Narrow-Band Red-Emitting Phosphors with High Color Purity, Trifling Thermal and Concentration Quenching for Hybrid White LEDs and Li3Y3BaSr(MoO4)8:Sm3+, Eu3+-Based Deep-Red LEDs for Plant Growth Applications.

Trivalent europium-based monochromatic red light-emitting phosphors are an essential component to realize high-performance smart lighting devices; however, the concentration and thermal quenching restrict their usage. Here, we report a series of efficient Eu3+-substituted Li3Y3BaSr(MoO4)8 red-emitting phosphors based on a stratified scheelite structure with negligible concentration and thermal quenching. All of the host and phosphor compositions crystallize in monoclinic crystal structure (space group C2/c). All of the phosphor compositions produce narrow-band red emission (FWHM ∼6 nm), which is highly apparent to the human eyes, and lead to exceptional chromatic saturation of the red spectral window. Concurrently, detailed investigations were carried out to comprehend the concentration and thermal quenching mechanism. Absolute quantum yields as high as 88.5% were obtained for Li3Y0.3Eu2.7BaSr(MoO4)8 phosphor with virtuous thermal stability (at 400 K, retaining 87% of its emission intensity). The light-emitting diodes were constructed by coupling Li3BaSrY0.3Eu2.7(MoO4)8 red phosphor with a near-UV LED chip (395 nm) operated at 20 mA forward bias, and the hybrid white LED (an organic yellow dye + red Li3Y3BaSr(MoO4)8:Eu3+ phosphor integrated with an NUV LED chip) showed a low CCT (6645 K), high CRI (83) values, and CIE values of x = 0.303; y = 0.368, which indicated that the synthesized phosphors can be a suitable red component for white LEDs. In addition, we have systematically investigated the Sm3+ and Sm3+, Eu3+ activation in Li3Y3BaSr(MoO4)8 to display the latent use of the system in plant growth applications and establish that the phosphor exhibits orange red emission with an intense deep-red emission (645 nm (4G5/2 → 6H9/2)). The phytochrome (Pr) absorption spectrum well matched the fabricated deep-red LED (by integrating a NUV LED + Li3Y3BaSr(MoO4)8:Sm3+ and Eu3+ phosphor) spectral lines.

Europium sulfide nanoprobes predict antiretroviral drug delivery into HIV-1 cell and tissue reservoirs.

Background: Delivery of long-acting nanoformulated antiretroviral drugs (ARVs) to human immunodeficiency virus type one cell and tissue reservoirs underlies next generation antiretroviral therapeutics. Nanotheranostics, comprised of trackable nanoparticle adjuncts, can facilitate ARV delivery through real-time drug tracking made possible through bioimaging platforms. Methods: To model HIV-1 therapeutic delivery, europium sulfide (EuS) nanoprobes were developed, characterized and then deployed to cells, tissues, and rodents. Tests were performed with nanoformulated rilpivirine (NRPV), a non-nucleoside reverse transcriptase inhibitor (NNRTI) used clinically to suppress or prevent HIV-1 infection. First, CD4+ T cells and monocyte-derived macrophages were EuS-treated with and without endocytic blockers to identify nanoprobe uptake into cells. Second, Balb/c mice were co-dosed with NRPV and EuS or lutetium177-doped EuS (177LuEuS) theranostic nanoparticles to assess NRPV biodistribution via mass spectrometry. Third, single photon emission computed tomography (SPECT-CT) and magnetic resonance imaging (MRI) bioimaging were used to determine nanotheranostic and NRPV anatomic redistribution over time. Results: EuS nanoprobes and NRPV entered cells through dynamin-dependent pathways. SPECT-CT and MRI identified biodistribution patterns within the reticuloendothelial system for EuS that was coordinate with NRPV trafficking. Conclusions: EuS nanoprobes parallel the uptake and biodistribution of NRPV. These data support their use in modeling NRPV delivery to improve treatment strategies.

Detection and quantification of γ-H2AX using a dissociation enhanced lanthanide fluorescence immunoassay.

