Investigations into the structure and composition of beta-cyclodextrin/poly(acrylic acid) microspheres.
Microspheres composed of the hydrophilic polymer poly(acrylic acid) (PAA), with and without beta-cyclodextrin (beta-CD), were prepared by a water-in-oil (w/o) solvent evaporation technique. Microspheres were characterised for particle size, beta-CD and residual oil content. The type of matrix formed during microsphere synthesis was investigated by solid state carbon 13C NMR, in vitro release of beta-CD and swelling measurements. A high encapsulation efficiency of the beta-CD was observed (?90%). The in vitro release of beta-CD in water over 24 h was initially rapid ( approximately 70% in 3 h) with no further loss thereafter, suggesting potential covalent binding of the residual beta-CD. NMR indicated that in the presence of beta-CD, two concomitant chemical processes occur during microsphere synthesis: (i) esterification of the hydroxyl group(s) of the beta-CD with the carboxylic acid groups of the PAA; and (ii) the formation of intra-/inter-polymer acid anhydrides.
Bibby
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DC
School of Pharmacy, University of Otago, P.O. Box 913, Dunedin, New Zealand.
Davies
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NM
Tucker
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IG
D000180:Acrylic Resins / Q000737:chemistry*; D000268:Adhesiveness; D002247:Carbon Isotopes; D003505:Cyclodextrins / Q000737:chemistry*; D003692:Delayed-Action Preparations; D006361:Heating; D008863:Microspheres; D019906:Nuclear Magnetic Resonance, Biomolecular; D019301:Oleic Acid / Q000737:chemistry; D010316:Particle Size; D010592:Pharmaceutic Aids / Q000737:chemistry*; D012997:Solvents; D047392:beta-Cyclodextrins
D000180:Acrylic Resins; D002247:Carbon Isotopes; D003505:Cyclodextrins; D003692:Delayed-Action Preparations; D010592:Pharmaceutic Aids; D012997:Solvents; D047392:beta-Cyclodextrins; D019301:Oleic Acid; C006903:carbopol 940; C031215:betadex