Portable and Smartphone-Integrated B-CDs@MOF-5-Based Selective Fluorescent Probe for Rapid Detection of Cartap Pesticide

Rapid and on-site monitoring of pesticide residues remains a critical challenge in food safety and environmental analysis. Herein, we report a portable, smartphone-integrated fluorescent sensing platform based on blue-emissive carbon dots (B-CDs) encapsulated within MOF-5 (B-CDs@MOF-5) for the selective detection of the pesticide cartap. The composite was synthesized via a one-pot in situ encapsulation strategy, preserving the crystalline structure and porosity of MOF-5 while imparting strong and stable fluorescence from the embedded CDs. The B-CDs@MOF-5 probe exhibits excellent water stability, pH tolerance, and long-term photostability. A pronounced fluorescence quenching response toward cartap is observed, with high selectivity over other commonly used pesticides and strong anti-interference capability. Quantitative analysis reveals a Stern–Volmer quenching constant of 2.31 × 106 M–1 and a detection limit of 5.24 nM. The sensing mechanism is attributed to strong host–guest interactions and photoinduced electron transfer between cartap and the composite. Integration with a smartphone-based RGB analysis system enables rapid, visual, and quantitative on-site detection of cartap, demonstrating its successful applicability for real water and food sample analysis, showcasing the potential of B-CDs@MOF-5 as a practical platform for a field-deployable pesticide monitoring system.