Zuzana Němečková

Czech Academy of Sciences, Institute of Inorganic Chemistry

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Jiří Henych

Czech Academy of Sciences, Institute of Inorganic Chemistry

MŠ

Martin Šťastný

Czech Academy of Sciences, Institute of Inorganic Chemistry

Pavel Janoš

Jan Evangelista Purkyně University in Ústí nad Labem

ŠS

Štěpán Stehlík

Czech Academy of Sciences, Institute of Physics

Martin Kormunda

Jan Evangelista Purkyně University in Ústí nad Labem

Jakub Tolasz

Czech Academy of Sciences, Institute of Inorganic Chemistry

Alexander Kromka

Czech Academy of Sciences, Institute of Physics

Nadia Licciardello

Max Bergmann Zentrum für Biomaterialien

Gianaurelio Cuniberti

TU Dresden

Ivan Gordeev

Czech Academy of Sciences, Institute of Physics

Cooperative Institutions

Czech Academy of Sciences

Charles University

Czech Academy of Sciences, Institute of Physics

Jan Evangelista Purkyně University in Ústí nad Labem

Czech Academy of Sciences, Institute of Inorganic Chemistry

University of Chemistry and Technology, Prague

Centre National de la Recherche Scientifique

Bulgarian Academy of Sciences

VSB - Technical University of Ostrava

National University of Singapore

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Electrochemical Detection of Sialic Acid Using Phenylboronic Acid‐modified Poly(Diaminobenzoic Acid) Electrodes

Electroanalysis (2017)

Gabriela Broncová Pavel Matějka Zuzana Němečková Vladimír Vrkoslav Tatiana V. Shishkanová

Abstract This study is focused on the electrochemical detection of sialic acid (SA) using electrochemical impedance spectroscopy (EIS) and potentiometric approaches with the polymeric film derived from 3,4‐diaminobenzoic acid (3,4‐DABA) and modified with 3‐aminophenylboronic acid (3‐APBA). The polymeric film derived from 3,4‐DABA was prepared using cyclic voltammetry at 0.5 M H 2 SO 4 on a platinum disc electrode from 0 to 1.20 V vs. Ag/AgCl and characterized by FTIR‐Raman spectroscopy. It has been found that the polymerization process goes through the amino group and a free carboxyl group serves for the covalent binding of 3‐APBA onto the polymeric backbone. Both the electrochemical approaches independently confirmed the recognition of SA by APBA‐modified PDABA electrodes. In contrast to known electrochemical sensors in the literature, the APBA‐modified PADABA sensor for SA gave a response in the range from 0.025 to 0.998 mM at neutral pH using the EIS method. The decrease in the EIS signal of ca 12 % was observed after two weeks of intensive use. Importantly, the selective APBA‐modified polymeric electrode enabled the use of SA determination in artificial urine samples in a concentration range that is useful for diagnostic purposes, specifically 12–102 μg mL −1 .

Phenylboronic acid

Boronic acid

10.1002/elan.201700634

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Citations (14)

Zvládání extrémních situací

Miloslav Stehlík Zuzana Němečková Zdenko Reguli

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Enhanced visible-light photodegradation of fluoroquinolone-based antibiotics and E. coli growth inhibition using Ag–TiO₂ nanoparticles

RSC Advances (2021)

