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DNA-Silver Cluster Complexes for Fluorescent Diagnostics

用于荧光诊断的 DNA-银簇复合物

基本信息

批准号：
7456777
负责人：
Jeffrey Thomas Petty
金额：
$ 21.45万
依托单位：
FURMAN UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
2008
资助国家：
美国
起止时间：
2008-06-01 至 2011-05-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7456777
关键词：
Address Base Sequence Binding Binding Sites Biocompatible Biodiversity Biological Biological Monitoring Biological Process Calorimetry Cations Characteristics Class Color Complement Complex Condition DNA DNA Sequence Dependence Detection Development Diagnostic Educational process of instructing Electronics Encapsulated Environmental Risk Factor Fluorescence Fluorescence Spectroscopy Free Energy Goals Heating Image Individual Ionic Strengths Label Lasers Ligands Measures Medicine Metals Modeling Molecular Molecular Conformation Molecular Structure Oligonucleotides Optics Oxygen Pathway interactions Philosophy Public Health Publications Range Reaction Relative (related person)Research Science Screening procedure Shapes Silver Solutions Solvents Spectrum Analysis Sterile coverings Structure Students Thermodynamics Time Titrations Variant Work base chromophore design enthalpy experience in vivo innovation interest macromolecule oxidation programs quantum research study residence single molecule stoichiometry tool

项目摘要

DESCRIPTION (provided by applicant): Fluorescence is a powerful tool for biological analysis, including high sensitivity detection and in vivo imaging. The proposed studies consider a new class of biocompatible and biofunctional fluorescent labels that are comprised of small (< 10 atoms) silver clusters encapsulated by oligonucleotides. These molecular metals have discrete electronic energy levels from which strong fluorescence is observed. The DNA stabilizes the clusters in a base and sequence specific manner. Via the following experiments, our goal is to vary the types of clusters and hence their fluorescence color by varying the sequence of the DNA. I. DNA arrays will be used to systematically evaluate the sequence dependence of cluster formation. Interesting sequences will be identified based on high fluorescence intensities and distinctive fluorescence spectra. Two types of binding motifs - single-stranded and hairpin oligonucleotides - will be used as templates for synthesis of the silver clusters. This approach will also be used to consider how reaction conditions such as pH influence cluster formation. II. On the basis of the rapid screening using DNA arrays, the photophysical characteristics of specific complexes will be evaluated. Limited photostability is characteristic of other chromophores. For example, reaction with oxygen results in photodestruction of the chromophore. In addition, long residence times in spin-forbidden excited states result in intermittent fluorescence that reduces the net fluorescence yield and inhibits single molecule detection. Preliminary studies indicate that the silver clusters are much less susceptible to these problems, and our studies will focus on the sequence dependence of the photostability using the sequences identified using the arrays. III. The array studies provide the basis for assessing how the clusters are formed, so the silver cation complexes with these DNA sequences will be studied. Isothermal titration calorimetry will characterize the thermodynamic parameters of the cation-DNA conjugates. The interaction of Ag+ with the binding sites of the individual bases will be studied using the variations of the thermodynamic parameters with the pH and ionic strength of the solution. In addition, the effect of Ag+ on the conformation of the single-stranded oligonucleotides will be studied by measuring the cation-induced changes in the solvent exposure of the bases. Optical spectroscopy will be used to determine the structure and stabilities of the complexes. PUBLIC HEALTH RELEVANCE: Fluorescence is a powerful tool in medicine with applications such as molecular diagnostics and in vivo imaging. We are developing a new class of biocompatible and biofunctional fluorescence probes based on DNA encapsulated silver clusters. Their favorable photostability, bright fluorescence, and distinctive spectra indicate the promise of this new class of fluorescence labels.

描述（由申请人提供）：荧光是生物分析的强大工具，包括高灵敏度检测和体内成像。拟议的研究考虑了一类新型生物相容性和生物功能性荧光标记，其由寡核苷酸封装的小（< 10 个原子）银簇组成。这些分子金属具有离散的电子能级，从中可以观察到强荧光。 DNA 以碱基和序列特定的方式稳定簇。通过以下实验，我们的目标是通过改变 DNA 序列来改变簇的类型，从而改变它们的荧光颜色。 I. DNA 阵列将用于系统评估簇形成的序列依赖性。将根据高荧光强度和独特的荧光光谱来识别感兴趣的序列。两种类型的结合基序——单链和发夹寡核苷酸——将用作合成银簇的模板。该方法还将用于考虑 pH 等反应条件如何影响簇形成。二.在使用DNA阵列快速筛选的基础上，将评估特定复合物的光物理特性。有限的光稳定性是其他发色团的特征。例如，与氧气的反应导致发色团的光破坏。此外，自旋禁激发态的长时间停留会导致间歇性荧光，从而降低净荧光产量并抑制单分子检测。初步研究表明，银簇不太容易受到这些问题的影响，我们的研究将集中于使用阵列识别的序列来研究光稳定性的序列依赖性。三．阵列研究为评估簇的形成方式提供了基础，因此将研究银阳离子与这些 DNA 序列的复合物。等温滴定量热法将表征阳离子-DNA 缀合物的热力学参数。将利用热力学参数随溶液 pH 值和离子强度的变化来研究 Ag+ 与各个碱基结合位点的相互作用。此外，将通过测量碱基溶剂暴露中阳离子诱导的变化来研究Ag+对单链寡核苷酸构象的影响。光谱将用于确定复合物的结构和稳定性。公共卫生相关性：荧光是医学上的一种强大工具，具有分子诊断和体内成像等应用。我们正在开发一类基于 DNA 封装银簇的新型生物相容性和生物功能荧光探针。它们良好的光稳定性、明亮的荧光和独特的光谱表明了这类新型荧光标记的前景。