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Zinc oxide nanoparticles were synthesized with microwave hydrothermal technique and tested as luminescent contrast for biological imaging. Luminescence was activated by Eu3+ ions embedded in the nanoparticle matrix in the increasing concentrations of 1, 5 and 10 %mol. It was found that europium did not create a separate crystalline phase up to the concentration as high as 5 %mol. However, Eu3+ ions did not substitute Zn2+ in the host lattice, but allocated in the low symmetry environment. It was proposed that europium was locating in the inter-grain space or on the surface of nanoparticles. The luminescence intensity in ZnO:Eu, as well as the size of particles, increased with the Eu ion concentration. Moreover, in 10 %mol Eu sample, the separate phase of Eu-hydroxide was identified with crystals of micrometre length. Interestingly, in vivo study revealed, that contrary to the in silico experiments, following gastric gavage, the brightest nanoparticle-related luminescence signal was observed at 1 %mol. concentration of Eu. Since the alimentary uptake of nanoparticles was related to their size, we concluded that the increase in luminescence at 5 and 10 %mol. Eu concentrations was associated with the largest ZnO:Eu and Eu-hydroxide particles that did not cross the gastrointestinal barrier.

The use of nanoparticles in medicine is a rapidly growing research field with numerous potential applications, especially in the field of cancer diagnosis and therapy. Nanoparticles can be intrinsically diagnostic of therapeutic, or they can be conjugated with diagnostic or therapeutic compounds. Nanoparticles may also passively or actively target tumor cells specifically using the enhanced permeation and retention (EPR) effect, or the addition of targeting ligands to their surface. This may provide a diagnostic or/and therapeutic tools to target primary as well as metastatic tumors. The transport, distribution and toxicity of nanoparticles depends greatly on their size and composition, thus every new formulation needs to be extensively researched. This work was focused on the development of Tb-doped ZrO2 nanoparticles (NPs) for application in cancer imaging. Obtained nanoparticles were below 10 nm with very low influence of Tb concentration on size. Terbium stabilization of ZrO2 had influence on the luminescence properties of obtained material. Partially stabilized zirconium dioxide exhibited broad host related emission peaking at 500 nm, disappearing with the terbium content. We confirmed alimentary absorption and wide distribution of luminescent ZrO2:Tb nanoparticles in mice with their gradual accumulation in the experimentally induced mammary cancers. Furthermore, a high concentration of NPs was found within the lung metastases as opposed to healthy lung tissue, where no NPs-related signal was observed.

Europium doped ZnO nanopowders made by microwave hydrothermal method are investigated. As zinc oxide precursor zinc nitrate(V) hexahydrate (Zn(NO3)2·6H2O) was used. Two types of nanopowder samples are examined: as grown and annealed at 750 °C in air atmosphere. We investigate the structural, morphological and optical prosperities of europium doped ZnO. Results of scanning electron microscopy, X-ray diffraction, photo- and cathodoluminescence investigations and also CIE1961 chromaticity diagram are presented.

Microwave hydrothermal growth of Y2O3 crystallites results in needle-shaped aggregates of μm length. Thermal treatment has little influence on the material microstructure, but significant impact on the nanometric level. Nanoparticles doped with europium show an intense red luminescence, related to the 5D0 → 7F2 transition of Eu3+ ions. The luminescence intensity increases with the calcination temperature and is accompanied by increasing size of Y2O3:Eu crystallites. EPR studies show the absence of Eu2+ related signals in the material. Y2O3:Eu nanoparticles crystallized via a microwave hydrothermal method were employed as luminescent biomarkers in mice. The initial tests confirmed their applicability as biological markers. Persorption of the Y2O3:Eu nanoparticles after IG in the adult mouse duodenum, brain and liver is reported.

