In Situ TEM Study of DNA/Gold Nanoparticles in Liquid Environment

Abstract In recent years the assembly of nanometer sized building blocks into two- and three-dimentional structures and functional materials has been an extremely active area of scientific research. A new class of materials, the DNA/nanoparticle hybrid materials and assemblies, which might have useful electrical, optical and structural properties, have been developed at Northwestern University. While characterizing particle morphology (size and shape) by subjecting it to the high vacuum environment in an electron microscope, the structure may have changed drastically from its natural state. The study of morphology of these DNA/Au nanoparticles in the liquid state was thus undertaken to further our understanding of the dynamics of the nanoparticles in a specific environment. This paper presents an in-situ observation of DNA/Au nanoparticle assembles in liquid media using environmental TEM. Experiments were carried out with citrate-stabilized colloidal Au particles averaging 8 and 31 nm in diameter. Colloidal Au nanoparticles were obtained from a commercial source. 8 nm particles were modified with propylthiol-capped oligonucleotide, 3’HS(CH2)3-O(O)P(O)O-ATG-CTC-AAC-TCT, 1,whereas the 31 nm particles were modified with hexlylthiol-capped oligonucleotide, 3’TAG-GAC-TTA-CGC-O(O)P(O )O-(CH2)6SH, 2.