Transfer of orally administered ZnO:Eu nanoparticles through the blood-testis barrier: the effect on kinetic sperm parameters and apoptosis in mice testes.

Zinc-based nanoparticles are promising materials for various applications, including in biomedicine. The aim of our study was to determine the effect of fluorescent europium-doped zinc oxide nanoparticles (ZnO:Eu NPs) on sperm parameters, cell apoptosis and integrity of the blood-testis barrier (BTB) in mice. Nanostructures were orally administered to adult mice (n = 34). Animals were sacrificed after 3 h, 24 h, 7 d and 14 d following oral administration. Sperm was collected and analysed for viability and kinetic parameters. Collected testes were quantitatively analysed for accumulation of ZnO:Eu NPs. Microscopic evaluation based on immunofluorescence and histopathological studies were also conducted. Results showed that ZnO:Eu NPs were able to overcome the BTB with their subsequent accumulation in the testis. No toxic or pro-apoptotic effects of nanoparticles on the male reproductive system were observed. The results suggested that ZnO:Eu NPs were able to accumulate in the testis with no negative impact on sperm parameters, tissue architecture or the integrity of the BTB.

A novel high-strength photoluminescent hydrogel for tissue engineering.

In this work, Eu-containing poly (vinyl acetate) and poly (vinyl alcohol) are made into triple physical cross-linked hydrogels. The hydrogels exhibit good tensile strength, ultrahigh toughness, excellent compressive recovery and identifiability. The superior mechanical properties of the hydrogels originate from the synergetic interactions of hydrogen bonding, molecular crystals, and hydrophobic interactions. The hydrogels are identifiable due to the introduction of the Eu(iii) organic complex [Eu(DBM)2(Phen)MA] into vinyl acetate and the identifiability of the hydrogel proves the uniformity of two types of polymers (Eu-PVAc and PVA) in the hydrogels. This strategy not only provides a new idea for the synthesis of the hydrogel containing hydrophilic and hydrophobic materials but also opens an avenue to fabricate multifunctional hydrogels applied in the field of bio-sensors, biological imaging, drug delivery and tissue engineering.

Biodegradation of the ZnO:Eu nanoparticles in the tissues of adult mouse after alimentary application.

Biodegradable zinc oxide nanoparticles (ZnO NPs) are considered promising materials for future biomedical applications. To fulfil this potential, biodistribution and elimination patterns of ZnO NPs in the living organism need to be resolved. In order to investigate gastrointestinal absorption of ZnO NPs and their intra-organism distribution, water suspension of ZnO or fluorescent ZnO:Eu (Europium-doped zinc oxide) NPs (10mg/ml; 0.3ml/mouse) was alimentary-administered (IG: intra-gastric) to adult mice. Internal organs collected at key time-points after IG were evaluated by AAS for Zn concentration and analysed by cytometric techniques. We found that Zn-based NPs were readily absorbed and distributed (3 h post IG) in the nanoparticle form throughout the organism. Results suggest, that liver and kidneys were key organs responsible for NPs elimination, while accumulation was observed in the spleen and adipose tissues. We also showed that ZnO/ZnO:Eu NPs were able to cross majority of biological barriers in the organism (including blood-brain-barrier).

Translocation and biokinetic behavior of nanoscaled europium oxide particles within 5 days following an acute inhalation in rats.

Nanoscaled europium oxide (Eu2O3) particles were inhaled by rats after acute exposure and the potential translocation of particles followed by chemical analysis and transmission electron microscopy (TEM) was investigated. An aqueous dispersion (phosphate buffer/bovine serum albumin) of a commercially available Eu2O3 particle fraction consisting partially of nanoscaled particles was aerosolized with pressurized air. After rapid evaporation, rats inhaled the dry aerosol for 6 h in a single exposure resulting in an alveolar calculated dose of approximately 39.5 µg Eu2O3. Using chemical analysis, 36.8 µg Eu2O3 was detected 1 h after lung inhalation. The amount declined slightly to 34.5 µg after 1 day and 35.0 µg after 5 days. The liver showed an increase of Eu2O3 from 32.3 ng 1 h up to 294 ng 5 days after inhalation. Additionally, lung-associated lymph nodes, thymus, kidneys, heart and testis exhibited an increase of europium over the period investigated. In the blood, the highest amount of europium was found 1 h after treatment whereas feces, urine and mesenteric lymph nodes revealed the highest amount 1 day after treatment. Using TEM analysis, particles could be detected only in lungs, and in the liver, no particles were detectable. In conclusion, the translocation of Eu2O3 within 5 days following inhalation could be determined very precisely by chemical analysis. A translocation of Eu2O3 particulate matter to liver was not detectable by TEM analysis; thus, the overproportional level of 0.8% of the lung load observed in the liver after 5 days suggests a filtering effect of dissolved europium with accumulation.

