Spatial distribution tracing of MOFs in cucumber seedlings by fluorescence imaging and LA-ICP-MS

Metal-organic frameworks (MOFs) show great potential in agricultural applications, and clarifying their in-plant distribution is essential for assessing their ecological effects and biosafety. Single imaging method suffers from limited spatial resolution and inaccurate localization, restricting reliable analysis of plant-MOF interactions. Herein, we established a synergistic imaging approach combining fluorescence and LA-ICP-MS to characterize the translocation of Eu-BDC-NH₂ and UiO-66-NH₂ in cucumber seedlings. The imaging results demonstrate the preferential accumulation of two MOF in cucumber root tissues, which is further verified by quantitative ICP‑MS analysis. Especially in the high-exposure group (200 mg/L), compared with the corresponding Eu and Zr levels in stems and leaves, substantially higher concentrations of both elements were detected in cucumber roots. Furthermore, MOF aggregates are not limited to root peripheral zones. Eu-BDC-NH₂ and UiO-66-NH₂ displays efficient translocation from roots to stems and leaves, alongside favorable biocompatibility. By combining the intuitive visualization of fluorescence and the high sensitivity elemental tracing of LA-ICP-MS, this strategy overcomes the limitations of single detection. This study provides a robust analytical tool for evaluating the bio-safety of agricultural nano-materials, advances the understanding of MOF and plant interactions, and benefits the development of sustainable agriculture.