A novel and ultrasensitive fluorescent probe derived from labeled carbon dots for recognitions of copper ions and glyphosate.

Labeling materials with special functional groups are very valuable for the creation of novel probes. Hence, a novel fluorescent probe was constructed by conjugating 4-butyl-3-thiosemicarbazide (BTSC) with carbon dots (CDs). The CDs labeled by BTSC (BTSC-CDs) displayed a strong capability for recognition of Cu and Cu could quench the emission of BTSC-CDs significantly. The fluorescence quenching was proved to be a static quenching which was resulted from the interaction between BTSC-CDs and Cu to form a ground-state BTSC-CDs/Cucomplex, and the fluorescence intensities showed a good linear correlation with Cu concentrations in the range of 0.20-30 μM. What is more important, by adding glyphosate into the sensor system of BTSC-CDs/Cu the fluorescence of the probe turned on again owing to the stronger chelating between glyphosate and Cu than between BTSC-CDs and Cu. This could realize the specific detection of glyphosate and the limit of detection was low to 0.27 μM. Detecting glyphosate using the complex BTSC-CDs/Cu system in actual samples with satisfactory outcomes indicated that a novel fluorescent probe for Cu and subsequent glyphosate detections has been provided.