Imaging of high-amylose starch tablets. 3. Initial diffusion and temperature effects.
The penetration of water into cross-linked high amylose starch tablets was studied at different temperatures by nuclear magnetic resonance (NMR) imaging, which follows the changes occurring at the surface and inside the starch tablets during swelling. It was found that the swelling was anisotropic, whereas water diffusion was almost isotropic. The water proton image profiles at the initial stage of water penetration were used to calculate the initial diffusion coefficient. The swelling and water concentration gradients in this controlled release system show significant temperature dependence. Diffusion behavior changed from Fickian to Case II diffusion with increasing temperature. The observed phenomena are attributed to the gelatinization of starch and the pseudo-cross-linking effect of double helix formation.
Thérien-Aubin
Héloïse
H
Département de chimie, Université de Montréal, C.P. 6128, Succ. Centre-ville, Montréal, Québec, H3C 3J7 Canada.
Baille
Wilms E
WE
Zhu
Xiao Xia
XX
Marchessault
Robert H
RH
D000688:Amylose / Q000737:chemistry*; D016880:Anisotropy; D001672:Biocompatible Materials / Q000737:chemistry*; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004058:Diffusion; D004337:Drug Carriers; D007700:Kinetics; D046911:Macromolecular Substances / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015233:Models, Statistical; D011522:Protons; D012995:Solubility; D013213:Starch / Q000737:chemistry*; D013607:Tablets; D013696:Temperature; D013997:Time Factors; D014867:Water / Q000737:chemistry
D001672:Biocompatible Materials; D003432:Cross-Linking Reagents; D004337:Drug Carriers; D046911:Macromolecular Substances; D011522:Protons; D013607:Tablets; D014867:Water; D013213:Starch; D000688:Amylose