A RhB@Tb-MOF sensor for selective detection of malachite green and leucomalachite green

The misuse of malachite green (MG) has led to significant water pollution, and its metabolite, leucomalachite green (LMG), poses a serious health risk. Rapid detection of drug residues in aquaculture is crucial for food safety. In this study, the dual-emission fluorescent sensor RhB@Tb-MOF (RhB = Rhodamine B) was synthesized based on fluorescence resonance energy transfer (FRET). MG significantly quenches the fluorescence of RhB and affects the fluorescence of Tb-MOF to different extents, making it a suitable ratiometric fluorescent sensor for sensitive MG detection with a limit of detection (LOD) of 9.6 × 10 −3 μg/mL. Although LMG did not affect the fluorescence of RhB@Tb-MOF, it formed a ratio with the fluorescence of RhB@Tb-MOF due to its intrinsic fluorescence properties, and the LOD was 3.5 × 10 −3 μg/mL. Additionally, increasing MG concentrations shifted the sensing system's color from pink to blue, with a colorimetric LOD of 0.15 μg/mL. This paper introduced a colorimetric/fluorescent dual-mode sensor for MG and LMG detection. Furthermore, this sensor was combined with smart labeling technology to achieve rapid on-site quantification of MG, offering significant potential for broad application.