Dynamics of Excited States in DNA Strands and DNA-Silver Nanoclusters

DNA 链和 DNA 银纳米团簇中激发态的动力学

• 批准号: 1800471
• 负责人: Bern Kohler
• 金额: $ 43.5万
• 依托单位: Ohio State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-08-15 至 2023-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1800471&HistoricalAwards=false
• 关键词: Dynamics; Excited; States; DNA; Strands

Silver ions (Ag+) can bind to the nitrogen and oxygen atoms in DNA giving rise to unusual and interesting molecular structures. DNA acts as a scaffold that precisely controls the positions of individual silver ions. When another chemical reagent is added to provide electrons to the Ag+ ions, the array of Ag+ ions in the DNA become small clusters containing no more than a few dozen metal atoms. These miniscule clusters have remarkable optical properties, including for example fluorescence. Fluorescence is a process by which a molecule absorbs light at one wavelength and shortly afterwards emits light of another color. This is a property that macroscopic silver objects do not possess. Their fluorescence properties makes these silver clusters attractive for sensing and imaging applications. However, despite widespread interest in these clusters, very little is known about what controls their light emission. In this project funded by the Chemical Structure Dynamics and Mechanism (CSDM-A) program of the Chemistry Division, Professor Bern Kohler of The Ohio State University and students working under his direction are investigating DNA-metal assemblies that are excited by short laser pulses (a few hundred femtoseconds, where a femtosecond is one quadrillionth of one second). The Kohler team observes how the color of the light emitted from the silver clusters depends on the color and time interval of the impinging laser pulse. Under some conditions, no light is emitted at all. These studies are revealing the mysteries of how light energy is absorbed by small metal clusters, and either emitted again as light or dissipated into the clusters' surroundings. The undergraduate and graduate students involved in this project are gaining experience in state-of the-art laser techniques, and the kinds of analysis needed to solve problems at the interface of spectroscopy and nanoscience. This multidisciplinary training is important for upholding the nation's workforce of scientists. This project targets fundamental understanding of excited electronic states formed by UV and visible excitation of DNA-metal complexes and nanostructures. Silver ions coordinate to the nitrogen and oxygen atoms of the nucleobases, giving rise to metal-mediated base pairs and a rich variety of self-assembled structures. Reduction of the bound silver ions produces compact metal nanostructures containing small numbers of silver atoms with remarkable, but poorly understood photophysical properties. Using femtosecond spectroscopy, nonradiative and radiative decay pathways are being observed and characterized in mononucleotide-metal ion complexes and their self-assembled nanostructures, and in DNA-hosted silver nanoclusters. Time-domain measurements are employed to develop a comprehensive photophysical model of silver nanoclusters. Fundamental understanding of the electronic interactions between DNA and metals can provide new insights into hybrid organic-inorganic interfaces that are attractive for controlling the separation and recombination of photogenerated carriers and redox equivalents. The study of few-atom noble metal nanoclusters by ultrafast spectroscopy promises to accelerate societally beneficial advances in science and technology. The ability to control and manipulate the excited states of metal nanoparticles could advance the fields of chemical imaging and sustainable energy production.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

