Unique Approach To Develop Carbon Dot-Based Nanohybrid Near-Infrared Ratiometric Fluorescent Sensor for the Detection of Mercury Ions.

The ratiometric fluorescence assay, which can eliminate the external effects, has attracted great attention. In this work, a carbon dot (CD)-based nanohybrid dual-emission system was simply prepared by a unique approach of solvothermal treating corn bract and used as a ratiometric fluorescent sensor for Hg detection. Under a single excitation, the obtained nanohybrid sensor had two emission bands around 470 and 678 nm, which may originate from the intrinsic structure of CDs and chlorophyll-derived porphyrins, respectively. In the presence of Hg, the fluorescence at 678 nm could be remarkably quenched, while the fluorescence intensity at 470 nm was only slightly altered. The fluorescence intensity ratio at 470 and 678 nm exhibited a good linear relationship in the Hg concentration range from 0 to 40 μM with a detection limit of about 9.0 nM. It also had a satisfying assay performance in serum and river water samples. The prepared CD-based nanohybrid sensor here may hold the further potential applications in biomedicine study, environmental protection, and food safety.