华人科学家利用DNA分子为模板排列金纳米粒子

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　　科学家们正在积极研究十亿分之一米的金原子团簇（金纳米粒子），因为它能够在从癌症药物携带者到数字资料存储器的很广泛的领域内得到应用。但是很多应用，尤其是电子学上的应用都需要把金纳米粒子排列成有序阵列，这是很难达到的。近日，美国亚利桑那州立大学的研究人员们用DNA链做成的格子为模板，把金纳米粒子排成了非常整齐的图案。

　　亚利桑那州立大学化学家颜浩（音译）说：“纳米粒子的集团性质非常依赖于它们组成集团的方式。使粒子间距均匀尤为重要，但是同时这又是很难达到的。现在，我们利用DNA链上的格子毫不费力的就把纳米粒子沉降成整齐的排列团。”

　　颜浩和他的研究小组采用的金纳米粒子直径为五纳米，这种纳米粒子并不是裸粒子，它们的表面包裹着上了一层称为T15序列的DNA碎片，这些碎片像手臂一样从金纳米粒子上伸出来。科学家们然后把这些纳米粒子沉降到两片十字形排列的DNA片上，分别是“A片”和“B片”，它们交替排列紧密结合在一起就形成了DNA格子。

　　每隔一段距离，每个A片就有一段短的单链（称为A15链）伸出DNA表面。这些单链就是被T15覆盖的纳米粒子的束缚点，它们使纳米粒子粘在DNA表面。

　　这种结构使得金纳米粒子能够自排列成正方形图案——每个纳米粒子都粘在A片上，而且粒子间距都非常均匀，约为38纳米。研究小组已经用功能强大的成像设备——原子力显微镜——证实了他们的结论。

　　但是，科学家看到的现象并不是他们所期望的。颜浩说：“我们很高兴看到金纳米粒子排列成非常规则的正方形图案，但是这不是我们所预期的。如果你用九个DNA片画出一个正方形，我们希望有五个粒子能够在上面排成正方形——四个角落和中间各一个。但是我们观察到的图案中没有中间的那一个粒子。”

　　科学家们猜测这可能是由T15序列层造成的，T15序列会增大每个纳米粒子的直径，而且使每个粒子带有很强的负电。所以如果把纳米粒子排列得太紧密的话，它们就会相互排斥，从而限制粒子间可以达到的最小距离。而中间的那个粒子会破坏这个约束，所以它不能存在。

　　接下来的研究工作中，颜浩和同事们想用同样的排列方法构造更复杂的纳米粒子阵列，比如更紧凑或者不同形状的图案。

HAO YAN

Assistant Professor
Ph.D., New York University,

  Office: BDA A124B  Lab: –
  Phone: (480)727-8570
  Fax: (480) 965-2747
  Email

Research Interests

Our research program is highly interdisciplinary which combines Chemistry, Biology, Physics and Material Science. Our goal is to achieve programmed design and assembly of biologically inspired nanomaterials and to explore its applications in nanoelectronics, controlled macromolecular interactions and biosensing. Our research is focused in the following four themes:

1) Bio-Nanotechnology: Design of novel DNA nanostructures, implementation of the designed structure in the construction of patterned DNA arrays and nanomechanical devices. Develop modular methods to achieve biomimetic molecular motors.

2) Nanoelectronics: Utilize rationally designed DNA nanostructure to template nanoelectronic components such as nanoparticles or carbon nanotubes into functional nanodevices.

3) Macromolecule Structure Elucidation: Develop methods to self-assemble 2D and 3D protein arrays for structural determination using Electron Microscopy or X-ray Crystallography.

4) Biomolecular Imaging: Investigation of protein-DNA interactions using high resolution imaging technology such as Atomic Force Microscopy and Electron Microscopy.

Major techniques in our group include: DNA/RNA/Protein manipulation (gel electrophoresis, labeling, hybridization, PCR and footprinting, cloning), electron-beam lithography, Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Electron Microscopy (EM), Fluorescence Spectroscopy, UV-Vis, Circular Dichroism (CD) and chemical synthesis.

Dr. Yan and his research group

Representative Publications

"DNA templated self-assembly of two-dimensional and periodical gold nanoparticle arrays," J. Sharma, R. Chhabra, Y. Liu, Y. Ke and H. Yan, Angew. Chem. Int. Ed. 45 730-735 (2006)

"Self-assembly of symmetric finite size DNA nanoarrays," Liu, Y. Ke and H. Yan, J. Am. Chem. Soc. 127 17140-17141 (2005)

"Self-assembling a Molecular Pegboard," K. Lund, Y. Liu, S. Lindsay and H. Yan, J. Am. Chem. Soc. 127 17606-17607 (2005)

"Aptamer-directed self-assembly of protein arrays on a DNA nanostructure," Y. Liu, C. Lin, H. Li and H. Yan, Angew. Chem. Int. Ed 44 4333-4338 (2005)

"DNA templated self-assembly of protein and nanoparticle linear arrays," H. Li, S.H. Park, J.H. Reif, T.H. LaBean and H. Yan, J. Am. Chem. Soc. 126 418 (2004)

"Nucleic Acid Nanotechnology," H. Yan, Science 306 2048-2049 (2004)

"An autonomous Unidirectional DNA walker," P. Yin, H. Yan, X.J. Guan, A.J. Turberfield and J.H. Reif, Angew. Chem. Int. Ed 43 4906-4911 (2004)

"Paranemic Crossover DNA: A Generalized Holliday Structure with Applications in Nanotechnology," Z. Shen, H. Yan, T. Wang and N.C. Seeman, J. Am. Chem. Soc. 126 1666 (2004)

"DNAtemplated Self-assembly of Protein Arrays and Highly Conductive Nanowires," H. Yan, S.H. Park, G. Ginkelstein, J.H. Reif and T.H. LaBean, Science 301 1882 (2003)

" A two-state DNA lattice switched by DNA nanoactuator," L. Feng, S.H. Park, J.H. Reif and H. Yan, Angew. Chem. Int. Ed. 42 4342 (2003)

"Directed Nucleation Assembly of DNA tile Complexes for Barcode Patterned Lattices," H. Yan, T.H. LaBean, L. Feng and J.H. Reif, Proc. Natl. Acad. Sci. U.S.A. 100 8103 (2003)

"Edge-sharing DNA triangles and One-dimensional self-assembly," H. Yan and N.C. Seeman, J. Supramol. Chem 1 229-237 (2003)

"Parallel Molecular Computation of Pair-wise Exclusive-Or (XOR) using DNA “String Tile” Self-Assembly," H. Yan, L. Feng, T.H. LaBean and J.H. Reif, J. Am. Chem. Soc. 125 14246 (2003)

"Paranemic Cohesion of Topologically-Closed DNA Molecules," X. Zhang, H. Yan, Z. Shen and N.C. Seeman, J. Am. Chem. Soc. 124 12940-12941 (2002)

"A Robust Sequence-dependent Rotary DNA Device," H. Yan, X. Zhang, Z. Shen and N.C. Seeman, Nature 415 62-65 (2002)

"The Construction, analysis, ligation and self-assembly of DNA Triple Crossover Molecules," T.H. LaBean, H. Yan, J. Kopatsch, F. Liu, E. Winfree, J.H. Reif and N.C. Seeman , J. Am. Chem. Soc. 122 1848-1860 (2000)