A novel ICT ratiometric fluorescent probe for intelligent visualization, and quantitative detection of residual daminozide in food.

Background: Daminozide is a commonly utilized plant growth regulator. Both daminozide and its hydrolysis product, 1,1-dimethyl hydrazine ((CH)NNH), exhibit carcinogenic and teratogenic toxicity. Accurate detection of daminozide in food is of great significance to human health. At present, most methods used to detect daminozide residues in food require the assistance of large-scale instruments and equipment. These detection methods are complex, costly, and time-consuming. Therefore, we need to develop an intelligent, portable, rapid, real-time and accurate method to detect daminozide residues in fruits and vegetables.

Results: A ratiometric fluorescent probe (MPIBID) for quantitative detection of daminozide was developed by coupling an electron withdrawing group 1,3-indanedione group to the molecular skeleton, which contains a phenanthrimidazole fluorophore. The probe MPIBID achieved rapid response (110 s), high selectivity and low detection limit (LOD = 68.7 nM) for the detection of (CH)NNH. Due to its strong intramolecular charge transfer (ICT) effect, the red fluorescence emitted by the probe MPIBID changes to blue fluorescence upon contact with the hydrolysate ((CH)NNH) of daminozide. Based on these findings, we optimized the hydrolysis conditions for daminozide and the probe recognition system. An intelligent visual sensing platform with two different detection modes (probe detection liquid chroma analysis and probe detection label headspace detection in-situ) was constructed by combining the alkaline hydrolysis process of daminozide, probe detection process and fluorescence color analysis process of smart devices.

Significance: The detection method developed in this work has successfully analyzed the residual amount of daminozide in actual food samples. For the first time, the detection of daminozide in food was reported using a small molecule fluorescent probe. We believe that the probe MPIBID has the potential to become a powerful tool for the quantitative detection of daminozide and can provide new ideas for the development of food quality detection.