One-step synthesis of a dual-emitting carbon dot-based ratiometric fluorescent probe for visual assay of Pb2+, PPi and paper sensor

An easy and effective ratiometric fluorescence nanoprobe for the selective detection of Pb2+ and pyrophosphate (PPi) has been developed based on label-free carbon dots (CDs). The CDs show dual emission bands at 477 and 651 nm under single-wavelength excitation (391 nm). The Pb2+ and PPi can be sequentially detected by sensor with high reliability and accuracy via exploiting the fluorescence intensity ratio (F477/F651), respectively. The dual emission sensor exhibits high selectivity and excellent sensitivity for Pb2+ and PPi compared to other analytes with detection limits as low as 0.055 μM and 0.089 μM, respectively. Concurrently, the fluorescent color of the CDs was changed (pink-cyan-pink) and can be used as fluorescent paper sensor for visual detecting Pb2+ and PPi. To our knowledge, it is the first ratiometric fluorescence CDs for Pb2+ and PPi assays. Therefore, the as-synthesized CDs show great potential application for the determination of Pb2+ and PPi in real samples.