DNA Nanoparticle Assembly and Diagnostics

We are developing chemical methodology to assemble nanoparticles into macroscopic materials. This "bottom up" approach involves the linking of nanometer sized colloidal particles, using molecular interactions, into aggregate stuctures. Since these macroscopic structures are comprised of discrete particles, the resulting mechanical, structural, electronic, and optical properites of the aggregates can be tailored by controlling particle size, chemical composition, and shape as well as linker molecule types.

Presently we are are using DNA modified gold colloids in our assembly scheme (viewgraph 1). The formation of nanoparticle aggregates relies on the ability of the thiol functionalized DNA to adsorb onto gold surfaces while retaining its ability to strongly bind to a complementary linking oligonucleotide strand. Linking of the colliods results in a solution color change, and within hours the aggregates precipitate out of solution, but can be redispersed by thermally denaturing the DNA attached to the particles (viewgraph 2). The reversible formation of these aggregates also can be monitored using spectroscopic methods (viewgraph 3), and the aggregates may be imaged easily by Transmission Electron Microscopy (viewgraph 4). Since hybridization of the modified colloids is triggered by solution DNA, the described system may have application in the development of sequence specific gene detection methods (viewgraph 5).