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A New Method for 2D Materials Properties Modulation by Controlled Induced Mechanical Strain
(MDPI, 2018-12-07) Gablech, Imrich; Pekárek, Jan; Klempa, Jaroslav; Vyroubal, Petr; Svatoš, Vojtěch; Neužil, Pavel
This paper proposes a new method for characterization of 2D materials under the precisely specified conditions. It is achieved by integration of a 2D material as a field effect transistors structures with a piezoelectric resonator. Properties of the 2D material can be mechanically adjusted by the resonator. It results in the independent and precise control of an amplitude of induced mechanical strain, its modulating frequency, which all influence the 2D material properties. The electrical field required to measure 2D material field effect transistors will not be affected by the vibrations, thus giving us a chance to perform the precise measurement of the electrical properties of the 2D material. This approach has a great potential for measuring and monitoring cells, enzymes, nucleic acids, deoxyribonucleic acid and ribonucleic acid. It can be also used for measurement of toxic, combustive or waste gases.
Microfluidic Technology for Clinical Applications of Exosomes
(MDPI, 2019-06-12) Iliescu, Florina Silvia; Vrtačnik, Danilo; Neužil, Pavel; Iliescu, Ciprian
Exosomes, a type of nanovesicle, are distinct cellular entities specifically capable of carrying various cargos between cells. It has been hypothesized that exosomes, as an enriched source of biomolecules, may serve as biomarkers for various diseases. This review introduces general aspects of exosomes, presents the challenges in exosome research, discusses the potential of exosomes as biomarkers, and describes the contribution of microfluidic technology to enable their isolation and analysis for diagnostic and disease monitoring. Additionally, clinical applications of exosomes for diagnostic purposes are also summarized.
Effect of Ampicillin, Streptomycin, Penicillin and Tetracycline on Metal Resistant and Non-Resistant Staphylococcus aureus
(MDPI AG, POSTFACH, 2014-03-19) Hegerová, Dagmar; Dostálová, Simona; Blažková, Iva; Michálek, Petr; Ruttkay-Nedecký, Branislav; Sklenář, Matěj; Nejdl, Lukáš; Kudr, Jiří; Gumulec, Jaromír; Tmejová, Kateřina; Konečná, Marie; Vaculovičová, Markéta; Hynek, David; Masařík, Michal; Kynický, Jindřich; Kizek, René; Adam, Vojtěch
There is an arising and concerning issue in the field of bacterial resistance, which is confirmed by the number of deaths associated with drug-resistant bacterial infections. The aim of this study was to compare the effects of antibiotics on Staphylococcus aureus non-resistant strain and strains resistant to cadmium or lead ions. Metal resistant strains were created by the gradual addition of 2 mM solution of metal ions (cadmium or lead) to the S. aureus culture. An increasing antimicrobial effect of ampicillin, streptomycin, penicillin and tetracycline (0, 10, 25, 50, 75, 150, 225 and 300 mu M) on the resistant strains was observed using a method of growth curves. A significant growth inhibition (compared to control) of cadmium resistant cells was observed in the presence of all the four different antibiotics. On the other hand, the addition of streptomycin and ampicillin did not inhibit the growth of lead resistant strain. Other antibiotics were still toxic to the bacterial cells. Significant differences in the morphology of cell walls were indicated by changes in the cell shape. Our data show that the presence of metal ions in the urban environment may contribute to the development of bacterial strain resistance to other substances including antibiotics, which would have an impact on public health.
Induction of Laccase, Lignin Peroxidase and Manganese Peroxidase Activities in White-Rot Fungi Using Copper Complexes
(MDPI, 2016-11-01) Vršanská, Martina; Voběrková, Stanislava; Langer, Vratislav; Palovčíková, Dagmar; Moulick, Amitava; Adam, Vojtěch; Kopel, Pavel
Ligninolytic enzymes, such as laccase, lignin peroxidase and manganese peroxidase, are biotechnologically-important enzymes. The ability of five white-rot fungal strains Daedaleopsis confragosa, Fomes fomentarius, Trametes gibbosa, Trametes suaveolens and Trametes versicolor to produce these enzymes has been studied. Three different copper(II) complexes have been prepared ((Him)[Cu(im)4(H2O)2](btc) 3H2O, where im = imidazole, H3btc = 1,3,5-benzenetricarboxylic acid, [Cu3(pmdien)3(btc)](ClO4)3 6H2O) and [Cu3(mdpta)3(btc)](ClO4)3 4H2O, where pmdien = N,N,N0,N0 0, N0 0-pentamethyl-diethylenetriamine and mdpta = N,N-bis-(3-aminopropyl)methyl-amine), and their potential application for laccase and peroxidases induction have been tested. The enzyme-inducing activities of the complexes were compared with that of copper sulfate, and it has been found that all of the complexes are suitable for the induction of laccase and peroxidase activities in white-rot fungi; however, the newly-synthesized complex M1 showed the greatest potential for the induction. With respect to the different copper inducers, this parameter seems to be important for enzyme activity, which depends also on the fungal strains.
Amalgam electrode-based electrochemical detector for on-site direct determination of cadmium(II) and lead(II) from soils
(MDPI, 2017-08-01) Nejdl, Lukáš; Kynický, Jindřich; Brtnický, Martin; Vaculovičová, Markéta; Adam, Vojtěch
Toxic metal contamination of the environment is a global issue. In this paper, we present a low-cost and rapid production of amalgam electrodes used for determination of Cd(II) and Pb(II) in environmental samples (soils and wastewaters) by on-site analysis using difference pulse voltammetry. Changes in the electrochemical signals were recorded with a miniaturized potentiostat (width: 80 mm, depth: 54 mm, height: 23 mm) and a portable computer. The limit of detection (LOD) was calculated for the geometric surface of the working electrode 15 mm(2) that can be varied as required for analysis. The LODs were 80 ng.mL(-1) for Cd(II) and 50 ng.mL(-1) for Pb(II), relative standard deviation, RSD <= 8% (n = 3). The area of interest (Dolni Rozinka, Czech Republic) was selected because there is a deposit of uranium ore and extreme anthropogenic activity. Environmental samples were taken directly on-site and immediately analysed. Duration of a single analysis was approximately two minutes. The average concentrations of Cd(II) and Pb(II) in this area were below the global average. The obtained values were verified (correlated) by standard electrochemical methods based on hanging drop electrodes and were in good agreement. The advantages of this method are its cost and time effectivity (approximately two minutes per one sample) with direct analysis of turbid samples (soil leach) in a 2 M HNO3 environment. This type of sample cannot be analyzed using the classical analytical methods without pretreatment.

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