Many important plant functions, such as carbon dioxide reduction or energy generation is carried out within the chloroplast – a plant organelle that appears greatly under explored as an engineering material. Here, we examine the subcellular uptake and kinetic trapping of a wide range of nanoparticles for the first time, using the plant chloroplast as a model system, but validated in vivo in living plants. Confocal visible and near-infrared fluorescent microscopy and single particle tracking of gold-cysteine- AF405 (GNP-Cys- AF405), streptavidin-quantum dot (SA-QD), dextran and poly(acrylic acid) nanoceria, and various polymer-wrapped single-walled carbon nanotubes (SWCNTs), including lipid-PEG- SWCNT, chitosan-SWCNT and 30-base (dAdT) sequence of ssDNA (AT)15
wrapped SWCNTs (hereafter referred to as ss(AT)15
-SWCNT), are used to demonstrate that particle size and the magnitude, but not the sign, of the zeta potential are key in determining whether a particle is spontaneously and kinetically trapped within the organelle, despite the negative zeta potential of the envelope. We develop a mathematical model of this lipid exchange envelope and penetration (LEEP) mechanism, which agrees well with observations of this size and zeta potential dependence. The theory predicts a critical particle size below which the mechanism fails at all zeta potentials, explaining why nanoparticles are critical for this process. LEEP constitutes a powerful particulate transport and localization mechanism for nanoparticles within the plant system.
Reference: Wong MH, Misra R, Giraldo JP, Kwak SY, Son YW, Landry MP, Swan JW, Blankschtein D, Strano MS. 2016. Lipid Exchange Envelope Penetration (LEEP) of Nanoparticles for Plant Engineering: a Universal Localization Mechanism. Nano lett, 16 (2), pp 1161–1172