NPs Suspension Research Articles

Multifunctional GQDs-Coated Fe/Bi Nanohybrids for CT/MR Dual Imaging and in vitro Photothermal Therapy

Introduction: The multipurpose nanocomposites have gained growing biomedical attention as promising nanotheranostics to improve The effectiveness of cancer treatment, which concurrently combine advantages of the therapeutic and diagnostic techniques into one nanosystem. The “all-in on” probes not only help to ablate cancerous tumors, but also allow to optimize and monitoring of treatment. Materials and Methods: iron/bismuth nanohybrid was synthesized in presence of graphene quantum dots for the co-integration of diagnostic and therapeutic functions into a single nanoprobe (referred to as GQDs-Fe/Bi NPs). Then, for further applications, blood compatibility and cytotoxicity, as important tissues, of different concentration of GQDs-Fe/Bi NPs were investigated by hemolysis test and MTT test, respectively. A 1.5 T MRI scanner (Siemens Avanto- Germany) was employed to measure MR contrast ability of GQDs-Fe/Bi NPs with various concentrations of Fe. In additional, the phantom CT images were taken at the various concentrations of the Bi and iodine using a clinical CT scanner (GE HiSpeed) at operating voltages of 80,120 and 140 kVp. The acquired images were analyzed with imageJ software. To study the photothermal performance, the GQDs-Fe/Bi NPs suspension with a series of concentrations of active Bi metal were exposed to a NIR laser (808 nm, 1.7 W ・cm−2) for 10 min. Results: Such theranostic agent not only shows strong near-infrared (NIR) absorbance, but also offers high contrast for X-ray computed tomography (CT) and magnetic resonance (MR) imaging to the imaging-guided NIR laser irradiation deliver and selectively heating of tumor. Fe3O4 component involved in the hybrid showed the good magnetization property (48.59 emu/g) with excellent performance on magnetic resonance imaging and high relaxivity time (62.34 mM−1 s−1). Synergistically, the presence of the Bi component with high atomic number (Z=83) in the GQDs-Fe/Bi nanohybrid offered high- X-ray contrast for CT imaging. Furthermore, thanks to the high photothermal conversion efficiency of 31.88%, co-delivery of GQDs-Fe/Bi NPs and NIR-radiation can effectively kill the cancer cells. Conclusion: the high theranostic performance of GQDs-Fe/Bi NPs can simultaneously use for CT/MR imaging-guided cancer photothermal therapy purposes.

In-situ remediation of hexavalent chromium contaminated groundwater and saturated soil using stabilized iron sulfide nanoparticles

Hexavalent chromium (Cr(VI)) is one of prevalent toxic and mobile heavy metal contaminants in the environment. In this study, synthetic iron sulfide nanoparticles (FeS NPs) stabilized with carboxymethyl cellulose (CMC) were applied to remediate Cr(VI) contaminated groundwater and saturated soil. The batch test results showed that aqueous Cr(VI) was removed with a capacity as high as 1046.1 mg Cr(VI) per gram of FeS NPs. The removal of aqueous Cr(VI) mainly involves adsorption, reduction and co-precipitation. Aqueous Cr(VI) removal by using FeS NPs was a strong pH-dependent process. Dissolved oxygen (DO) would compete with Cr(VI) for Fe(II) and S(-II) and inhibit the process of Cr(VI) reduction at pH 5.6. For ionic strength and natural organic matter (NOM), there were no significant influences on the aqueous Cr(VI) removal. Column tests demonstrated that the concentrations of Cr(VI) in the effluent were lower than 0.005 mg L−1 after an elution of 45 pore volumes (PVs) of stabilized FeS NPs suspension. The leached Cr(VI) decreased from 4.58 mg L−1 of raw Cr(VI)-contaminated soil to 46.8–80.7 μg L−1 from the surface to bottom treated soil in column through Toxicity Characteristic Leaching Procedure (TCLP). Therefore, the synthesized FeS NPs hold high potential for the in-situ remediation of Cr(VI)-contaminated groundwater and saturated soil.

