基于石墨相氮化碳量子点的比率型荧光探针用于细胞成像的研究

It is of great significance for clinical diagnoses of diseases to in situ monitor the concentration levels and distributions of some essential substances in living cells by fluorescence imaging. Due to high quantum yield, low toxicity, good biocompatibility, graphitic carbon nitride (g-C3N4) has been demonstrated promising application prospect in cellular imaging. However, it is still a great challenge to overcome the interferences of blue autofluorescence and complicated matrix in living cells. In this project, a series of g-C3N4 nanomaterials with long fluorescence wavelength will be prepared by doping of different π-conjugated small molecules. The relationship between π-conjugated doping and fluorescent properties of g-C3N4 will be studied and the regulation mechanism of fluorescent properties of g-C3N4 will be disclosed. For the imaging of intracellular Cu2+, pH, microRNA, ratiometric fluorescent probes based on g-C3N4 quantum dots with green fluorescence will be designed. The concentration levels and distributions of Cu2+, pH, microRNA in cancer cells will be monitored in situ by fluorescence imaging. After these studies, not only the regulation rule of fluorescence properties of g-C3N4 nanomaterials will be obtained, but also the interferences such as autofluorescence and complicated matrix in living cells will be overcome by the as-prepared dual-emission ratiometric fluorescent probes via built-in self-calibration and a more accurate reliable monitoring method will be provided for clinical diagnoses of diseases related to cancers.

利用荧光成像原位监测细胞内某些重要物质的浓度水平和空间分布，对于临床疾病诊断具有十分重要意义。石墨相氮化碳（g-C3N4）具有量子产率高、毒性低、生物相容性好等优点，已初步显示了细胞成像的应用前景。然而，如何克服活细胞内自发荧光以及复杂基质等干扰仍然是一个挑战。本项目拟利用π共轭小分子掺杂制备一系列长荧光波长的g-C3N4纳米材料，研究π共轭掺杂的g-C3N4与其荧光性能的构效关系，揭示g-C3N4荧光性能的调控机制；以细胞内Cu2+、pH、microRNA等为分析对象，构建基于绿色荧光g-C3N4量子点的比率型荧光探针；利用荧光成像原位监测癌细胞内Cu2+、pH、microRNA等的浓度水平和空间分布。本项目的研究，可获得g-C3N4荧光性能的调控规律，且利用比率型荧光探针双发射波长的内置式自我校正，有效克服细胞自发荧光、样品基质等干扰，为癌症相关疾病的临床诊断提供更准确可靠的监测手段。

利用荧光成像原位监测细胞内某些重要物质的浓度水平和空间分布，对于临床疾病诊断具有十分重要意义。石墨相氮化碳聚合物具有量子产率高、毒性低、生物相容性好等优点，已初步显示了在细胞成像的应用前景。然而，普通石墨相氮化碳聚合物由于存在较大能带带隙而发射紫外到蓝色的荧光，在进行生物荧光成像时容易受到背景荧光和复杂基质干扰等问题。本项目利用含有苯基的前驱体制备了多种苯基掺杂的石墨相氮化碳荧光聚合物，通过苯基π共轭小分子等的掺杂，降低石墨相氮化碳聚合物的能带、调控其荧光发射波长向长波方向移动。利用所制备的石墨相氮化碳聚合物作为荧光猝灭平台、参比信号和载体，以细胞内miRNA、Cu2+、半胱氨酸（Cys）以及血清中腺苷等为分析对象构建了多种比率型荧光探针。利用共聚焦荧光显微镜对细胞进行荧光成像，原位监测石墨相氮化碳荧光探针在细胞内的空间分布以及癌细胞内miRNA、Cu2+、Cys等浓度变化。利用对miRNA响应的荧光信号可以区分正常细胞和癌细胞。利用比率型荧光探针的自我校正，有效地克服细胞的自发荧光、样品基质等干扰，为癌症相关疾病的临床诊断提供更准确可靠的监测手段。此外，利用研究过程中的新发现进一步拓展石墨相氮化碳聚合物在NO2气体传感、光热驱动器、高级信号防伪以及癌细胞光动力治疗中的应用。