Eszter Drotár

Inherently fluorescent and porous zirconia colloids: preparation, characterization and drug adsorption studies

Porous, fluorescent zirconia particles of nearly 380 nm diameter were prepared without template molecules or labeling dyes. The porous structure is the result of aggregation-induced particle formation. The inherent fluorescence is assigned to coordinatively unsaturated Zr4+ ions at the sol-gel derived ZrO2 surface. After physico-chemical characterization of the native zirconia particles carboxyl and/or amine bearing drug molecules (d,l-α-difluoromethylornithine - DFMO, ursolic acid - UA and doxorubicin - DOX) were adsorbed onto their surface, and the products were analyzed with Fourier-transform infrared spectroscopy (FTIR), thermogravimetry (TG), small-angle X-ray scattering (SAXS), fluorimetry and zeta potential vs. pH measurements. We have found that DOX complexes coordinatively unsaturated Zr4+ ions without dislocating them, while carboxyl-bearing drugs interact with basic surface Zr-OH sites eliminating some of the carbonate species. The adsorption of UA at the zirconia surface shifts considerably the isoelectric point of the surface and thus provides kinetic stability to the particles at physiological pH. An in vivo biodistribution study in two healthy dogs performed by SPECT/CT detection after 99mTc labeling of the nanocarriers has shown the possibility of drug delivery application.

Photocatalytic WO3/TiO2 nanowires: WO3 polymorphs influencing the atomic layer deposition of TiO2

50–70 nm hexagonal (h-) and 70–90 nm monoclinic (m-) WO3 nanoparticles (NPs) were prepared by controlled annealing of (NH4)xWO3 in air at 470 and 600 °C, respectively. In addition, 5–10 nm thick and several micrometer long h-WO3 nanowires (NWs) were obtained by microwave hydrothermal synthesis at 160 °C with Na2WO4, HCl and (NH4)2SO4 as starting materials. TiO2 was deposited on h-WO3 NWs by atomic layer deposition (ALD) at 300 °C using Ti(iOPr)4 and H2O as precursors. The as-prepared materials were studied by TG/DTA-MS, XRD, Raman, SEM-EDX, TEM, ellipsometry, UV-Vis, and their photocatalytic activity was also tested by the photodecomposition of aqueous methyl orange. Our study is the first evidence of diverse ALD nucleation on various WO3 polymorphs, since on h-WO3 NWs TiO2 nucleated only as particles, whereas on m-WO3 conformal TiO2 film was formed, explained by the different surface OH coverage of h- and m-WO3. The h-WO3 NWs had significantly higher photocatalytic activity compared to h-WO3 NPs, and similar performance as m-WO3 NPs. By adding TiO2 to h-WO3 NWs by ALD method, the photocatalytic performance increased by 65%, showing clearly the uniqueness of ALD to obtain superior oxide composite photocatalysts.

Optical emission spectra analysis of thermal plasma treatment of poly(vinyl chloride)

Abstract Decomposition of poly(vinyl chloride) (PVC) was investigated in radiofrequency thermal plasma in neutral, oxidative and reductive conditions. Optical emission spectroscopy (OES) was applied for the characterization of the plasma column. OES was used to identify active plasma components such as excited atoms, ions, radicals and molecules. The spectra were dominated by molecular C2, CN, OH, and CH bands, and atomic H, Ar, C, Cl and O lines. Emission intensities of main species were monitored versus various experimental parameters. The rotational-vibrational temperatures determined from different bimolecular species were considered in the range of 2000–6400 K. Solid soot samples were collected and purified to investigate the possibility of graphene formation as a by-product of the decomposition process. Graphical Abstract

Lu-177-Labeled Zirconia Particles for Radiation Synovectomy

The present article describes the preparation of β-emitter lutetium-177-labeled zirconia colloid and its preliminary physicochemical and biological evaluation of suitability for local radionuclide therapy. The new (177)Lu-labeled therapeutic radiopharmaceutical candidate was based on the synthesis mode of a previously described zirconia nanoparticle system. The size and shape of the developed radiopharmaceutical compound were observed through a scanning electron microscope and dynamic light scattering methods. The radiocolloid had a 1.7 μm mean diameter and showed high in vitro radiochemical and colloid size stability at room temperature and during the blood sera stability test. After the in vitro characterizations, the product was investigated in the course of the treatment of a spontaneously diseased dog veterinary patients hock joint completed with single-photon emission computed tomography (SPECT) imaging follow-up measurements and a dual-isotope SPECT imaging tests with conventional (99m)Tc-methanediphosphonic acid bone scintigraphy. In the treated dog, no clinical side-effects or signs of histopathological changes of the joints were recorded during the treatment. SPECT follow-up studies clearly and conspicuously showed the localization of the (177)Lu-labeled colloid in the hock joint as well as detectable but negligible leakages of the radiocolloid in the nearest lymph node. On the basis of biological follow-up tests, the orthopedic team assumed that the (177)Lu-labeled zirconia colloid-based local radionuclide therapy resulted in a significant and long-term improvement in clinical signs of the patient without any remarkable side-effects.

Mono- and double carbonylation of iodobenzene in the presence of reusable supported palladium catalysts

Abstract Various silica-supported palladium catalysts were prepared and tested in the carbonylation of aryl iodides in the presence of aliphatic amines and aniline. In the former reaction, the main products are the α-ketoamides, whereas monocarbonylation is favoured with aniline. Small modification of the support, of the palladium precursor, or of the conditions of immobilisation were found to affect considerably the outcome of the reactions and recyclability of the catalysts. Under optimum conditions, the phosphine-free palladium catalysts can be reused six to ten times without considerable loss of activity. By the proper selection of the solvent, the leaching of palladium into the reaction mixtures can be reduced considerably.

Acetic acid hydroconversion over mono-and bimetallic indium doped catalysts supported on alumina and silicas of various textures

Abstract Consecutive hydroconversion of acetic acid (AA) to ethanol was compared over monometallic and novel bimetallic (containing In as guest metal) catalysts on alumina and silica supports (inter alia highly ordered SBA-15) of different porosity and pore structure. The transformation was studied in a fixed bed, flow-through reactor in the temperature range of 220–380°C using hydrogen flow at 21 bar total pressure. AA hydroconversion activity of Cu and Pt catalysts and the yield of selectively produced alcohol were increased drastically by applying SBA-15 as highly ordered, mesoporous silica support instead of alumina. The most active nickel catalysts do not allow the selective addition of hydrogen to carbon-oxygen bonds independently of supports producing mainly CH4; however, indium doping can completely eliminate the hydrodecarbonylation activity as found in earlier studies. The textural properties of studied silica supports of various textures such as SBA-15, CAB-O-SIL, and Grace Sylobead have a profound impact on the catalytic performance of Ni and Ni2In particles. Graphical Abstract