Microwave-assisted synthesis, characterization, cell imaging of fluorescent carbon dots using l-asparagine as precursor

Abstract

L-Asparagine, a common amino acid, is a cost-effective and ideal precursor for carbon dots because of its high nitrogen content and its abundance in nature. By using L-asparagine as a biocompatible precursor, fluorescent nitrogen-doped carbon dots (A-CDs) were prepared by a one-pot microwave-assisted method. Then, a reasonable structure for A-CDs was put forward, which confirmed that unconjugated small molecules could transform into carbon dots with the sp² core, and was helpful in the discussion of the photoluminescence mechanism. It was concluded that the photoluminescence origin of A-CDs was from the graphite-like structure and surface defects. The A-CDs showed high stability in strong ionic solutions and negligible cytotoxicity even when the incubation concentration was up to 800 μg mL⁻¹. Long-time bioimaging tests suggested that A-CDs have great potential for use in a wide variety of biological applications.