Nano-scale selective and sensitive optical sensor for metronidazole based on fluorescence quenching: 1H-Phenanthro[9,10-d]imidazolyl-calix[4]arene fluorescent probe

It is crucial to determine and control the metronidazole (MET) ingredient in food and pharmaceuticals for human health and food safety. Even though many sensors have been previously reported to detect MET, there is still a need for a highly selective and sensitive, easy, fast, cost-effective sensor in this area. Herein, we report a fluorescent calix[4]arene derivative (PIMC) for highly selective and sensitive and facile and rapid MET detection based on fluorescence (FL) quenching. The highest FL quenching occurs when PIMC is exposed to MET solution at 400 nm (λ_ex = 340). Owing to the quenching efficacy of MET linearly up to 5.5 × 10⁴ nM was obtained a detection limit of 2.44 nM. Besides, interferences of other pharmaceuticals and ions on probe performance were investigated. The FL probe was successful in MET detection without the assistance of any separation techniques in a pharmaceutical sample (tablet) with an acceptable recovery of 101.3%. The applicability of the current probe as a paper-based sensor to MET detection has been successfully tested. As a result, the proposed probe presents a fast and suitable strategy to sensitive and selective detect MET and proves a good potential for practical applications, especially pharmaceutical preparations.