Development of Reliable Experimental Models for the Study of the Biological Behavior of Drug Nanocarriers

The curative effectiveness of current and new drugs is often limited by poor pharmacokinetics in-vivo. The use of nanoparticles as drug carriers seems promising in solving this problem. In this work we aimed to further explore and improve common drug delivery components and techniques. Starting with the synthesis of nanoparticles with a controlled number of molecular recognition ligands, we used bulky ligands and gel separation to obtain nanoparticles with a discrete number of chemical functional groups, used later to conjugate the same number of molecular recognition ligands. These nanoparticles later showed substantial difference in the in-vivo behavior. A second project focused on the in-depth characterization of the relationship between hydrophobic inorganic nanoparticles and the polymer surfactants used to enable their water dispersibility, as well enabling their functionalization. This investigation was done through separate quantification of polymer and inorganic nanoparticles and assessment of stability. Our results showed that the removal of excess polymer from such systems can result in loss of colloidal stability. A third project was aimed to describe the mechanism of polymeric nanoparticle’s endosomal escape and provide a platform for qualitative investigation and enhancement of this process. This goal was accomplished through two complementary in-vitro experiments testing two proposed mechanisms of endosomal escape. These results raised a key consideration when matching a particle capable of endosomal escape to a specific cell type as well as methods reduce interaction with serum proteins. A fourth project focused on developing an assay to quantify cytosolic delivery of nanoparticles and theoretically assessed the possibility of using fluorescence resonance energy transfer (FRET) - which was found to be not practical in this case - as well as implementing a pro-fluorophore to generate a measurable signal. Our preliminary results indicate this method might indeed be useful for this purpose in the future.