Nano-Biohybrids: In Vivo Synthesis of Metal-Organic Frameworks inside Living Plants

Abstract

Plants have a complex passive fluid transport system capable of internalizing small molecules from the environment, and this system offers an ideal route for augmenting plants with functional nanomaterials. Current plant augmentation techniques use pre-formed nanomaterials and permeabilizing agents or plant cuttings. A so far unexplored concept is the formation of the functional material, in situ, from precursors small enough to be passively internalized through the roots without harming the plants. Metal-organic frameworks are ideal for in situ synthesis as they are composed of metal ions coordinated with organic ligands and have recently been mineralized around single-celled organisms in mild aqueous conditions. Herein, the synthesis of two types of metal-organic frameworks, zinc(2-methylimidazole)2 and lanthanide2 (terephthalate)3 , are reported inside a variety of plants. In situ synchrotron experiments help elucidate the formation kinetics and crystal phases of the nano-biohybrid plants. Plants augmented with luminescent metal-organic frameworks are utilized for small molecule sensing, although other applications, such as pathogen sensing, proton conductive plants, improved CO2 capture, bacteria-free nitrogen fixation, drought and fungi-resistance, and enhanced photosynthesis and photocatalysis, are foreseeable. Overall, the generation of functional materials inside of fully intact plants could lead to more complex nano-biohybrid sensors and organisms augmented with superior performance characteristics.