| Summary: | Modern day medicine is on the brink of a new age of therapy, which aims to harness the natural power of molecular biology for disease treatment. This therapy could include replacement of dysfunctional genes that cause disorders such as cystic fibrosis (Lommatzsch and Aris, 2009), or silencing the overexpression of genes that cause disorders such as cancer (Pelengaris and Khan, 2003). In both examples, the treatment of these genetic diseases lies in the delivery of synthetic nucleic acids into diseased cells, the former being called gene replacement therapy (Dobson, 2006a), and the latter being called RNA interference (RNAi) therapy (Whitehead et al., 2009). While these techniques have long been in use as genetic research tools for gene transfection or silencing in vitro, their translation for use in clinical disease treatment has yet to be achieved. The main problem facing the development of these novel therapies is the specific delivery of nucleic acids into diseased cells within the body. It is hoped that nanoparticles (NPs) can be used to overcome this problem, by acting as vehicles to transport nucleic acids through the body for specific delivery into diseased cells. This feat can be aided by the attachment of additional functional molecules such as cell penetrating peptides (CPPs), targeting peptides, additional drug types and molecules for imaging during treatment. Many different NP design strategies are currently under development. It is essential for new designs to be extensively tested for toxicity and efficiency in human cells before they can be successfully released into the clinic. As part of this effort, this PhD project has investigated two different NP design strategies for drug delivery: 1) the use of a magnetic field (MF) and a CPP to increase the delivery of iron oxide magnetic NPs (mNPs) to cells grown in tissueequivalent 3D collagen gels, and 2) gold NPs (AuNPs) for the delivery of siRNA to silence the c-myc oncogene for cancer treatment. In the first investigation, a MF and the CPP penetratin were found to increase mNP delivery to cells grown in 3D. In the second investigation, AuNPs were assessed in a range of different cell types (grown in 2D) for their performance in 4 main areas; cellular toxicity, cellular uptake, c-myc knockdown and effect on the cell cycle.
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