour of ca-alginate spheres when put in contact with different solvents (water, diesel, ethanol, methanol, acetone, n-hexane, isopropyl alcohol, THF, acetonitrile, and toluene), or solvent-water mixtures (i.e., ethanol-water), regarding the resistance of the alginate spheres after days of contact. calcium alginate particles suffered different damages, depending on the solvent they were put in contact. Water did not damaged the ca-alginate structure with or without ca present. On the other hand different solvents lost a proportion of volume, i.e., n-hexane (16%), methanol (19%), ethanol (19.5%), toluene (22%), diesel (34%), acetone (765), isopropyl alcohol (80%), THF and acetonitrile (total loss, total destruction). Nor the dielectric constant nor the polarity indexes were capable of explaining the difference on the volume loss or total sphere destruction, except for water-ethanol mixtures.

关键词： Dielectric Constant ca-alginate Immobilization Solvents Spheres Polarity Index

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Micro-environmentally Restricted Yeast Cell Growth within ca-alginate Microbeads

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Engineering（科研） 2012年第10期4卷 180-183页

作者： Ivana Pajic-Lijakovic Branko Bugarski Branko Bugarski Milenko Plavsic Steva Levic Ana Kalusevic Viktor Nedovic Dept. of Chem. and Polymer Eng. University of Belgrade Faculty of Technology and Metallurgy Belgrade Serbia Dept. of Food Technol. University of Belgrade Faculty of Agriculture Belgrade Serbia

Micro-environmental restriction effects to yeast cell growth obtained within ca-alginate microbeads are considered. It is complex phenomenon influenced by: (1) relaxation of expanded polymer network around the cellular clusters, (2) forces generated by cell growth inside the beads and (3) interactions between solvent, network parts and cells. The resulting effects are measured experimentally by estimating volume of microbeads and yeast cell concentration as function of time of cultivation. Comparative analysis of dynamics of cell growth and increase of microbead volume through four regimes indicates that reversible and irreversible local structural changes of ca-alginate hydrogel induces micro-environmental restrictions to cell growth. The mechanism of restrictions includes both mechanical and electrostatic effects.

关键词： Yeast Cells Micro-environmental Restrictions ca-alginate Hydrogel Matrix Structural Changes Pattern of Volumetric Yeast Growth

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Diffusion Characteristics in Microcapsules

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Chinese Journal of Chemical Engineering 1998年第2期6卷 26-33页

作者：姚善泾赵万纪 College of Chemical Engineering Zhejiang University Department of Food Engineering Dong-Seo University

An equation of diffusion for microcapsules（hollow sphere）was developed,employing the mathematicalmodel for the diffusion characteristics of solid *** the proposed equation,a combination diffusion coeffi-cient was introduced as a substitute for the diffusion coefficient in the solid sphere mathematical model and ex-pressed as a function of the diffusion coefficient inside solution of hollow sphere,as well as in the polymer *** this modified model,the diffusion coefficients of glucose in NaCS（sodium cellulose sulfate）-PDADMAC（Poly-diallyl-dimethyl-ammonium chloride）membrane and in ca-alginate gel membrane were *** diffusion coefficient in NaCS-PDADMAC membrane was found to be 2.12×10-11m2·s-1and thatin ca-alginate membrane 2.62×10-10m2·s-1.

关键词： diffusion coefficient glucose NaSC-PDADMAC membrane ca-alginate membrane microcapsule hollow sphere immobilization

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