Leaf age-dependent effects of foliar-sprayed CuZn nanoparticles on photosynthetic efficiency and ROS generation in <i>Arabidopsis thaliana</i>

Young and mature leaves of Arabidopsis thaliana were exposed by foliar spray to 30 mg L&minus;1 of CuZn nanoparticles (NPs). The NPs were synthesized by a microwave-assisted polyol process and characterized by dynamic light scattering (DLS), X-ray diffraction (XRD), and transmission electron microscopy (TEM). CuZn NPs effects in Arabidopsis leaves were evaluated by chlorophyll fluorescence imaging analysis that revealed spatiotemporal heterogeneity of the quantum efficiency of PSII photochemistry (&Phi;PS&Iota;&Iota;) and the redox state of the plastoquinone (PQ) pool (qp), measured 30 min, 90 min, 180 min, and 240 min after spraying. Photosystem II (PSII) function in young leaves was observed to be negatively influenced, especially 30 min after spraying, at which point increased H2O2 generation was correlated to the lower oxidized state of the PQ pool. Recovery of young leaves photosynthetic efficiency appeared only after 240 min of NPs spray when also the level of ROS accumulation was similar to control leaves. On the contrary, a beneficial effect on PSII function in mature leaves after 30 min of the CuZn NPs spray was observed, with increased &Phi;PS&Iota;&Iota;, an increased electron transport rate (ETR), decreased singlet oxygen (1O2) formation, and H2O2 production at the same level of control leaves.An explanation for this differential response is suggested

Polyol synthesis and bioapplications of bimetallic, CuFe, CuZn, and zinc ferrite, ZnxFe3-xO4, nanoparticles

In the current thesis, synthesis (under polyol process), characterization and bioapplications of hydrophilic coated CuFe bimetallic nanoparticles, CuFeO2 heterostructured nanoparticles, CuZn bimetallic nanoparticles and ZnxFe3-xO4 zinc ferrite nanoparticles are presented. Synthesis of the nanoparticles was carried out in autoclaves via the solvothermal and/or microwave-assisted approaches. Several experimental conditions were investigated including the effect of polyols by the means of different molecular weight, boiling point, reductive ability and tangent loss of microwave irradiation, the effect of temperature, the effect of the synthetic route and the nature of the precursors as well as their ratio. Through synthetic regulations, copper and/or iron rich CuFe nanoalloys, CuFeO2 delafossite oxide, copper and/or zinc rich CuZn nanoalloys and ZnxFe3-xO4 nanoparticles with different zinc doping were effectively produced. The oxidation and fragmentation of polyols during syntheses were evaluated. Addionally the preservation of the polymeric nature of the coating of the nanoparticles was investigated after the synthesis. The isolated nanoparticles were characterized through XRD, TEM, SEM, FTIR, Raman, UV-Vis, FL, NMR, ICP-AES, FAAS, TGA, DLS and VSM. Bioapplications of nanoparticles were recorded on the basis of the composition and physicochemical characterization of the nanoparticles and biological evaluations were recorded. Under these studies, the synergistic antimicrobial activity of CuFe and CuFeO2 nanoparticles as well as their interaction with various forms of DNA and biomolecules was investigated. Additionally, the synergistic antifungal activity and phytotoxicity of CuZn were evaluated. Moreover, the theranostic (therapy and diagnosis) action of ZnxFe3-xO4 was examined through their imaging ability in MRI, their drug delivery characteristics and their interaction with proteins related to central nervous system disorders.Στην παρούσα διατριβή παρουσιάζεται η σύνθεση μέσω πολυολών, ο χαρακτηρισμός και οι βιοεφαρμογές υδρόφιλων επικαλυμμένων διμεταλλικών νανοσωματιδίων CuFe, νανοσωματιδίων CuFeO2, διμεταλλικών νανοσωματιδίων CuZn και νανοσωματιδίων φερρίτη ψευδαργύρου, ZnxFe3-xO4. Η σύνθεση των νανοσωματιδίων πραγματοποιήθηκε σε αυτόκλειστες συνθήκες μέσω διαλυτοθερμικής προσέγγισης ή/και υποβοηθούμενη μέσω μικροκυματικής ακτινοβολίας. Οι πειραματικές συνθήκες που διερευνήθηκαν είναι η επίδραση πολυολών με διαφορετικά μοριακά βάρη, σημεία ζέσεως, αναγωγική ικανότητα και εφαπτόμενη απώλεια μικροκυματικής ακτινοβολίας, η επίδραση της θερμοκρασίας, η επίδραση της συνθετικής προσέγγισης και η επίδραση των προδρόμων ενώσεων καθώς και της αναλογίας τους. Παρασκευάστηκαν πλούσια σε χαλκό ή/και σίδηρο νανοκράματα CuFe, καθώς και CuFeO2, πλούσια σε χαλκό ή/και ψευδάργυρο νανοκράματα CuZn καθώς και νανοσωματίδια ZnxFe3-xO4 με διαφορετικά ποσοστά-doping ψευδαργύρου. Επιπρόσθετα, μελετήθηκε ο βαθμός οξείδωσης και θραυσματοποίησης των πολυολών κατά τη σύνθεση, και η διατήρηση του πολυμερικού χαρακτήρα στην επικάλυψη των νανοσωματιδίων μετά τη σύνθεση. Τα νανοσωματίδια χαρακτηρίστηκαν μέσα XRD, TEM, SEM, FTIR, Raman, UV-Vis, FL, NMR, ICP-AES, FAAS, TGA, DLS και VSM. Μελετήθηκε η συνεργιστική αντιμικροβιακή δράση των CuFe, CuFeO2 και η αλληλεπίδραση τους με μορφές DNA και βιομόρια, η συνεργιστική αντιμυκητιακή δράση και η φυτοτοξικότητα των CuZn καθώς και η δράση των ZnxFe3-xO4 ως παράγοντες θεραπείας και διάγνωσης μέσα από την απεικονιστική τους δράση, τη δράση τους ως μεταφορείς φαρμάκων και την αλληλεπίδραση τους με πρωτεΐνες που σχετίζονται με παθήσεις του κεντρικού νευρικού συστήματος

