The surface modification of the silica-coated magnetic nanoparticles and their application in molecular diagnostics of virus infection.

The study presents a series of examples of magnetic nanoparticle systems designed for the diagnosis of viral diseases. In this interdisciplinary work, we describe one of the most comprehensive synthetic approaches for the preparation and functionalization of smart nanoparticle systems for rapid and effective RT-PCR diagnostics and isolation of viral RNA. Twelve different organic ligands and inorganic porous silica were used for surface functionalization of the Fe3O4 magnetic core to increase the number of active centres for efficient RNA binding from human swab samples. Different nanoparticle systems with common beads were characterized by HRTEM, SEM, FT-IR, XRD, XPS and magnetic measurements. We demonstrate the application of the fundamental models modified to fit the experimental zero-field cooling magnetization data. We discuss the influence of the nanoparticle shell parameters (morphology, thickness, ligands) on the overall magnetic performance of the systems. The prepared nanoparticles were tested for the isolation of viral RNA from tissue samples infected with hepatitis E virus-HEV and from biofluid samples of SARS-CoV-2 positive patients. The efficiency of RNA isolation was quantified by RT-qPCR method.

Gadolinium-oxide nanoparticles for cryogenic magnetocaloric applications.

The series of advanced nanocomposites consisting of Gd2O3 nanoparticles (NPs) embedded into periodic porous SiO2 matrix have been investigated with respect to their structural and magnetocaloric properties. By means of small angle neutron scattering and transmission electron microscopy, regular nanopores organized in the cubic or hexagonal superlattice have been documented. The pores are occupied by the NPs of progressive concentration within the nanocomposite series. All of the examined systems have exhibited extraordinarily high values of magnetic entropy change (up to 70 J kg-1 K-1) at low temperatures with the absence of thermal hysteresis, indicating their perspective utilization in cryogenic refrigeration. Profound analysis of magnetic entropy change data via scaling laws has been applied to the nanocomposite materials for the very first time. With the aid of scaling analysis, conclusions on magnetic properties and phase transition type have been made, even for the conditions unavailable in the laboratory.

Fe2O3 and Gd2O3 nanoparticles loaded in mesoporous silica: insights into influence of NPs concentration and silica dimensionality.

Fine Fe2O3 and Gd2O3 magnetic nanoparticles (NPs) with sizes 7 nm and 10 nm embedded into mesoporous silica have been prepared using a wet-impregnation method. A comparative study of the reactant concentration along with the hosting matrix symmetry on mesostructuring and the magnetic properties of the nanocomposites have been investigated. Reactants with four different concentrations of Fe3+ and Gd3+ ions and silica matrices with two different kinds of symmetry (hexagonal and cubic) have been utilized for the study. The structural characterization of the samples has been carried out by the N2 adsorption/desorption method, high-energy X-ray diffraction (HE-XRD), TG/DTA, and high resolution transmission electron microscopy (HRTEM). The magnetic properties of the nanocomposites have been examined by means of SQUID magnetometry. It has been found that a range of different magnetic states (diamagnetic, paramagnetic, ferromagnetic, superparamagnetic) can be induced by the feasible tailoring of the particle concentration, the porous matrix symmetry and the composition. Furthermore, the existence of a "critical concentration limit" for embedding the particles within the body of the matrix has been confirmed. Exceeding the limit results in the expulsion of nanoparticles on the outer surface of the mesoporous matrix. Revelation of the relationships between particle concentration, matrix symmetry and magnetic properties of the particular composite reported in this study may facilitate the design and construction of advanced intelligent nanodevices.

Novel Zn(II) complexes with non-steroidal anti-inflammatory ligand, flufenamic acid: Characterization, topoisomerase I inhibition activity, DNA and HSA binding studies.

A series of new Zn(II) complexes with flufenamic acid (flu) has been synthesized, namely [Zn3(dmso)2(flu)6] (1), [Zn3(flu)6(py)2] (2), [Zn(flu)2(tmen)] (3), [ZnCl(flu)(neo)] (4), and [Zn(cyclam)(flu)2] (5), where py=pyridine, tmen=N,N,N',N'-Tetramethylethylene diamine, neo=2,9-Dimethyl-1,10-phenanthroline and cyclam=1,4,8,11-Tetraazacyclotetradecane. These complexes have been characterized by infrared spectroscopy, single-crystal X-ray structure analysis, elemental and thermal analysis. All complexes contain deprotonated flufenamic acid coordinated via carboxylato group to zinc atoms, but their structures differ in the carboxylato binding mode, the coordination number of the central atom, the shape of the coordination polyhedra and the resultant supramolecular structures. Furthermore, an interaction of complexes with calf-thymus DNA (CT DNA) and human serum albumin (HSA) has been investigated by spectroscopic techniques. Moreover, the complexes 1 and 2 inhibit the catalytic activity of topoisomerase I at 60µM.

Utilization of IR spectral detailed analysis for coordination mode determination in novel Zn-cyclen-aminoacid complexes.

