Carbon quantum dots: synthesis, characterization, and assessment of cytocompatibility

A simple method for the synthesis of water-soluble carbon quantum dots (CQDs) has been developed by chemical oxidation treatment of the flour. The as-synthesized CQDs were monodispersed sphere particles with the approximate diameter of 5-8 nm, and exhibited strong fluorescence, excitation-dependent photoluminescence behavior and high photostability in a wide range of pH values. We investigated the cytotoxicity of as-prepared CQDs using rat mesangial cells (RMC). Compared with CdTe quantum dots, CQDs show no apparent cytotoxicity and much better biosafety property. The as-synthesized CQDs were also tested to label and image RMC in vitro and demonstrated to be highly promising biological fluorescent probes.