Maria_Story Tuesday, May 5th 1:30 Pm in Web 2325

By Maria Olubunmi Ogunyankin, Ph.D., Post Doctoral Fellow, University of Minnesota

Nanotechnology is a fast growing area of research that has wide applications in different disciplines. Here we describe the use of lipid bilayers in combination with nanosurfaces, and the application of nanoparticles for controlled cargo release from liposomes. Lipid mixtures self-assemble to form planar bilayers containing coexisting lipid phases in many compositional regimes, a significant challenge exists in forming uniformly sized lipid domains existing as single addressable elements that could be arrayed at high density and provide compatibility with current nanometer-scale device elements. This work describes a technique to form nanometer-scale pixelated lipid domains that are self-organized into high curvature geometric patterns residing on a square lattice. In this process, a lipid multibilayer stack is deposited onto a silicon substrate patterned with a square lattice array of poly(methyl methacrilate) (PMMA) hemispherical features formed by electron beam lithography. We show that lipid domain patterns are confined to the flat grid between the hemispheres and comprised of connected and individual domain pixels. Analysis of lattices of varying sizes shows that domain pattern formation is driven by mechanical energy minimization and packing constraints. We will also show the use of hollow gold nanoparticles (HGN) to improve liposome drug delivery systems that are faced by the quandary of minimizing non-specific drug release and initiating fast release at the site of interest. A novel strategy is to separate the mechanism of drug release from drug retention by using an external agent to trigger content release. Near infra-red (NIR) light is an appropriate choice as it is physiologically friendly with minimal thermal injury to normal tissues. We can synthesize HGN to absorb NIR light over the range from 700-900 nm by manipulating the diameter to shell thickness ratio. A fluorescent dye was encapsulated within a liposome as a model agent to study release kinetics triggered by a picosecond pulsed NIR laser irradiation of the HGN coupled to the liposome. The study provides design parameters for engineering drug delivery systems that ultimately could be apply to tumor targeting therapeutics.