Phosphorylation of the histone protein H2AX to form γ-H2AX foci directly represents DNA double-strand break formation. Traditional γ-H2AX detection involves counting individual foci within individual nuclei. The novelty of this work is the application of a time-resolved fluorescence assay using dissociation-enhanced lanthanide fluorescence immunoassay for quantitative measurements of γ-H2AX. For comparison, standard fluorescence detection was employed and analyzed either by bulk fluorescent measurements or by direct foci counting using BioTek Spot Count algorithm and Gen 5 software. Etoposide induced DNA damage in A549 carcinoma cells was compared across all test platforms. Time resolved fluorescence detection of europium as a chelated complex enabled quantitative measurement of γ-H2AX foci with nanomolar resolution. Comparative bulk fluorescent signals achieved only micromolar sensitivity. Lanthanide based immunodetection of γ-H2AX offers superior detection and a user-friendly workflow. These approaches have the potential to improve screening of compounds that either enhance DNA damage or protect against its deleterious effects.

Ligand-Sensitised LaF3 :Eu3+ and SrF2 :Eu3+ Nanoparticles and in Vitro Haemocompatiblity Studies.

Luminescent Ln3+ -doped nanoparticles (NPs) functionalised with the desired organic ligand molecules for haemocompatibility studies were obtained in a one-pot synthesis. Chelated aromatic organic ligands such as isophthalic acid, terephthalic acid, ibuprofen, aspirin, 1,2,4,5-benzenetetracarboxylic acid, 2,6-pyridine dicarboxylic acid and adenosine were applied for surface functionalisation. The modification of the nanoparticles is based on the donor-acceptor character of the ligand-nanoparticle system, which is an alternative to covalent functionalisation by peptide bonding as presented in our recent report. The aromatic groups of selected ligands absorb UV light and transfer their excited-state energy to the dopant Eu3+ ions in LaF3 and SrF2 NPs. Herein, we discuss the structural and spectroscopic characterisation of the NPs and the results of haemocompatibility studies. Flow cytometry analysis of the nanoparticles' membrane-binding is also presented.

On the use of Europium (Eu) for designing new metal-based anticancer drugs.

Europium oxide (Eu2O3) was used to evaluate the affinity of this rare earth element for interacting with double-stranded (ds) DNA molecules. To perform the study, we used single molecule force spectroscopy with optical tweezers and gel electrophoresis assays. Force spectroscopy experiments show that Eu2O3 presents a strong interaction with dsDNA, and the binding is independent on the ionic strength used in the surrounding environment. Among the main characteristics of the interaction, Eu2O3 tends to bind in a cooperative way, forming bound clusters of ∼ 3 molecules, and presents a high equilibrium association binding constant on the order of 105 M-1. In addition, gel electrophoresis confirm the weak electrostatic character of the interaction and explicit show that Eu2O3 does not interfere on drug intercalation into the double-helix. Such results demonstrate the potential of europium for interacting with nucleic acids and strongly suggest that this rare earth element may be considered for the design of new metal-based anticancer drugs in the future.

Attenuation of cadmium-induced vascular toxicity by pro-angiogenic nanorods.

Cadmium (Cd) is a common heavy metal that causes major environmental pollution with adverse effects on human health and well-being. Exposure to Cd is known to exhibit detrimental consequences on all the vital organ systems of the body, especially the vascular system. Certain approaches using anti-oxidants and chelating agents have been demonstrated previously to mitigate Cd-induced toxicity. However, these approaches are associated with their own limitations. In this context, there is a critical need for the development of alternative treatment strategies to address the conditions associated with Cd-poisoning. One such novel approach is the application of nanomedicine which is well-known to resolve several health complications by improving disease therapy. Recently, our group demonstrated the role of europium hydroxide nanorods (EHN) in promoting vascular growth using in vitro and in vivo assay systems. Therefore, in the present study, we have evaluated the effect of EHN on health of endothelial cells (EA.hy926) and fibroblasts (NIH 3T3) intoxicated by Cd. The results revealed that EHN significantly improved the viability of EA.hy926 and NIH 3T3 cells, reduced apoptotic cell population, increased nitric oxide (NO) production and promoted blood vasculature development in the chick embryo model, which were hampered due to Cd insult. Molecular studies demonstrated the reduced expression of tumor suppressor (p53) and elevated anti-apoptotic protein (Bcl-xL) levels along with enhanced NO production through endothelial nitric oxide synthase (eNOS) activation as the plausible mechanisms underlying protective role of EHN against Cd-induced vascular toxicity. Considering the above observations, we strongly believe that EHN could be a potential nanomedicine approach for overcoming Cd-induced toxicity by improving vascular health and functioning.

