掺杂氮化碳荧光量子点的可控制备及生物应用研究

Due to the problems of traditional semiconductor quantum dots such as photobleaching, low quantum yields, high biological toxicity et al., this project plans to combine doping technique and microwave assisted hydrothermal method to adjusting the structure, design and synthesis of doped carbon nitride quantum dots with low toxicity, high stability, good biocompatibility, high fluorescent quantum efficiency and crystallinity. Combining the advantage of microwave method with high frequency heating and hydrothermal mehtod with easily aging crystallization to controlled synthesis of size controlled doped carbon nitride quantum dots with high crystallinity, solve the problem of bulk carbon nitride material with low fluorescent quantum efficiency and hardly controlled emission wavelength. Clarify the influence rules of doping atoms, doping ratios, the size and the crystallinity of quantum dots on fluorescent properties. Clarify the fluorescence enhancement mechanism of doped carbon nitride quantum dots. Utilizing the easily connecting ability of the amino group on the carbon nitride surface and biomolecules such as antibody, investigate the possible applications of doped carbon nitride quantum dots in biological labelling and biological imaging or other fields. The research on the effective preparation of high crystalline doped carbon nitride quantum dots will provide theoretical basis for the development of nonmental semiconductor quantum dots with high fluorescent quantum efficiency, provide new technical support for the applications of quantum dots in biological system.

针对传统半导体荧光量子点常存在荧光淬灭，荧光量子产率低、生物毒性大等问题，本课题拟通过掺杂技术和微波辅助水热技术，调控掺杂氮化碳量子点的结构，制备低毒性、高稳定性、良好生物相容性、高荧光量子产率、高结晶性的掺杂氮化碳量子点。利用微波的高频加热结合水热易于陈化结晶的优点制备尺寸可控高结晶性掺杂氮化碳量子点，解决氮化碳体相材料荧光量子产率低、发光波长不易调控的难题。阐明掺杂原子、掺杂比例、量子点尺寸、结晶性对发光性能的影响规律，明确掺杂氮化碳量子点的荧光增强机理。利用氮化碳表面的氨基基团可与抗体等生物分子直接相接的特性，进行掺杂氮化碳量子点在生物荧光标记及生物成像等领域应用性能的探讨。本项目提出的高效制备高结晶性掺杂氮化碳量子点的研究，将为高荧光量子产率非金属半导体量子点的开发提供理论依据，为荧光量子点在生物体系中的应用提供新的技术支持。

针对传统半导体荧光量子点常存在荧光淬灭，荧光量子产率低、生物毒性大等问题，本项目提出了设计制备掺杂氮化碳荧光量子点的研究思路，制备了3种低毒性、高稳定性、良好生物相容性、高荧光性能的掺杂氮化碳量子点。本项目利用两类原子富电子原子（氟、硫）和缺电子原子（硼）作为掺杂原子，系统探索了掺杂原子对氮化碳结构和荧光性能的影响规律。在一定的溶剂体系中，细胞破碎仪的超声破碎下，以及水热、微波的处理下，实现了掺杂氮化碳量子点的制备。所制备的量子点粒径分布较为均一，尺寸位于1-5 nm左右。所制备的氟掺杂氮化碳量子点和硫掺杂氮化碳量子点实现了对氮化碳荧光发光位置的红移。与氮化碳相比，氟掺杂氮化碳量子点和硫掺杂氮化碳量子点的荧光发光位置，分别从氮化碳的435.9 nm红移到了437.9 nm和459.6 nm。缺电子原子硼实现了对氮化碳荧光发光位置的蓝移。从氮化碳的435.9 nm蓝移到了360 nm。其中水热-微波处理的硼掺杂氮化碳量子点具有明显的晶格结构，说明结晶性能较好。所制备的掺杂量子点与块体材料相比，荧光强度得到明显的增强。荧光发光机理研究表明，富电子原子氟、硫原子具有孤电子对，能够与氮化碳三聚三嗪环中的大π键形成P-π共轭。而缺电子原子硼则容易吸引氮化碳三聚三嗪环中的电子，从而增大氮化碳带隙宽度。所制备的量子点不仅可以对细菌（如大肠杆菌）进行标记和荧光成像，还实现了对细胞（如PC-3细胞）的标记和荧光成像。以上研究结果为掺杂氮化碳量子点的批量制备及在生物体系中的广泛应用提供了一定的理论依据和技术支持。