Field-responsive fluids of carbon-coated magnetic nanoparticles for plant biology and agronomy

Abstract

The ongoing research on magnetic nanoparticles (MNPs) for bio-medical applications and the achievements related to their use in diagnosis and therapy open a wide range of possibilities for using MNPs in other disciplines, such as general plant research and agronomy. For this purpose, the first stage is to work out the penetration and transport into living plants, and how inorganic nanoparticles interact with plant cells and tissues1. We have used biocompatible suspensions of iron-oxide carbon-coated nanoparticles, synthesized by a gas-phase condensation method. They have been injected into pumpkin (Cucurbita pepo) living plants. The graphitic shell of our nanoparticles has made possible their visualization into plant cells and tissues, by microscopy techniques (fluorescence, confocal, light and electron microscopy). Moreover, their magnetic character has allowed the MNPs to be positioned in the desired plant tissue by applying magnetic field gradients. We have observed that the nanoparticles can travel along the vascular system, reaching different cell and tissues. They have been found both in the cytoplasm and in the extracellular space between cells. A size-based selection mechanism seems to be operating, probably involving cell walls and waxes acting as a barrier. Accumulation of MNPs has been detected in leaf trichomes, suggesting a way for nanoparticle excretion and detoxification. Cyto-and phyto-toxicity have been as well evaluated. Although more studies are necessary, our results open a wide range of possibilities for using magnetic nanoparticles in general plant research and agronomy.