Phase-Selective Synthesis of Anatase and Rutile TiO2 Nanocrystals and Their Impacts on Grapevine Leaves: Accumulation of Mineral Nutrients and Triggering the Plant Defense.

László Kőrösi,Simone Lauciello,Balázs Bognár,Gyula Czégény

doi:10.3390/nano12030483

László Kőrösi, Simone Lauciello + Show 2 more

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https://doi.org/10.3390/nano12030483

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Abstract

Titanium dioxide nanocrystals (TiO2 NCs), through their photocatalytic activity, are able to generate charge carriers and induce the formation of various reactive oxygen species (ROS) in the presence of O2 and H2O. This special feature makes TiO2 an important and promising material in several industrial applications. Under appropriate antioxidant balancing, the presence of ROS is crucial in plant growth and development, therefore, the regulated ROS production through the photocatalytic activity of TiO2 NCs may be also exploited in the agricultural sector. However, the effects of TiO2 NCs on plants are not fully understood and/or phase-pure TiO2 NCs are rarely used in plant experiments. In this work, we present a phase-selective synthesis of TiO2 NCs with anatase and rutile crystal phases. The nanomaterials obtained were characterized by means of X-ray diffraction (XRD), transmission electron microscopy (TEM), diffuse reflectance UV-Vis spectroscopy, and electron paramagnetic resonance spectroscopy (EPR). In field experiments, Vitis vinifera cv. Cabernet Sauvignon leaves developed under natural sunlight were treated with aqueous dispersions of TiO2 NCs at concentrations of 0.001, 0.01, 0.1, and 1 w/v%. The effect of the applied nanocrystals was characterized via leaf photochemistry, mineral nutrient contents, and pyridoxine levels. We found that stress responses of grapevine to anatase and rutile NCs treatments are different, which can be related to the different ROS profiles of the two polymorphs. Our results indicate that TiO2 NCs may be utilized not only for direct pathogen inactivation but also for eliciting plant defense mechanisms.

Highlights

Nowadays, research on engineered nanomaterials with unique physical and chemical properties is rapidly growing, which is clearly indicated by a large number of publications and patents [1,2]
We found that P25 TiO2, which is a mixture of anatase and rutile, was able to boost the biosynthesis of polyphenols and elevated the level of some mineral nutrients in grapevine leaves in a genotype-dependent manner [35]
Hereafter the synthesis was continued with the hydrothermal treatment with the same steps and heating program as we described for anatase nanocrystals

Summary

Introduction

Research on engineered nanomaterials with unique physical and chemical properties is rapidly growing, which is clearly indicated by a large number of publications and patents [1,2]. The related scientific work is focused on two main fields. Great efforts have been devoted to exploring nanomaterials with novel properties and exploiting their advantages in various fields [3,4]. The impact of nanomaterials on living organisms including plants and humans has been investigated intensively [5,6,7]. The application of nanomaterials can revolutionize the old technologies, the threshold between their beneficial effects and their potential toxicity has yet to be explored. The application of nanomaterials can revolutionize the old technologies, the threshold between their beneficial effects and their potential toxicity has yet to be explored. 4.0/).

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