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Development of cyclodextrin-hydrogel polymeric systems in scCO2 for drug delivery
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This work describes the studies on the development of new cyclodextrin-hydrogel systems in supercritical carbon dioxide (scCO2) with potential application in drug delivery. Three β-cyclodextrin (CDs) derivatives were synthesized: 6-monoacryloyl-β-CD, 2-monoacryloyl-β-CD and 6-monoacryloly-heptakis-(2,3-di-O-benzyl)-β-CD. Their structures were assigned by nuclear magnetic resonance (NMR), infrared (IR) and mass spectrometry (MS) using the technique of matrix-assisted laser desorption/ionisation-time-of-flight (MALDI-TOF). These functionalized β-CDs were co-polymerized in scCO2 and the resulting co-polymers were characterized by high resolution magnetic angle spinning (HR-MAS) NMR. Swelling tests were performed showing that the presence of CD decreases the swelling capacity of the corresponding co-polymers. The β-CD co-polymers were impregnated with a model drug, metronidazole, using a batch supercritical fluid impregnation process. Experiments in vitro were realized in order to evaluate the performance of the cyclodextrin-hydrogel system as drug release device at different pHs, 2.2 and 7.4. The co-polymer with 2.5 % of 2-monoacryloyl-β-CD was the one that impregnated more drug and showed more interesting results, since at pH 2.2 the release is more controlled. The effect of the percentage of β-CD in the co-polymers performance was also investigated. The co-polymer with more percentage of 2-monoacryloyl-β-CD (8.8%) showed a more controlled drug release at pH 7.4. The results with 2.5 % of β-CD indicate that the co-polymer would be more suitable for oral administration, whereas with 8.8 % would be suitable for parenteral administration.
Descrição
Thesis for the Degree of Master of Science in Bioorganic Universidade Nova de Lisboa,
Faculdade de Ciências e Tecnologia