Tailoring Nanomaterial Surface Properties for Cuticular Uptake of Foliarly-applied Nanoparticles and Translocation in Plant Vasculature

Engineered nanomaterials have the potential to revolutionize agrochemical applications. However, limited scientific understanding of the fundamental interactions of nanoparticles at the plant-leaf interface currently hinders the development and application of nano-enabled agrochemicals. We hypothesize that the nanomaterial properties, including charge, size, and coating hydrophobicity can be engineered to promote efficient uptake and translocation of engineered nanomaterials in plants. To test these hypothesis, we foliarly exposed wheat plants to gold nanoparticles with different sizes and selected coatings to elucidate the impact of nanoparticle size and coating chemistry on their interaction with the leaves, leaf uptake pathways, translocation to other regions in the plant, and impacts on plant health. Spatially resolved synchrotron X-ray imaging tools at different scales demonstrated that coating identity controls both route and extent of nanoparticle uptake across the plant leaf cuticle. A relatively more hydrophobic coating afforded 100% uptake through the leaf cuticle due to hydrophobic interactions, contradicting dogma that the leaf cuticle is impermeable to particle uptake. Spatially resolved metal transport in leaf cross sections indicate that coating identity also impacts the ease of transport through leaf mesophyll into the plant vasculature. Interestingly, NP size up to 50nm did not influence NP uptake, but size did influence their leaf-to-root transport. Finally, for NP<50nm, approximately 20% of the foliar applied Au NPs were exuded from roots into the rhizosphere soil. Thus, we have also demonstrated an efficient method to deliver NP-enabled active ingredients to plant roots. Experiments exposing plant roots to CeO2 NPs indicates that NP charge affects the distribution of the NPs in plant leaves, with dicots and monocots showing different behaviors. Overall, the body of evidence indicates great potential for manipulating nanomaterial properties for beneficial applications in agriculture and for increasing agrochemical utilization efficiency and sustainability of food production.

Professor Greg Lowry is the Walter J. Blenko, Sr. Professor of Civil and Environmental Engineering at Carnegie Mellon University. He is the Deputy Director of the NSF/EPA Center for Environmental Implications of Nanotechnology (CEINT). His research aims to safely harness the unique properties of engineered nanomaterials for making crop agriculture and water treatment more resilient and sustainable. Recent work aims at understanding how a nanomaterial’s properties and environmental conditions influence their fate in soils, nanomaterial-plant interactions, nutrient uptake efficiency, and crop disease management. He has authored more than 150 peer-reviewed journal articles (H index=66) and one book. He served on the board of directors of the Association of Environmental Engineering and Science Professors, and on the US EPA Science Advisory Board (Environmental Engineering committee). He is a fellow of the American Association for the advancement of Science, and was a member of the National Academy of Science Committee on Science Breakthroughs 2030: A Strategy for Food and Agricultural Research. Dr. Lowry holds a B.S. in Chemical Engineering from the University of California at Davis, an M.S. from the University of Wisconsin at Madison, and a Ph.D. in Civil & Environmental Engineering from Stanford University.