Supramolecular fluorescent sensor enables rapid visual detection of pesticide phoxim

Researchers led by Prof. JIANG Changlong from the Institute of Solid State Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences, have developed a simple fluorescent sensing system that can quickly and visually detect phoxim, an organophosphorus pesticide of concern in food safety and environmental monitoring.

The study has been published in Analytical Chemistry.

Organophosphorus pesticide residues remain a major concern due to their potential risks to human health and the environment. Conventional methods such as gas chromatography–mass spectrometry (GC–MS) and liquid chromatography–mass spectrometry offer high accuracy, but rely on bulky instruments, complex sample preparation, and trained operators, making them less suitable for rapid on-site screening.

To address this, the team designed a flavonoid-based fluorescent dye (BFL) and combined it with whey protein to construct a supramolecular probe (BFL@WP). The system works through changes in the local protein environment: fluorescence is enhanced when BFL binds to whey protein, while exposure to phoxim disrupts this interaction, leading to rapid signal quenching and a visible green-to-colorless change.

The probe shows a concentration-dependent response to phoxim from 0 to 130 nM, with a detection limit of 1.143 nM in solution. It also responds quickly and remains highly selective even in the presence of common ions, making it suitable for complex samples.

To improve practicality, the researchers further developed a paper-strip platform and a smartphone-based readout system. Fluorescence images recorded under Ultraviolet light can be analyzed through RGB signals for quantitative detection. In this format, the detection limit reaches 3.277 nM. Tests in tap water, lake water, and juice showed good recovery and reproducibility.

The work provides a simple and portable strategy for pesticide detection, offering potential for rapid on-site screening in food safety and environmental monitoring.

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