Total synthesis of isotopically enriched Si-29 silica NPs as potential spikes for isotope dilution quantification of natural silica NPs

A new method was developed for the preparation of highly monodisperse isotopically enriched Si-29 silica nanoparticles (29Si-silica NPs) with the purpose of using them as spikes for isotope dilution mass spectrometry (IDMS) quantification of silica NPs with natural isotopic distribution. Si-29 tetraethyl orthosilicate (29Si-TEOS), the silica precursor was prepared in two steps starting from elementary silicon-29 pellets. In the first step Si-29 silicon tetrachloride (29SiCl4) was prepared by heating elementary silicon-29 in chlorine gas stream. By using a multistep cooling system and the dilution of the volatile and moisture-sensitive 29SiCl4 in carbon tetrachloride as inert medium we managed to reduce product loss caused by evaporation. 29Si-TEOS was obtained by treating 29SiCl4 with absolute ethanol. Structural characterisation of 29Si-TEOS was performed by using 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and Fourier-transform infrared (FTIR) spectroscopy. For the NP preparation, a basic amino acid catalysis route was used and the resulting NPs were analysed using transmission electron microscopy (TEM), small angle X-ray scattering (SAXS), dynamic light scattering (DLS) and zeta potential measurements. Finally, the feasibility of using enriched NPs for on-line field-flow fractionation coupled with multi-angle light scattering and inductively coupled plasma mass spectrometry (FFF/MALS/ICP-MS) has been demonstrated

Lu-177-labeled zirconia particles for radiation synovectomy

The present article describes the preparation of beta emitter lutetium-177-lebeled zirconia colloid and its preliminary physico-chemical and biological evaluation of suitability for local radionuclide therapy. The new 177Lu-labeled therapeutic radiopharmaceutical candidate was based on the synthesis mode of a previously described zirconia nanoparticle system. Morphology and size of developed radiopharmaceutical compound were evaluated through scanning electron microscope and dynamic light scattering methods. The radiocolloid had a 1.7 micrometer mean diameter and showed suitable radiolabeling and colloid size in vitro stability at RT and during 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 patient’s hock joint completed with SPECT imaging follow-up measurements and a dual-isotope SPECT imaging tests with conventional 99mTc-MDP bone scintigraphy. In the treated dog any clinical side effects or signs of histopatological alterations of the joints could not be observed during the treatment. SPECT follow-up studies unequivocally showed appropriately high localization of the 177Lu-labeled colloid in hock joint and detectable but negligible radiocolloid leakages in the nearest lymph node, respectively

Speciális tulajdonságokkal rendelkező nanostrukturált vékonyrétegek előállítása nedves kolloidkémiai eljárásokkal. = Preparation of functionalized nanostructured thin layers by wet colloid chemical methods

Eljárásokat fejlesztettünk ki nanostrukturált, anorganikus (SiO2, ZnO, TiO2) vékonyrétegek különböző anyagú (fém, szilícium, üveg, kvarc) hordozók felületén történő előállítására. Tanulmányoztuk ezeknek a bevonatoknak optikai, fotokatalitikus, valamint nedvesedési tulajdonságait. Igazoltuk, hogy a vékonyrétegek multifunkcionalitása a szerkezet és összetétel megfelelő tervezésével kialakítható. Pásztázó szögű reflektometriai, valamint UV-Vis spektroszkópiai módszereken alapuló optikai modelleket fejlesztettünk ki a Langmuir-Blodgett-technikával előállított filmek törésmutatójának, törésmutató gradiensének és vastagságának meghatározására, amelyek közvetett információt adtak a filmek szerkezetéről. Reflektometriai, valamint termodinamikai eljárások felhasználásával új módszereket dolgoztunk ki nanoméretű szilárd részecskék nedvesedésének (gömb-ekvivalens peremszögének) meghatározására víz-levegő határfelületen. Számítógépes szimulációt alkalmazva elemeztük a részecskék polidiszperzitásának Langmuir-filmjeik szerkezetére gyakorolt hatását, ami új ismeretekkel szolgált a határrétegbeli filmek tömörödésének mechanizmusáról. Fontos eredményeket nyertünk továbbá a szol-gél-technikával kialakított ón-dioxid filmek vastagságát és morfológiáját meghatározó paraméterekeről. | New methods were developed for fabrication of thin coatings of inorganic (SiO2, ZnO, TiO2) nanoparticles on different (metal, silicon, glass, quartz) substrates. We studied optical, photocatalytical and wetting behaviours of the solid supported films that revealed multifunctional properties, which could be controlled by the composition and the structure of the films. Novel optical models were developed for the characterization of nanoparticulate Langmuir-Blodgett films by scanning angle reflectometry and UV-Vis spectroscopy methods. Refractive index, refractive index gradient and thickness of those transparent coatings were calculated which provided information about the film structure. Novel optical and thermodynamic approaches to the determination of sphere-equivalent contact angles of nanoparticles at water-air interface were suggested. Applying computer simulations we analyzed the effect of particle polydispersity on the structure formation of their Langmuir films that provided new findings about the mechanism of two-dimensional ordering of particles. Additionally, novel information was obtained about the experimental parameters which control the morphology and thickness of tin-dioxide sol-gel coatings

