Jiri Tucek

Palacký University of Olomouc, Olmütz, Olomoucký, Czech Republic

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Publications (64)188.69 Total impact

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    ABSTRACT: The synthesis of tin–titanate nanotubes (Sn-titanate) by reacting hydrogen titanate (H-titanate) with a tin salt through ion adsorption–incorporation is reported. The interactions between tin(II) ions and H-titanate are thoroughly investigated. Tin ions can be easily adsorbed by H-titanate, owing to its large surface area and lattice spacing, and the negatively charged layered structures. With Sn-titanate nanotubes as precursors, Sn-doped TiO2 nanoparticles are prepared by annealing and are investigated as anode materials in lithium-ion batteries, which show much enhanced capacity and rate capability. Such improved electrochemical properties of Sn-doped TiO2 benefit from structural characteristics such as the small size of the constituent nanoparticles, high crystallinity, and uniform tin doping. This synthetic strategy towards Sn-doped TiO2 anode materials, thus offers the synergistic effect of combining the advantages of TiO2 (cycle life and rate) and SnO2 (high capacity).
    ChemElectroChem. 09/2014;
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    ABSTRACT: Owing to the three different orbital hybridizations carbon can adopt, the existence of various carbon nanoallotropes differing also in dimensionality has been already affirmed with other structures predicted and expected to emerge in the future. Despite numerous unique features and applications of 2D graphene, 1D carbon nanotubes or 0D fullerenes, nanodiamonds and carbon quantum dots, which have been already heavily explored, any of existing carbon allotropes does not offer competitive magnetic properties. For challenging applications, carbon nanoallotropes are functionalized with magnetic species, especially of iron oxide nature, due to their interesting magnetic properties (superparamagnetism and strong magnetic response under external magnetic fields), easy availability, biocompatibility, and low cost. In addition, combination of iron oxides (magnetite, maghemite, hematite) and carbon nanostructures brings enhanced electrochemical performance and (photo)catalytic capability due to synergetic and cooperative effects. This work aims at reviewing these advanced applications of iron-oxide-supported nanocarbon composites where iron oxides play a diverse role. Various architectures of carbon/iron oxide nanocomposites, their synthetic procedures, physicochemical properties, and applications are discussed in details. A special attention is devoted to hybrids of carbon nanotubes and rare forms (mesoporous carbon, nanofoam) with magnetic iron oxide carriers for advanced environmental technologies. The review also covers the huge application potential of graphene/iron oxide nanocomposites in the field of energy storage, biomedicine, and remediation of environment. Among various discussed medical applications, magnetic composites of zero-dimensional fullerenes and carbon dots are emphasized as promising candidates for complex theranostics and dual magneto-fluorescence imaging.
    ACS Nano 07/2014; · 12.03 Impact Factor
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    ABSTRACT: An efficient and sustainable protocol is described for the oxidative esterification of aldehydes and the reduction of aromatic nitro compounds that uses a magnetically separable and reusable maghemite-supported gold nanocatalyst (nanocat-Fe–Au) under mild conditions. The complex chemical, morphological, structural and size analyses, including e.g. XPS, HRTEM, in-field Mössbauer spectroscopy and HRTEM, revealed that the hybrid material is composed of a well-defined stoichiometric maghemite support (20–30 nm) decorated with ultrasmall (5–6 nm) gold nanoparticles. The hybrid catalytic system containing 4 wt% of nanogold has been generated using simple impregnation methods in aqueous medium from readily available starting materials and was recycled five times without any significant loss in catalytic activity; high yields, 40–95% and 83–94% for oxidative esterification and reduction reactions, respectively, were obtained.
    Green Chemistry 06/2014; · 6.83 Impact Factor
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    ABSTRACT: Magnetization and low temperature in-field 57Fe Mössbauer spectroscopy measurements have been performed on a Fe[C(SiMe3)3]2/ferrihydrite hetero-mixture. The results indicate the presence of ferromagnetic coupling of magnetic moments involving Fe[C(SiMe3)3]2 with a hyperfine magnetic field of about 151 T, attributable mainly to the non-frozen atomic orbital contribution. The present findings show the sensitivity of single-ion molecular magnets to local alterations of their lattice-environment and might explain and reconcile some of the differences found in the literature for the observed bulk magnetic properties of the title Fe[C(SiMe3)3]2 compound.
