Recent development of nanotechnology has reshaped the landscape of modern science and technology, while in the meantime raised concerns about the adverse effects of nanomaterials on biological systems and the environment. [1,2] Owing to their mutual interaction, carbon-based nanomaterials readily aggregate and are not considered potential contaminants in the liquid phase. [3] However, when discharged into the environment, the hydrophobicity of nanomaterials can be averted through their interaction with natural organic matter (NOM), [4] a heterogeneous mixture of decomposed animals and plants and a major pollutant carrier [5] in nature. Consequently, mobile NOM-modified nanomaterials may pose a threat to ecological terrestrial species through further physical, chemical, and biological processes.The impact of nanomaterials on high plants has scantly been examined in the current literature. Among the studies available, [6][7][8][9][10][11][12] none have used major food crops or carbon nanoparticles (a major class of nanomaterials) for their evaluations. Although both enhanced and inhibited growth have been reported for vegetations exposed to nanomaterials at various developmental stages, [6][7][8][9][10][11][12] including seed germina-tion, root growth, and photosynthesis, fundamental questions remain regarding the uptake, accumulation, translocation, and transmission of nanomaterials in plant cells and tissues, and the impact of these processes on plant reproduction. [13] Here, we provide the first evidence on the uptake, accumulation, and generational transmission of NOM-suspended carbon nanoparticles in rice plants, the staple food crops of over half the world's population. The data presented in this Communication suggest the potential impact of nanomaterial exposure on plant development and the food chain, and prompt further investigation into the genetic consequences through plantnanomaterial interactions.NOM in freshwater ecosystems ususally has a concentration between 1-100 mg L À1 . [14] To mimic the natural ecosystems we formed a NOM solution of 100 mg L À1 in Milli-Q water and suspended fullerene C 70 and multiwalled carbon nanotubes (MWNTs) in the NOM. Using a Zetasizer (S90, Malvern Instruments) we identified three hydrodynamic diameters of 1.19 (major), 17.99, and 722.10 nm for C 70 -NOM and one major hydrodynamic diameter of 239.70 nm for MWNT-NOM (see Supporting Information, Sections 1C and 1D). The nonspecific assembly of NOM with C 70 or MWNTs is believed to be a dynamic equilibrium process [4] with the hydrophobic moieties of the NOM interacting and p-stacking with the hydrophobic carbon nanoparticle surfaces.Newly harvested rice seeds were incubated in Petri dishes that contained 15 mL of different concentrations of C 70 -NOM and MWNT-NOM in rice germination buffer. After germination at 25 AE 1 8C for 2 weeks the seedlings were transplanted to soil in big pots and grown in a green house to maturity without addition of nanoparticles. For each sample concentration, 5 pots of plants were maintained f...

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Fullerene derivative C(60)(OH)(20) inhibited microtubule polymerization at low micromolar concentrations. The inhibition was mainly attributed to the formation of hydrogen bonding between the nanoparticle and the tubulin heterodimer, the building block of the microtubule, as evidenced by docking and molecular dynamics simulations. Our circular dichroism spectroscopy measurement indicated changes in the tubulin secondary structures, while our guanosine-5'-triphosphate hydrolysis assay showed hindered release of inorganic phosphate by the nanoparticle. Isothermal titration calorimetry revealed that C(60)(OH)(20) binds to tubulin at a molar ratio of 9:1 and with a binding constant of 1.3 ± 0.16 × 10(6) M(-1), which was substantiated by the binding site and binding energy analysis using docking and molecular dynamics simulations. Our simulations further suggested that occupancy by the nanoparticles at the longitudinal contacts between tubulin dimers within a protofilament or at the lateral contacts of the M-loop and H5 and H12 helices of neighboring tubulins could also influence the polymerization process. This study offered a new molecular-level insight on how nanoparticles may reshape the assembly of cytoskeletal proteins, a topic of essential importance for illuminating cell response to engineered nanoparticles and for the advancement of nanomedicine.

Seed coat permeability was examined using a model that tested the effects of soaking tomato (Solanum lycopersicon) seeds in combination with carbon-based nanomaterials (CBNMs) and ultrasonic irradiation (US). Penetration of seed coats to the embryo by CBNMs, as well as CBNMs effects on seed germination and seedling growth, was examined. Two CBNMs, C60(OH)20 (fullerol) and multiwalled nanotubes (MWNTs), were applied at 50 mg/L, and treatment exposure ranged from 0 to 60 minutes. Bright field, fluorescence, and electron microscopy and micro-Raman spectroscopy provided corroborating evidence that neither CBNM was able to penetrate the seed coat. The restriction of nanomaterial (NM) uptake was attributed to the semipermeable layer located at the innermost layer of the seed coat adjacent to the endosperm. Seed treatments using US at 30 or 60 minutes in the presence of MWNTs physically disrupted the seed coat; however, the integrity of the semipermeable layer was not impaired. The germination percentage and seedling length and weight were enhanced in the presence of MWNTs but were not altered by C60(OH)20. The combined exposure of seeds to NMs and US provided insight into the nanoparticle-seed interaction and may serve as a delivery system for enhancing seed germination and early seedling growth.