State Key Laboratory of Chemical Resource Engineering, Beijing Key Laboratory of Advanced Functional Polymer Composites, Beijing University of Chemical Technology, 100029 Beijing, China.
Institute of Clinical Medical Sciences, China-Japan Friendship Hospital, Beijing 100029, China.
J Mater Chem B. 2022 Sep 21;10(36):6991-7002. doi: 10.1039/d2tb01330d.
Fluorescent carbon dots (CDs)-based nanomaterials exhibited promising potential in the fields of biomedicine, bioanalysis, and biosensors. In this work, multi-colored fluorescent carbonized polymer dots (CPDs) ranging from blue to red are obtained using different synthesis methods using citric acid and urea as raw materials, and the controllable synthesis of CPDs with multi-color fluorescence is successfully realized. Then, the photoluminescence (PL) mechanism of CPDs is studied using multiple characterization methods, and the key factors affecting the fluorescence emission wavelength of CPDs are discussed. It is shown that the fluorescence of the CPDs originates from three main components: the carbon nuclei in the intrinsic state, the functional groups in the surface state, and the molecular fluorophores adsorbed on the surface of the CPDs. The reaction temperature and reaction time affect the effective conjugation size of the carbon nuclei, which in turn affects the fluorescence redshift of CPDs; the reaction solvent greatly alters the surface state of CPDs ( surface defects and functional groups), which leads to a significant redshift in the fluorescence of CPDs; the presence of molecular fluorophores facilitates the fluorescence redshift of CPDs. Finally, we have successfully applied the prepared red fluorescent CPDs for cell imaging. The study on the color regulation mechanism of CPDs is of great significance for the controllable preparation of high-performance fluorescent CDs and their application in the field of biomedicine.
基于荧光碳点（CDs）的纳米材料在生物医学、生物分析和生物传感器领域表现出了巨大的应用潜力。在这项工作中，以柠檬酸和尿素为原料，通过不同的合成方法得到了从蓝色到红色的多色荧光碳化聚合物点（CPDs），成功实现了对 CPDs 多色荧光的可控合成。然后，使用多种表征方法研究了 CPDs 的光致发光（PL）机制，并讨论了影响 CPDs 荧光发射波长的关键因素。结果表明，CPDs 的荧光源于三个主要成分：本征态的碳核、表面态的官能团和吸附在 CPDs 表面的分子荧光团。反应温度和反应时间影响碳核的有效共轭尺寸，进而影响 CPDs 的荧光红移；反应溶剂极大地改变了 CPDs 的表面状态（表面缺陷和官能团），导致 CPDs 的荧光发生显著红移；分子荧光团的存在促进了 CPDs 的荧光红移。最后，我们成功地将制备的红色荧光 CPDs 应用于细胞成像。CPDs 的颜色调控机制的研究对于高性能荧光 CDs 的可控制备及其在生物医学领域的应用具有重要意义。
