荧光小分子调控碳点碳核与表面结构及光学性能的研究

Carbon nanodots (C-dots), as a new class of carbon nano-materials, have excited great interest among researchers. Due to the size and wavelength depending luminescence emission, low toxicity, good biocompatibility and wide raw material sources, C-dots have shown great promise in a variety of applications recently, like bio-labeling, imaging, detection, catalysis, and so on. However, how to prepare C-dots with controllable structure and property remains a challenge. In this project, we aim to develop a new procedure to make high performance C-dots with tunable structure and luminescence by adding fluorophore as raw material, using hydrothermal method. The synthesized route of C-dots with fluorophore in it will be studied in detail by optimizing the temperature, time, proportion of fluorophore, etc. The method tuning the proportion of carbon atoms with different hybridization manner, and that tuning the content of nitrogen atom, will be established. The dependence of C-dots structure and optical properties, like the fluorescence emission wavelength, peak width at half height, Stoke’s shift, and fluorescent quantum yield, on the proportion of carbon atoms with different hybridization manner and content of nitrogen atom will be investigated. The results will give a new thought to control the structure of C-dots and improve its properties. And it will also be helpful for the application of C-dots.

碳点是一类新兴的纳米炭材料，具有低毒、生物相容性良好、原料来源广泛等优点，在生物标记与成像、离子荧光探针和光催化等领域有独特的应用潜力与价值，而结构可控、性能优良的碳点的制备，仍旧是一项富有挑战性的研究课题。本项目提出以荧光小分子为原料，用水热合成法制备碳点，借助其分子结构与光学性质，对碳点结构及光学性能进行调控。课题将优化水热合成法制备碳点的技术路线，研究建立在碳点结构中保存一部分荧光小分子完整发光团结构的方法，诠释荧光小分子发光团结构与碳点的荧光发射波长的相关性；建立调节碳点结构中sp2杂化碳与sp3杂化碳比例的方法，揭示碳点碳核与表面结构中sp2杂化碳与sp3杂化碳的比例对碳点的光学性质（如荧光发射波长、半峰宽、斯托克位移、荧光量子产率等）的影响规律；建立碳点结构中氮含量的调控方法，诠释氮含量对碳点的光学性质的影响规律。项目的实施将为发展碳点的应用奠定基础。

结构可控、荧光可调的碳点的制备，仍旧是一项富有挑战性的研究课题。本项目以碳点结构及光学性能的调控为目标，首先研究了以荧光小分子为原料、水热合成法制备碳点的路线、规律及其应用，然后选择特定荧光小分子，研究了碳点和荧光小分子之间具有能量共振转移效应的体系的构筑与应用。研究结果表明：1）以荧光素、罗丹明B等荧光小分子作为原料，水热法合成碳点时，在130-190℃可以一步合成出含有荧光小分子荧光特征的荧光碳点，合成条件仅影响碳点和荧光小分子的荧光强度；2）以碳点作为能量供体、钙黄绿素为能量受体，可以分别用两步法、一步水热合成法构筑能量转移体系，其能量转移效率受合成条件、碳点和钙黄绿素比例的影响而改变；同时，该能量转移体系可以应用于H+浓度的检测；3）用色氨酸为原料可以合成色氨酸作为能量供体、碳点作为能量受体的能量转移体系，该体系表现出了与众不同的特性，其能量转移效率随光照时间延长而逐渐增强；同时，构建的能量转移体系可以应用于离子检测方面，如对Fe3+、Pb2+等。本项目建立了在碳点结构中内嵌荧光小分子完整发光团结构的方法，实现了一步合成内含能量转移特性的荧光碳点。项目的研究为合成特定荧光特性的碳点开辟了一种新的方法，为调控碳点的组成、结构与性质提供了新的思路。