    Berichte der deutschen chemischen Gesellschaft 06/2014; · 2.94 Impact Factor
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    ABSTRACT: Airless planetary bodies are directly exposed to space weathering. The main spectral effects of space weathering are darkening, reduction in intensity of silicate mineral absorption bands, and an increase in the spectral slope towards longer wavelengths (reddening). Production of nanophase metallic iron (npFe$^{0}$) during space weathering plays major role in these spectral changes. A laboratory procedure for the controlled production of npFe$^{0}$ in silicate mineral powders has been developed. The method is based on a two-step thermal treatment of low-iron olivine, first in ambient air and then in hydrogen atmosphere. Through this process, a series of olivine powder samples was prepared with varying amounts of npFe$^{0}$ in the 7-20 nm size range. A logarithmic trend is observed between amount of npFe$^{0}$ and darkening, reduction of 1 um olivine absorption band, reddening, and 1 um band width. Olivine with a population of physically larger npFe$^{0}$ particles follows spectral trends similar to other samples, except for the reddening trend. This is interpreted as the larger, ~40-50 nm sized, npFe$^{0}$ particles do not contribute to the spectral slope change as efficiently as the smaller npFe$^{0}$ fraction. A linear trend is observed between the amount of npFe$^{0}$ and 1 um band center position, most likely caused by Fe$^{2+}$ disassociation from olivine structure into npFe$^{0}$ particles.
    Icarus. 04/2014; 237.
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    ABSTRACT: A chiral metal-organic framework exhibiting spin crossover (SCO) property, [Fe(II)(mptpy)2]·EtOH·0.2DMF (·solv), has been solvothermally synthesized through spontaneous resolution. It displays remarkable stability and two-step SCO at (Tc1 = 200 K) and above (Tc2 = 357 K) room temperature.
    Chemical Communications 03/2014; · 6.38 Impact Factor
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    ABSTRACT: Most of the spectral changes related to space weathering and presence of iron nanoparticles evolve logarithmically with time.
    02/2014;
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    ABSTRACT: Clustering of biocompatible magnetic iron oxide nanocrystallites (MIONs) is a synthetic strategy which improves magnetic manipulation, imaging, and sensing for biomedical applications. In this work we describe the synthesis of condensed clustered MIONs obtained through biomineralization and epitaxial aggregation in the presence of alginate at ambient conditions, mimicking the process that so far has been achieved only by nature, in iron-oxidizing bacteria. These condensed-type magnetic nanostructures exhibit higher magnetophoretic responses compared to other types of magnetic colloids and clustered systems. The soft environ mental conditions used for the synthesis of the magnetic nanosystems enables the alginate coating material to retain high drug loading ability for the doxorubicin molecule as well as strong binding proclivity for radionuclides. The strong binding of doxorubicin forms the physical basis to obtain magnetic nanocarriers, where the selective release of the drug occurs only under the action of external stimuli, such as remote magnetic hyperthermia or increased temperature (i.e., inflamed tissue). Furthermore, the strong binding proclivity of radionuclides facilitates in vivo SPECT imaging. The witnessed properties are obtained by using only ∼17 wt % alginate content in the magnetic superstructures; thus, very high saturation magnetization value is imparted to the condensed system, expressed in terms of the hybrid’s mass. In spite of the fact that the magnetic nanoassemblies are characterized by low hydrodynamic diameter, ∼45 nm, the transverse relaxivity reaches the remarkable value of 250 s−1 mM−1 Fe (for negative MION contrast agents of this size), a property that va+lidates the use of these nanostructures as effective MRI contrast agents.
