Hydrophobic sodium fluoride-based nanocrystals doped with lanthanide ions: assessment of in vitro toxicity to human blood lymphocytes and phagocytes

Suppressive effects of sodium fluoride on cultured splenic lymphocyte proliferation in mice

Fluoride-induced immunotoxicity has been documented in vivo, but limited reports have focused on the effects of fluoride on lymphocytes in vitro. Therefore, we have examined the suppressive effects of sodium fluoride on cultured splenic lymphocytes in mice. CD3+ T lymphocytes, CD19+ B lymphocytes, cytokines, and cell-cycle markers were analyzed through the use of a cell-counting kit, western blot, and flow cytometery. Splenic lymphocytes were isolated from 3-week-old male ICR mice and exposed to sodium fluoride (0, 100, 500, and 1000 μmol/L) for 24 h. The percentages of CD3+, CD3+CD4+, CD3+CD8+ T lymphocytes and CD19+ B lymphocytes were decreased (P<0.05 or P<0.01) in the sodium fluoride-exposed cells. This finding was correlated with the alterations in expression levels of cytokine proteins and with evidence of cell-cycle arrest. Thus, protein expression levels of IL-2, TNF-α, IFN-γ, TGF-β were decreased (P<0.05 or P<0.01), and IL-10 protein expression levels were increased (P<0.05 or P<0.01). The percentage of lymphocyte in G1 phase was significantly increased (P<0.05 or P<0.01), while expression levels of cyclin E/D and CDK2/4 were markedly decreased (P<0.05 or P<0.01). These findings demonstrate that sodium fluoride exposure suppresses splenic lymphocyte proliferation, which is represented by reducing populations and activation of splenic T and B lymphocytes. Alterations of cytokine protein expression and cell cycle arrest are the molecular basis of the sodium fluoride-suppressed splenic lymphocyte proliferation, while reduction of T lymphocytes and B lymphocytes is the explanation of sodium fluoride-decreased splenic immune function in vitro.

Correlation of nasopharyngeal carcinoma with rare earth elements and the Epstein-Barr virus

The concentration and distribution of rare earth elements (REE) in nasopharyngeal carcinoma (NPC) were measured to investigate connections with tumor size, lymph node metastasis, clinical stages, and Epstein-Barr virus (EBV) infection. There were 30 patients with NPC who met the criteria for inclusion in the present study. The EBV copy number, as well as the concentration and distribution of REE, was analyzed. EBV was detected using reverse transcription-polymerase chain reaction, with the concentrations of REE in NPC tissues measured using inductively coupled plasma-tandem mass spectrometry. The mean values were used when comparing concentrations of REE in NPC tissues as the standard deviation of this parameter was the lowest. Light REE had the highest concentrations, followed by medium, and then heavy REE. The concentrations of REE decreased with increasing tumor size and with the presence of lymph node metastasis. The concentrations of REE gradually increased between stage II and IVa, but markedly decreased thereafter. The elements that exhibited the greatest decreases were terbium, holmium and ytterbium. Furthermore, the concentrations of REE in NPC were not associated with sex (r=0.301, P=0.106) or age (r=−0.011, P=0.955), and were negatively associated with EBV (r=−0.744, P<0.001). By contrast, the EBV copy number increased alongside advancements in clinical stage. Changes in the concentrations of REE in NPC were more prominent for medium and heavy elements. Additionally, alterations in the concentrations of heavy REE may affect the occurrence and development of NPC.

Effects of surface functionalization of hydrophilic NaYF4 nanocrystals doped with Eu3+ on glutamate and GABA transport in brain synaptosomes

Specific rare earth doped nanocrystals (NCs), a recent class of nanoparticles with fluorescent features, have great bioanalytical potential. Neuroactive properties of NaYF4 nanocrystals doped with Eu3+ were assessed based on the analysis of their effects on glutamate- and γ-aminobutyric acid (GABA) transport process in nerve terminals isolated from rat brain (synaptosomes). Two types of hydrophilic NCs were examined in this work: (i) coated by polyethylene glycol (PEG) and (ii) with OH groups at the surface. It was found that NaYF4:Eu3+-PEG and NaYF4:Eu3+-OH within the concentration range of 0.5-3.5 and 0.5-1.5 mg/ml, respectively, did not influence Na+-dependent transporter-dependent l-[14C]glutamate and [3H]GABA uptake and the ambient level of the neurotransmitters in the synaptosomes. An increase in NaYF4:Eu3+-PEG and NaYF4:Eu3+-OH concentrations up to 7.5 and 3.5 mg/ml, respectively, led to the (1) attenuation of the initial velocity of uptake of l-[14C]glutamate and [3H]GABA and (2) elevation of ambient neurotransmitters in the suspension of nerve terminals. In the mentioned concentrations, nanocrystals did not influence acidification of synaptic vesicles that was shown with pH-sensitive fluorescent dye acridine orange, however, decreased the potential of the plasma membrane of synaptosomes. In comparison with other nanoparticles studied with similar methodological approach, NCs start to exhibit their effects on neurotransmitter transport at concentrations several times higher than those shown for carbon dots, detonation nanodiamonds and an iron storage protein ferritin, whose activity can be registered at 0.08, 0.5 and 0.08 mg/ml, respectively. Therefore, NCs can be considered lesser neurotoxic as compared to above nanoparticles.

