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Novel folate amphiphile conjugates for targeted drug delivery

Author

Shiladitya Bhattacharya, University of the Pacific

Date of Award

2008

Document Type

Dissertation - Pacific Access Restricted

Degree Name

Doctor of Philosophy (Ph.D.)

Department

Pharmaceutical and Chemical Sciences

First Advisor

Bhaskara Jasti

First Committee Member

Xialing Li

Second Committee Member

Andreas Franz

Third Committee Member

William Chan

Fourth Committee Member

Dongxiao Zhang

Abstract

Cancer is not only difficult to treat but the patients also suffer from the pain associated with anticancer treatments. Targeted chemotherapeutics can reduce the adverse effects by reducing the dose required for tumor cell kill. Cancers of various origins often have characteristic marker molecules that distinguish them from the normal tissues. Folate receptors are such marker molecules present in ovarian and cervical cancers. The hypothesis for the current study is that amphiphiles constructed out of folic acid, the natural ligand for the folate receptor, can deliver paclitaxel, a chemotherapeutic compound, to folate receptor expressing cancer cells. To test this hypothesis, amphiphilic molecules were synthesized out of folic acid and fatty acids or long chain aliphatic amines. The gamma carboxylic group of folic acid was converted to an N-alkyl substituted amide. The alkyl group had various chain lengths varying from eleven methylene groups to seventeen methylene groups giving rise to a number of amphiphiles. The amphiphiles formed micelles in aqueous solutions. The critical micellization concentrations of the amphiphiles were measured by pyrene fluorescence and were found to be in the range of 10–70μM. HeLa and Caco-2 cells were taken as in vitro tumor models. Folate receptor expression was verified in HeLa and Caco-2 cells by western blot analysis. HeLa showed more than forty fold expression of the receptor when compared to Caco-2 and was chosen as receptor positive cell line while Caco-2 served as a negative control. Uptake of the folate labeled delivery system in the cell lines was tested by a fluorescent probe (aminocoumarin) labeled amphiphile. To test the specificity of the delivery system towards the receptor positive HeLa cells, the receptors were knocked down (70%) by folate receptor specific siRNA. Fluorescent amphiphile uptake in the knockdown cells was comparable to that of the negative control, Caco-2. Finally cytotoxicity studies were performed for paclitaxel formulated with the folate labeled amphiphiles and compared to free drug treatment in HeLa and Caco-2. IC50 values in HeLa for formulations with the folate labeled amphiphiles were ten folds less than those observed for free drug treatment whereas in Caco-2 no significant difference was noted.

Pages

157

ISBN

9780549502074

Recommended Citation

Bhattacharya, Shiladitya. (2008). Novel folate amphiphile conjugates for targeted drug delivery. University of the Pacific, Dissertation - Pacific Access Restricted. https://scholarlycommons.pacific.edu/uop_etds/2360