Ray Supratim Guha, Cohen Hagai, Naaman Ron, Rabin Yitzhak
Department of Chemical Physics and Chemical Research Support, Weizmann Institute, Rehovot 76100, Israel.
J Am Chem Soc. 2005 Dec 14;127(49):17138-9. doi: 10.1021/ja055201n.
Monolayers of single-stranded DNA (ssDNA) immobilized on surfaces form the basis of a number of important biotechnology applications, including DNA microarrays and biosensors. The organization of ssDNA as layer on a solid substrate allows one to investigate various properties of the DNA in a controlled manner and to use DNA for analytical applications as well as for exploring futuristic schemes for molecular electronics. It is commonly assumed that the adsorbed DNA layer contains some structural water and the cations. Here we show, based on XPS studies, that when monolayers of ssDNA are formed from sodium phosphate buffer and washed thoroughly, no Na+ signal is detected. A finite concentration of ions is observed when the DNA is made from a solution of Mg2+ ions, but it is still only a fifth of what it would be if all the phosphate ions were fully neutralized by the metal cations.
固定在表面的单链DNA（ssDNA）单层构成了许多重要生物技术应用的基础，包括DNA微阵列和生物传感器。将ssDNA组织成固体基质上的层，使人们能够以可控的方式研究DNA的各种特性，并将DNA用于分析应用以及探索分子电子学的未来方案。通常认为吸附的DNA层含有一些结构水和阳离子。在这里，我们基于XPS研究表明，当由磷酸钠缓冲液形成ssDNA单层并彻底洗涤时，未检测到Na+信号。当DNA由Mg2+离子溶液制成时，观察到有限浓度的离子，但这仍然只是如果所有磷酸根离子都被金属阳离子完全中和时的五分之一。