Jiao Wang Ladislav Svoboda Zuzana Němečková Massimo Sgarzi Jiří Henych

Antibiotics in wastewater represent a growing and worrying menace for environmental and human health fostering the spread of antimicrobial resistance. Titanium dioxide (TiO2) is a well-studied and well-performing photocatalyst for wastewater treatment. However, it presents drawbacks linked with the high energy needed for its activation and the fast electron-hole pair recombination. In this work, TiO2 nanoparticles were decorated with Ag nanoparticles by a facile photochemical reduction method to obtain an increased photocatalytic response under visible light. Although similar materials have been reported, we advanced this field by performing a study of the photocatalytic mechanism for Ag-TiO2 nanoparticles (Ag-TiO2 NPs) under visible light taking in consideration also the rutile phase of the TiO2 nanoparticles. Moreover, we examined the Ag-TiO2 NPs photocatalytic performance against two antibiotics from the same family. The obtained Ag-TiO2 NPs were fully characterised. The results showed that Ag NPs (average size: 23.9 ± 18.3 nm) were homogeneously dispersed on the TiO2 surface and the photo-response of the Ag-TiO2 NPs was greatly enhanced in the visible light region when compared to TiO2 P25. Hence, the obtained Ag-TiO2 NPs showed excellent photocatalytic degradation efficiency towards the two fluoroquinolone-based antibiotics ciprofloxacin (92%) and norfloxacin (94%) after 240 min of visible light irradiation, demonstrating a possible application of these particles in wastewater treatment. In addition, it was also proved that, after five Ag-TiO2 NPs re-utilisations in consecutive ciprofloxacin photodegradation reactions, only a photocatalytic efficiency drop of 8% was observed. Scavengers experiments demonstrated that the photocatalytic mechanism of ciprofloxacin degradation in the presence of Ag-TiO2 NPs is mainly driven by holes and ˙OH radicals, and that the rutile phase in the system plays a crucial role. Finally, Ag-TiO2 NPs showed also antibacterial activity towards Escherichia coli (E. coli) opening the avenue for a possible use of this material in hospital wastewater treatment.

Photodegradation

Visible spectrum

Titanium Dioxide

Rutile

10.1039/d0ra10403e

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Size Effects on Surface Chemistry and Raman Spectra of Sub-5 nm Oxidized High-Pressure High-Temperature and Detonation Nanodiamonds

The Journal of Physical Chemistry C (2021)

Štěpán Stehlík Michel Mermoux Bernhard Schummer Ondřej Vaněk Kateřina Kolářová

Understanding materials with dimensions down to a few nanometers is of major importance for fundamental science as well as prospective applications. Structural transformation and phonon-confinement effects in the nanodiamonds (NDs) have been theoretically predicted below 3 nm in size. Here, we investigate the effect of size on the surface chemistry, microscopic structure, and Raman scattering of high-pressure high-temperature (HPHT) and detonation nanodiamonds (DNDs) down to 2–3 nm. The surface and size of NDs are controlled by annealing in air and ultracentrifugation resulting in three ND fractions. Particle size distribution (PSD) of the fractions is analyzed by combining dynamic light scattering, analytical ultracentrifugation, small-angle X-ray scattering, X-ray diffraction, and transmission electron microscopy as complementary techniques. Based on the obtained PSD, we identify size-dependent and synthesis-dependent differences of ND properties. In particular, interpretation of Raman scattering on NDs is revisited. Comprehensive comparison of detonation and pure monocrystalline HPHT NDs reveals effects of diamond core size and defects, chemical and temperature (in)stability, and limitations of current phonon confinement models. In addition, low-frequency Raman scattering in the 20–200 cm–1 range is experimentally observed. The size dependence of this signal for both HPHT NDs and DNDs suggests that it may correspond to confined acoustic vibrational, "breathing-like" modes of NDs.

Nanometre

10.1021/acs.jpcc.0c09190

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Graphene Oxide Sheets Decorated with Octahedral Molybdenum Cluster Complexes for Enhanced Photoinactivation of Staphylococcus aureus

Inorganic Chemistry (2023)

