Mechanical Engineering Department, University of California, Santa Barbara, California, United States.
Langmuir. 2011 Jul 19;27(14):8923-33. doi: 10.1021/la200837z. Epub 2011 Jun 17.
Silver-DNA nanoclusters (Ag:DNAs) are novel fluorophores under active research and development as alternative biomolecular markers. Comprised of a few-atom Ag cluster that is stabilized in water by binding to a strand of DNA, they are also interesting for fundamental explorations into the properties of metal molecules. Here, we use in situ calibrated electrokinetic microfluidics and fluorescence correlation spectroscopy to determine the size, charge, and conformation of a select set of Ag:DNAs. Among them is a pair of spectrally distinct Ag:DNAs stabilized by the same DNA sequence, for which it is known that the silver cluster differs by two atoms. We find these two Ag:DNAs differ in size by ∼30%, even though their molecular weights differ by less than 3%. Thus a single DNA sequence can adopt very different conformations when binding slightly different Ag clusters. By comparing spectrally identical Ag:DNAs that differ in sequence, we show that the more compact conformation is insensitive to the native DNA secondary structure. These results demonstrate electrokinetic microfluidics as a practical tool for characterizing Ag:DNA.
银- DNA 纳米团簇（Ag:DNAs）是一种新型荧光团，目前正在积极研究和开发，作为替代生物分子标记物。它们由几个原子的 Ag 簇组成，通过与 DNA 链结合稳定在水中，这也使它们成为研究金属分子性质的基础的有趣对象。在这里，我们使用原位校准的电动微流控和荧光相关光谱法来确定一组选定的 Ag:DNA 的大小、电荷和构象。其中有一对由相同的 DNA 序列稳定的光谱上明显不同的 Ag:DNA，已知银团簇的原子数相差两个。我们发现这两种 Ag:DNA 的大小相差约 30%，尽管它们的分子量相差不到 3%。因此，当结合略有不同的 Ag 簇时，单个 DNA 序列可以采用非常不同的构象。通过比较序列不同但光谱相同的 Ag:DNA，我们表明更紧凑的构象对天然 DNA 二级结构不敏感。这些结果表明电动微流控是一种用于表征 Ag:DNA 的实用工具。
