AVS 51st International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI2-WeM

Paper BI2-WeM7
Formation of ssDNA Brushes with Controlled Length and Spacing on Gold

Wednesday, November 17, 2004, 10:20 am, Room 213C

Session: Oligo Nucleotide - Surface Interactions
Presenter: A. Opdahl, National Institute of Standards and Technology
Authors: A. Opdahl, National Institute of Standards and Technology
D.Y. Petrovykh, University of Maryland
H. Kimura-Suda, National Institute of Standards and Technology
L.J. Whitman, Naval Research Laboratory
M.J. Tarlov, National Institute of Standards and Technology
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A method is presented that uses block-oligonucleotides to generate single stranded (ss)DNA brushes with controlled length and density on gold surfaces. The method is based on previously reported observations that adenine oligonucleotides (dA) have a higher affinity than thymine oligonucleotides (dT) for adsorbing on gold substrates (Kimura-Suda, H.; Petrovykh, D. Y.; Tarlov, M. J.; Whitman, L. J.; J. Am. Chem. Soc.; 2003; 125(30); 9014-9015). In this study, adenine/thymine block-oligonucleotides, d(T@sub m@-A@sub n@), with specific (dT) and (dA) sequence lengths, m and n, were adsorbed on gold substrates from aqueous solution and were characterized by FTIR and by XPS. The FTIR and XPS experimental results support a model where the (dA) nucleotides preferentially adsorb on the gold substrate and the (dT) sequences extend away from the substrate. The surface density of the (dA@sub n@) blocks decreases with their length n, such that the overall surface density of (dA) nucleotides adsorbed on the gold is approximately independent of the (dA@sub n@) block length. Therefore d(T@sub m@-A@sub n@) oligonucleotides with long (dA) sequences (larger n) have lower densities of (dT) brush strands in the adsorbed layer. Oligonucleotides with long (dT) sequences, m, are observed to have longer brush strands extending away from the substrate. The n and m dependent adsorption behaviors and the stabilities of the brush layers will be compared to the behavior of alkanethiol derivatized ssDNA monolayers on gold.