A Race for the Gold

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Science  25 Jul 2003:
Vol. 301, Issue 5632, pp. 438-439
DOI: 10.1126/science.301.5632.438e

The adsorption of DNA molecules on gold surfaces is a convenient platform for emerging methods in bioanalysis and nanotechnology. Results from Kimura-Suda et al. indicate that caution is needed when interpreting such experiments, especially when oligo(dA) strands are involved. A combined x-ray photoemission and infrared spectroscopy study of competitive adsorption of homo-oligomers from solution onto gold surfaces shows that, whereas oligo(dC) and (dG) strands have similar adsorption affinity, oligo(dA) strands have much greater affinity than oligo(dT)—so much so that a solution of dA·dT 25-mers leads to deposition of only the dA strands. Although the affinity of the bicyclic G and A would be expected to be greater than that for the pyrimidines C and T, the adsorption preference actually does not follow the thermodynamic preference of G > A > C > T. This finding may explain some previously puzzling results where AT hybridization would have been expected to dominate over adsorption. — PDS

J. Am. Chem. Soc. 10.1021/ja035756n (2003).

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