Harnessing Amplified Fluorescence Resonance Energy Transfer in Conjugated Polymer Nanoparticles

在这个由化学系化学结构、动态和机理B计划资助的项目中，威廉和玛丽学院化学系的伊丽莎白·J·哈布伦教授将开发高度荧光的有机纳米颗粒，用于需要在特定刺激下改变荧光的应用。这些纳米颗粒是从荧光共轭聚合物中提取出来的，并在每种应用中掺入了刺激响应型染料。聚合物和染料之间的相互作用产生对刺激的放大响应，这意味着可以在较低的输入光级和/或比单独使用染料更高的灵敏度下检测到它。目标应用包括开启和关闭用于超分辨率显微镜的荧光的纳米颗粒，以及改变其荧光颜色和/或强度以控制或检测水中的pH和汞离子的纳米颗粒。这些项目非常适合本科生和硕士生的培训和教育，因为它们涉及到使用高度彩色的荧光材料进行视觉上有吸引力的工作，以及在物理、有机和分析化学的界面上工作的机会。该小组将继续努力，通过指导针对女性的项目以及针对其他传统上在化学中代表不足的基团的咨询和指导，增加化学中代表不足的基团的代表性。共轭聚合物纳米颗粒(CPN或PDOT)由于其强烈的荧光亮度、高的光稳定性和水中的胶体稳定性，在传感和成像应用方面具有特殊的前景。它们独特的优势是能够充当捕光单位，通过荧光共振能量转移(FRET)将众多发色团的激发能量转移到少数低能位点。由于这种捕光效应，FRET受体染料官能化的CPN显示出放大的染料发射强度。在这项工作中，将开发具有刺激响应性染料的新型CPN。刺激响应型染料有两种分子形式，它们对特定的刺激做出反应而相互转换，但只有一种形式可以作为CPN的FRET受体。因此，刺激通过激活/去激活FRET来诱导荧光强度或颜色的调制。由于扩增的FRET，与单独使用染料相比，CPN中刺激反应的敏感度显著增加。染料功能化CPN的能量传递过程的优化将在以下系统中探索：1)对可见光进行关断光切换的光活化CPN，2)同时光调节pH并提供荧光读数的CPN，以及3)在完全水环境中提供pH和汞离子的比率检测的CPN。

In this project funded by the Chemical Structure, Dynamic & Mechanism B Program of the Chemistry Division, Professor Elizabeth J. Harbron of the Department of Chemistry at The College of William and Mary will develop highly fluorescent organic nanoparticles for use in applications that require a change in fluorescence in response to a specific stimulus. The nanoparticles are derived from fluorescent conjugated polymers and are doped with stimulus-responsive dyes specific to each application. The interaction between the polymer and the dyes yields an amplified response to the stimulus, which means that it can be detected with lower input light levels and/or with much greater sensitivity than with the dyes alone. The targeted applications include nanoparticles that switch their fluorescence on and off for super-resolution microscopy and nanoparticles that change their fluorescence color and/or intensity to control or detect pH and mercury ions in water. These projects are ideally suited to the training and education of undergraduate and masters students because they involve visually appealing work with highly colored, fluorescent materials as well as the opportunity to work at the interface of physical, organic, and analytical chemistry. This group will continue its efforts to increase representation of underrepresented groups in chemistry through mentoring projects targeted toward women as well as advising and mentoring targeted to other groups traditionally underrepresented in chemistry.Conjugated polymer nanoparticles (CPNs or Pdots) hold exceptional promise as fluorophores for sensing and imaging applications due to their intense fluorescence brightness, high photostability, and colloidal stability in water. Their unique strength is the ability to act as light harvesting units, transferring the excitation energy of numerous chromophores to a small number of low-energy sites by fluorescence resonance energy transfer (FRET). CPNs functionalized with FRET-acceptor dyes exhibit amplified dye emission intensities due to this light harvesting effect. In this work, new CPNs functionalized with stimulus-responsive dyes will be developed. The stimulus-responsive dyes have two molecular forms that interconvert in response to a specific stimulus, but only one form can act as a FRET acceptor for the CPNs. Thus, the stimulus induces modulation of fluorescence intensity or color by activating/deactivating FRET. The sensitivity of the stimulus response is substantially increased in the CPNs as compared to the dye alone due to amplified FRET. Optimization of the energy transfer processes in dye-functionalized CPNs will be explored in the following systems: 1) photoactivated CPNs that undergo off-on photoswitching in response to visible light, 2) CPNs that can simultaneously photomodulate pH and provide fluorescence readout, and 3) CPNs that provide ratiometric detection of pH and of mercury ions in completely aqueous environments.