Three dimensional (3D) printed polylactic acid with nano-hydroxyapatite doped with europium(III) ions (nHAp/PLLA@Eu3+) composite for osteochondral defect regeneration and theranostics.

In the current research previously developed composites composed from poly (l-lactide) (PLLA) and nano-hydroxyapatite (10 wt% nHAp/PLLA) were functionalized with different concentrations of europium (III) (Eu3+). The aim of this study was to determine whether Eu3+ ions doped within the 10 wt% nHAp/PLLA scaffolds will improve the bioactivity of composites. Therefore, first set of experiments was designed to evaluate the effect of Eu3+ ions on morphology, viability, proliferation and metabolism of progenitor cells isolated from adipose tissue (hASC). Three different concentration were tested i.e. 1 mol%, 3 mol% and 5%mol. We identified the 10 wt% nHAp/PLLA@3 mol% Eu3+ scaffolds as the most cytocompatible. Further, we investigated the influence of the composites doped with 3 mol% Eu3+ ions on differentiation of hASC toward bone and cartilage forming cells. Our results showed that 10 wt% nHAp/PLLA@3 mol% Eu3+ scaffolds promotes osteogenesis and chondrogenesis of hASCs what was associated with improved synthesis and secretion of extracellular matrix proteins specific for bone and articular cartilage tissue. We also proved that obtained biomaterials have bio-imaging function and their integration with bone can be monitored using micro computed tomography (µCT).

Dual red-NIR luminescent EuYb heterolanthanide nanoparticles as promising basis for cellular imaging and sensing.

The present work introduces ternary Ln(III) (Ln = Eu, Yb, Lu) complexes with thenoyltriflouro1,3-diketonate (TTA-) and phosphine oxide derivative (PhO) as building blocks for core-shell nanoparticles with both Eu(III)- or Yb(III)-centered luminescence and the dual Eu(III)-Yb(III)-centered luminescence. Solvent-mediated self-assembly of the complexes is presented herein as the procedure for formation of EuLu, EuYb and YbLu heterometallic or homometallic cores coated by hydrophilic polystyrenesulfonate-based shells. Steady state and time resolved Eu-centered luminescence in homolanthanide and heterolanthanide EuLu and EuYb cores is affected by Eu → Eu and Eu → Yb energy transfer due to a close proximity of the lanthanide blocks within the core of nanoparticles. The Eu → Yb energy transfer is highlighted to be the reason for the enhancement of the NIR Yb-centered luminescence. Efficient cellular uptake, low cytotoxicity towards normal and cancer cells, and sensing ability of EuYb nanoparticles on lomefloxacin additives via both red and NIR channels make them promising as cellular imaging agents and sensors.

Lithium ions (Li+) and nanohydroxyapatite (nHAp) doped with Li+ enhance expression of late osteogenic markers in adipose-derived stem cells. Potential theranostic application of nHAp doped with Li+ and co-doped with europium (III) and samarium (III) ions.

Lithium (Li+) ion due to its excellent bioactivity is one of the most well-studied element in bone-tissue engineering. In this study, we fabricated nanohydroxyapatite (nHAp) doped with Li+ ions (5 mol% Li+:nHAp) and co-doped with lanthanide ions. We investigated the effects of nHAp, 5 mol% Li+:nHAp or Li+ alone, on osteogenic differentiation of human Adipose Tissue-derived Stem Cells (hASCs), their proliferation, mitochondrial dynamics and apoptosis. Moreover, we monitored cell proliferation after treatment with samarium (III) (Sm3+) and europium (III) (Eu3+) ions co-doped 5 mol% Li+:nHAp as well as their luminescent property. The hASCs treated with 5 mol% Li+:nHAp and Li+ ions proliferated more rapidly and differentiated effectively than control cells without undergoing apoptosis. Both, 5 mol% Li+:nHAp and Li+ ions improved osteogenic differentiation of hASCs. Moreover they decreased expression of glycogen synthase kinase 3ß (GSK3ß) while increased ß-catenin mRNA level. In addition, Li+, nHAp and 5 mol% Li+:nHAp improved mitochondrial dynamics and enhanced expression of neural differentiation marker genes. Collectively, the study indicates on pro-osteogenic and anti-apoptotic properties of nHAp doped with Li+ and Li+ alone. Moreover, unique properties of 5 mol% Li+:nHAp and 5 mol% Li+:nHAp co-doped with rare earth ions, such as Sm3+ and Eu3+ have shed a promising light on their potential application in theranostics.

