Sodium Alginate Essay

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Sodium alginate (SA) is a natural anionic polysaccharide obtained from sea weeds. It contains β-D-mannuronate (M) and α-L-glucuronate (G) residues linked by (1-4)- glycosidic linkages (Fig. 7.1) and arranged in homopolymeric blocks of each type and in heteropolymeric blocks [1]. It is a water soluble polysaccharide and has pKa values of 3.38 for the ‘M’ and 3.65 for ‘G’ units [2]. It can form complexes with positively charged polymers due to its anionic character. It is utilized as emulsifier, thickening agent, foaming agent, bulking agent and gelling agent in pharmaceutical, medical and food industries [3].
Alginate presents a number of interesting properties with regard to drug delivery; such as biocompatibility and low toxicity [4]. The particle size, viscosity and concentration of alginate solution affected both drug release rates and the release mechanisms [5-7].
Polyacrylamide (PAm) is one of the water soluble polymers with a hydrophilic side group and a hydrophobic main chain and is non-toxic [7]. PAm can form aqueous solution of high concentration. Crosslinked PAm is a well known hydrogel, whose swelling nature is not very sensitive to pH or to the presence of electrolytes. Due to its gelling property, it is used in gel electrophoresis, in manufacture of soft contact lens and as
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The higher weights of the grafted product as compared to that of SA, has been taken as evidence of grafting. An attempt to polymerize just acrylamide under similar conditions resulted in no homopolymer formation. Hence it was concluded that under the reaction conditions employed in this investigation, the free radicals were generated exclusively on the polysaccharide backbone and polyacrylamide chains were formed as graft on SA. Similar results were reported by Desmukh et al.

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