Single stranded (ss) DNA Brushes with Grafting Density Controlled by Adenine Nucleotide Adsorption on Gold
Aric Opdahl,1,4 Dmitri Y. Petrovykh,2,3 Hiromi Kimura-Suda,1, 5 Lloyd J. Whitman,3 and Michael J. Tarlov1
1 National Institute of Standards and Technology, Gaithersburg, MD 20899
2 Physics Department, University of Maryland, College Park, MD 20742
3 Naval Research Laboratory, Washington, DC 20375
4 National Research Council Postdoctoral Associate at NIST
5 Currently with: National Institute of Advanced Industrial Science and Technology, Tsukuba, Japan
We have studied the attachment of single stranded (ss) DNA on gold surfaces via adenine nucleotides, dA, using block oligonucleotides, d(Tm-An), with systematically varied thymine (dT) and adenine nucleotide block lengths, m and n. The block-oligos were adsorbed on gold substrates from aqueous buffer solution and characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The experimental results support a model where the d(A) blocks preferentially adsorb on the gold substrate and the d(T) blocks extend away from the substrate.
Oligonucleotide attachment via dA nucleotides is distinctly different from the more conventional thiol-gold attachment strategy. The unique aspect of the dA attachment strategy is that the dA-Au interaction is sufficiently strong such that dA nucleotides occupy essentially all of the available binding sites on the gold. Thus, to a large extent, the length of the d(A) block determines the ssDNA grafting density. That is, increasing the length of the d(A) block leads to a decrease in grafting density [e.g. d(T5-A10) adsorbs with lower grafting density than d(T5-A5)].
Name: Aric Opdahl,
Mentorís name: Michael J. Tarlov
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