一般論文
反対荷電を持つデキストラン誘導体間の複合体形成に関する検討
キーワード:
dextran derivatives,
polyion complex,
turbidity measurement,
potentiometric titration,
salting-out effect
2001 年 61 巻 2 号 p. 59-70
詳細
2001 年 61 巻 2 号 p. 59-70
Complexations between opposite-charged dextran derivatives were investigated focusing on an application as a device of sustained or controlled-release drug delivery systems. Dextran and its derivatives are naturally occurring polysaccharides with biocompatibility and are used in pharmaceutical and cosmetic fields. Carboxymethyldextran (CMD) and dextran sulfate (DS) were used as a polyanion, and [2-(diethylamino) ethyl] dextran (EA) and [2-hydroxypropyltrimethylanmonium] dextran (CDC) as a polycation. Each polyelectrolyte was characterized by potentiometric titrations. The complex formation was followed by turbidity measurement in the media of various pH values and FT/IR spectroscopy in the solid state. The formation of the complexes was dependent on pH values in the reaction mixture in CMD/EA, CMD/CDC and DS/EA systems, except in DS/CDC. At pH 1.2 and 2.0, no complex was formed in CMD/EA and CMD/CDC systems because of no dissociation of CMD molecules in the acidic media. A maximum turbidity shifted from the greater weight fraction of polyanion to the lower one as an increase of pH values. At pH 6.8, the maximum turbidity was observed at the weight ratio of 7:13 in CMD/EA and CMD/CDC, and at 1:3 in DS/EA and DS/CDC. No complex was formed stoichiometrically in DS/EA and DS/CDC systems because of the high degree of substitution on DS. FT/IR spectroscopy suggested that the N(C2H5)2+ groups in EA molecules interacted with COO- and SO3- groups in CMD and DS, respectively.
