Dual-Mode Fluorescence Turn-On Bentazone Determination and Ratiometric/Colorimetric Vitamin B2 Quantification Based on an AIE-Active Zn MOF Sensor

Abstract

Monitoring bentazone (BEN) residues in agricultural products and quantifying vitamin B2 (VB2) in fortified foods are essential for ensuring food safety and regulatory compliance. Herein, an AIE-active zinc-based metal–organic framework, {[ZnNa(HTCPP)]·3H2O·DMF}n (ZnTCPP, where H4TCPP = 2,3,5,6-(4-carboxyl-tetraphenyl)pyrazine) was synthesized and explored as a dual-mode fluorescence sensor for turn-on BEN determination and ratiometric/colorimetric VB2 quantification. Sensing mechanisms involve the collaborative contribution of competitive absorption, photoinduced electron transfer (PET), and host–guest interactions for BEN, and Förster resonance energy transfer (FRET) for VB2. ZnTCPP exhibited remarkable fluorescence enhancement toward BEN with a constant of 5.14 × 104 M–1 and a detection limit of 11.7 nM, and an outstanding ratiometric response to VB2 with a constant of 8.77 × 104 M–1 and a detection limit of 6.1 nM. Rapid fluorescence responses were observed within 1 min upon the addition of BEN or VB2. Practical applicability was validated in fruit, milk, and vitamin tablet samples with recoveries of 95.3–103.4% for BEN and 95.6–104.5% for VB2. Furthermore, paper-based and hydrogel-based platforms enabled on-site BEN and VB2 analysis, respectively, while a smartphone-assisted RGB analysis allowed rapid quantification. These results highlight ZnTCPP as a convenient, sensitive sensing platform for food safety and environmental monitoring.