银离子 (Ag+) 可以与 DNA 中的氮原子和氧原子结合，产生不寻常且有趣的分子结构。 DNA 充当精确控制单个银离子位置的支架。 当添加另一种化学试剂为 Ag+ 离子提供电子时，DNA 中的 Ag+ 离子阵列变成包含不超过几十个金属原子的小簇。这些微小的簇具有显着的光学特性，包括例如荧光。荧光是分子吸收一种波长的光，然后不久发射另一种颜色的光的过程。 这是宏观银物体所不具备的特性。它们的荧光特性使这些银簇对传感和成像应用具有吸引力。然而，尽管人们对这些团簇广泛感兴趣，但人们对控制其发光的因素却知之甚少。在这个由化学系化学结构动力学和机理 (CSDM-A) 项目资助的项目中，俄亥俄州立大学的 Bern Kohler 教授和在他指导下工作的学生正在研究由短激光脉冲（几百飞秒，其中飞秒是一秒的千万亿分之一）激发的 DNA-金属组装体。 科勒团队观察了银簇发出的光的颜色如何取决于撞击激光脉冲的颜色和时间间隔。 在某些条件下，根本不发光。 这些研究揭示了光能如何被小金属团簇吸收，并以光的形式再次发射或消散到团簇周围环境的奥秘。参与该项目的本科生和研究生正在获得最先进的激光技术以及解决光谱学和纳米科学交叉领域问题所需的分析经验。这种多学科培训对于维护国家科学家队伍非常重要。该项目的目标是对 DNA-金属复合物和纳米结构的紫外和可见光激发形成的激发电子态进行基本了解。银离子与核碱基的氮原子和氧原子配位，产生金属介导的碱基对和丰富多样的自组装结构。结合银离子的还原产生包含少量银原子的致密金属纳米结构，其具有显着但人们知之甚少的光物理性质。使用飞秒光谱，可以在单核苷酸-金属离子复合物及其自组装纳米结构以及 DNA 承载的银纳米团簇中观察和表征非辐射和辐射衰变途径。采用时域测量来开发银纳米团簇的综合光物理模型。对 DNA 和金属之间电子相互作用的基本了解可以为杂化有机-无机界面提供新的见解，这对于控制光生载流子和氧化还原当量的分离和重组具有吸引力。 通过超快光谱研究少原子贵金属纳米团簇有望加速科学技术领域对社会有益的进步。 控制和操纵金属纳米粒子的激发态的能力可以推动化学成像和可持续能源生产领域的发展。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

Probing the heterogeneous structure of eumelanin using ultrafast vibrational fingerprinting

• DOI: 10.1038/s41467-020-18393-w
• 发表时间: 2020-09-11
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Grieco, Christopher;Kohl, Forrest R.;Kohler, Bern
• 通讯作者: Kohler, Bern

Probing eumelanin photoprotection using a catechol:quinone heterodimer model system

使用儿茶酚：醌异二聚体模型系统探测真黑素光保护

• DOI: 10.1039/c8fd00231b
• 发表时间: 2019
• 期刊: Faraday Discussions
• 影响因子: 3.4
• 作者: Grieco, Christopher;Empey, Jennifer M.;Kohl, Forrest R.;Kohler, Bern
• 通讯作者: Kohler, Bern

Time-Resolved Vibrational Fingerprints for Two Silver Cluster-DNA Fluorophores

• DOI: 10.1021/acs.jpclett.0c02486
• 发表时间: 2020-11-05
• 期刊: JOURNAL OF PHYSICAL CHEMISTRY LETTERS
• 影响因子: 5.7
• 作者: Zhang, Yuyuan;He, Chen;Kohler, Bern
• 通讯作者: Kohler, Bern

Vibrational relaxation by methylated xanthines in solution: Insights from 2D IR spectroscopy and calculations

溶液中甲基化黄嘌呤的振动弛豫：二维红外光谱和计算的见解

• DOI: 10.1063/5.0135412
• 发表时间: 2023
• 期刊: The Journal of Chemical Physics
• 作者: Hanes, Alex T.;Grieco, Christopher;Lalisse, Remy F.;Hadad, Christopher M.;Kohler, Bern
• 通讯作者: Kohler, Bern

Isotopic substitution affects excited state branching in a DNA duplex in aqueous solution

同位素取代影响水溶液中 DNA 双链体的激发态分支

• DOI: 10.1039/c9cc01105f
• 发表时间: 2019
• 期刊: Chemical Communications
• 影响因子: 4.9
• 作者: Zhang, Yuyuan;de La Harpe, Kimberly;Kohl, Forrest R.;Kohler, Bern
• 通讯作者: Kohler, Bern