AVS 50th International Symposium
    Biomaterial Interfaces Thursday Sessions
       Session BI+SS-ThA

Paper BI+SS-ThA3
Base-dependent Competitive Adsorption of DNA on Gold

Thursday, November 6, 2003, 2:40 pm, Room 318/319

Session: Biodiagnostics
Presenter: D.Y. Petrovykh, University of Maryland and Naval Research Laboratory
Authors: D.Y. Petrovykh, University of Maryland and Naval Research Laboratory
H. Kimura-Suda, National Institute of Standards and Technology
M. Tarlov, National Institute of Standards and Technology
L.J. Whitman, Naval Research Laboratory
Correspondent: Click to Email
We characterize the room-temperature adsorption of single-stranded DNA (ssDNA) homo-oligonucleotides from solution onto polycrystalline Au films, including competitive adsorption between all possible pairs of unmodified oligomers. Although recent studies have shown that different DNA bases and homo-oligonucleotides interact differently with Au surfaces, competitive interactions among the bases - which will occur in most practical applications - have not been systematically addressed. We use Fourier transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopy to characterize the resulting films, and observe that oligonucleotides adsorb with a strongly base-dependent affinity, adenine (A) > cytosine (C) >= guanine (G) > thymine (T). In competitive adsorption experiments on Au, oligo(dA) strongly dominates over the other oligonucleotides. The relative adsorption affinity of oligo(dA) is so great that it competes effectively against adsorption of thiolated oligomers, and even causes hybridized oligo(dA)*oligo(dT) duplexes to denature in the presence of Au. The asymmetric adsorption affinities of the oligonucleotides must be carefully considered in systems using gold substrates, electrodes, or nanoparticle labels, and are likely to also occur on other substrates of practical importance.