One-pot hydrothermal synthesis of highly luminescent nitrogen-doped amphoteric carbon dots for bioimaging from Bombyx mori silk - natural proteins.

Nitrogen-doped carbon dots (CDs) have attracted great interest due to their extraordinary properties, especially their enhanced emission efficiency, and thus a facile synthesis of nitrogen-doped CDs with high emission efficiency is critical for practical applications. To improve the emission efficiency of CDs, herein we employed Bombyx mori silk, which has high nitrogen content, as a raw material to prepare photoluminescent nitrogen-doped carbon dots through one-pot hydrothermal synthesis, and found that the as-prepared CDs have a photoluminescence (PL) quantum yield of 13.9%, and display amphoteric properties depending on the pH, are highly photostable, have low toxicity and are suitable for bioimaging.