Synthesis and characterization of cadmium selenide quantum dots doped by europium and investigation of their chemiluminescence properties and antibacterial activities.

Nanoparticles of cadmium selenide (CdSe) doped with europium, were synthesized as stabilizing agents using thioglycolic acid ligand. This method is based on the enhancing effect of CdSe quantum dots (QDs) doped with europium on chemiluminescence (CL) emission. This emission was generated by mixing CdSe QDs with manganese (II), iron (II) and chrome (II) sulfates as catalysts in the presence of hydrogen peroxide (H2 O2 ). The structural characteristics and morphology of these nanoparticles were investigated by scanning electron microscopy, Fourier transform infrared spectroscopy, ultraviolet-visible absorption spectroscopy, X-ray pattern and dynamic light scattering methods. The CdSe QDs doped with europium were used as the sensitizer in a luminol-hydrogen peroxide CL system. The sensitized CdSe QDs were analyzed for antibacterial activity against Gram-positive or Gram-negative bacteria. The results showed that the CdSe QDs are effective against all the studied bacteria, effectiveness was especially higher for Bacillus subtilis.

Smart All-in-One Thermometer-Heater Nanoprobe Based on Postsynthetical Functionalization of a Eu(III)-Metal-Organic Framework.

Real-time temperature feedback in tissue based on photothermal therapy is an urgent problem to be solved in cancer treatment. Herein, a smart all-in-one nanoprobe THA@Eu-NMOF@Fe/TA was designed and assembled by postsynthetical functionalization of an Eu(III)-based nanoscale metal-organic framework (Eu-NMOF) with a two-photon-absorbing ß-diketonate ligand 4,4,4-trifluoro-1-(9-hexylcarbazol-3-yl)-1,3-butanedione (HTHA) and Fe(III)/tannic acid assembly (Fe/TA). Such a functionalized material can simultaneously achieve the temperature-sensing and optical heating under a single beam of near-infrared (NIR) light. Under 808 nm laser excitation, real-time feedback of temperature by monitoring thermoresponsive fluorescence emission ratio ( I616/ I590) and fluorescence lifetime of Eu(III) ions were realized. Meantime, Fe/TA served as the photothermal agent and antibacterial agent to implement photothermal therapy (PTT) and antibacteria simultaneously. The functions of the nanoprobe were proved with ex vivo experiments, and the antibacterial activity against Gram-positive and Gram-negative bacteria of the probe was also elaborately evaluated. Our work paves a new avenue for engineering a new cancer treatment probe which can achieve real-time temperature sensing feedback during PTT and antibacterial process.

Determination of human γδ T cell-mediated cytotoxicity using a non-radioactive assay system.

The adoptive transfer of immune effector cells, such as CD8+ killer αß T cells, γδ T cells, NK (natural killer) cells, and genetically-modified T cells, has been receiving increasing attention. It is essential to determine cellular cytotoxicity so as to monitor the function and quality of ex vivo-expanded immune effector cells before infusion. The most common method is the [51Cr]-sodium chromate release assay. It is, however, preferable to avoid the use of radioactive materials in clinical laboratories. In order to establish a non-radioactive alternative to the standard radioactive assay, we previously synthesized a chelate-forming prodrug (BM-HT) and demonstrated that a combination of BM-HT and europium (Eu3+) was useful to determine NK cell-mediated cytotoxicity. In the present study, we examined whether or not this improved assay system could be used to determine the cellular cytotoxicity exhibited by Vγ2Vδ2+ γδ T cells. In addition, we compared Eu3+ and terbium (Tb3+) in the measurement of cellular cytotoxicity. Our assay system using BM-HT could be used successfully for the analysis of both γδ T cell receptor (TCR)- and CD16-mediated cytotoxicity. When the intensity of fluorescence was compared between Eu3+ and Tb3+, Tb3+ chelate was more sensitive than Eu3+ chelate, suggesting that the detection system using Tb3+ is superior to Eu3+ when tumor cells are not efficiently labeled with BM-HT. The method established herein is expected to promote the development of novel adoptive cell therapies for cancer.

