A yellow-emitting nitrogen-doped carbon dots for sensing of vitamin B12 and their cell-imaging

A simple approach for the synthesis of novel yellow luminescent carbon dots (Y-CDs) has been developed via solvothermal method using l-tartaric acid and urea as precursors. The obtained Y-CDs were found to emit bright yellow luminescence under UV illumination with a quantum yield of 16.7%. Meanwhile, the Y-CDs exhibited excitation-dependence, photo-stability, and well dispersibility. The Y-CDs efficiently and selectively detected the VB12 in aqueous solution through a fluorescent “Turn Off” phenomenon. Excellent linear relationship between Y-CDs emission ratio and VB12 concentration from 0 μM to 200 μM is observed, in which the correlation coefficient is 0.997 and the detection limit is 2.045 μmol/L. The quenching mechanism was investigated through proper microscopic and spectroscopic studies. In a parallel experiment, the Y-CDs were used as a cell-imaging probe for MDA-MB-231 cells. Our results demonstrated that as-obtained Y-CDs can be simply used as versatile probes, highlighting their potential in different biological studies.