Date

2013

Author

Kandemir, Berke Bilgenur

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Cancer is the most serious disease of in this century and death rates due cancer are increasing rapidly. Since the conventional cancer treatment techniques like chemotherapy, radiation therapy and surgical operations are not sufficiently efficient and they even are harmful for healthy tissues, there is an urgent need for effective treatment techniques with minimal or no side effects. Controlled drug delivery systems are offered as an alternative approach to cancer therapy that helps prevent excessive drug use and may even target the drug to the disease site. It was shown that one of the most efficient therapeutic agents is the use of gene therapy involving siRNA. Cationic nanoparticles are known to be efficient tools in siRNA delivery specificially into the targeted tumor cells. This study aims to develop an autophagic siRNA delivery system to cancer cells using positively charged nanospheres of polyethylenimine(PEI) – starch which possess the required positive charge by employing PEI molecules while lowering the cytotoxic effect of PEI through complexation with starch. PEI-starch nanospheres were prepared by water-in-oil microemulsion method. The size and zeta potential of the PEI-starch nanospheres were characterized by measuring the zeta potential and the particle size, and studying the topography with SEM. Mean diameter of unloaded particles was 60.3 nm and upon loading with siRNA this increased to 84.6 nm. SEM micrographs revealed that the nanospheres were very uniform (NIH Image J was used to measure the diameter using the micrographs) and had smooth surfaces. However, batch-to-batch size variation of the particles was observed. vi Zeta potential of PEI-starch nanoparticles increased when the PEI /starch ratios were increased, with the highest surface charge of 8.7 mV (PEI:Starch, 9:1 (w/w)). The encapsulation efficiency of the nanospheres was 1.5 % and this could be increased by optimizing pH conditions of water phase, and also the crosslinking and washing conditions. The nanospheres released 50 % of their siRNA content in the first 3 days and all of the content in a week. Confocal laser scanning microscopy (CLSM) micrographs show the nanoparticles affiliated with MCF 7 cells and additional staining of the nucleus is able to show their location more adequately. Western blot of breast cancer cells treated with EF2K siRNA loaded nanoparticles showed that the EF2K production which leads to proliferation of cancer cells was silenced after the treatment with the siRNA loaded nanoparticles.

Subject Keywords

Cancer, Nanoparticles., Gene therapy., Drug delivery systems.

URI

http://etd.lib.metu.edu.tr/upload/12616490/index.pdf
https://hdl.handle.net/11511/22926

Collections

Graduate School of Natural and Applied Sciences, Thesis