PREPARATION OF CHITOSAN-TPP NANOPARTICLES: THE INFLUENCE OF CHITOSAN POLYMERIC PROPERTIES AND FORMULATION VARIABLES

Objective: The aim of this work was to prepare chitosan nanoparticles (CS NPs) using sodium tripolyphosphate (TPP) as crosslinker and to study the effect of chitosan polymeric properties and experimental conditions on the properties and stability of NPs.Methods: CS NPs were prepared by ionic gelation method, using TPP as a crosslinker. The particle size (PS), polydispersity index (PDI), zeta potential (ZP) and the morphologies of the NPs were studied. CS NPs prepared by varying the concentration of TPP, Chitosan molecular weight and its degree of deacetylation, the stirring speed, the rate of TPP addition and the freeze-drying method to study the effect of these variables on the NPs. The stability of the CS NPs was evaluated by storing aqueous suspensions of NPs and comparing the PS, PDI and ZP at the beginning and the end of the experiment.Results: This study shows that the PS, ZP and dispersity of the NPs depend on the chitosan polymeric properties and experimental conditions. The NPs sizes range between 145.73 and 724.23 nm. They all carried positive charges ranging between+4.32 and+43.67 mV. Most of the NPs have the same sizes after freeze-drying, but showed higher monodispersity and ZP, indicating higher stability. After twenty days of studying the stability, the NPs that had low ZP showed a large increment in size in comparison to the highly charged NPs.Conclusion: In conclusion, the polymeric properties and formulation variables in the ionic gelation method have a great influence on the CS NPs formed.

Radiation-induced nucleation and pH-controlled nanostructure shape of polyaniline dispersed in DMF

Different nanostructure shapes of polyaniline (PAni) particles such as rod and spherical shapes were prepared using gamma radiation. Gamma radiation is advantageous over other conventional methods because it provides a pure nanoparticle without by-products or any additives. The four solutions of aniline monomer Ani were dissolved in aprotic polar solvent N,N-dimethyl formamide (DMF) in different pH values and exposed to gamma radiation at a dosage of 50 kGy. The pH effect in terms of size and structure of PAni was investigated with four values 1, 5, 8 and 13 adjusted by adding HCl. A common polymerization mechanism induced by radiation is proposed as a radical cation polymerization, which is an environment friendly and cost effective mechanism without any side products or contaminants. The size and size distribution of PAni NPs suspension in DMF solvent were investigated by TEM and DLS. The results clearly showed that the ionizing radiation is an effective tool to produce a shape-controllable size. The changes of the spectrum with the pH of the polymerization solution obtained from UV–visible spectroscopy revealed that the smallest particles of PAni NPs can easily be obtained at low pH. The PAni particles are obtained with two morphologies (such as rod and spherical shapes).

Gold nanoparticles dispersion stability under dynamic coating conditions in capillary zone electrophoresis

Capillary zone electrophoresis (CZE) of unmodified gold nanoparticles (Au NPs) was investigated in terms of dispersion stability in a presence of buffering counter-ions in background electrolyte (BGE). Capillary length, migration time and electric field strength were identified among factors influencing particles CZE. Moreover, BGE electrolysis was found to significantly affect analyses repeatability. The adsorption of NPs to capillary wall was recognized as the main problem. It was shown that this inconvenience can be overcome by the application of relatively big counter-ions. According to this observation, steric stabilization of NPs suspension by BGE components during CZE was hypothesized. In result, repeatable CZE of bare Au NPs under dynamic coating conditions was shown.

Defect-Mediated Reactive Oxygen Species Generation in Mg-Substituted ZnO Nanoparticles: Efficient Nanomaterials for Bacterial Inhibition and Cancer Therapy.

