Phase Change Nanoemulsions for Cancer Therapy and Imaging

Much of the biological therapeutics currently available struggle to function as effective drug delivery vehicles due in part to their poor stability, solubility, and permeability across barriers such as the tight junctions between endothelial cells in tumor vasculature. Given this understanding, there is currently a significant interest in designing nanocarriers (< 100 nm in diameter) which are able to increase the bioavailability of drugs. In particular, much attention has been focused on nanoemulsions whose liposome-like structure protects drugs against physico-chemical and enzymatic degradation and charged surface favors drug adsorption. One novel class of nanoemulsions called perfluorocarbon (PFC) emulsions are of particular interest because they can be used both for delivering drugs and imaging tumors. In this work we show that nanoemulsions with a PFC core and Zonyl FSP surfactant shell can be produced using an oil-in-water technique via sonication. This technique is successful in producing PFC emulsions that are on average 50 nm in diameter with long-term stability at physiological conditions, as determined by Electron Microscopy, Fluorescence Correlation Spectroscopy and Dynamic Light Scattering. Using laser excitation, these nanoemulsions can vaporize into microbubbles in the presence of silica coated gold nanoparticles for efficient drug release and imaging using high contrast imaging modalities such as photoacoustic microscopy. Taken together, the size and stability of these PFC nanodroplets make them cost effective drug delivery vehicles suitable for efficient internalization by cancer cell lines.