    Chemistry of Materials 02/2014; · 8.24 Impact Factor
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    ABSTRACT: Superparamagnetic iron oxide nanoparticles (SPIO) are regarded as advanced tools in biomedical science in disease diagnostics and therapies. We report the synthesis of antibody-conjugated nanoparticles (Ab-SPIO) that combine MRI behavior of nanoparticles with the selective and specific targeting of cellular proteins. Our novel Ab-SPIO will serve as a MRI biomarker for preventive PAH diseases. It is known that adenosine 1-type receptors (A1R) are involved in several cardiovascular diseases and offer promising therapeutic potential. In our study, we developed new A1R antibodies (Ab) conjugated SPIO nanocar-riers as a specific Ab-MRI contrast agent. Spherical magnetite nanoparticles with a hydrodynamic diameter of 145 nm and particle size distribution of 15 -60 nm were obtained. Surface of SPIO nanoparticles was stabilized by biocompatible polymer carboxymethyl cellulose (CMC) and precisely charac-terized in stability by measuring of zeta potential (-43 mV). Strong magnetic response with a saturation magnetization of 75 Am 2 /kg confirmed appropriate magnetic behavior for MRI application. Oriented immobilization of antibody (Adenosine A1-R Antibody (H-40)) on free carboxyl groups of CMC provides active targeting of adenosine receptors. We conducted microscopic evaluation of the Ab-SPIO probe in VVEC cells, localization (plasma membrane vs. intracellular), and we determined the effects of hypoxia on A1R expression, compared A1R expression in VVEC-Hyp vs. VVEC-Co, and determined the effects of acute hypoxia on A1R expression in VVEC-Hyp vs. VVEC-Co. The experiments are proposed for MRI imaging of VV in control and hyp-oxic animals. Functionalized A1R-Ab-SPIO complexes will be utilized as a specific MRI biomarker in early disease diagnostics.. Living systems control transport of ions or small molecules across biological membranes using ion channels that form highly efficient and selective pores in lipid bilayers. Although bottom-up synthesis and top-down fabrication could produce pores of comparable size, an unresolved challenge remains to build nanopore scaffolds that fully replicate transport properties of mem-brane channels. We will show that pores in lipid membranes formed by ultra-short carbon nanotubes (CNTs) have transport properties that come remark-ably close to that goal. These carbon nanotube channels can transport water, protons, small ions, and DNA and their ion-rejection properties can be controlled by the charge at the pore mouth. Interestingly, these pores also display the stochastic "gating" behavior common for biological ion channels. We attribute this effect to a spontaneous reversible ionic "penetration-exclu-sion" transition, suggesting that it represents a general feature of nanofluidic transport in sub-2-nm pores. Overall, transmembrane CNT ion channels represent a robust and versatile biomimetic scaffold for studying fundamen-tals of transport in biological channels, artificial cell design, and stochastic sensing.. Polymeric systems have been purposed for drug delivery, tissue engineering and bioimaging by the medical community due to a host of properties and functions that may be designed into their structure. The most recently recog-nized members of the polymer family, dendrimers, are garnering significant
    58th Annual Meeting of the Biophysical Society; 02/2014
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    ABSTRACT: Magnetic properties of anion-radical TCNQ salt [Fe(dipy)3](TCNQ)4·(CH3)2CO have been investigated (dipy is 2,2′-dipyridil). X-ray diffraction data allow presence of two types of TCNQ stacks: tetramerized (diamagnetic) and partly dimerized (paramagnetic). Due to Mössbauer spectroscopy data iron cation appears as two-valent ion in low-spin state. Magnetic susceptibility temperature dependence is described by Bonner–Fischer model with additional weak impurity paramagnetism. Susceptibility curve is in good qualitative agreement with ESR spectra.
    Synthetic Metals 01/2014; 194:7–10. · 2.11 Impact Factor
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    ABSTRACT: When developing new nanoparticles for bio-applications, it is important to fully characterize the nanoparticle's behavior in biological systems. The most common techniques employed for mapping nanoparticles inside cells include transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). These techniques entail passing an electron beam through a thin specimen. STEM or TEM imaging is often used for the detection of nanoparticles inside cellular organelles. However, lengthy sample preparation is required (i.e., fixation, dehydration, drying, resin embedding, and cutting). In the present work, a new matrix (FTO glass) for biological samples was used and characterized by field emission scanning electron microscopy (FE-SEM) to generate images comparable to those obtained by TEM. Using FE-SEM, nanoparticle images were acquired inside endo/lysosomes without disruption of the cellular shape. Furthermore, the initial steps of nanoparticle incorporation into the cells were captured. In addition, the conductive FTO glass endowed the sample with high stability under the required accelerating voltage. Owing to these features of the sample, further analyses could be performed (material contrast and energy-dispersive X-ray spectroscopy (EDS)), which confirmed the presence of nanoparticles inside the cells. The results showed that FE-SEM can enable detailed characterization of nanoparticles in endosomes without the need for contrast staining or metal coating of the sample. Images showing the intracellular distribution of nanoparticles together with cellular morphology can give important information on the biocompatibility and demonstrate the potential of nanoparticle utilization in medicine.