Mesoporous multi-silica layer-coated Y2O3:Eu core-shell nanoparticles: Synthesis, luminescent properties and cytotoxicity evaluation.

Mesoporous multi-layered silica-coated luminescent Y2O3:Eu nanoparticles (NPs) were prepared by a urea-based decomposition process, and their surfaces were gradually modified with nanoporous and mesoporous silica layers using modified sol-gel methods. The synthesized luminescent core-shell NPs were characterized thoroughly to investigate their structural, morphological, thermal, optical, photo luminescent properties and their surface chemistry. The morphology of the core NPs were nearly spherical in shape and were nano-sized grains. The observed luminescent efficiency of the mesoporous multi-layered silica-coated luminescent core NPs was gradually reduced because of bond formation between the Y2O3:Eu core and the amorphous silica shell via YOSiOH bridges on the surface of the NPs; the bonds suppressed the non-radiative transition pathways. Biocompatibility tests on Human breast cancer cells using the 3­(4,5­Dimethylthiazol­2­yl)­2,5­diphenyltetrazolium bromide and lactate dehydrogenase assays indicated that the core-shell NPs were non-toxic even at high concentrations. The mesoporous SiO2 layer played a key role in perfecting the solubility, biocompatibility, and non-toxicity of the NPs. The zeta potential, surface chemistry (Fourier transform infrared spectroscopy), and optical absorption spectral analyses revealed the high hydrophilicity of the as-prepared core-shell NPs because of the active surface-functionalized silanol (SiOH) groups, which could potentially offer many exciting opportunities in photonic-based biomedical applications.

Amine-functionalized, porous silica-coated NaYF4:Yb/Er upconversion nanophosphors for efficient delivery of doxorubicin and curcumin.

Upconversion nanoparticles (UCNP) with unique multi-photon excitation photo-luminescence properties have been extensively explored as novel contrast agents for low-background biomedical imaging. There is an increasing interest in employing UCNPs as carrier for drug delivery as these offers a unique opportunity to combine therapy and diagnostics in one platform (theranostics). In the present work, we report microwave-assisted synthesis of hexagonal NaYF4:Yb/Er UCNPs coated with porous silica and functionalized with amine (UCNP@mSiO2). The UCNP@mSiO2 were investigated for controlled delivery of a chemotherapeutic agent, doxorubicin (DOX, hydrophilic), and a chemosensitizing agent, curcumin (CCM, hydrophobic). The drug loading was relatively higher for DOX (17.4%), in comparison to CCM (8.1%). The cumulative drug release from DOX-loaded UCNP@mSiO2 were 30 and 41% at physiological (7.4) and tumoral (6.4) pH, following a pseudo Fickian release pattern, whereas the release from CCM-loaded UCNP@mSiO2 were 27 and 50% at pH 7.4 and 6.4, following a non-Fickian and pseudo-Fickian release patterns, respectively. Both DOX and CCM-loaded UCNP@mSiO2 exhibited pH-dependent controlled drug delivery but the effect was more pronounced for CCM, the hydrophobic chemosensitizer. Cell viability assay using HeLa cells showed that DOX-loaded UCNP@mSiO2 inhibit cell growth in a dose-dependent manner, similar to free DOX, but the cell inhibition activity of free CCM was lower than CCM passively entrapped in UCNP@mSiO2. Confocal microscopy studies revealed cell uptake of both the drug by HeLa cells. Thus, UCNP@mSiO2 exhibited the unique capability to deliver hydrophilic and hydrophobic drugs, individually. UCNP@mSiO2 carrier, equipped with theranostic capabilities, may potentially be used for pH-responsive release of chemotherapeutic agents in cancer environment.

Europium(III)-doped yttrium vanadate nanoparticles reduce the toxicity of cisplatin.

