'Cookbook recipes' would cure disease with nontoxic DNA delive...( stick a negatively charged lipid to a ...)

Using synchrotron small angle X-ray scattering and confocal microscopy, Wong and his colleagues -- former Illinois graduate student Hongjun Liang (now a postdoctoral researcher at the University of California at Santa Barbara) and theoretician Daniel Harries at the National Institutes of Health -- investigated how different ion-mediated interactions were expressed in self-assembled anionic lipid-DNA structures.

At low membrane charge densities, for example, anionic lipids and DNA molecules self-assemble into structures with alternating layers of DNA and anionic membranes bound together by cations, Wong said. At high membrane charge densities, there is a surprise: The DNA is expelled, leaving a stack of anionic membranes glued together by cations -- a feature that could prove useful in other controlled drug delivery applications.

The researchers also produced inverted hexagonal structures with encapsulated DNA. "First, the strands of DNA are coated with positively charged ions," Wong said. "The strands are then wrapped with negatively charged lipids and resemble tubes, which are then grouped into hexagonal arrangements."

Utilizing naturally occurring anionic lipids instead of cationic lipids "creates a whole hierarchy of interactions and a much richer range of structures," Wong said, "which really opens up new possibilities."

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Contact: James E. Kloeppel, Physical Sciences Editor
kloeppel@uiuc.edu
217-244-1073
University of Illinois at Urbana-Champaign
10-Aug-2005