Thermally induced crystallization of cubic Eu2O3 obtained with the microwave hydrothermal method has been investigated. The starting material crystallized in the form of needle-shaped agglomerates of nanocrystalline hexagonal Eu(OH)3. Thermal treatment up to 800 °C induced the crystallization of cubic Eu2O3, after further calcination at 1200 °C in the air a monoclinic phase appeared. The phase transformation caused abnormal reduction of Eu3+ ions, related to the oxygen vacancy creation during sintering of the oxide crystallites. The crystallization process of cubic Eu2O3 occurred within the agglomerates without change of their shapes. The cubic form exhibited bright emission of Eu3+ related luminescence with intensity increasing with the size of crystallites.

In this paper a new generation of non-toxic nanoparticles based on the zirconium oxide doped with 0.5%Tb and co-doped by the range of 0–70% with Y was evaluated for the use as a fluorescent biomarker of neuronal trafficking. The ZrO 2 :Tb nanoparticles were created by microwave driven hydrothermal method. Influence of the yttrium content and thermal processing on the Tb 3+ related luminescence emission was discussed. The higher intensities were achieved, when host was cubic and for the nanoparticles with 33 nm. Presence of yttrium was associated with the energy coupling of the host and dopant, wide excitation band is present at 309 and 322 nm before and after calcination respectively. For the experiment on living primary neurons, nanoparticles doped with 0.5%Tb and 7%Y were chosen based on their luminescence emission intensity. Recently transfer of the nanoparticles through the barriers in the organism including blood–brain barrier following their alimentary absorption was confirmed (Godlewski and Godlewski, 2012). This raised the possibility of the nanoparticle application as a tool in the neuroscience, and the question of potential mechanisms of nanoparticle turnover in neurons. Concentration of 0.001 mg/ml of ZrO 2 :0.5%Tb 7%Y in growth medium was added to the primary murine culture medium, and the intracellular trafficking of nanoparticles was observed following 15 min pre-incubation period. ZrO 2 :0.5%Tb 7%Y nanoparticles were dynamically absorbed by the neurons and the dynamic passage of transport vesicles containing ZrO 2 :0.5%Tb 7%Y nanoparticles was observed along the neuronal processes and in between two neighbouring neurons. Reassuming, the ZrO 2 :0.5%Tb 7%Y nanoparticles proved to be biocompatible and a valid tool to assess intracellular trafficking dynamics in the neurobiology.

While doping with rare earth ions is used for emission activation, doping with transition metal ions is often used to get specific magnetic properties of a given host material. Recently investigations of transition metal doped materials focused on chances of achieving a room temperature ferromagnetic response. This is because carrier mediated room temperature ferromagnetic order was theoretically predicted for ZnO doped with Mn or Co ions. Such order is required for some of spintronics applications. To realize RT FM both Mn and Co should stay in 2+ charge state, expected when Mn/Co substitute zinc in ZnO. Both ZnMnO and ZnCoO alloys show a strong absorption band, which appears below ZnO band gap transitions. The origin of this absorption in ZnCoO is discussed in the present work. We show based on the results of photoluminescence and photo-ESR investigations that the broad absorption band is related to Co photo-ionization.

Iron doped (in the range from 1 to 10 mol %) ZnO nanoparticles (NPs) were obtained by microwave hydrothermal method. The effects of iron content on morphology, crystal structure, optical and magnetic properties of ZnO nanoparticles were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), cathodoluminescence (CL), photoluminescence (PL) and magnetic measurements. XRD studies revealed presence of ZnFe2O4 foreign phase in NPs for iron doping concentrations above 5% placing the solubility limit of Fe in ZnO NPs near this value. The photoluminescence and cathodoluminescence spectra show an increase of the intensity ratio between near band edge (NBE) and deep level emission band (DLE) of ZnO, which is tentatively related by us with intrinsic cracking of ZnO crystals. The blue-shift of NBE band maxima was observed as a concentration of Fe dopant increases. The results of magnetic measurements indicate superparamagnetic behavior of nanoparticles.