Designing a Novel Drug Delivery System Based on Gold Nanoparticles for Breast Cancer Therapy

Author: Zahrah Alhalili

Alhalili, Zahrah, 2016 Designing a Novel Drug Delivery System Based on Gold Nanoparticles for Breast Cancer Therapy, Flinders University, School of Chemical and Physical Sciences

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Developing novel strategies to improve limitations of commercially available chemotherapeutics is critically important. This thesis details efforts toward the development of a novel drug delivery system based on anticancer drug paclitaxel (PTX) loaded gold nanoparticles that targets T47D breast cancer cells to attain a more efficient cancer treatment. By combining gold nanoparticles as nanocarriers, PTX as anticancer agent and alkanethiol acids (LA and 16-MHDA) as linkers, a novel drug delivery system was engineered. This thesis focuses on synthesis, functionalising and characterising gold nanoparticles complexes. The study shows that when functionalising the surface of gold nanoparticles with targeting ligands and the chemotherapeutic agent, their unique properties remain unchanged. Alkanethiol acids were used as linkers and stabilisers for gold nanoparticles to enhance their biocompatibility and suitability for intracellular delivery. The alkanethiol-gold nanoparticles platform was nontoxic. However, after loading the anticancer agent PTX onto the thiolated gold nanoparticles, significant cytotoxicity was induced. Different composites based on gold nanoparticles were used to determine cytotoxicity to T47D cells using the MTT assay. It was noticed that the synthetic method of PTX-AuNPs composites affects their toxicity. Significant reduction in cell viability was observed when T47D cells were exposed to PTX-thiol-AuNPs hybrid and the PTX-thiol-AuNPs direct conjugate. However, a reverse conjugate PTX-16-MHDA-AuNPs was less effective at killing cancerous cells. The designed PTX-thiol-AuNPs hybrid induced more cell death in vitro than the commercially available formulation of PTX used as a solution of PTX in ethanol. This means the PTX is extremely bioavailable when a part of nanoparticle system and more efficient for breast cancer T47D cell treatment in comparison to the current PTX formulation. The intracellular uptake of gold nanoparticles by T47D cells was also evaluated by conjugating fluorescent dyes as probes with the thiolated gold nanoparticles. Gold nanoparticles were internalised via an endocytosis mechanism and taken up by the cells. Additionally, EpCAM or TARP antibodies conjugated to thiol-AuNPs in the presence and the absence of the anticancer agent, PTX, were synthesised using EDC/NHS coupling reaction and characterised to investigate their targeting ability against T47D cells. It was found that, antibodies conjugated thiolated AuNPs without PTX were nontoxic. However, the cytotoxicity of the cells exposed to antibodies and PTX attached simultaneously to the functionalised AuNPs shows that at low concentrations no significant reduction in cell viability was induced. However, when using high concentration the reduction of cell viability was significantly high. The number of cells killed by antibodies and PTX attached simultaneously to the functionalised AuNPs systems was significantly higher than that for cells killed by PTX-thiol-AuNPs direct conjugate system where no antibodies were used. The results indicate the effectiveness of combining EpCAM or TARP antibodies with PTX-thiol-AuNPs system to target T47D breast cancer cells.

Keywords: Gold nanoparticles, Paclitaxel, Breast cancer, Chemotherapy, Cytotoxicity, Fluorescent agents, Cellular uptake, Antibodies, Active targeting

Subject: Medical Biochemistry thesis, Medical Biotechnology thesis, Medicine thesis

Thesis type: Doctor of Philosophy
Completed: 2016
School: School of Chemical and Physical Sciences
Supervisor: Professor Joseph G.Shapter