新型“水淬灭”近红外荧光探针的设计及其在纳米粒体内过程研究中的应用

Exploring the in vivo transport of nanoparticles is very important to disclose their action mechanisms, which is dependent on fluorescent or radiolabeled probes. However, the signal of traditional probes is not able to represent the intact nanoparticles completely due to lack of responsiveness. Our group previously found a “water-quenching” probe which is able to emit strong fluorescence in nanoparticles, but quench upon releasing in aqueous environment due to strong aggregate caused quenching (ACQ) effect. This “water-quenching” probe has been employed to establish the platform of identifying the intact nanoparticles in vivo, which played important roles on the studies of in vivo transport of nanoparticles. However, our previous study also demonstrated the fluorescence of quenched probes could reoccur in vivo, which significantly interfered the accurate tracking. Therefore, this project designed various new “water-quenching” probes to eliminate or weaken the fluorescent recurrence, which could guarantee the accuracy in monitoring the in vivo transport of nanoparticles. This study will optimize the structure of probes by the “water-quenching” sensitivity and fluorescent recurrence extent and then employ these probes to evaluate the in vivo traffic mechanisms of nanoparticles. These probes are able to be widely used in elucidating the in vivo transport of many nanoparticles.

探索纳米粒的体内过程对于揭示其作用机制具有十分重要的意义，体内过程的研究极大的依赖于荧光或放射探针，而传统探针因无响应性无法完全代表纳米粒本身的行为。申请人课题组前期发现一种“水淬灭”荧光探针，包载于纳米粒内部可发射强烈荧光，从纳米粒释放后因团聚导致淬灭效应（ACQ）使荧光完全淬灭。利用该类探针已建立体内纳米粒整体识别技术平台，在纳米粒的体内过程研究中发挥了重要的作用。然而研究中发现该探针淬灭后，在体内可发生解聚而重新与组织结合，导致荧光复现，造成一定的干扰。为此本项目基于前期研究发现，根据ACQ效应原理设计了一系列新型“水淬灭”荧光探针，旨在消除荧光复现现象，以保证纳米粒体内过程监测的准确性。本项目主要以“水淬灭”灵敏度和复现程度优化探针结构，进一步将其用于纳米粒体内转运过程的研究。该类探针具有普适性，可推广应用于多种纳米载体体内转运机制的研究。

解析纳米制剂的体内过程对于其优化设计具有重要的意义，而体内过程的研究手段依赖于荧光或放射探针。课题组前期所发展的一类聚集诱导效应（ACQ）探针可在一定程度上指示完整纳米粒体内的转运过程，但是其在体内的复现不可避免的对纳米粒的体内行为研究造成了一定的干扰。本项目在前期ACQ探针的基础上，根据ACQ效应原理设计并合成了一系列新型探针，并通过体内外研究对其荧光淬灭和荧光复现进行评价，研究表明新型ACQ探针FD-B21和FD-C7增强了疏水性、平面性和形成π-π共轭的能力，具有绝对ACQ效应和可忽略的荧光复现，有利于更准确的生物成像，并通过分子模拟对ACQ的机制进行详细的探讨。在此基础上，进一步以脂质纳米粒、PCL纳米粒以及胶束为主要纳米制剂，研究了该探针在纳米制剂标记及体内过程、细胞摄取等研究方面的优势，为纳米制剂的体内命运的深入研究奠定了基础。并进一步拓展研究了口服脂质纳米粒、介孔硅纳米粒以及静脉脂肪乳的体内过程，提出了形状依赖的“黏膜穿透滞留”效应，为口服纳米粒的设计提供了重要的理论依据；同时发现脂肪乳粒子与所包载药物在体内行为具有明显的差异，提出纳米粒子和药物体内行为的差异化分析可使纳米制剂体内命运研究更加清晰准确。