Alginates Subject

Based on the results of preliminary investigations it was concluded that capsules could be formed from emulsions containing about 2-10% (mass fraction) monomer and 0.5-2% (mass fraction) alginate subjected to radiation doses greater than about 7.5 x 10 2 M Rad to reduce residual monomer levels below toxic limits. Emulsions may be prepared in distilled water, saline, or buffered saline, but not in calcium containing solution. 

W e know of many examples of the effect of impurities of crystallization. In many cases impurities will completely inhibit (2-4) nucleus formation. Reading the literature on this subject impresses one with the frequent occurrence of hydrocolloids as crystal modifiers, particularly where sugar or water is the material being crystallized. The use of gelatin, locust bean gum, or sodium alginate in ice cream is just one example of many practical applications of hydrocolloids in crystal modification. 

Besides the previously mentioned collagen, a wide variety of natural polymers have been involved in the synthesis of bio-nanohybrid materials with potential application in bone repair and dental prostheses. For instance, some recent examples refer to bionanocomposites based on the combination of HAP with alginate [96,97], chitosan [98,99], bovine serum albumin (BSA) [100], sodium caseinate [101], hyaluronic acid [102], silk fibroin [103,104], silk sericin [105], or polylactic add (PLA) [106,107]. These examples illustrate the increasing interest in the subject of HAP-based biohybrid materials, which has led to almost 400 articles appeared in scientific journals in 2006 alone. 

Formation of L-guluronic acid, a component of the alginic acid-like polysaccharide produced by P. aeruginosa and Azotobacter vinelandii, requires special comment. In this case, a polymer built from /3-(l- 4)-linked D-mannosyluronic acid residues serves as an intermediate in the biosynthesis.204,205 Part of the D-mannosyluronic acid residues in the polymer is subjected to an epimerization at C-5 catalyzed by an exocellular enzyme of the micro-organism,205-207 producing a polysaccharide composed of structural blocks that contain only D-mannosyluronic acid or only l-gulosyluronic acid residues, as well %s some having both. The mechanism of the epimerization remains unclear. 

Quantitative spectrophotometric methods for pectin utilize carbazole (diphenyleneimine Bitter and Muir, 1962) and m-hydroxydiphenyl (Kintner and Van Buren, 1982). The intense red-to-brown color with carbazole in sulfuric acid, relatively specific for uronans (pectin and alginate), is much less intense with ketohexoses, aldohexoses, and pentoses (Snell and Snell, 1953). The m-hydroxydiphenyl assay is subject to less interference than the carbazole assay. 

Alginate obtained from brown seaweed is subjected to demineralization, extraction, and precipitation of alginic acid. Following neutralization, the potassium alginate obtained is dried and milled. 

Although this article deals with complexes of neutral carbohydrates, brief mention should be made of the aldonate and alduronate anions (the undissociated acids do not form complexes), which show complexing behavior similar to those of the neutral polyols. Interest in these acids, and particularly in the poly(hexuronates), is due to the industrially important gel-formation of alginic acid and pectin with calcium ions, caused by complex-formation. There is an extensive literature on this subject,which is not fully discussed here. 

Gong YF, Huang ZJ, Qiang MY et al. 1991. Suppression of radioactive strontium absorption by sodium alginate in animals and human subjects. Biomed Environ Sci 4 273-282. 

Harrison J, McNeill KG, Janiga A. 1966c. The effect of sodium alginate on the absorption of strontium and calcium in human subjects. Can Med Assoc J 95 532-534. 

The structure of the Ca -alginate gel has been the subject of some speculation. The eggbox model is widely cited. In the eggbox model adjacent G residues in one polymer strand form a pocket that contributes ligands to occupy half of the coordination sites of a second strand provides the remaining ligands, thus... 

In a second paper (/ 75) the production of ajmalicine by calcium alginate-entrapped cells of C. roseus in a continuous flow reactor was described. The authors reported that, as was described earlier in their first paper on the subject, only a small amount of the produced alkaloid was excreted into the medium and that the greater part was trapped within the cells. The maximum productivity of the reactor was 73.3 g/liter/day at a dilution rate of 0.72 day . ... 

Paxman, J. R., Richardson, J. C., Dettmar, P. W., and Corfe, B. M. (2008). Alginate reduces the increased uptake of cholesterol and glucose in overweight male subjects a pilot study. Nutr. Res. 28(8), 501-505. 

The potential of alginate produced by bacteria as an industrial polymer is still a controversial subject. However, the possibility of using raw materials free of seasonal and geographical variations employing selected strains under carefully... 

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