Nanobrass CuZn Nanoparticles as Foliar Spray Nonphytotoxic Fungicides

Inorganic nanoparticles (NPs) have been proposed as alternative fertilizers to suppress plant disease and increase crop yield. However, phytotoxicity of NPs remains a key factor for their massive employment in agricultural applications. In order to investigate new effective, nonphytotoxic, and inexpensive fungicides, in the present study CuZn bimetallic nanoparticles (BNPs) have been synthesized as antifungals, while assessment of photosystem II (PSII) efficiency by chlorophyll fluorescence imaging analysis is utilized as an effective and noninvasive phytotoxicity evaluation method. Thus, biocompatible coated, nonoxide contaminated CuZn BNPs of 20 nm crystallite size and 250 nm hydrodynamic diameter have been prepared by a microwave-assisted synthesis. BNPs’ antifungal activity against <i>Saccharomyces cerevisiae</i> was found to be enhanced compared to monometallic Cu NPs. Reactive oxygen species (ROS) formation and photosystem II (PSII) functionality at low light (LL) and high light (HL) intensity were determined on tomato plants sprayed with 15 and 30 mg L^–1 of BNPs for the evaluation of their phytotoxicity. Tomato leaves sprayed with 15 mg L^–1 of BNPs displayed no significant difference in PSII functionality at LL, while exposure to 30 mg L^–1 of BNPs for up to 90 min resulted in a reduced plastoquinone (PQ) pool that gave rise to H₂O₂ accumulation, initiating signaling networks and regulating acclimation responses. After 3 h of exposure to 30 mg L^–1 of BNPs, PSII functionality at LL was similar to control, indicating nonphytotoxic effects. Meanwhile, exposure of tomato leaves either enhanced (15 mg L^–1) or did not have any significant effect (30 mg L^–1) on PSII functionality at HL, attributed to the absence of semiconducting oxide phases and photochemical toxicity-reducing modifications. The use of chlorophyll fluorescence imaging analysis is recommended as a tool to monitor NPs behavior on plants