Localization of coated iron oxide (Fe3O4) nanoparticles on tomato seeds and their effects on growth

IFood demand due to the growing population globally has been stretching the agriculture sector to the limit. This demands the cultivation of plants in shrinking land areas which makes the search for highly effective systems for plant nutrition and pest control important. In this context, the application of nanoparticles (NPs) in agriculture can have a transformative effect on food production techniques as it can enable the delivery of bioactive agents (including growth factors, pesticides and fungicides) directly to plants. Herein we report the application of unfunctionalized as well as amine-functionalized and polycaprolactone-coated Fe3O4 nanoparticles (NP) to seed treatment and plant growth. The study reveals that the treatment has no side effects on plant germination and development. Furthermore, the penetration of NPs in tomato seeds (Solanum Lycopersicum) and their translocation in tomato seedlings post-treatment depends on the level of the NPs functionalization. The research also demonstrates that a fraction of NP is preferentially translocated to tomato seedling roots and shoots, however, uptake is lower for functionalized NPs (both amine and PCL). Thus, the results suggest that the functionalization of NPs can act as a versatile platform for delivering of active compounds, such as fungicides and growth factor agents

Synthesis, structure, and thermal stability of poly(methyl methacrylate)-co- poly(3-tri(methoxysilyil)propyl methacrylate)/ montmorillonite nanocomposites

The structure and the thermodegradation behavior of both poly(methyl methacrylate)-co-poly(3-tri(methoxysilyil)propyl methacrylate) polymer modified with silyl groups and of intercalated poly(methyl methacrylate)-co-poly(3- tri(methoxysilyil)propyl methacrylate)/Cloisite 15A™ nanocomposite have been in situ probed. The structural feature were comparatively studied by Fourier transform infrared spectroscopy (FTIR), 13C and 29Si nuclear magnetic resonance (NMR), and small angle X-ray scattering (SAXS) measurements. The intercalation of polymer in the interlayer galleries was evidenced by the increment of the basal distance from 31 to 45 Å. The variation of this interlayer distance as function of temperature was followed by in situ SAXS. Pristine polymer decomposition pathway depends on the atmosphere, presenting two steps under air and three under N2. The nanocomposites are more stable than polymer, and this thermal improvement is proportional to the clay loading. The experimental results indicate that clay nanoparticles play several different roles in polymer stabilization, among them, diffusion barrier, charring, and suppression of degradation steps by chemical reactions between polymer and clay. Charring is atmosphere dependent, occurring more pronounced under air. © 2012 Society of Plastics Engineers

XAS/WAXS time-resolved phase speciation of chlorine LDH thermal transformation: emerging roles of isovalent metal substitution.

International audienceThe XAS/WAXS time-resolved method was applied for unraveling the complex mechanisms arising from the evolution of several metastable intermediates during the degradation of chlorine layered double hydroxide (LDH) upon heating to 450 °C, i.e., Zn2Al(OH)6*nH2O, ZnCuAl(OH)6*nH2O, Zn2Al0.75Fe0.25(OH)6*nH2O, and ZnCuAl0.5Fe0.5(OH)6*nH2O. After a contraction of the interlamellar distance, attributed to the loss of intracrystalline water molecules, this distance experiences an expansion (T > 175-225 °C) before the breakdown of the lamellar framework around 275-295 °C. Amorphous prenucleus clusters with crystallo-chemical local order of zinc-based oxide and zinc-based spinel phases, and if any of copper-based oxide, are formed at T > 175-225 °C well before the loss of stacking of LDH layers. This distance expansion has been ascribed to the migration of ZnII from octahedral layers to tetrahedral sites in the interlayer space, nucleating the nano-ZnO or nano-ZnM2O4 (M = Al or Fe) amorphous prenuclei. The transformation of these nano-ZnO clusters toward ZnO crystallites proceeds through an agglomeration process occurring before the complete loss of layer stacking for Zn2Al(OH)6*nH2O and Zn2Al0.75Fe0.25(OH)6*nH2O. For ZnCuAl(OH)6*nH2O and ZnCuAl0.5Fe0.5(OH)6*nH2O, a cooperative effect between the formation of nano-CuO and nano-ZnAl2O4 amorphous clusters facilitates the topochemical transformation of LDH to spinel due to the contribution of octahedral CuII vacancy to ZnII diffusion

