Interfacial Properties of Particles and Pickering Emulsions
Particles have been shown to be outstanding interfacial agents and in particular nanoparticles have been shown to drive the interfacial tension between oil and water to values below 15 mN/m at concentrations of the order of a few ppm. It is conjectured that the unique surfactancy behavior attributed to nanoparticles results from their ability to enrich the interface and form a two-dimensionally ordered structure at the interface. To understand the origins of these interfacial properties we propose using grazing incidence x-ray scattering from oil (alkane) water interfaces with particles with tailored surface properties to understand the interfacial structuring of the particles. Further, the tunability of such two-dimensional ordering of particles at the interface and the potential creation of anisotropic structures at the surface by altering particle-particle interactions are the focus of the research program described here. We hypothesize that the creation of anisotropic assembled structures at the oil-water interface will be critical in further reducing the concentration at which the enhanced interfacial activity is achieved. Anisotropic nanoparticles assemblies have been shown to be created in bulk systems by tuning the interparticle interactions, typically modulated by grafted non-ionic polymers or by changes of surface charge density, and are yet to be fully manifested in two-dimensions at the interface of oil and water. We anticipate that the results of this project would be critical in determining the ability to direct the assembly of particles and from a technological perspective have implications for oil and gas exploration and recovery as well as mitigating the effects of oil spills.
Nanoparticle Encapsulated RNA Antagonists for Lung Cancer Therapy
Recent efforts to develop therapeutics for lung cancer have focused on evolving RNA aptamers that bind selectively to the nicotinic acetylcholine receptors (nAChR) that are expressed on bronchial epithelial and non-small cell lung cancer cells and are involved in cell growth regulation. A significant issue with such RNA based therapeutics involves effective delivery of such aptamers to the deep lung. We have proposed to develop a new generation of poly(lactide-co-glycolide) nanoparticle coated with a dense poly(ethylene glycol) brush that target the lung cancer cells and delivered as micron-scale porous aggregates. Nanoparticles will be functionalized to be able to recognize lung cancer cells with antibodies towards known lung cancer cell marker proteins that are the c-Met the receptor for hepatocyte growth factor, and the epidermal growth factor receptor. The RNA release properties and preferential binding properties to lung cancer cells relative to normal human bronchial epithelial cells will be investigated for single and multi functionalized nanoparticles using fluorescence methods. The RNA encapsulated nanoparticles will be tested for anti-proliferative properties and compared to the existing EGFR inhibitors and to a-cobratoxin, a non-selective inhibitor of nAChRs, which have previously been shown to be mediate apoptosis in lung cancer cell lines.