多功能聚胺基碳量子点的制备及其应用于siRNA基因转运和示踪成像的研究

Because of large stokes shift, continuously variable emission spectra, resistance to photobleaching, carbon dots (CDs) are new fluorescence probes which are widely used in bio-medical fields. However, their fluorescence performance and functionalization needs to be further optimized. Previous studies have found that primary amine compounds as surface passivation molecules could significantly enhance the fluorescence quantum yield of the CDs. In this grant, we first use arginine as functionalized molecular to fabricate polyamino carbon dots (PCDs) which are able to self-passivated and bind with nucleic acid through hydrothermal treatment. Optical and physicochemical properties of PCDs can be characterized by a series of methods, photoluminescene mechanism can also be studied. Furthermore, we plan to estimate biological compatibility of PCDs and investigate potential application of PCDs in living cell labeling and real-time imaging. Finally, according to the principle of FRET, we use PCDs as visualized gene carrier to track intracellular delivery and endosomal esacpe of siRNA. This project aims to discuss the optical properties and assembly mechanism of PCDs, strives to develop safe, convenient, low toxic PCDs which can track and transfect genes and provides a new strategy for the application of quantum dots in biological medicine.

碳量子点（CDs）是一种新型的荧光探针，因具有较大的斯托克位移、连续可调的发射光谱和耐光漂白的特点，有望被广泛应用于生物医学领域，但其荧光性能和功能化修饰尚需进一步优化。研究表明，伯胺型胺基化合物作为表面钝化分子可显著增强CDs的荧光量子产率。因此，本项目拟首次利用精氨酸为功能化分子，采用水热法制备能自我钝化且能与核酸分子组装的多功能聚胺基碳量子点（PCDs）。采用一系列方法表征PCDs光学特性和理化性质，并详细阐述发光机制。在此基础上，评价碳量子点的生物相容性，并探究其在活细胞成像和标记的应用潜能。根据荧光共振能量原理，以PCDs为可视化基因载体，长程实时示踪siRNA的跨膜运输和溶酶体逃逸过程。本项目旨在探讨PCDs的光学特性及其与核酸分子的组装机制，力求开发出高量子产率、安全低毒、集示踪成像和基因转运于一体的多功能碳量子点，为量子点在生物医学的应用提供新的策略。

本项目围绕碳量子点(CDs)的功能化进行了初步探索与研究。利用自下而上的水热反应分别进行无机元素和金属元素掺杂制备多功能碳量子点。一方面，利用镧系金属钆元素与螯合物螯合，并与伯氨化合物脱水碳化，成功制备多功能的钆掺杂性碳量子点。结果表明钆离子被包裹于生物惰性的碳颗粒之内，可有效防止因离子交换而造成的泄露，并赋予较高的弛豫效率和生物相容性，使得钆掺杂型碳量子在荧光/MR双模态成像表现出巨大的应用潜能。另一方面，无机元素掺杂进一步丰富了碳量子点的功能化。成功制备的碘元素掺杂型碳量子点具有优异的X-射线衰减系数，使其成为荧光与CT成像的双功能的影像探针。氮元素掺杂可显著提升聚氨基碳量子点(PCDs) 的荧光性能，并加速脱水碳化有利于碳量子点的形成。经试验表征和理论计算，揭示PCDs内部呈现类石墨与氧化石墨的异质多层物相结构。PCDs表面的化学基团赋予其良好的水分散性、生物相容性和荧光性能。经过透明质酸(HA)功能化的PCDs可靶向CD44高表达的肿瘤，并具有良好的基因装载能力和细胞内实时成像功能。本项目的研究对于拓展碳量子点功能化以及生物医学应用具有重要的指导意义。