Régis Guégan Xiaoxue Cheng Xiang Huang Zuzana Němečková Michaela Kubáňová

The emergence of multidrug-resistant microbial pathogens poses a significant threat, severely limiting the options for effective antibiotic therapy. This challenge can be overcome through the photoinactivation of pathogenic bacteria using materials generating reactive oxygen species upon exposure to visible light. These species target vital components of living cells, significantly reducing the likelihood of resistance development by the targeted pathogens. In our research, we have developed a nanocomposite material consisting of an aqueous colloidal suspension of graphene oxide sheets adorned with nanoaggregates of octahedral molybdenum cluster complexes. The negative charge of the graphene oxide and the positive charge of the nanoaggregates promoted their electrostatic interaction in aqueous medium and close cohesion between the colloids. Upon illumination with blue light, the colloidal system exerted a potent antibacterial effect against planktonic cultures of Staphylococcus aureus largely surpassing the individual contributions of the components. The underlying mechanism behind this phenomenon lies in the photoinduced electron transfer from the nanoaggregates of the cluster complexes to the graphene oxide sheets, which triggers the generation of reactive oxygen species. Thus, leveraging the unique properties of graphene oxide and light-harvesting octahedral molybdenum cluster complexes can open more effective and resilient antibacterial strategies.

10.1021/acs.inorgchem.3c01502

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Reusable and Antibacterial Polymer‐Based Nanocomposites for the Adsorption of Dyes and the Visible‐Light‐Driven Photocatalytic Degradation of Antibiotics

Global Challenges (2022)

Jiao Wang Massimo Sgarzi Zuzana Němečková Jiří Henych Nadia Licciardello

Adsorption and advanced oxidation processes, especially photocatalysis, are amongst the most common water treatment methodologies. Unfortunately, using each of these techniques independently does not fully eliminate the pollutants of diverse nature, which are present in wastewater. Here, an avenue for multifunctional materials for water treatment is opened by reporting for the first time the preparation, characterization, and study of the properties of a novel multifunctional nanocomposite with both adsorption and visible-light-driven photocatalysis abilities. These multifunctional nanocomposites, namely iron (II, III) oxide/poly(

Titanium Dioxide

Cationic polymerization

Visible spectrum

10.1002/gch2.202200076

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Room-temperature synthesis of nanoceria for degradation of organophosphate pesticides and its regeneration and reuse

RSC Advances (2020)

Jakub Tolasz Jiří Henych Martin Šťastný Zuzana Němečková Michaela Slušná

A simple low-temperature water-based and one-pot synthesis was developed for the preparation of nanocrystalline CeO2 that was used for degradation of the toxic organophosphate pesticide parathion methyl. By changing the reaction temperature in the range from 5 °C to 95 °C, several properties (i.e., crystallinity, grain size and surface area) of nanoceria can be easily controlled. The catalytic decomposition of parathion methyl to its degradation product 4-nitrophenol was highly dependent on the CeO2 preparation temperature. It was demonstrated that at low temperature (i.e. 5 °C), CeO2 with very small crystallites (<2 nm) and high surface area can be obtained. For practical use, it was demonstrated that highly crystalline CeO2 can be prepared at room-temperature (30 °C) in at least 100 g batches. It was shown that precipitated nanoceria had high thermal stability and its post-synthesis annealing up to 400 °C did not significantly alter the material properties and hence the catalytic activity. Furthermore, as shown by the reusability tests, the sorbent can be reactivated by simply washing with water which demonstrated its durability.

Nanocrystalline material

Degradation

Specific surface area

Thermal Stability

10.1039/d0ra00937g

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Využívanie všeobecne platných princípov vo vyučovaní pohybovýchvzorcov profesnej sebaobrany na Strednej odbornej školePolicajného zboru v Pezinku

