Excellence in Research: Near-Infrared Molecular Probes as Potential Tools for Bioimaging

有了这个奖项，化学结构，动力学和机制-B计划正在支持摩根州立大学的Fasil Abebe博士开发合成近红外荧光探针，用于快速可视化和定量细胞金属离子。这一具有挑战性的目标首先需要合成一系列结构相关的有机染料分子，这些分子被设计成在金属离子配位后发生结构变化。由此产生的荧光团（发光结构）预计能够通过使用高分辨率荧光显微镜成像活细胞中的金属离子。本项目将探索这些染料分子的合成、光学和电化学性质。荧光探针已经成为现代生物学和生物技术中不可或缺的工具，因为它们提供关于活细胞内感兴趣的离子或分子的量的真实的时间信息。因此，在这个项目中开发的探针可能会刺激我们对金属细胞生物学的理解取得重大进展。开发在生理条件下表现良好的金属离子的近红外荧光探针是非常可取的。该项目丰富了对来自代表性不足的少数群体的研究生和本科生的教育和培训，让他们参与尖端研究活动。学生将在微波辅助合成、光谱分析和荧光成像方面发展实验室专业知识。本项目的中心主题是利用有机化学、微波辅助合成和光化学知识的原理，制作一系列能够研究生物金属离子的分子工具。今后的工作重点是开发具有良好水溶性、细胞通透性和光稳定性的菁偶联染料衍生物。该项目包括以下目标：（1）开发一种有效的微波辅助合成和表征近红外染料分子;（2）通过多种方法研究菁偶联染料衍生物的光谱，计算和电化学性质;（3）研究菁偶联染料衍生物用于HeLa细胞中金属成像的潜力。首先合成了一系列若丹明-菁偶联染料。在金属如铜的存在下，这些染料的近红外荧光通过配位诱导的螺环开放反应和光诱导电子转移（CIPET）过程发生。将研究影响近红外探针分析特性的各种因素的作用，它们对特定金属离子的选择性和灵敏度，以及其他重要特性。将研究具有生物和环境意义的金属离子，如铜。该项目的一个组成部分是使用密度泛函理论（DFT）和含时DFT来理解金属离子的荧光变化和金属染料络合物作为阴离子传感器的能力。在这一研究领域，为代表性不足的少数民族学生（包括本科生和研究生）提供详细的培训计划，预计将为国家发展多样化的劳动力做出重要贡献。该奖项反映了NSF的法定使命，并被认为值得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来支持。

With this award, the Chemical Structure, Dynamics, and Mechanism-B program is supporting Dr. Fasil Abebe at Morgan State University to develop synthetic near-infrared fluorescent probes for rapid visualization and quantification of cellular metal ions. This challenging objective first requires the synthesis of a series of structurally related organic dye molecules that are designed to undergo structural change upon metal ion coordination. The resulting fluorophores (light-emitting structures) are expected enable the imaging of metal ions in live cells by using high-resolution fluorescence microscopy. This project will explore the synthesis, optical and electrochemical properties of these dye molecules. Fluorescent probes have become indispensable tools in modern biology and biotechnology because they provide real time information concerning the quantity of ions or molecules of interest within the living cell. Thus, the probes developed in this project may spur significant advances in our understanding of metal-cell biology. Developing near-infrared fluorescent probes for metal ions that behave well under physiological conditions is highly desirable. The project enriches education and training of graduate and undergraduate students from underrepresented minority groups by involving them in cutting-edge research activities. Students will develop laboratory expertise in microwave-assisted synthesis, spectroscopic analysis, and fluorescence imaging.The central theme of this project is that principles of organic chemistry, microwave-assisted synthesis and knowledge of photochemistry can be exploited to make an array of molecular tools capable of investigating biological metal ions. Efforts will be focused on the development of cyanine-coupled dye derivatives with good water solubility, cell permeability and photostability. This project includes the following aims: (1) to develop an efficient microwave-assisted synthesis and characterization of near-infrared dye molecules; (2) to examine the spectroscopic, computational, and electrochemical properties of cyanine-coupled dye derivatives by diverse methods; and (3) to investigate the potential of cyanine-coupled dye derivatives for imaging of metals in HeLa cells. A series of rhodamine-cyanine-coupled dyes will first be synthesized. In the presence of metals such as copper, near infrared fluorescence of these dyes occurs by a coordination-induced spirocycle-opening reaction and photo-induced electron transfer (CIPET) process. The role of various factors affecting the analytical characteristics of near-infrared probes, their selectivity and sensitivity toward specific metal ions, as well as other important characteristics will be studied. Metal ions of biological and environmental interest such as copper will be studied. An integral part of this project is the use of density functional theory (DFT) and time-dependent DFT to understand the fluorescence change by metal ions and the ability of metal-dye complexes to act as anion sensors. The detailed training program for underrepresented minority students, both undergraduate and graduate, in this area of research is expected to make an important contribution in the development of a diverse workforce for the nation.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.