Fluorescent β-cyclodextrin-based hydrogel for enhanced adsorption and fluorescence detection of malachite green

Malachite green (MG), a synthetic dye widely used in industrial applications and aquaculture, poses significant health hazards due to its genotoxic and carcinogenic properties. Addressing these risks requires innovative methods for the efficient MG removal and sensitive detection. In this study, we developed a novel β-cyclodextrin/carbon dots-loaded cellulose nanofibrils/MIL-100(Fe) hydrogel (βCCM) for enhanced adsorption and fluorescence detection of MG. The βCCM demonstrated an exceptional maximum adsorption capacity of 1789 mg/g. Furthermore, βCCM exhibited bright orange fluorescence, which was significantly quenched upon exposure to MG through inner filter effect and static quenching. The fluorescence detection platform exhibited high sensitivity, with a limit of detection (LOD) of 0.09 μg/L and excellent linearity. Its practical applicability was validated through successful MG removal and detection in real water samples, achieving high recoveries and reproducibility. Mechanistic investigations revealed that the enhanced adsorption performance resulted from the incorporation of MIL-100(Fe) and the formation of a three-dimensional (3D) porous structure, which also stabilized the fluorescent signal and amplified detection sensitivity. This study highlights the effectiveness of βCCM for both MG adsorption and detection, presenting a novel strategy for designing advanced β-cyclodextrin-based hydrogels tailored for water treatment.