MOF@activated carbon: a new material for adsorption of aldicarb in biological systems.

A new composite was synthesized by the hydrothermal method using a 3D coordination network [Ln2(C4H4O4)3(H2O)2]·H2O (Ln = Eu and Tb) and activated carbon. The coordination network is formed within the pores of the charcoal, allowing for the use of this material as a detoxifying agent.

Urinary monitoring of exposure to yttrium, scandium, and europium in male Wistar rats.

On the assumption that rare earth elements (REEs) are nontoxic, they are being utilized as replacements of toxic heavy metals in novel technological applications. However, REEs are not entirely innocuous, and their impact on health is still uncertain. In the past decade, our laboratory has studied the urinary excretion of REEs in male Wistar rats given chlorides of europium, scandium, and yttrium solutions by one-shot intraperitoneal injection or oral dose. The present paper describes three experiments for the suitability and appropriateness of a method to use urine for biological monitoring of exposure to these REEs. The concentrations of REEs were determined in cumulative urine samples taken at 0-24 h by inductively coupled plasma atomic emission spectroscopy, showing that the urinary excretion of REEs is <2 %. Rare earth elements form colloidal conjugates in the bloodstream, which make high REEs accumulation in the reticuloendothelial system and glomeruli and low urinary excretion. The high sensitivity of inductively coupled plasma-argon emission spectrometry analytical methods, with detection limits of <2 µg/L, makes urine a comprehensive assessment tool that reflects REE exposure. The analytical method and animal experimental model described in this study will be of great importance and encourage further discussion for future studies.

Hydroxyapatites and europium(III) doped hydroxyapatites as a carrier of silver nanoparticles and their antimicrobial activity.

Hydroxyapatites (Ca10(PO4)6(OH)2 and Eu3+:Ca10(PO4)6(OH)2) were synthesized by aqueous synthesis route. Hydroxyapatites were impregnated with silver ions that were subsequently reduced. XRD, TEM, and SAED measurements were used in order to determine the crystal structure and morphology of the final products. The results showed the well crystallized hydroxyapatite grains with diameter of about 35 nm and with silver nanoparticles on their surface. The antimicrobial activity of the nanoparticles against: Staphylococcus aureus ATCC 6538 as model of the Gram-positive bacteria, Escherichia coli ATCC 11229, and Klebsiella pneumoniae ATCC 4352 as model of Gram-negative bacteria, were shown with the best activity against K. pneumoniae. These nanocomposite powders can be a promising antimicrobial agent and a fluorescent material for biodetection due to their optical and bioactive properties.

Synthesis and functionalization of persistent luminescence nanoparticles with small molecules and evaluation of their targeting ability.

We have recently reported the design and use of inorganic nanoparticles with persistent luminescence properties. Such nanoparticles can be excited with a UV lamp for 2min and emit light in the near-infrared area for dozen of minutes without any further excitation. This property is of particular interest for small animal optical imaging, since it avoids the autofluorescence of endogenous fluorophores which is one major problem encountered when using fluorescent probes. We report herein the synthesis of persistent luminescence nanoparticles (PLNPs) and their functionalization with two small targeting molecules: biotin and Rak-2. We provide characterization of each PLNP as well as preliminary evidence of the ability of PLNP-PEG-Biotin to target streptavidin and PLNP-PEG-Rak-2 to bind prostate cancer cells in vitro.

Preferential accumulation within tumors and in vivo imaging by functionalized luminescent dendrimer lanthanide complexes.

We have created a dendrimer complex suitable for preferential accumulation within liver tumors and luminescence imaging by substituting thirty-two naphthalimide fluorophores on the surface of the dendrimer and incorporating eight europium cations within the branches. We demonstrate the utility and performance of this luminescent dendrimer complex to detect hepatic tumors generated via direct subcapsular implantation or via splenic injections of colorectal cancer cells (CC531) into WAG/RijHsd rats. Luminescence imaging of the tumors after injection of the dendrimer complex via hepatic arterial infusion revealed that the dendrimer complex can preferentially accumulate within liver tumors. Further investigation indicated that dendrimer luminescence in hepatic tumors persisted in vivo. Due to the incorporation of lanthanide cations, this luminescence agent presents a strong resistance against photobleaching. These studies show the dendrimer complex has great potential to serve as an innovative accumulation and imaging agent for the detection of metastatic tumors in our rat hepatic model.