Andrej Poláček Zdenko Reguli Martin Sebera Miloslav Stehlík Zuzana Němečková

Cilem studie bylo zjistit vliv obecných principů ve výcviku pohybových struktur v profesni sebeobraně. Sledovali jsme 20 studentů Středni odborne skoly Policejniho sboru Slovenske republiky v experimentalni skupině a 20 studentů stejne skoly v kontrolni skupině.. Po dobu řizeneho pedagogickeho experimentu obě skupiny absolvovaly výcvik specialni tělesne výchovy (144 hodin). Vzdělavaci program byl u obou skupin stejný z hlediska objemu (144 hodin tělesne připravy), struktury (stala struktura vyucovaci hodiny), frekvence (dvě vyucovaci hodiny a jedna hodina docvicovani týdně) a intenzity (dane tematickým planem tělesne připravy). Pohybova připrava byla stejna ve složkach: psychicke (odstraňovani stresu z fyzickeho kontaktu a strachu z padů), fyzicke (objem, frekvence a intenzita treninkových jednotek), takticke (zejmena legislativni podminky), technicke (předepsane tematickým planem tělesne připravy). U experimentalni skupiny byly použivane didakticke pravidla aikido, ktere byly experimentalnim faktorem. Na konci experimentu byli vsichni participanti testovani ve specifických sebeobranných dovednostech. Pět zaměrně vybraných expertů hodnotilo podle specificke skaly sebeobranný dovednosti z videozaznamů. Experimentalni faktor měl statisticky významný vliv na kvalitu osvojeni specifických sebeobranných dovednosti.

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Laser-Induced Modification of Hydrogenated Detonation Nanodiamonds in Ethanol

Nanomaterials (2021)

Irena Bydzovska Ekaterina Shagieva Ivan Gordeev O. Romanyuk Zuzana Němečková

Apart from the frequently used high-temperature annealing of detonation nanodiamonds (DNDs) in an inert environment, laser irradiation of DNDs in a liquid can be effectively used for onion-like carbon (OLC) formation. Here, we used fully de-aggregated hydrogenated DNDs (H-DNDs) dispersed in ethanol, which were irradiated for up to 60 min using a 532 nm NdYAG laser with an energy of 150 mJ in a pulse (5 J/cm2) at a pulse duration of 10 ns and a repetition rate of 10 Hz. We investigated the DND surface chemistry, zeta potential, and structure as a function of laser irradiation time. Infrared spectroscopy revealed a monotonical decrease in the C–Hx band intensities and an increase of the C–O and C=O features. Transmission electron microscopy (TEM) revealed the formation of OLC, as well as a gradual loss of nanoparticle character, with increasing irradiation time. Surprisingly, for samples irradiated up to 40 min, the typical and unchanged DND Raman spectrum was recovered after their annealing in air at 450 °C for 300 min. This finding indicates the inhomogeneous sp3 to sp2 carbon transformation during laser irradiation, as well as the insensitivity of DND Raman spectra to surface chemistry, size, and transient structural changes.

Zeta potential

10.3390/nano11092251

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Citations (6)

Size Effects on Surface Chemistry and Raman Spectra of Sub-5 nm Oxidized High-Pressure High-Temperature and Detonation Nanodiamonds

The Journal of Physical Chemistry (2021)

Štěpán Stehlík Michel Mermoux Bernhard Schummer Ondřej Vaněk Kateřina Kolářová

Understanding materials with dimensions down to a few nanometers is of major importance for fundamental science as well as prospective applications. Structural transformation and phonon-confinement effects in the nanodiamonds (NDs) have been theoretically predicted below 3 nm in size. Here, we investigate the effect of size on the surface chemistry, microscopic structure, and Raman scattering of high-pressure high-temperature (HPHT) and detonation nanodiamonds (DNDs) down to 2–3 nm. The surface and size of NDs are controlled by annealing in air and ultracentrifugation resulting in three ND fractions. Particle size distribution (PSD) of the fractions is analyzed by combining dynamic light scattering, analytical ultracentrifugation, small-angle X-ray scattering, X-ray diffraction, and transmission electron microscopy as complementary techniques. Based on the obtained PSD, we identify size-dependent and synthesis-dependent differences of ND properties. In particular, interpretation of Raman scattering on NDs is revisited. Comprehensive comparison of detonation and pure monocrystalline HPHT NDs reveals effects of diamond core size and defects, chemical and temperature (in)stability, and limitations of current phonon confinement models. In addition, low-frequency Raman scattering in the 20–200 cm–¹ range is experimentally observed. The size dependence of this signal for both HPHT NDs and DNDs suggests that it may correspond to confined acoustic vibrational, “breathing-like” modes of NDs.

Nanometre

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