In this study, tomato plants were grown in vitro with and without incorporation of TiO2 nanoparticles in Murashige and Skoog (MS) growth medium. The aim of this study was to describe the morphological (area and roundness cell) and mechanical (Young’s Modulus) change in the different tissue of tomato root, epidermis (Ep), parenchyma (Pa), and vascular bundles (Vb), when the whole plant was exposed to TiO2 nanoparticles (TiO2 NPs). light microscopy (LM), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM), wavelength dispersive X-ray fluorescence (WDXRF) techniques were used to identify changes into the root cells when TiO2 NPs were incorporated. TiO2 NPs incorporation produces changes in the area, roundness, and Young’s Modulus of the tomato root. When tomato root is exposed to TiO2 NPs, the Ep and Vb area size decreases from 260.92 µm2 to 160.71 µm2 and, 103.08 µm2 to 52.13 µm2, respectively, compared with the control area, while in Pa tissue the area size was increased considerably from 337.72 mm2 to 892.96 mm2. Cellular roundness was evident in tomato root that was exposed to TiO2 NPs in the Ep (0.49 to 0.67), Pa (0.63 to 0.79), and Vb (0.76 to 0.71) area zones. Young’s Modulus in Pa zone showed a rigid mechanical behavior when tomato root is exposed to TiO2 NPs (0.48 to 4.98 MPa control and TiO2 NPs, respectively). Meanwhile, Ep and Vb were softer than the control sample (13.9 to 1.06 MPa and 6.37 to 4.41 MPa respectively). This means that the Pa zone was stiffer than Ep and Vb when the root is exposed to TiO2 NPs. Furthermore, TiO2 NPs were internalized in the root tissue of tomato, accumulating mainly in the cell wall and intercellular spaces, with a wide distribution throughout the tissue, as seen in TEM.

Here, different tissue surfaces of tomato root were characterized employing atomic force microscopy on day 7 and day 21 of growth through Young's modulus and plasticity index. These parameters provide quantitative information regarding the mechanical behavior of the tomato root under fresh conditions in different locations of the cross-section of root [cell surface of the epidermis, parenchyma (Pa), and vascular bundles (Vb)]. The results show that the mechanical parameters depend on the indented region, tissue type, and growth time. Thereby, the stiffness increases in the cell surface of epidermal tissue with increasing growth time (from 9.19 ± 0.68 to 13.90 ± 1.68 MPa) and the cell surface of Pa tissue displays the opposite behavior (from 1.74 ± 0.49 to 0.48 ± 0.55); the stiffness of cell surfaces of Vb tissue changes from 10.60 ± 0.58 to 6.37 ± 0.53 MPa, all cases showed a statistical difference (p < 0.05). Viscoelastic behavior dominates the mechanical forces in the tomato root. The current study is a contribution to a better understanding of the cell mechanics behavior of different tomato root tissues during growth.

Background Monoamine oxidase (MAO) is an enzyme that has been targeted pharmacologically for the treatment of depression and neurodegenerative diseases such as Parkinson's disease. To avoid side effects, drugs currently in use must selectively target either of the enzyme's two isoforms, A or B. In this study, we designed molecules derived from chalcone as potential reversible and selective inhibitors of isoform A of the MAO enzyme. Results Ten thousand one hundred compounds were designed and screened using molecular docking, considering the pharmacokinetic processes of chemical absorption, distribution, metabolism, and excretion. Density functional theory calculations were performed for the main ligands to evaluate their reactivity. Six drugs qualified as reversible and irreversible inhibitors of both isoform A and isoform B. Among these, molecule 356 was found to be a reversible inhibitor with the best performance in selectively targeting isoform A of the MAO enzyme. The interaction stability of ligand 356 in the isoform A binding site was confirmed by molecular dynamics. One hydrogen bond was found between the ligand and the cofactor, and up to six hydrogen bonds were formed between the ligand and the protein. Conclusions We selected a drug model (molecule 356) for its high affinity to isoform A over isoform B of the MAO enzyme. This proposal should decrease experimental costs in drug testing for neurodegenerative diseases. Therefore, our silico design of a reversible inhibitor of isoform A of enzyme monoamine oxidase can be used in further experimental designs of novel drugs with minimal side effects. Graphical Abstract