Nanoparticle-immersed paper imprinting mass spectrometry imaging reveals uptake and translocation mechanism of pesticides in plants

Design and discovery of carrier-mediated modified pesticides are vital for reducing pesticide dosage and increasing utilization, yet it remains a great challenge due to limited insights into plant translocation mechanisms. Nanostructure/nanoparticle assisted laser desorption/ionization strategy has established itself as a preferential analytical tool for biological tissue analysis, whereas potential applications in plant sciences are hindered with regard to the inability to slice plant leaves and petals. Herein, we report gold nanoparticle (AuNP)-immersed paper imprinting mass spectrometry imaging (MSI) for the spatiotemporal visualization of pesticide translocation in plant leaves. This approach plays a dual role in preserving spatial information and improving ionization efficiency for pesticides regardless of imaging artifacts due to homogenous AuNP deposition. Using this MSI platform, we proposed the elaborate plant translocation mechanism of agrochemicals for the first time, which is currently poorly understood. The dynamic processes of carrier-mediated pesticides can be clearly visualized, including crossing of plasma membranes by transporters, translocation downward in stems through the phloem, diffusion to the xylem and, conversely, accumulation at margins of the treated leaves. Moreover, this AuNP-assisted paper imprinting method could be highly compatible with laser-based MSI instruments, expediting researches across a broad range of fields, especially in nanomaterial development and life sciences.