1998 Fiscal Year Final Research Report Summary
pH-Sensitive swelling of polyelectrolyte complex gels prepared from natural polymers and its application to controlled release systems for oral drug delivery
| Project/Area Number |
09650880
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
生物・生体工学
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| Research Institution | Okayama University |
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Principal Investigator |
SAKIYAMA Takaharu OKAYAMA UNIV., ENGINEERING,LECTURER, 工学部, 講師 (70170628)
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| Project Period (FY) |
1997 – 1998
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| Keywords | response to external conditions / polyelectrolyte complex gel / drug-delivery system / pH-sensitive swelling / natural polymer / dextran sulfate / chitosa |
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| Research Abstract |
Polyelectrolyte complex gel prepared from a basic polysaccharide chitosan together with an acidic polysaceharide shows pH-sensitive swelling. In this study, the pH- sensitive swelling behavior and its applicability to pH-controlled release systems for drugs were investigated mainly on complex gels prepared from dextran sulfate and chitosan : The swelling behaviors of the complex gels were analyzed on the basis of Donnan equilibrium, It was shown that dissociation of protonated amino groups was a key step for the prominent volume change observed when the complex gel swelled or shrank. To study the courses of drug release under various conditions from a complex gel with excess amino group, dextran, bovine serum albumin (BSA), lactoferrin, and Indomethacin were used as model drugs. The complex gel with excess amino group shrank at around pH 7. The apparent diffusion coefficient of dextran inside the gel increased by 3 to 10 times due to squeezing effect caused by shrinking of the complex gel. Release of BSA from the complex gel was accelerated at pHs above 6 where the complex gel shrank. Sustained release of lactoferrin was observed at pH 8.8, above the isoelectric point of lactoferrin. These results indicate that the electrostatic interaction between the gel and model drugs affects the releasing behavior as well as the squeezing effect by shrinking of the complex gel. Sustained release of Indomethacin from the complex gel was observed at pHs above 6. Thus the complex gel would be useful as a material for p H-controlled release of drags.
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Research Products
(2 results)
