Institute of Clean Energy Chemistry, Key Laboratory for Green Synthesis and Preparative Chemistry of Advanced Materials of Liaoning Province, College of Chemistry, Liaoning University, Shenyang 110036, China.
Centre for Translational Atomaterials, School of Science, Swinburne University of Technology, Hawthorn, VIC 3122, Australia.
ACS Appl Bio Mater. 2021 Apr 19;4(4):3623-3629. doi: 10.1021/acsabm.1c00121. Epub 2021 Mar 10.
In this study, carbon dots (CDs) with red color are successfully prepared via hydrothermal treatment of -phenylenediamine and urea. The as-prepared red CDs exhibit an acidichromism feature, making them turn purple at pH 4.4 and become blue at pH 3.3. Further investigations reveal that the surface chemical bond species of CDs are responsible for the acidichromism feature. Taking advantage of the acidichromism feature, the CDs are employed as a titration indicator for analysis of alkali samples, which gives rise to satisfactory results without significant difference between the titration methods using CDs and methyl orange or a mixture of methyl red and bromocresol green as indicators. The CDs show excitation-independent fluorescence with dual-emission at 600 and 650 nm, along with a respectable quantum yield of 20.1%, which provides the CDs with deep tissue penetration and minimum autofluorescence background that is desirable in bioimaging. In addition, the CDs are found to light up endoplasm reticulum particularly, indicating their endoplasm reticulum targeting capability, which is proven by a colocalization study with other classical subcellular dyes. Endocytosis inhibiting investigations confirm that the endoplasm reticulum targeting ability is mainly attributed to the caveolin/lipid-raft-mediated endocytosis pathways of CDs. This study not only presents a facile approach for red CDs but also explores the possibility of CDs in titration analysis and in endoplasm reticulum targeting imaging.
在这项研究中，通过 - 苯二胺和尿素的水热处理成功制备了红色碳点（CDs）。所制备的红色 CDs 表现出酸致变色特征，在 pH 4.4 时变为紫色，在 pH 3.3 时变为蓝色。进一步的研究表明，CDs 的表面化学键种类是酸致变色特征的原因。利用酸致变色特征，将 CDs 用作分析碱样品的滴定指示剂，结果令人满意，使用 CDs 和甲基橙或甲基红和溴甲酚绿混合物作为指示剂的滴定方法之间没有显著差异。CDs 表现出激发独立的荧光，在 600nm 和 650nm 处具有双重发射，量子产率为 20.1%，这为其在生物成像中提供了深组织穿透和最小的自发荧光背景。此外，发现 CDs 特别点亮内质网，表明其具有内质网靶向能力，这通过与其他经典亚细胞染料的共定位研究得到证实。内吞抑制研究证实，内质网靶向能力主要归因于 CDs 的小窝蛋白/脂筏介导的内吞途径。本研究不仅提出了一种制备红色 CDs 的简便方法，还探索了 CDs 在滴定分析和内质网靶向成像中的可能性。
