A label-free multifunctional nanosensor based on N-doped carbon nanodots for vitamin B and Co detection, and bioimaging in living cells and zebrafish.

Multifunctional N-doped carbon nanodots (N-CNDs) with a fluorescence (FL) quantum yield (QY) of 13.6% have been synthesized via a facile one-step hydrothermal process using Artemisia annua and 1,2-ethylenediamine as precursors. As-prepared N-CNDs showed excellent FL properties and were developed as a multifunctional sensing platform for vitamin B (VB) and Co determination, and bioimaging in living cells and zebrafish. The FL of N-CNDs is quenched efficiently in the presence of VB on the basis of the inner filter effect (IFE) or Co by static quenching, respectively. EDTA as a masking agent enables Co to be effectively eliminated and N-CNDs were used to selectively detect VB in the presence of both VB and Co. The present FL nanosensor can detect VB and Co in the linear ranges of 0.5-35 μM and 2.5-25 μM with the corresponding detection limits of 47.4 nM and 230.5 nM, respectively. The study proved that the determination of Co was based on the static quenching to form a complex between the amino group of N-CNDs and Co. Inspired by these outstanding properties, practical applications of this nanosensor for the detection of VB in actual samples (human serum, egg yolk, VB tablets and VB injection) and Co in water samples were further verified with satisfactory results. The as-constructed N-CNDs have negligible toxicity and good biocompatibility, which facilitates utilization of N-CNDs in bioimaging of A549 cells and zebrafish, and sensing VB in living cells.