硫酸催化合成高性能荧光聚合物碳点及其在近红外生物成像中的应用

Fluorescent polymer-carbon dots (referred to as carbon dots) have a great application prospect in the field of bioimaging. However, due to the insufficient knowledge on photoluminescence (PL) mechanism of carbon dots (CDs), controllable synthesis of water-soluble and highly efficient near-infrared fluorescent CDs is still a bottleneck hard to break through. In this project, a sulfuric acid catalyzed route is proposed to produce water-soluble CDs with PL peak larger than 800 nm and QY more than 30%, using carboxylic or hydroxyl, amino and benzene ring containing organic molecules as carbon source, which can be used to obtain deep-tissue PL images with high signal-to-noise ratio and high resolution. By varying the catalyst concentration and reaction conditions to regulate the dehydration reaction and carbonation degree occurring during the formation of CDs, an effective regulation of fluorescence properties of CDs is realized, which is good for building a structure-activity relationship between fluorescent properties and structural components, and putting forward a persuasive PL mechanism. Through the screening of carbon source, near-infrared emissive CDs with special functional groups on surface are produced, which can act as a fluorescence imaging and targeting agent for noninvasive glioma diagnosis. Carrying out this project is significant for the basic research of nanometer luminescent materials, as well as the practical application of bioluminescent probe.

荧光聚合物碳点（简称碳点）在生物成像领域具有重要的应用前景，但由于对荧光机理认识不足，水溶性高效近红外荧光碳点的可控制备一直是难以突破的瓶颈。本项目拟以富含羧基、羟基、氨基和苯环等结构的有机分子为碳源，利用硫酸催化合成的方法，制备出荧光发射峰位超过800纳米和发光效率大于30%的水溶性碳点，实现碳点强组织穿透力、高信噪比和高分辨率的生物成像效果。通过改变硫酸浓度和反应条件来调控碳点形成过程中的脱水反应和碳化程度，实现对碳点荧光性质的有效调控，构建碳点发射峰位置、量子效率、半峰宽宽度等荧光性质与自身尺寸、石墨化程度、杂原子含量、表面官能团等结构成分之间的构效关系，建立合理的荧光机理模型。通过筛选碳源合成表面具有特异性功能团的近红外光发射碳点，实现对肿瘤细胞的靶向识别，以及对小鼠神经胶质瘤的近红外靶向成像与诊断。本项目的开展对纳米发光材料基础研究和生物荧光探针实际应用都有重要的意义。

合成出高效红光/近红外/全色荧光聚合物碳点（简称碳点）对于开展这一新型纳米材料的发光机理研究和生物成像应用有着重要的意义。本项目以常见的芳香类有机物为碳源，围绕碳点结构成分调控、发光和生长机理以及荧光相关应用可行性等科学问题开展研究，主要内容如下：（1）采用无机盐代替有机溶剂作为反应介质的策略，研究建立了碳点发光性质在全色范围内可控的新方法，通过控制碳源分子之间的脱氨和脱氢反应，揭示了碳点结构成分与发光性质的构效关系，提出了令人信服的生长和发光机理；（2）以杂原子掺杂为手段，实现了近红外荧光碳点的批量化制备，并且量子产率（22%）和质量产率（68%）明显高于之前报道的近红外碳点，有助于推动高性能荧光碳点的工业化生产；（3）验证了制备的碳点在生物成像、发光薄膜、以及发光器件上等应用上的可行性。上述研究内容的成功实施，为荧光碳点的可控制备、结构成分调制、发光和生长机理探究提供了新思路，丰富和拓展了碳点基材料在生物成像/发光器件/光催化等应用研究领域的科学内涵，体现出重要的学术意义和应用潜力。