Quinoline derivative-functionalized carbon dots as a fluorescent nanosensor for sensing and intracellular imaging of Zn2.

Surface functionalization of nanomaterials with highly specific recognition elements, such as biomolecules and organic molecules, has made possible many novel nanosensors for bio/chemical analysis and target bioimaging. In this report, a fluorescent nanosensor which exhibits highly specific recognition capability towards Zn2+ over competing metal ions has been developed through covalently functionalizing carbon dots (C-dots) with the quinoline derivatives which show response to Zn2+. The nanosensor exhibits excellent water solubility, biocompatibility, and cell-membrane permeability, and demonstrates high selectivity towards Zn2+ with a detection limit as low as 6.4 nM. Additionally, the rapid response of the nanosensor towards Zn2+ can be achieved within 1 min. The large amount of recognition units on the outer surface of an individual nanoparticle enables the signal amplification, hence making the immediate and highly sensitive detection of Zn2+ possible. Therefore, a reliable and highly specific nanosensor has been demonstrated for both rapid quantitative detection of Zn2+ in aqueous solution and real-time imaging of intracellular Zn2+, suggesting its potential and significance in bioanalysis and biomedical detection in the future.