The Composites of Graphene Oxide with Metal or Semimetal Nanoparticles and Their Effect on Pathogenic Microorganisms

The present experiment describes a synthesis process of composites based on graphene oxide, which was tested as a carrier for composites of metal- or metalloid-based nanoparticles (Cu, Zn, Mn, Ag, AgP, Se) and subsequently examined as an antimicrobial agent for some bacterial strains (Staphylococcus aureus (S. aureus), methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia coli (E. coli). The composites were first applied at a concentration of 300 µM on all types of model organisms and their effect was observed by spectrophotometric analysis, which showed a decrease in absorbance values in comparison with the control, untreated strain. The most pronounced inhibition (87.4%) of S. aureus growth was observed after the application of graphene oxide composite with selenium nanoparticles compared to control. Moreover, the application of the composite with silver and silver phosphate nanoparticles showed the decrease of 68.8% and 56.8%, respectively. For all the tested composites, the observed antimicrobial effect was found in the range of 26% to 87.4%. Interestingly, the effects of the composites with selenium nanoparticles significantly differed in Gram-positive (G+) and Gram-negative (G−) bacteria. The effects of composites on bacterial cultures of S. aureus and MRSA, the representatives of G+ bacteria, increased with increasing concentrations. On the other hand, the effects of the same composites on G− bacteria E. coli was observed only in the highest applied concentration

A Reduced Graphene Oxide-based Electrochemical DNA Biosensor for the Detection of Interaction between Cisplatin and DNA based on Guanine and Adenine Oxidation Signals

A glassy carbon electrode (GCE) was modified by electrochemically reduced graphene oxide (ERGO) for subsequent dsDNA immobilization. The interaction of cisplatin with dsDNA was studied at this modified electrode. Quantitative investigations were performed by adsorptive transfer stripping voltammetry (AdTSV) using differential pulse voltammetry (DPV). The morphology and structure of graphene oxide (GO) and ERGO modified GCEs (GO/GCE and ERGO/GCE, respectively) were characterized by UV-vis, FT-IR, Raman spectroscopy and cyclic voltammetry. Compared with the bare GCE and the GO/GCE, the ERGO/GCE exhibited excellent electrocatalytic activity towards the oxidation of dsDNA due to guanine and adenine groups, testified by high oxidation peak currents and decreased oxidation potentials. The interaction of micromolar concentrations of cisplatin with surface confined dsDNA was readily detected as inferred from the decrease of the voltammetric oxidation peaks of guanine and adenine. This trend was significantly greater at the ERGO/GCE compared to the GO/GCE. The interaction of cisplatin with dsDNA was also studied in solution phase by AdTSV with detection at the ERGO/GCE.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Chování komplexů zinku a nanočástic a nanočástic sulfidu zinečnáteho s použitím tištěných elektrod a spektrometrie

In this study, we focused on microfluidic electrochemical analysis of zinc complexes (Zn(phen)(his)Cl-2, Zn(his)Cl-2) and ZnS quantum dots (QDs) using printed electrodes. This method was chosen due to the simple (easy to use) instrumentation and variable setting of flows. Reduction signals of zinc under the strictly defined and controlled conditions (pH, temperature, flow rate, accumulation time and applied potential) were studied. We showed that the increasing concentration of the complexes (Zn(phen)(his)Cl-2, Zn(his)Cl-2) led to a decrease in the electrochemical signal and a significant shift of the potential to more positive values. The most likely explanation of this result is that zinc is strongly bound in the complex and its distribution on the electrode is very limited. Changing the pH from 3.5 to 5.5 resulted in a significant intensification of the Zn(II) reduction signal. The complexes were also characterized by UV/VIS spectrophotometry, chromatography, and ESI-QTOF mass spectrometry.V této studii jsme se zaměřili na mikrofluidní elektrochemickou analýzu komplexů zinku (Zn (fenyl) (jeho) Cl-2, Zn (jeho) Cl-2) a ZnS kvantové tečky (QDS) za použití tištěných elektrod. Tato metoda byla zvolena z důvodu jednoduchému (snadné použití přístrojového vybavení) a variabilnímu nastavení toků. Byly studovány signály Redukční zinku v rámci přísně definovaných a kontrolovaných podmínek (pH, teplota, průtok, doba akumulace a aplikované potenciál). Ukázali jsme, že zvyšující se koncentrace komplexů (Zn (phen) (jeho) Cl-2, Zn (jeho) Cl-2) vede ke snížení elektrochemického signálu a významný posun potenciálu na více pozitivních hodnot. Nejpravděpodobnějším vysvětlením tohoto výsledku je, že zinek je silně vázána v komplexu a jeho rozložení na elektrodě je velmi omezený. Změna pH 3,5-5,5 vedlo k významnému zesílení Zn (II) signálu snížení. Komplexy byly také charakterizovány pomocí UV spektrofotometrie / VIS, chromatografie a ESI-QTOF hmotnostní spektrometrií. (Přeloženo strojově