The aim of this study was to evaluate the antitumor efficiency of chemotherapy with cisplatin alone and incorporated into europium(III)-doped yttrium vanadate nanoparticles functionalized with 3­chloropropyltrimethoxysilane with folic acid and without folic acid in a syngeneic mouse melanoma model. Histopathological, biochemical and genotoxic analyses of treated animals were performed to assess the toxicity of treatments. The treatment of the animals with cisplatin alone and the nanoparticles functionalized with cisplatin at a dose of 5 mg/kg b.w. for 5 days reduced tumor weight about 86% and 65%, respectively. Histopathological analysis showed lower mean frequency of mitoses in tumor tissue of the groups receiving cisplatin alone (90% reduction) and the nanoparticles functionalized with cisplatin (70% reduction) compared to the tumor control group. A reduction in body and liver weight and an increase in serum creatinine and urea levels were observed in animals treated with CDDP, but not in those receiving the nanoparticles functionalized with cisplatin. Genotoxicity assessment by the comet assay revealed lower frequencies of DNA damage in animals treated with the nanoparticles functionalized with cisplatin (mean score = 140.80) compared to those treated with cisplatin alone (mean score = 231.80). Marked toxic effects were observed in animals treated with cisplatin alone, while treatment with the nanoparticles functionalized with cisplatin showed no toxicity. Moreover, folic acid in the inorganic nanoparticles reduced the genotoxicity of cisplatin in the bone marrow micronucleus test (10 ±â€¯1.4 and 40 ±â€¯0.0 micronucleus, respectively). These results demonstrate the antitumor efficiency and significantly reduced systemic toxicity of the nanoparticles compared to CDDP.

Functionalized Eu(III)-Based Nanoscale Metal-Organic Framework To Achieve Near-IR-Triggered and -Targeted Two-Photon Absorption Photodynamic Therapy.

The postsynthetic-modified nanoscale metal-organic framework (NMOF) probes selected as potential drug delivery platforms and photodynamic therapy agents to fulfill the effective and safe treatment of neoplastic diseases have attracted increasing attention recently. Herein, a Eu(III)-based NMOF probe elaborately postsynthetically modified with a ß-diketonate two-photon-absorbing (TPA) ligand is rationally designed and further functionalized by assembling the photosensitizer molecule (methylene blue, MB) in the pores and a cyclic peptide targeting motif on the surface of the NMOF, which could achieve highly efficient near-infrared (NIR)-triggered and -targeted photodynamic therapy (PDT). On the basis of the luminescence resonance energy transfer process between the NMOF donor and the photosensitizer MB acceptor, the probe can achieve a high tissue-penetrable TPA-PDT effect. Thus, the NMOFs in this study play the role of not only the nanocontainer for the photosensitizer but also the energy-transfer donor. Studies in vitro show enhanced cellular uptake and satisfactory PDT effectiveness toward cancer cells compared to the free photosensitizer MB. It is highly expected that this study contributes to the development of smart luminescent diagnostic and therapeutic probes.

In-vitro biocompatibility, bioactivity and photoluminescence properties of Eu3+ /Sr2+ dual-doped nano-hydroxyapatite for biomedical applications.

In the present investigation, we have successfully synthesized luminescent Eu3+ -doped and Eu3+ /Sr2+ codoped hydroxyapatite (HA) nanoparticles through sol-gel assisted precipitation method with the aim of developing novel biomaterials containing osteoblast mineral (Sr2+ ) and luminescence activator (Eu3+ ). The structure, morphology, thermal stability, and luminescence properties of the resultant spherical nanoparticles (50-100 nm diameters) were studied. Moreover, the in-vitro bioactivity of Eu0.1 Sr0.1 HA nanoparticles was investigated by immersing in the simulated body fluid for many weeks. The antimicrobial activity results against gram positive and gram negative bacterial stains, showed better resistivity for the Eu0.1 Sr0.1 HA among the other compositions. The MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay of live/dead cells cultured with Eu3+ /Sr2+ -doped HA nanoparticles retained its normal morphology and did not show a significant impact on cell proliferation at various incubation days, which evidence for the material's superior biocompatible nature even at a higher concentration of 375 µg/mL. Thus, the incorporation of dual ions in HA nanoparticles with strong luminescence properties develops potential biomaterial for live cell imaging and in nanomedicine. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2191-2201, 2018.

