| Abstract
| - We have examined the adsorption of short 16 base pair DNA to 14 nm protein-sized gold particles usingsurface-enhanced Raman spectroscopy and electronic absorption spectroscopy. In the presence of KCl, wefind greater Raman enhancement of adenine and guanine ring breathing vibrations (per adenine and guaninepresent in each sequence) for crystallographically “kinked” oligonucleotide than for the DNA−particleinteractions for “bent” A-tract and “straight” oligonucleotides. The calculated binding constants are withinthe range of nonspecific protein−DNA interactions and are nearly the same for each sequence. The differencein the surface plasmon frequency of the gold particles in the presence of either straight, bent, or kinked DNAis attributed to differences in the DNA-mediated aggregation of the nanoparticles. Specifically, the displacementof the gold's stabilizing citrate ions seems to vary with DNA sequence, and this controls the residual interparticleelectrostatic interaction and average interparticle separation in the aggregate.
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