Mg-substituted ZnO nanoparticles (MgZnO NPs) were synthesized by a soft chemical approach and were well-characterized by X-ray diffraction, transmission electron microscopy, UV–visible spectroscopy, and photoluminescence spectroscopy. The absorption and photoluminescence spectra show that substitution of Mg ions results in the widening of the band gap and a significant enhancement in the concentration of defects in ZnO NPs. A systemic study of generation of reactive oxygen species (ROS) under dark, daylight, and visible light conditions suggests that the aqueous suspension of MgZnO NPs generates a higher level of ROS because of the surface defects (oxygen vacancies). This capability of MgZnO NPs makes them a more promising candidate for the inhibition of bacterial growth and for killing of cancer cells as compared to pure ZnO NPs, possibly because of the enhanced interaction and accumulation of MgZnO NPs in the cytoplasm or cell membrane in the presence of both Zn2+ and Mg2+ ions. Further, MgZnO NPs exhibit excellent selective killing of nasopharyngeal carcinoma cells (KB) and cervical cancer cells (HeLa) with minimal toxicity to normal fibroblast cells (L929). The results suggest that the generation of ROS and Zn2+ ions are possibly responsible for the higher activity toward the depolarization of cell membrane potential, the lipid peroxidation in bacterial cells, depolarization of the mitochondrial membrane, and cell cycle arrest in the S phase in cancer cells.

Effects of ZnO nanoparticles in the Caspian roach (Rutilus rutilus caspicus)

Most studies investigating the toxicity of zinc oxide nanoparticles (ZnO NPs) focused on the effect of size, whereas exposure concentration and duration remained poorly understood. In this study, the effect of acute and sub-acute exposures of ZnO NPs on Zn compartmentalization and biomarkers' expression were investigated in Rutilus rutilus caspicus (Caspian roach) considering various exposure scenarios: i) the assessment of the concentration-response curves and median lethal concentration (LC50); ii) the assessment of the effects of organisms exposed at LC50 value and one tenth of LC50 value of ZnO NPs suspensions for 4 d and 28 d, respectively; iii) the assessment of 14 d depuration period. The same concentrations of ZnSO4 were investigated. The highest Zn accumulation was detected in gill after sub-acute exposure (4.8 mg/L; 28 d) followed by liver, kidney and muscle. In gill, liver and muscle, Zn from Zn NPs accumulated higher concentrations. Depuration (14 d) decreased Zn content in each organ, but no complete removal occurred except for muscle. Biomarkers' activity was significantly over expressed after treatments, but depuration brought back their values to background levels and most effects were related to acute concentrations (48 mg/L; 4 d) and in presence of ZnSO4. Histopathological analyses showed that the exposure to ZnO NPs increased lesions in gill, liver and kidney, with a direct proportionality between alterations and Zn accumulated in the target organs. After depuration, lesions regressed for both ZnO NPs and ZnSO4, but not in a complete way. These data could contribute to increase the knowledge about ZnO NPs risk assessment in aquatic vertebrates, suggesting that the size of ZnO NPs can influence biomarker and histopathological effects.

Effect of PI3K/Akt signal pathway inhibitor on docetaxel nanoparticles in cell uptake, cell colony, caspase-3 & caspase-9 expression and pharmacokinetics

Docetaxel (DTX) is one kind of well-known anticancer drugs against tumors. GDC0941 was used to inhibit PI3K/Akt signal pathway and improve anti-tumor activity. PLGA-PEG-R7 (poly lactic-co-glycolic acid polyethylene glycol bending with cell penetrating peptide R7)/poly sulfadimethoxine-Folate nanoparticles (R7/PSD-Fol NPs) were made to load DTX and GDC0941 simultaneously. In vitro, the release capacity of DTX and GDC0941 inside nanoparticles was determined and both drugs could release from nanoparticles to 70% within 48h. The result of flow cytometry showed that GDC0941 had no interference on cell uptake and R7/PSD-Fol NPs could enhance MCF-7 cells uptake the most significantly. In cell colony study, GDC0941 could further improve the anti-tumor effect of DTX and inhibit the formation of cell clones on the basis of enhancing the uptake of R7/PSD-Fol NPs. The capability of cell colony formation was as follows: DTX > DTX + GDC0941 > R7 NPs > R7/PSD-Fol NPs. The expression of cell apoptosis proteins treated with R7/PSD-Fol NPs was the lowest. The addition of GDC0941 could decrease the full-length content of apoptotic proteins caspase-3 and caspase-9. In vivo, pharmacokinetic parameters results showed us that GDC0941 had no interference on pharmacokinetic study. Main pharmacokinetic parameters of DTX suspension and R7/PSD-Folate NPs suspension showed significant differences.

