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Conformation of Oligonucleotides Attached to Gold Nanocrystals Probed by Gel Electrophoresis
figure
posted on 2002-12-03, 00:00 authored by Wolfgang J. Parak, Teresa Pellegrino, Christine M. Micheel, Daniele Gerion, Shara C. Williams, A. Paul AlivisatosThiol-modified single stranded oligonucleotides of different lengths (8 to 135 bases) were attached to the surface of 10 nm diameter Au
nanocrystals with different DNA/Au ratios (1, 2, ..., saturation). The electrophoretic mobility of these conjugates was determined on 2% agarose
gels, and the effective diameter of the DNA/Au conjugates was determined. This diameter depends on the conformation of the oligonucleotides
adsorbed on the Au surface. For low surface coverage, nonspecific wrapping of the DNA around the nanoparticles was observed. For high
surface coverage, short oligonucleotides were shown to be oriented perpendicular to the surface and fully stretched. For high surface coverage
and long oligonucleotides, the inner part close to the Au surface was determined to be fully stretched and pointed perpendicular to the
surface, whereas the outer part adopts random coil shape.