Easy synthesis of highly fluorescent carbon dots from albumin and their photoluminescent mechanism and biological imaging applications.

A simple and green approach was developed to synthesize highly fluorescent carbon dots (CDs) using albumin as a carbon source in aqueous solution at room temperature. The CDs were characterized by excellent monodispersion, superior photostability, pH-independent emission, long fluorescence lifetime and high quantum yield (QY). The photoluminescent (PL) mechanism of CDs was explored by means of time-resolved PL decay, and the results revealed that PL originated from the emission of both defect state and intrinsic state. In addition, biological imaging with the application of CDs was carried out in human breast cancer Bcap-37 cell, which demonstrated that CDs were provided with an excellent biocompatibility, low cytotoxicity and good transmembrane ability. Besides, CDs could be considered as a potential substitute for organic dyes or semiconductor quantum dots (SQDs) in biological imaging.