Aging of silver nanocolloids in sunlight: particle size has a major influence

Environmental contextTransformation of silver nanoparticles in the environment is an important issue because the form they take directly influences what effect they have. We show that the size of the primary particles of silver nanosuspensions is a major factor determining their evolution under sunlight irradiation (dissolution, formation of nanoseeds and nanoprisms, agglomeration). The persistence of nano-sized silver particles after exposure to sunlight irradiation implies that their ecotoxicological impact will likely last well beyond their introduction in the environment. AbstractThe environmental fate of silver nanoparticles (Ag NPs) is a serious cause for concern with regard to their ecotoxicity. In this study, an aging scenario intended to evaluate the effect of sunlight on three Ag NP suspensions of various particle size was assessed. Suspensions of citrate-stabilised Ag NPs of 20, 60, and 100 nm diameter were aged for a week in a climatic chamber under controlled temperature (40 °C) and irradiation (1.44 W m−2 at 420 nm). The suspensions were analysed by asymmetric flow field flow fractionation – inductively coupled plasma mass spectrometry (AF4-ICP-MS), dynamic light scattering (DLS) and transmission electron microscopy (TEM). The AF4-ICP-MS monitoring showed that only a small fraction (10 % at most) of the primary 20 nm particles are converted into multi-faceted particles. Larger particles undergo shape modifications correlated with dissolution (60 nm Ag NPs) and aggregation (100 nm Ag NPs) processes. Silicate structures – supposedly originating from the glassware degradation – stabilise the primary particles. The occurrence of smaller Ag seeds, also associated with silicates, was revealed and quantified by AF4-ICP-MS and confirmed by TEM. The physical fractionation of the particles according to their size provided by AF4, together with the quantitative analysis provided by ICP-MS, helped to determine the role of size in the fate of silver nanoparticles under sunlight exposure.

Acute toxicity, uptake, and elimination of zinc oxide nanoparticles (ZnO NPs) using saltwater microcrustacean, Artemia franciscana

This study aims to evaluate the potential toxic effects of ZnO nanoparticles on Artemia franciscana nauplii. The ZnO NPs suspension was characterized by TEM, EDS and DLS techniques. Acute toxicity was investigated by exposure of nauplii to concentrations of 1, 5, 7.5, 10, 15, 20, 25 and 30 mg/L of ZnO NPs for 48 h and 96 h. The 96-h EC10 and EC50 values of ZnO NPs were found to be 1.39 mg/L and 4.86 mg/L respectively. The ZnO NPs suspensions did not cause any significant acute toxicity after 48 h of exposure, but the immobilization rate increase significantly compare to control group after 96 h (P < 0.05). The results showed that the uptake, accumulation, and elimination of NPs in nauplii depends on the concentration of NPs and time. The elimination rates of 46.66% and 83.85% were recorded at 1 and 10 mg/L of NPs after 24 h of depuration period, respectively.

Dissolution of zinc oxide nanoparticles in exposure media of algae, daphnia, and fish embryos for nanotoxicological testing

ABSTRACTZinc oxide nanoparticles (ZnO NPs) are being widely investigated in a bioassay due to potential negative effects to biological receptor. The dissolution of metal nanoparticles such as ZnO NPs is crucial to interpret nanotoxicity results because ZnO NPs can release toxic-free ions in exposure media. In the present study, dissolution of ZnO NPs was evaluated in three selected synthetic media for aquatic toxicological testing: Elendt M4 daphnia medium, OECD algal medium, and fish embryo rearing solution. Both media are currently recommended for OECD testing for daphnia and algae. Time-dependent dissolution of ZnO NPs has been investigated in terms of sonication time to be used for the preparation of aqueous NPs suspension, and dissolution time corresponding to exposure period in toxicity testing. Since sonication is widely applied for NPs dispersion in the most of nanotoxicological testing, the emphasis of this study was on the dissolution of NPs as a function of sonication time. We also investigated the concentration-dependent dissolution of ZnO NPs. Our results demonstrated that dissolution of ZnO NPs was significantly affected by sonication and dissolution time, as well as NPs concentration. This study showed that parameters affecting dissolution of ZnO NPs should be considered in nanotoxicological testing.