    Micron 01/2014; · 1.88 Impact Factor
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    ABSTRACT: We present a simple molecular approach to control the lipophilic/hydrophilic nature of photoluminescent carbon dots (CDs) based on pyrolysis of alkyl gallate precursors. Depending on the gallic acid derivative used, CDs with different alkyl groups (methyl, propyl, lauryl) on the surface can be obtained by isothermal heating at 270 °C. This precursor-derived approach allows not only the control of lipophilicity but also the length of the particular alkyl chain enables the control over both the size and photoluminescence (PL) of the prepared CDs. Moreover, the alkyl chains on the CDs surface can be readily converted to carboxylate groups via a mild base hydrolysis to obtain water dispersible CDs with a record biocompatibility. The observed differences in PL properties of CDs and time-resolved PL data, including contributions from carbogenic cores and surface functional group, are rationalized and discussed in detail using time-dependent density functional theory (TD-DFT) calculations.
    Carbon. 01/2014; 70:279–286.
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    ABSTRACT: Speed of data processing is regarded as a crucial parameter in the nuclear physics experiment, where a dead time elimination or reduction is needed. In the case of computer-based systems, fast data processing algorithms are necessary to be exploited for saving a computational time and to reduce a total duration of the experiment. Time of measurement is one of the key parameters for implementation of specific experiments. Fast pulse processing algorithm (FPPA) of detector events was developed in LabVIEW™ and is capable to run up to 70% faster compared to the performance of previously used algorithm. The results show increased performance and applicability in complex experiments. Detailed description of the overall algorithm with relevant data flow processing and its utilization in Mössbauer spectrometer is presented.
    12/2013; 9(01).
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    ABSTRACT: Lunar-type space weathering of airless bodies is associated with nanophase iron (npFe0) production in Fe bearing silicate minerals that is often responsible for observable changes of its reflectance spectra. A new method of controlled npFe0 production on olivine grains was developed in order to quantitatively evaluate spectral changes related to space weathering and presence of npFe0. Through a two-step thermal treatment a series of olivine samples with increasing concentration of iron nanoparticles on the grain surfaces was prepared. The grain size of the npFe0 particles was kept in the same range 5-20 nm). Magnetic methods were used to estimate npFe0 concentration. Compared to fresh olivine, treated samples exhibit the spectral characteristics of lunar type space weathering (darkening, shallowing of 1 µm olivine absorption band, and reddening) related to increasing presence of npFe0. From quantitative point of view, a logarithmic trend was found between spectral changes and npFe0 concentration. One sample with additional population of larger ~50 nm npFe0 particles follows the darkening and the 1 µm band shallowing trend, but does not fully follow the reddening trend. This is due to fact that the larger 40 50 nm sized) npFe0 particles do not contribute to the spectral slope change. The observed logarithmic trend between the spectral changes and the npFe0 concentration give constrains on time evolution of space weathering. In the case of constant micro impact, solar wind and cosmic radiation on a regolith, the npFe0 concentration increases linearly with time while spectral changes related to space weathering evolve logarithmically with time.
    10/2013;
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    ABSTRACT: A novel core-shell nanomaterial based on prussian blue (PB) coating on peculiar surface active maghemite nanoparticles (SAMNs), was developed. The synthetic process involves the direct crystallization of Fe(II)(CN)6(4-) onto the surface of SAMNs by simple incubation in water at controlled pH, demonstrating the presence of under-coordinated Fe(III) on nanoparticle surface. The coating reaction occurs in a narrow pH range and the synthetic procedure was optimized. The resulting SAMN@PB hybrid nanostructures were characterized by transmission and scanning electron microscopy, Mössbauer, UV-vis and FTIR spectroscopy and X-ray powder diffraction. The nanomaterial, characterized by high stability in alkaline media, behave as excellent electro-catalyst for hydrogen peroxide reduction. The stability of SAMN@PB hybrid has been investigated as a function of pH, showing excellent stability up to pH 9.0 and demonstrating the feasibility of SAMNs, superficially derivatized with prussian blue, to produce an efficient and extremely stable nanostructured material. This maghemite supported nanostructured prussian blue was applied to develop a sensor, based on a simple carbon paste electrode, which was able to catalyze the electro-reduction of hydrogen peroxide, in aqueous solutions, buffered at pH 7.0, at low applied potentials (0.0V vs. SCE).
