A simple one-step synthesis of melanin-originated red shift emissive carbonaceous dots for bioimaging.

Carbonaceous dots (CDs) are superior nanomaterials owing to their promising luminescence properties and good biocompatibility. However, most CDs have relatively short excitation/emission, which restrict their application in bioimaging. In this study, a simple one-step procedure was developed for synthesis of melanin-originated CDs (MNPs). The MNPs showed two long red shift emissions at 570nm and 645nm with broad absorptions from 200nm to 400nm and 500nm to 700nm, suggesting the great potential of MNPs in bioimaging. Besides, several experiments indicated that MNPs possessed good serum stability and well blood compatibility. In vitro, MNPs could be taken up by C6 cell in a concentration- and time-dependent manner with endosomes involved. In conclusion, MNPs were prepared using a simple one-step method with unique optical and good biological properties and could be used for bioimaging.