Physical properties alginates

Bejar, P., Casas, C., Godia, F., and Sola, C., The Influence of Physical Properties on the Operation of a Three Phase Fluidized-Bed Fermenter with Yeast Cells Immobilized in Ca-Alginate, App. Biochem. Biotechnol., 34/35 (1992)... 

Polymer grafting can be used to alter chemical and physical properties of a homopolymer. For example, Sawhney and Hubbell [18] grafted polyethyleneoxide to poly L-lysine to enhance biocompatibility of polylysine and improve the polylysine-alginate capsules. Stevenson and Sefton [19] modified alginate by grafting it with hydroxyalkyl methacrylate, again to improve the biocompatibility and to allow for polymerization by means of y-irradiation. Covalently modified (co)-polymers have not been evaluated in this study. 

C. Alginate "Snakes" This makes an excellent demonstration on an overhead projector. Fill a crystallizing dish or beaker to a depth of Vi to 3A inch with 2% Ca(N03)2 solution. Introduce a stream of 2% sodium alginate solution directly into the- Ca2+ solution using a pipet. You should be able to cause the formation of a long strand of gel (a snake ). For the most part, the properties of the strands should be the same as those of the beads that you explored above. To test the physical properties of your snakes, wash them in fresh water and let them dry. As they are drying, periodically test their strength and note their appearance. 

Bugaj J, Gorecki M. Rheometrical estimation of physical properties of sodium alginate and sodium carboxymethylcellulose aqueous solutions. Acta Pol Pharm Drug Res 1996 53(2) 141-146. 

Alginates are composed of (1—>4)-linked (3-D-mannuronic acid (M units) and a-L-guluronic acid (G units) monomers (Figure 16.9), with different sequential distribution along the polymer chain [142]. The composition, sequence, and molecular weight generally determine the physical properties of alginate [143]. 

A number of hydroxylated water soluble polymers were examined as coreactants with polymer 52 in the absence of calcium alginate, and were judged on the basis of the rate of gel formation and the physical properties of the gel These polymers included sodium alginate, polyvinyl alcohol, and copolymers of HEMA with MAA. Of the polymers tested, best results were obtained with polymer 10a, a copolymer of HEMA with a mole fraction of about 10% MAA, which rapidly produced an elastic gel on exposure to polymer 52 in solution. Simple condensation of the carboxyls in polymer 10a with the epoxide functionality was ruled out as a competing reaction due to the measurable but slow reaction between polymer 52 and poly methacrylic acid. It is, therefore, likely... 

The biological function of the different epimerases is not certain. However, it is known that A. vinelandii can form metabolically inactive cysts, and that alginate is the primary carbohydrate constituent of the cyst. Alginates with different compositions have different physical properties, so the multiple AlgE epimerases may allow the bacteria to tailor the mechanical properties of alginate for different functions in different locations in the cyst. 

Ishikawa K, Ducheyne P, Radin S (1993) Determination of the Ca/P ratio in calcium-deficient hydroxylapatite using X-ray diffraction analysis. J Mater Sci Mater in Med 4 165-168 Ishikawa K, Miyamoto Y, Kon M, Nagayama M, Asaoka K (1995) Non-decay type fast-setting calcium phosphate cement composite with sodium alginate. Biomaterials 16 527-532 Itatani K, Iwafune K, Howell FS, Aizawa M (2000) Preparation of various calcium-phosphate powders by ultrasonic spray freeze-drying technique. Mater Res Bull 35 574-85 Ito M, Hidaka Y, Nakajima M, Yagasaki H, Kafrawy AH (1999) Effect of hydroxylapatite content on physical properties and coimective tissue reactions to a chitosan-hydroxylapatite composite membrane. J Biomed Mater Res 45 204-208... 

Columns of calcium alginate gel pellets have excellent physical properties when used as supports for cell immobilization. Saccharomyces uvarum cells have been mixed with high concentrations of sodium alginate, precipitated by addition of calcium chloride, and extruded as discrete droplets which were found to be very resistant to compression and abrasion during passage of high concentrations of sucrose at high flow rate. 

The physical properties and characteristics of calcium alginate gels for cell immobilization have been investigated using Saccharomyces uvarum cells. 

Martinsen, A., Skjak-Braek, C., and Smidsrod, O. 1989. Alginate as immobilization material. 1. Correlation between chemical and physical properties of alginate gel beads. Biotechnol. Bioeng. 33 79-89. 

Smidsrod, O. Molecular basis for some physical properties of alginates in the gel state. Jourrml of Chemical Society, Faraday Transactions. 1974, 57, 263-274. 

This selective binding of multivalent cations, which is the basis for gel formation is the most important feature of alginate s physical properties, and the fact that the sol/gel transition of alginates is not particularly influenced by temperature [14]. 

Avella, M., Di Pace, E., Immirzi, B., Impallomeni, G., Malinconico, M., Santagata, G. Addition of glycerol plasticizer to seaweeds derived alginates Influence of microstracture on chemical-physical properties. Carbohydr. Polym. 69, 503-511 (2007)... 

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