    Biosensors & bioelectronics 08/2013; 52C:159-165. · 5.43 Impact Factor
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    ABSTRACT: Hierarchical assembly of Ti(iv)/Sn(ii)-doped SnO2 nanosheets along titanate nanowires serving as both sacrificial templates and a Ti(iv) source is demonstrated, using SnCl2 as a tin precursor and Sn(ii) dopants and NaF as the morphology controlling agent. Excess fluoride inhibits the hydrolysis of SnCl2, promoting heterogeneous nucleation of Sn(ii)-doped SnO2 on the titanate nanowires due to the insufficient oxidization of Sn(ii) to Sn(iv). Simultaneously, titanate nanowires are dissolved forming Ti(4+) species under the etching effect of in situ generated HF resulting in spontaneous Ti(4+) ion doping of SnO2 nanosheets formed under hydrothermal conditions. Compositional analysis indicates that Ti(4+) ions are incorporated by substitution of Sn sites at a high level (16-18 at.%), with uniform distribution and no phase separation. Mössbauer spectroscopy quantified the relative content of Sn(ii) and Sn(iv) in both Sn(ii)-doped and Ti(iv)/Sn(ii) co-doped SnO2 samples. Electrochemical properties were investigated as an anode material in lithium ion batteries, demonstrating that Ti-doped SnO2 nanosheets show improved cycle performance, which is attributed to the alleviation of inherent volume expansion of the SnO2-based anode materials by substituting part of Sn sites with Ti dopants.
    Nanoscale 08/2013; · 6.23 Impact Factor
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    ABSTRACT: MCM-41-supported nanoscale zero-valent iron (nZVI) was sytnhesized by impregnating the mesoporous silica martix with ferric chloride, followed by chemical reduction with NaHB4. The samples were studied with a combination of characterization techniques such as powder X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) and Mössbauer spectroscopy, N2 adsorption measurements, transmission electron microscopy (TEM), magnetization measurements, and thermal analysis methods. The experimental data revealed development of nanoscale zero-valent iron particles with an elliptical shape and a maximum size of ∼80nm, which were randomly distributed and immobilized on the mesoporous silica surface. Surface area measurements showed that the porous MCM-41 host matrix maintains its hexagonal mesoporous order structure and exhibits a considerable high surface area (609m(2)/g). Mössbauer and magnetization measurements confirmed the presence of core-shell iron nanoparticles composed of a ferromagnetic metallic core and an oxide/hydroxide shell. The kinetic studies demonstrated a rapid removal of Cr(VI) ions from the aqueous solutions in the presence of these stabilized nZVI particles on MCM-41, and a considerably increased reduction capacity per unit mass of material in comparison to that of unsupported nZVI. The results also indicate a highly pH-dependent reduction efficiency of the material, whereas their kinetics was described by a pseudo-first order kinetic model.
    Journal of hazardous materials 07/2013; 261C:295-306. · 4.14 Impact Factor
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    ABSTRACT: We present the first direct evidence that reactant particle size determines the mechanism of thermally induced solid-state reactions and can be used as the tuner of the product crystal structure. This control of the polymorphous character of the products through the particle size of precursor is demonstrated upon following the process of isothermal decomposition of Prussian Blue at 350 uC in air. The reaction mechanism was studied by 57Fe Mo¨ssbauer spectroscopy, X-ray powder diffraction, magnetization measurements, and transmission and scanning electron microscopy. The decomposition of Prussian Blue nanoparticles (10–15 nm) gave preferential formation of c-Fe2O3 nanoparticles (10–20 nm), while Prussian Blue microcrystals (20–50 mm) afforded formation of b-Fe2O3 nanoparticles (50–70 nm). The final polymorphous composition of the iron(III) oxide product is thought to be driven by the different diffusion conditions for penetration of the reaction gas (oxygen) into the Prussian Blue crystals as well as release of the gas (dicyane) during the Prussian Blue decomposition. Therefore, the reactant particle size control provides a new method for the large-scale preparation of rare b-Fe2O3 nanoparticles.
    RSC Advances 07/2013; · 3.71 Impact Factor
  • Polyhedron 05/2013; · 2.05 Impact Factor

Publication Stats

178 Citations
188.69 Total Impact Points

Institutions

  • 2004–2014
    • Palacký University of Olomouc
      • • Regional Centre of Advanced Technologies and Materials
      • • Faculty of Science
      • • Department of Experimental Physics
      Olmütz, Olomoucký, Czech Republic
  • 2012
    • Academy of Sciences of the Czech Republic
      • Botanický ústav
      Praha, Hlavni mesto Praha, Czech Republic
    • University of Zanjan
      • Department of Chemistry
      Zanjān, Zanjan, Iran
    • Helmholtz-Zentrum Berlin
      Berlín, Berlin, Germany