Effects of ZnO Nanoparticles on Phaseolus vulgaris Germination and Seedling Development Determined by X-ray Spectroscopy

There is still little information on the potential use of nanomaterials for seed nutrient enhancement through seed priming. The use of nanoparticles (NPs) in agriculture is promising, but in-depth knowledge on their interaction with plants is required. The aim of this study was to evaluate the effects of different concentrations (1-5000 mg L-1) and sizes (20, 40, and 60 nm) of uncoated ZnO NP compared to ionic ZnSO4 (positive control) on common bean (Phaseolus vulgaris) seed germination. The seeds were soaked in ZnO NP aqueous dispersions for 20 min. The ZnO nanoparticles did not affect the germination rate. The 10 mg L-1 40 nm ZnO treatment showed a tendency to increase weight after 5 days (8.26 ± 0.11 g) when compared to the negative control (7.7 ± 0.7 g). However, at 5000 mg L-1 40 nm ZnO NP and ZnSO4 weight was reduced to 7.7 ± 0.8 g and 6.05 ± 0.08 g, respectively. Microprobe X-ray fluorescence showed that most of the Zn absorbed was trapped in the seed coat, while a small fraction entered the cotyledon. X-ray absorption spectroscopy indicated the biotransformation of the ZnO NP. In the hilum and cotyledon, Zn was found associated with organic molecules such as citrate, malate, and histidine-like compounds. Seedling weight reduction depended on the concentration of Zn taken up by the tissue and on the biotransformation of ZnO into organically bound Zn. Considering the properties of the studied NP, in particular the slow Zn release and lower toxicity compared to ZnSO4, the results represent a step forward toward the application of ZnO NP as an agrochemical

XAS/WAXS Time-Resolved Phase Speciation of Chlorine LDH Thermal Transformation: Emerging Roles of Isovalent Metal Substitution

The XAS/WAXS time-resolved method was applied for unraveling the complex mechanisms arising from the evolution of several metastable intermediates during the degradation of chlorine layered double hydroxide (LDH) upon heating to 450 °C, i.e., Zn₂Al­(OH)₆·<i>n</i>H₂O, ZnCuAl­(OH)₆·<i>n</i>H₂O, Zn₂Al_0.75Fe_0.25(OH)₆·<i>n</i>H₂O, and ZnCuAl_0.5Fe_0.5(OH)₆·<i>n</i>H₂O. After a contraction of the interlamellar distance, attributed to the loss of intracrystalline water molecules, this distance experiences an expansion (<i>T</i> > 175–225 °C) before the breakdown of the lamellar framework around 275–295 °C. Amorphous prenucleus clusters with crystallo-chemical local order of zinc-based oxide and zinc-based spinel phases, and if any of copper-based oxide, are formed at <i>T</i> > 175–225 °C well before the loss of stacking of LDH layers. This distance expansion has been ascribed to the migration of Zn^II from octahedral layers to tetrahedral sites in the interlayer space, nucleating the nano-ZnO or nano-ZnM₂O₄ (M = Al or Fe) amorphous prenuclei. The transformation of these nano-ZnO clusters toward ZnO crystallites proceeds through an agglomeration process occurring before the complete loss of layer stacking for Zn₂Al­(OH)₆·<i>n</i>H₂O and Zn₂Al_0.75Fe_0.25(OH)₆·<i>n</i>H₂O. For ZnCuAl­(OH)₆·<i>n</i>H₂O and ZnCuAl_0.5Fe_0.5(OH)₆·<i>n</i>H₂O, a cooperative effect between the formation of nano-CuO and nano-ZnAl₂O₄ amorphous clusters facilitates the topochemical transformation of LDH to spinel due to the contribution of octahedral Cu^II vacancy to Zn^II diffusion