Europium-doped mesoporous silica nanosphere as an immune-modulating osteogenesis/angiogenesis agent.

Although much research has gone into the design of nanomaterials, inflammatory response still impedes the capacity of nanomaterial-induced tissue regeneration. In-situ incorporation of nutrient elements in silica-based biomaterials has emerged as a new option to endow the nanomaterials modulating biological reactions. In this work, europium-doped mesoporous silica nanospheres (Eu-MSNs) were successfully synthesized via a one-pot method. The nanospheres (size of 280-300 nm) possess uniformly spherical morphology and mesoporous structure, and well distributed Eu elements. The nanospheres show distinct fluorescent property at 615 nm for potential bio-labeling. Noticeably, the Eu-MSNs stimulate pro-inflammatory response of macrophages and induce a modulated immune microenvironment, which further activates the osteogenic differentiation of bone marrow stromal cells (BMSCs) as well as angiogenic activity of human umbilical vein endothelial cells (HUVECs). During the process, osteogenesis-related genes (e.g. ALP, OCN, OPN and COL-I) of BMSCs, and angiogenesis-related genes (e.g. CD31, MMP9, VEGFR1/2, and PDGFRα/ß) of HUVECs were significantly upregulated by Eu-MSNs modulating immune environment of macrophages. The in vivo study further demonstrated that the Eu-MSNs could not only stimulate osteogenesis by accelerating the new bone formation at critical-sized cranial defect site, but also support the blood vessel formation as well as collagen deposition and re-epithelialization at chronic skin wound sites, showing an improved angiogenesis activity when comparing with MSNs alone. Given the easy handling characteristics and extensive application potential, the results suggest that Eu-MSNs could be used as immunity-modulated osteogenesis/angiogenesis agent for skin and bone regeneration.

Selectively switching on europium emission in drug site one of human serum albumin.

A luminescent europium probe has been discovered that binds selectively to drug-site I in human serum albumin, signalled by a 'switching on' of europium emission, and accompanied by strong induced circularly polarised luminescence.

Complementary approaches for the evaluation of biocompatibility of 90Y-labeled superparamagnetic citric acid (Fe,Er)3O4 coated nanoparticles.

Magnetic nanoparticles (MNPs) are of immense interest for diagnostic and therapeutic applications in medicine. Design and development of new iron oxide-based MNPs for such applications is of rather limited breadth without reliable and sensitive methods to determine their levels in body tissues. Commonly used methods, such as ICP, are quite problematic, due to the inability to decipher the origin of the detected iron, i.e. whether it originates from the MNPs or endogenous from tissues and bodily fluids. One of the approaches to overcome this problem and to increase reliability of tracing MNPs is to partially substitute iron ions in the MNPs with Er. Here, we report on the development of citric acid coated (Fe,Er)3O4 nanoparticles and characterization of their physico-chemical and biological properties by utilization of various complementary approaches. The synthesized MNPs had a narrow (6-7nm) size distribution, as consistently seen in atomic pair distribution function, transmission electron microscopy, and DC magnetization measurements. The particles were found to be superparamagnetic, with a pronounced maximum in measured zero-field cooled magnetization at around 90K. Reduction in saturation magnetization due to incorporation of 1.7% Er3+ into the Fe3O4 matrix was clearly observed. From the biological standpoint, citric acid coated (Fe,Er)3O4 NPs were found to induce low toxicity both in human cell fibroblasts and in zebrafish (Danio rerio) embryos. Biodistribution pattern of the MNPs after intravenous administration in healthy Wistar rats was followed by the radiotracer method, revealing that 90Y-labeled MNPs were predominantly found in liver (75.33% ID), followed by lungs (16.70% ID) and spleen (2.83% ID). Quantitative agreement with these observations was obtained by ICP-MS elemental analysis using Er as the detected tracer. Based on the favorable physical, chemical and biological characteristics, citric acid coated (Fe,Er)3O4 MNPs could be further considered for the potential application as a diagnostic and/or therapeutic agent. This work also demonstrates that combined application of these techniques is a promising tool for studies of pharmacokinetics of the new MNPs in complex biological systems.