Facile synthesis of B,N-doped CQDs as versatile fluorescence probes for sensitive detection of cobalt ions in environmental water and biological samples

Fabrication of carbon quantum dots (CQDs) as versatile fluorescence probes for simultaneous detection of cobalt ion (Co2+) in various samples is still unmet. Herein, novel boron, nitrogen-doped carbon quantum dots (B,N-CQDs) were facile synthesized via one-step hydrothermal method, in which 3-carboxyphenylboronic acid and ethylenediamine were selected as precursors. Owing to the unique properties of the precursors, the obtained B,N-CQDs exhibited excellent recognition capability of Co2+, favorable biocompatibility, and high fluorescence quantum yield (FLQY, 64.8%), which enabled the B,N-CQDs as versatile fluorescence probes for sensitive detection of Co2+. The response of the probes to Co2+ was linear in two ranges of 0.5-10 and 10-2000 nM with limit of detection (LOD) of 0.52 nM. Feasibility of practical application of the probes was assessed by quantitative detection of trace Co2+ in real water samples including sewage water, river water and tap water. Furthermore, Co2+ in human urine was detected by using the probes with recoveries between 96% and 104%, indicating that the established probes could meet the requirements of practical detection in urine samples. Besides, the probes were successfully applied to monitoring Co2+ in A549 cells via fluorescence imaging attributed to their excellent photostability and high signal-to-background ratio. All these results show that the designed B,N-CQDs are ideal probes for simultaneously detecting Co2+ in environmental water and biological samples, which would expand the practical application of CQDs.

Automated summary

The study synthesized novel boron, nitrogen-doped carbon quantum dots (B,N-CQDs) with excellent recognition capability of Co2+ and high FLQY, allowing for sensitive detection of Co2+ and demonstrating practical applications in water and urine samples.