The infrared spectra, elemental and thermal (TG/DTG and DTA) analyses of novel [Zn(cyclen-κ4N1,4,7,10)(HGly-κ2O,O')](ClO4)2 (1), and [Zn2(cyclen-κ4N1,4,7,10)2(µ-S-Ala-κ2N,O)](ClO4)(3)·2H2O (2) complexes (cyclen - 1,4,7,10-tetraazacyclododecane) were recorded and analyzed in the relation to their structural peculiarities. IR spectral data indicate both mono- or bidentate coordination mode of a carboxylate group in the prepared complexes (at pH≈9). The results indicate unusual bidentate carboxylate coordination mode (in complex (1)) toward to Zn2+-cyclen unit. Therefore the crystal structure determination of the crystalline complex [Zn(cyclen-κ4N1,4,7,10)(NO3-κ2O,O')](NO3) was attached in order to support the coordination mode assignment in complex (1).

Correlation of infrared spectra of zinc(II) carboxylates with their structures.

The correlation of the infrared spectra of zinc(II) carboxylates with their structures was investigated in the paper. The complexes with different modes of the carboxylate binding, from chelating, through bridging (syn-syn, syn-anti, monatomic), ionic to monodentate were used for the study, namely [Zn(C6H5CHCHCOO)2(H2O)2] (I) with chelating carboxylate group (C6H5CHCHCOO=cinnamate), [Zn2(C6H5COO)4(pap)2] (II) with syn-syn bridging carboxylate (C6H5COO=benzoate; pap=papaverine), [Zn(C6H5CHCHCOO)2(mpcm)]n (III) with syn-anti carboxylate bridge (mpcm=methyl-3-pyridylcarbamate), [Zn(C5H4NCOO)2(H2O)4] (IV) with ionic carboxylate group (C5H4NCOO=nicotinate), [Zn(C6H5COO)2(pcb)2]n (V) with monodentate carboxylate coordination (pcb=3-pyridylcarbinol) and [Zn3(C6H5COO)6(nia)2] (VI) with syn-syn and monatomic carboxylate bridges (nia=nicotinamide). First, the mode of the carboxylate binding was assigned from the infrared spectra using the magnitude of the separation between the carboxylate stretches, Deltaexp=nuas(COO-)-nus(COO-). Then the values Deltaexp were compared with those calculated from structural data of the carboxylate anion (Deltacalc). The conclusions about the carboxylate binding which resulted from the Delta values, were confronted with the crystal structure of the complexes. The limitations and recommendations were formulated to assign the mode of the carboxylate binding from the infrared spectra. The dependence of the Deltaexp values on the magnitudes of Zn-O-C angles in bidentate carboxylate coordination was observed.

Oxidation behavior of Ru/TiO2 and metallic Ru fine particles on heating in air.

Thermogravimetry (TG) and differential thermal analysis (DTA) were used to investigate the oxidation behavior of Ru/TiO2 and metallic Ru fine particles during heating in air in the range 20-1000 degrees C. Temperature ranges of the oxidation for two samples of Ru/TiO2 with the compositions (92 wt% Ru, 8 wt% TiO2) and (75 wt% Ru, 25 wt% TiO2) and for pure metallic Ru fine particle agglomerates were determined. It was assumed that after the partial oxidation of Ru in the sample containing 75 wt% Ru and 25 wt% TiO2 and in the pure metallic Ru a diffusion barrier was formed, preventing further oxidation of Ru in Ru/RuO2 and Ru/RuO2/TiO2 matrices. XRD and TEM were used for the sample characterization.

Antibacterial and Antifungal Activity of Zinc(II) Carboxylates With/Without N-Donor Organic Ligands.

The antibacterial and antifungal activity of zinc(II) carboxylates with composition Zn(RCOO)(2)*nH(2)O(R =H-, CH(3) (-), CH(3)CH(2)CH(2) (-), (CH(3))(2)CH-, XCH(2) (-), X=Cl, Br, I, n=0 or 2), [ZnX(2)(Nia(+)CH(2)COO(-))(2)](Nia=nicotinamide, X=Cl, Br, I) and [Zn(XCH(2)COO)(2)(Caf)(2)]*2H(2)O (Car=caffeine, X=Cl, Br) is studied against bacterial strains Staphylococcus aureus, Escherichia coli and yeast Candida albicans. The structural types are assigned to the prepared compounds and the influence of (i) carboxylate chain length, (ii) substitution of hydrogen atom of carboxylate by halogen and (iii) presence of N-donor organic ligands on the biological activity is discussed.

Emanation thermal analysis study of the preparation of ruthenia-titania-based finely dispersed powders.

Emanation thermal analysis (ETA), thermogravimetry (TG), differential thermal analysis (DTA), X-ray diffraction analysis (XRD), and transmission electron microscopy (TEM) were used for the characterization of thermal behavior of hydrous oxides (RuO(2))(x)-(TiO(2))(1-x).nH(2)O and dehydrated oxides (RuO(2)) (x)-(TiO(2))(1-x), respectively (x=1, 0.9, and 0.7) on heating in argon and argon +10% hydrogen, respectively. The samples were heated in the range 20-600 degrees C at the constant heating rate 6 K/min. From the TG and DTA results the temperature intervals of dehydration and/or reduction of ruthenium dioxide into Ru metal were determined. ETA (based on the measurement of radon previously incorporated into the sample) brought about the information about surface area development and microstructure changes in the near surface layers up to 80 nm under in situ conditions of the heating. The temperature intervals of the annealing of near surface and structure defects serving as diffusion paths for radon were determined from the ETA results.