Fluorescence Entrenched Probe for Onsite Detection of Amoxicillin Residue in Bovine Milk

A novel fluorescent probe (E)-3-(4-hydroxyphenyl)-2-((pyrene-1-ylmethylene) amino)propanoic acid (PyT) was developed for the 'turn-on' detection of amoxicillin(AM), residues. The PyT molecule was developed by a simple condensation reaction between a biologically important tyrosine amino acid and pyrene carboxaldehyde. The small fluorophore molecule has spectacular photoluminescence properties such as large stock shift, high photostability, selectivity and sensitivity toward the analytes. The PyT upon dispersion in the liquid phase becomes highly luminescent possessing the restricted intramolecular rotation (RIR) and excited stated intramolecular proton transfer (ESIPT) properties which are the major criteria for aggregation induced emission enhancement (AIEE) mechanism prevailing the aggregation caused quenching (ACQ). PyT molecule shows a binding constant of 3.285 × 10⁴ L mol^-1 for amoxicillin (AM). The limit of detection (LOD) values are found to be 1.67µM. Consuming bovine milk with antibiotic residues exceeding the maximum residue limit (MRL) can lead to food toxicity and life threatening diseases in humans. The milk sample with AM antibiotic residue in presence of PyT probe shows a distinct blue colour which infers the selectivity and sensitivity of the probe towards the analyte. The fluorescence probe adheres with merits like on site and visual examination by naked eye without aid of any instruments.