Tracing microplastics uptake and translocation in plants using aggregation-induced emission materials

Microplastics (MPs) can be absorbed by plants and subsequently transferred into the food chain, posing ecological and health risks. However, the investigation of MP absorption and translocation in organisms is highly restricted by the difficulties in separating and quantifying MPs in biological samples. This study utilized aggregation-induced emission (AIE) materials as sensitive fluorescent probes that show potential as semi‑quantitative tracers for MPs transport in plants. Self-assembly and swelling methods were adopted to incorporate AIE materials (BB-066 and TPE-NH₂) in MPs (PS, PMMA, PLA). Hydroponic experiments and physiological factor analysis confirmed that BB-066 was non-toxic to lettuce (Lactuca sativa), as no significant difference was observed compared to the control groups (p > 0.05). The stability of the prepared fluorescent MPs was investigated through metal ion release and fluorescence leakage in the supernatant at varying pH levels as well as in the simulated plant internal liquid environment. Fluorescence imaging revealed treatment-associated signals within root, stem and leaf tissues, with a progressive decrease in fluorescence intensity from roots to stems and leaves. The spatial distribution was compatible with upward redistribution through vascular-associated pathways, although the predominantly diffuse fluorescence did not allow intact labelled microspheres to be distinguished unequivocally from dissociated or redistributed fluorophore.