[1,10-phenantroline europium complexes: their inclusion in liposomes and cytotoxicity].

For a series of 1,10-phenantroline tris-beta-diketonate europium complexes (EuC), cytotoxic activity on the HBL-100 human breast carcinoma cells was determined. Liposomal preparation of the most active EuC, V12, was also tested for cytotoxicity. Testing of this preparation in vivo on starting lethal murine model of T cell leukemic lymphoma ASF-LL showed that the inclusion of V12 in liposomes did not increase its antitumour activity in a local mode of administration.

[Effect of rare-earth element Eu3+ on callus growth and flavonoids content in Glycyrrhiza uralensis].

The effect of rare-earth element Eu3+ on callus growth and its flavonoids content in Glycyrrhiza uralensis was studied. The results showed that lower concentration of rare-earth element Eu3+ could promote the callus growth and flavonoids productions. 0.1 mg/l Eu3+ was the most suitable for the biomass accumulation of the callus and flavonoids biosynthesis. In that concentration flavonoids content was 2.7 times and liquiritigenin was 4 times as that of the control.

Use of genetically engineered lipid-tagged antibody to generate functional europium chelate-loaded liposomes. Application in fluoroimmunoassay.

Biosynthetically lipid-tagged single-chain antibody (Laukkanen et al., Protein Eng. 6 (1993) 449; Biochemistry 33 (1994) 11664) has been used to functionalize europium (Eu3+) chelate-loaded liposomes. The resulting Eu immunoliposomes displayed specific hapten-binding activity and little non-specific binding in time-resolved fluoroimmunoassay (TR-FIA). No loss of entrapped marker nor of binding activity was observed after storage of Eu immunoliposomes for 1 month at 4 degrees C. In comparison with Eu-labeled free single-chain antibody, Eu immunoliposomes produced a higher signal and provided increased sensitivity in a sandwich-type immunoassay. These results demonstrate the potential of Eu immunoliposomes as signal-amplifying reagents in TR-FIA.

Toxicity study of europium chloride in rats.

EuCl3.6H2O was administered by gavage for 28 consecutive days to groups of 10 male and 10 female rats (Slc:Wistar strain) at doses of 0, 40, 200, or 1000 mg/kg/day. Additional groups of male and female rats receiving the 0 and 1000 mg/kg doses were used to assess recovery after 14 days subsequent to cessation of compound administration. Body weights and food consumption were measured, and hematological, clinical biochemistry, and histopathological examination were performed. The concentrations of europium (Eu) and of essential elements in organs were determined by ICP-MS or ICP-AES. In the rats of each sex dosed at 200 and 1000 mg/kg, the body weight gain significantly decreased because of reduction in food consumption. Hyperkeratosis of the forestomach and eosinocyte infiltration of the stomach submucosa were found in both sexes receiving the 1000 mg/kg dose group, suggesting an irritation effect by EuCl3.6H2O. The Eu levels increased dose dependently in the liver, kidneys, spleen, and femurs, and the accumulated volume of Eu in these organs was estimated to be about 1/100,000 of the total dosed amount. The administration of EuCl3.6H2O increased the serum iron concentration in males and the serum total iron binding capacity in each sex and decreased cholinesterase activity in females in the 1000 mg/kg dosed group. Iron concentrations in the spleen and strontium concentrations in the femurs of rats of both sexes dosed at 1000 mg/kg were significantly decreased. We concluded that the no-observed-effect level is 200 mg/kg/day. Our investigation demonstrated that elemental analyses of organs is a useful approach to toxicological study.

Distribution and excretion of lanthanides: comparison between europium salts and complexes.

Europium (152,154Eu) was intravenously injected into rats as: (i) the chloride salt at pH 7.4, (ii) the chloride salt at pH 3, (iii) the albumin complex and (iv) the DTPA complex, and tissue uptake was determined 24 h later. For the chlorides, the target organ for uptake was liver (about 60% of dose) whilst europium complexes were rapidly excreted in urine and were predominantly taken up into the kidney (about 0.5% of dose) and bone. Liver uptake of EuCl3, pH 7.4, corresponded to that of a colloidal material with most 152Eu present in the non-hepatocyte population; however, EuCl3, pH 3, was handled in a different manner, with significant uptake by hepatocytes. The differing tissue distributions of EuCl3 and Eu-albumin suggest that plasma albumin does not readily bind injected EuCl3. Renal uptake of europium, although a relatively low proportion of the injected dose, was associated with many subcellular fractions, including lysosomes, suggesting significant intracellular uptake and thus possible retention.