The effect of core and lanthanide ion dopants in sodium fluoride-based nanocrystals on phagocytic activity of human blood leukocytes

Sodium fluoride-based β-NaLnF4 nanoparticles (NPs) doped with lanthanide ions are promising materials for application as luminescent markers in bio-imaging. In this work, the effect of NPs doped with yttrium (Y), gadolinium (Gd), europium (Eu), thulium (Tm), ytterbium (Yb) and terbium (Tb) ions on phagocytic activity of monocytes and granulocytes and the respiratory burst was examined. The surface functionalization of <10-nm NPs was performed according to our variation of patent pending ligand exchange method that resulted in meso-2,3-dimercaptosuccinic acid (DMSA) molecules on their surface. Y-core-based NCs were doped with Eu ions, which enabled them to be excited with UV light wavelengths. Cultures of human peripheral blood (n = 8) were in vitro treated with five different concentrations of eight NPs for 24 h. In summary, neither type of nanoparticles is found toxic with respect to conducted test; however, some cause toxic effects (they have statistically significant deviations compared to reference) in some selected doses tested. Both core types of NPs (Y-core and Gd-core) impaired the phagocytic activity of monocytes the strongest, having minimal or none whatsoever influence on granulocytes and respiratory burst of phagocytic cells. The lowest toxicity was observed in Gd-core, Yb, Tm dopants and near-infrared nanoparticles. Clear dose-dependent effect of NPs on phagocytic activity of leukocytes and respiratory burst of cells was observed for limited number of samples.

β-NaGdF4:Eu3+ nanocrystal markers for melanoma tumor imaging

Europium doped nanocrystals can be optimized to be successfully used as visualization markers for i.e. melanoma tumor.

The elementome of calcium-based urinary stones and its role in urolithiasis

Urolithiasis affects around 10% of the US population with an increasing rate of prevalence, recurrence and penetrance. The causes for the formation of most urinary calculi remain poorly understood, but obtaining the chemical composition of these stones might help identify key aspects of this process and new targets for treatment. The majority of urinary stones are composed of calcium that is complexed in a crystalline matrix with organic and inorganic components. Surprisingly, mitigation of urolithiasis risk by altering calcium homeostasis has not been very effective. Thus, studies to identify other therapeutic stone-specific targets, using proteomics, metabolomics and microscopy techniques, have been conducted, revealing a high level of complexity. The data suggest that numerous metals other than calcium and many nonmetals are present within calculi at measurable levels and several have distinct distribution patterns. Manipulation of the levels of some of these elemental components of calcium-based stones has resulted in clinically beneficial changes in stone chemistry and rate of stone formation. The elementome--the full spectrum of elemental content--of calcium-based urinary calculi is emerging as a new concept in stone research that continues to provide important insights for improved understanding and prevention of urinary stone disease.

Ion-ion interactions in β-NaGdF4:Yb(3+),Er(3+) nanocrystals--the effect of ion concentration and their clustering

In this work we report co-thermolysis as a suitable method for nanomaterial synthesis which allows the creation of hexagonal upconverting nanocrystals, NaGdF4:Yb(3+),Er(3+), in a wide range of sizes (20-120 nm). Only a very high Yb(3+) concentration (above 70%) results in pure cubic-phase nanocrystals with irregular shape. Additionally, we showed that the impact of Yb(3+), Er(3+) and Gd(3+) ions on the size and optical properties of nanocrystals is significant. We found that the main changes in optical properties do not depend on the nanocrystal size mostly, but are determined by the ion-ion interactions which include both Er(3+)-Er(3+) and Er(3+)-Yb(3+) cross relaxation.

In vitro hematological and in vivo immunotoxicity assessment of dextran stabilized iron oxide nanoparticles

Iron oxide nanoparticles have attracted enormous interest as potential therapeutic agents. The purpose of this study was to examine the in vitro hematological toxicity and in vivo immune response toward previously synthesized and characterized dextran stabilized iron oxide nanoparticles (DIONPs) developed for hyperthermia application. Peripheral whole blood from human volunteers was used to investigate hemolysis, platelet aggregation, lymphocyte proliferation and cytokine mRNA expression induced by DIONPs in vitro. In the concentration range of 0.008-1 mg/ml, DIONPs did not induce relevant levels of hemolysis or platelet aggregation. Assessment of lymphocyte function showed significant suppression of the proliferation activity of T-lymphocytes in cultures stimulated with the mitogen phytohemagglutinin (PHA). In addition, inhibition of PHA-induced cytokine mRNA expressions was also seen. However, systemic administration of DIONPs resulted in enhanced proliferation of mitogen-stimulated spleen derived lymphocytes and secretion of IL-1β at day 7 post exposure. In conclusion, our results demonstrate that immune response is influenced variably by nanoparticles and its degradation milieu. Further investigation of the observed immunosuppressive effects of DIONPs in immune stimulated animal models is required to assess the functional impact of such a response.