Fluorescent Carbon Dots for Selective Labeling of Subcellular Organelles

[Image: see text] With the recent advancement in understanding and control of the structure and optical properties of fluorescent carbon dots (CDs), they have been shown to be valuable in biolabeling of bacteria, tumor cells, tissues, and organelles. Their extremely small size and tunable functional properties coupled with ultrastable fluorescence enable CDs to be used for easy and effective labeling of various organelles. In addition, CDs with advantages of easy preparation and functionalization with recognition elements and/or drugs have emerged as nanocarriers for organelle-targeted drug delivery. In this review, we mainly discuss the applications of fluorescent CDs for the labeling of organelles, including lysosome, nucleoli, nucleus, endoplasmic reticulum, and mitochondria. We highlight the importance of the surface properties (functional groups, hydrophobicity/hydrophilicity, charges, zwitterions) and the size of CDs for labeling. Several interesting examples are provided to highlight the potential and disadvantages of CDs for labeling organelles. Strategies for the preparation of CDs for specific labeling of organelles are suggested. With the edge in preparation of diverse CDs, their potential in labeling and drug delivery is highly expected.