Calander Home 2001-2002 2002-2003 T. Andrew Taton Encased Gold Nanoparticles for DNA Detection Strategies Date: September 23 Time: Noon to 1 Place: BSBE 4-101 We have developed a number of strategies for detecting particular DNA sequences, both individually and in parallel, using gold nanoparticles as labels. Gold nanoparticles have a number of unique physical properties, including high extinction and scattering coefficients, catalytic activity, and fluorescence quenching, that make them extremely flexible labels for DNA detection schemes. As a result, we have developed DNA array protocols whereby target hybridization to array elements can be determined by electrical conductivity, scattered light, or even absorption visible to the naked eye. These technologies have offered a great deal of promise for simple and inexpensive, yet selective and sensitive, analysis of gene expression and mutation. However, the thiol chemistry that is commonly used to connect biomolecules to gold surfaces is sometimes not strong enough to survive molecular biology protocols (such as PCR). This has limited the direct impact of gold nanoparticle labels on the practice of DNA arrays. We are currently developing chemical strategies that permit more stable conjugates between gold nanoparticles and biomolecules. In particular, we find that encapsulating nanostructures in self-assembling polymer shells stabilizes them with respect to reagents, high temperatures, and high salt conditions. We expect that this strategy will allow enzyme reactions to be conducted directly on gold nanoparticle-bound DNA, and will further enable the labels' direct use in biological and clinical DNA sequence analysis.