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

Abstract

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.