A Functional Fluorescent Probe for Zn2+ and Cu2+ Detection in Food Products Based on Tetraphenylethylene Derivative

Zn2+ and Cu2+ related to transition metal ions present in foods play essential roles in the health of human and animal metabolism. However, the excess of these ions contaminates foods and causes many kinds of diseases. In recent years, designing chemosensors for detection of the two targets has been widespread but is still a great challenge for practical application. In this study, by reducing expenses, simplifying analytical procedures, and enabling multifunctions, a functional chemosensor was proposed by using tetraphenylethylene derivative (H4tcbpe) which could selectively and sensitively response to Zn2+ and Cu2+. H4tcbpe can be used to detect Zn2+ with fluorescence enhancement based on aggregation induced emission effect, while fluorescence of H4tcbpe can be quenched by Cu2+ due to the disassembly of H4tcbpe aggregates in a solvent/nonsolvent binary mixture of EtOH and H2O. Fluorophotometry, UV-Vis, and SEM were used to characterize behavior of the fluorescence sensor. In this work, the detection in liquid solutions was conducted, and a fluorescent test pen for the assay of Zn2+ and Cu2+ on a piece of filter paper was fabricated. The proposed fluorescent test pen contained H4tcbpe as a “fluorescent probe ink” and made it possible to write words on the area of a filter paper spiked with solutions with different concentrations of Zn2+ and Cu2+. The detection limits for Zn2+ and Cu2+ are 43 nM and 0.5 μM, respectively. This fluorescent sensor was applied to sense ions in black fungus samples. The proposed sensor could successfully detect Zn2+ and Cu2+, and the results were in agreement with the data from inductively coupled plasma mass spectrometry, which indicated the reliability of the proposed sensor for applications in the real samples.