Bioinspired carbon quantum dots for sensitive fluorescent detection of vitamin B12 in cell system.

Zwitterion-modification, as a bioinspired strategy, provides greatly promising platforms for biological detection and sensor applications. A green, low-cost and straight-forward method for synthesis of highly fluorescent biomimetic carbon quantum dots (BCQDs) has been developed via pyrolysis of cytidine diphosphate choline (CDPC) and ethylenediamine. The BCQDs with a strong emission at wavelength of 450 nm shows ultrasensitive sensing capability for vitamin B12 with high selectivity. Using the fluorometric assay, the detection limit (DL) for vitamin B12 was found to be as low as 81 nM. Meanwhile, the results of 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT), hemolysis measuring and morphological characterization of Red blood cells (RBCs) confirms the excellent biocompatibility of BCQDs. The imaging experiments of human cervical cancer cells (HeLa) certify that BCQDs could be served as an effective fluorescent sensing probe for label-free sensitive and selective detection of vitamin B12 in biological samples on account of their low toxicity and good biocompatibility. The BCQDs, further, were successfully applied to probe vitamin B12 in living cells, which broaden its potential application in vivo system.