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    Smart bactericide based on reduced graphene oxide decorated with copper and zinc nanoparticles
    (Springer Nature, 2023-10-24) Bytešníková, Zuzana; Pečenka, Jakub; Tekielska, Dorota; Pekárková, Jana; Ridošková, Andrea; Bezdička, Petr; Kiss, Tomáš; Eichmeier, Aleš; Adam, Vojtěch; Lukas, Richtera
    Graphene oxide (GO) synthesised by modified Tour's method was decorated with copper and zinc nanoparticles (NPs) and simultaneously reduced by sodium borohydride to obtain a nanocomposite of reduced GO with copper and zinc NPs (rGO-Cu-Zn). The nanocomposite rGO-Cu-Zn was characterised by transmission electron microscopy (TEM), energy dispersive X-ray (EDX) spectroscopy, X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The rGO-Cu-Zn was tested against Xanthomonas euvesicatoria (X. euvesicatoria), which attacks tomatoes and causes bacterial spots (BSs), and compared with the commercial product Champion 50 WG. Total bacterial growth inhibition was observed for the 1% rGO-Cu-Zn, whereas Champion 50 WG at the same concentration inhibited but did not eradicate all the bacterial colonies. To evaluate the negative effect of the rGO-Cu-Zn on the molecular level, the expression of the genes associated with the action of abiotic and biotic stress factors was analysed. Gene expression in the plants treated with 10% rGO-Cu-Zn did not exhibit a noticeable increase.
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    Optimization of a silver-nanoprism conjugated with 3,3 ',5,5 '-tetramethylbenzidine towards easy-to-make colorimetric analysis of acetaldehyde: a new platform towards rapid analysis of carcinogenic agents and environmental technology
    (ROYAL SOC CHEMISTRY, 2023-02-14) Farshchi, Fatemeh; Saadati, Arezoo; Hasanzadeh, Mohammad; Liu, Yu-Qian; Seidi, Farzad
    Acetaldehyde acts as an important mediator in the metabolism of plants and animals; however, its abnormal level can cause problems in biological processes. Although acetaldehyde is found naturally in many organisms, exposure to high concentrations can have effects on the eyes, respiratory system, etc. Due to the importance of detecting acetaldehyde in environmental samples and biofluids, determination of its concentration is highly demanded. There are some reports showing exposure to high concentrations of acetaldehyde for a long time can increase the risk of cancer by reacting with DNA. In this work, we presented a novel colorimetric method for rapid and sensitive detection of acetaldehyde with high reproducibility using different AgNPs with various morphologies. The redox reaction between AgNPs, 3,3 ',5,5 '-tetramethylbenzidine (TMB) solution, and analytes endows a color change in 15 minutes that is detectable by the naked eye. UV spectrophotometry was further used for quantitative analysis. An iron mold with a hexagonal pattern and liquid paraffin were also used to prepare the paper-based microfluidic substrate, as a low cost, accessible, and rapid detection tool. Different types of AgNPs showed different lower limits of quantification (LLOQ). The AgNPs-Cit and AgNPrs could identify acetaldehyde with linear range of 10(-7) to 10 M and an LLOQ of 10(-7) M. The AgNWs showed the best color change activity with a linear range 10(-5) to 10 M and the lowest diagnostic limit is 10(-5) M. Finally, analysis of human biofluids as real samples were successfully performed using this system.
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    Silver Nanoparticle-Decorated Reduced Graphene Oxide Nanomaterials Exert Membrane Stress and Induce Immune Response to Inhibit the Early Phase of HIV-1 Infection
    (WILEY, 2023-02-01) Mukherjee, Soumajit; Bytešníková, Zuzana; Martin, Sophie; Švec, Pavel; Ridošková, Andrea; Pekárková, Jana; Seguin, Cendrine; Weickert, Jean-Luc; Mesaddeq, Nadia; Mély, Yves; Richtera, Lukáš; Anton, Halina; Adam, Vojtěch
    Graphene-based 2D nanomaterials exhibit unique physicochemical, electric, and optical properties that facilitate applications in a wide range of fields including material science, electronics, and biotechnology. Recent studies have shown that graphene oxide (GO) and reduced graphene oxide (rGO) exhibit antimicrobial effects on bacteria and viruses. While the bactericidal activity of graphene-based nanomaterials is related to mechanical and oxidative damage to bacterial membranes, their antiviral activity has been less explored. Currently available experimental data are limited and suggest mechanical disruption of viral particles prior to infection. In this study, the antiviral properties of reduced GO-based nanocomposites decorated with Ag nanoparticles (rGO-Ag) are evidenced against human immunodeficiency virus-1 pseudovirus used as an enveloped virus model. By combining biochemical and original single virus imaging approaches, it is shown that rGO-Ag induces peroxidation of pseudoviral lipid membrane and that consequent alteration of membrane properties leads to a reduction in cell entry. In addition, rGO-Ag is found to be efficiently internalized in the host cell leading to the elevated expression of pro-inflammatory cytokines. Altogether, the presented results shed new light on the mechanisms of rGO-Ag antiviral properties and confirm the high potential of graphene derivatives as an antimicrobial material for biomedical applications.
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    The planar anodic Al2O3-ZrO2 nanocomposite capacitor dielectrics for advanced passive device integration
    (Taylor & Francis, 2023-12-31) Kamnev, Kirill; Pytlíček, Zdeněk; Bendová, Mária; Prášek, Jan; Gispert-Guirado, Francesc; Llobet, Eduard; Mozalev, Alexander
    The need for integrated passive devices (IPDs) emerges from the increasing consumer demand for electronic product miniaturization. Metal-insulator-metal (MIM) capacitors are vital components of IPD systems. Developing new materials and technologies is essential for advancing capacitor characteristics and co-integrating with other electronic passives. Here we present an innovative electrochemical technology joined with the sputter-deposition of Al and Zr layers to synthesize novel planar nanocomposite metal-oxide dielectrics consisting of ZrO2 nanorods self-embedded into the nanoporous Al2O3 matrix such that its pores are entirely filled with zirconium oxide. The technology is utilized in MIM capacitors characterized by modern surface and interface analysis techniques and electrical measurements. In the 95-480 nm thickness range, the best-achieved MIM device characteristics are the one-layer capacitance density of 112 nF center dot cm(-2), the loss tangent of 4 center dot 10(-3) at frequencies up to 1 MHz, the leakage current density of 40 pA center dot cm(-2), the breakdown field strength of up to 10 MV center dot cm(-1), the energy density of 100 J center dot cm(-3), the quadratic voltage coefficient of capacitance of 4 ppm center dot V-2, and the temperature coefficient of capacitance of 480 ppm center dot K-1 at 293-423 K at 1 MHz. The outstanding performance, stability, and tunable capacitors' characteristics allow for their application in low-pass filters, coupling/decoupling/bypass circuits, RC oscillators, energy-storage devices, ultrafast charge/discharge units, or high-precision analog-to-digital converters. The capacitor technology based on the non-porous planar anodic-oxide dielectrics complements the electrochemical conception of IPDs that combined, until now, the anodized aluminum interconnection, microresistors, and microinductors, all co-related in one system for use in portable electronic devices.