Rapid fluorescent sensing through heparin and chitosan encapsulated Eu³⁺ complexes for pesticide detection

Vegetables and fruits are essential sources of nutrients, minerals, vitamins, and dietary fiber for a well-balanced diet. However, excessive pesticide use, particularly 2,6-dichloro-4-nitroaniline (DCN), poses serious health and environmental risks. Traditional pesticide detection methods require expensive equipment, trained personnel and making them unsuitable for on-site sensing. In this study, we synthesized europium (Eu³⁺) complexes incorporating heparin sodium and chitosan to develop a rapid, cost-effective, and highly sensitive fluorescent sensor for DCN detection. The optimized Eu³⁺ complex (ETP-HS3) demonstrated excellent water stability, strong red fluorescence, and a long fluorescence lifetime (888.09 μs). It exhibited a low limit of detection (LOD = 0.9049 μM), a rapid sensing response (20 s), and a high quenching constant (Ksv = 1.226 × 10⁴ M^-1), rendering it an effective and portable fluorescence sensor for real-time pesticide monitoring. The fluorescence quenching mechanism was thoroughly investigated, confirming the selectivity and efficiency of the sensor.