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-a-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

Silica@zirconia@poly(malic acid) nanoparticles: promising nanocarriers for theranostic applications

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Preparation, purification and characterization of aminopropyl-functionalized silica sol

A new, simple and “green” method was developed for the surface modification of 20 nm diameter Stöber silica particles with 3-aminopropyl(diethoxy)methylsilane in ethanol. The bulk polycondensation of the reagent was inhibited and the stability of the sol preserved by adding a small amount of glacial acetic acid after appropriate reaction time. Centrifugation, ultrafiltration and dialysis were compared in order to choose a convenient purification technique that allows the separation of unreacted silylating agent from the nanoparticles without destabilizing the sol. The exchange of the solvent to acidic water during the purification yielded a stable colloid, as well. Structural and morphological analysis of the obtained aminopropyl silica was performed using transmission electron microscopy (TEM), dynamic light scattering (DLS) and zeta potential measurements, Fourier-transform infrared (FTIR), 13C and 29Si MAS nuclear magnetic resonance (NMR) spectroscopies, as well as small angle X-ray scattering (SAXS). Our investigations revealed that the silica nanoparticle surfaces were partially covered with aminopropyl groups, and multilayer adsorption followed by polycondensation of the silylating reagent was successfully avoided. The resulting stable aminopropyl silica sol (ethanolic or aqueous) is suitable for biomedical uses due to its purity

Thermotropic and structural effects of poly(malic acid) on fully hydrated multilamellar DPPC–water systems

The thermotropic and structural effects of low molecular weight poly(malic acid) (PMLA) on fully hydrated multilamellar dipalmitoylphosphatidylcholine (DPPC)-water systems were investigated using differential scanning calorimetry (DSC), small-angle X-ray scattering (SAXS), and freeze-fracture transmission electron microscopy (FFTEM). Systems of 20 wt% DPPC concentration and 1 and 5 wt% PMLA to lipid ratios were studied. The PMLA derivatives changed the thermal behavior of DPPC significantly and caused a drastic loss in correlation between lamellae in the three characteristic thermotropic states (i.e., in the gel, rippled gel and liquid crystalline phases). In the presence of PBS or NaCl, the perturbation was more moderate. The structural behavior on the atomic level was revealed by FTIR spectroscopy. The molecular interactions between DPPC and PMLA were simulated via modeling its measured infrared spectra, and their peculiar spectral features were interpreted. Through this interpretation, the poly(malic acid) is inferred to attach to the headgroups of the phospholipids through hydrogen bonds between the free hydroxil groups of PMLA and the phosphodiester groups of DPPC

Preparation and 68Ga-radiolabeling of porous zirconia nanoparticle platform for PET/CT-imaging guided drug delivery

This paper describes the preparation of gallium-68 (68Ga) isotope labeled porous zirconia (ZrO2) nanoparticle (NP) platform of nearly 100 nm diameter and its first pharmacokinetic and biodistribution evaluation accomplished with a microPET/CT (�Pet/CT) imaging system. Objectives of the investigations were to provide a nanoparticle platform which can be suitable for specific delivery of various therapeutic drugs using surface attached specific molecules as triggering agents, and at the same time, suitable for positron emission tomography (PET) tracing of the prospective drug delivery process. Radiolabeling was accomplished using DOTA bifunctional chelator. DOTA was successfully adsorbed onto the surface of nanoparticles, while the 68Ga-radiolabeling method proved to be simple and effective. In the course of biodistribution studies, the 68Ga-labeled DOTA-ZrNPs showed proper radiolabeling stability in their original suspension and in blood serum. �Pet/CT imaging studies confirmed a RESbiodistribution profile indicating stable nano-sized labeled particles in vivo. Results proved that the new method offers the opportunity to examine further specifically targeted and drug payload carrier variants of zirconia NP systems using PET/CT imaging