Mechanisms of Cellular Uptake and Intracellular Degradation of Polymeric Nanoparticles

Abstract

The effect of cancer therapy could be greatly improved by encapsulating existing drugs into nanoparticles. Nanoparticles can facilitate delivery of hydrophobic drugs with poor solubility in water, and allow you to target cancer cells specifically either through passive targeting, active targeting or triggered drug delivery. This thesis explores the cellular uptake and intracellular degradation of a novel, multimodal polymeric nanoparticle developed at SINTEF Materials and Chemistry. Two types of nanoparticles were evaluated for drug delivery purposes. Fluorescence lifetime imaging and analysis of emission spectra were used to assess the intracellular degradation, confocal laser scanning microscopy and flow cytometry were used to characterized the uptake.It was found that the poly(butyl cyanoacrylate) particle has degraded considerably after 24 hours intracellularly and is taken up through clathrin-mediated endocytosis. It was found that the cellular uptake was highly dependent on cell confluency and maturation. The poly (octyl cyanoacrylate) nanoparticle was not found to degrade readily within the first week of cell contact and is therefore less promising for drug delivery purposes. However, it was found that after 3 hours the particle had at least 3-fold higher uptake in prostate cancer cells than the poly(butyl cyanoacrylate) particle and that both clathrin- and caveolin-mediated uptake was important mechanisms in this uptake. This particle might be useful either for slow delivery or imaging. It was found indications that the nanoparticles escape the lysosomes and degrades in cytosol which is beneficial for drug delivery.