CHED 25 |
| Rf-PEG is functionally modified polyethylene glycol (PEG) with two hydrophobic fluoroalkyl (Rf) terminal groups. Rf-PEGs with certain middle blocks and end lengths exhibit interesting properties of sol-gel coexistence and surface erosion, which renders this hydrogel system a good candidate as a hydrophobic drug-delivery depot for controlled and sustained drug release application. To evaluate the feasibility and loading capacity of Rf-PEG micelles for hydrophobic drug delivery, we have made an electron spin labeled hydrophobic drug, Chlorambucil-Tempol adduct ( 4-hydroxy-2, 2, 6, 6-tetramethylpiperidine-N-oxyl) (CT). Chlorambucil (Brand name: Leukeran) belongs to the nitrogen mustard group of alkylating agents. It is most commonly used to treat chronic lymphocytic leukaemia, slow growing non-Hodgkin's lymphomas, Hodgkin's disease and ovarian cancer. Tempol contains a stable nitroxide free radical with an unpaired electron primarily located in the g-orbital of the nitroxide group. The free radical gives a hyperfine triplet EPR spectrum due to its interaction with the 14N nucleus. The free radical also acts as a relaxation reagent for monitoring the drug delivery using NMR relaxation technique. CT loaded Rf-PEG hydrogels were prepared using a sonication method and the CT's drug loading and dynamic properties in the Rf-PEG micelles were studied using variable temperature dependent EPR and 1H and 19F relaxation NMR techniques. The experimental results show that CT molecules were dominantly encapsulated in the Rf-cores of the micelles and the maximum loading capacity was also determined. This study is supported by NSF Grant #0351848. |
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NSF Partnership for Research and Education in Materials
8:30 AM-11:40 AM, Sunday, 10 September 2006 San Francisco Marriott -- Salon 11, Oral
Division of Chemical Education |