Effect of the operating conditions on the colloidal and microemulsion synthesis of Pt in aqueous phase

The syntheses of platinum nanoparticles (Pt NPs) using colloidal and microemulsion methods and different reducing agents (methanol, NaBH4, and N2H4) have been compared systematically. The colloidal synthesis was based on polyvinylpyrrolidone (PVP) as capping agent and water and methanol-water mixtures as reaction media. The microemulsion syntheses were carried out using the water-in-oil (w/o) system formed by dioctyl sulfosuccinate sodium salt (AOT), n-heptane and water. The influence of PVP/Pt, reducing agent/Pt and water/AOT molar ratios was studied. The Pt NPs prepared were characterized by transmission electron microscopy (TEM) and X-ray diffractometry (XRD). Both colloidal and microemulsion syntheses resulted in globular shaped NPs consisting mainly of a single crystal domain with fcc structure. Colloidal synthesis with methanol and NaBH4, yielded very stable NPs suspensions with small mean particle size (3–6nm) and distributions extending from 2 to 10nm. Narrower size distributions were obtained with NaBH4, whereas the use of N2H4 led to oversized particles. The most important synthesis variable was the PVP/Pt ratio. In the case of the microemulsion method, a broader range of NPs mean size was obtained (1–7nm). A better tailoring of the properties of the NPs was achieved varying the type of reducing agent, the reducing agent/Pt ratio and water/AOT ratio. The conditions for the synthesis of NPs suspensions with well differentiated mean size and distribution were identified.

Kinetic Analysis of the Uptake and Release of Fluorescein by Metal-Organic Framework Nanoparticles.

Metal-organic framework nanoparticles (MOF NPs) are promising guest-host materials with applications in separation, storage, catalysis, and drug delivery. However, on- and off-loading of guest molecules by porous MOF nanostructures are still poorly understood. Here we study uptake and release of fluorescein by two representative MOF NPs, MIL-100(Fe) and MIL-101(Cr). Suspensions of these MOF NPs exhibit well-defined size distributions and crystallinity, as verified by electron microscopy, dynamic light scattering, and X-ray diffraction. Using absorbance spectroscopy the equilibrium dissociation constants and maximum numbers of adsorbed fluorescein molecules per NP were determined. Time-resolved fluorescence studies reveal that rates of release and loading are pH dependent. The kinetics observed are compared to theoretical estimates that account for bulk diffusion into NPs, and retarded internal diffusion and adsorption rates. Our study shows that, rather than being simple volumetric carriers, MOF-NPs are dominated by internal surface properties. The findings will help to optimize payload levels and develop release strategies that exploit varying pH for drug delivery.

Ions-modified nanoparticles affect functional remineralization and energy dissipation through the resin-dentin interface

The aim of this study was to evaluate changes in the mechanical and chemical behavior, and bonding ability at dentin interfaces infiltrated with polymeric nanoparticlesstandard deviations and modes of failure are (NPs) prior to resin application. Dentin surfaces were treated with 37% phosphoric acid followed by application of an ethanol suspension of NPs, Zn-NPs or Ca-NPs followed by the application of an adhesive, Single Bond (SB). Bonded interfaces were stored for 24h, submitted to microtensile bond strength test, and evaluated by scanning electron microscopy. After 24h and 21 d of storage, the whole resin-dentin interface adhesive was evaluated using a Nano-DMA. Complex modulus, storage modulus and tan delta (δ) were assessed. AFM imaging and Raman analysis were performed. Bond strength was not affected by NPs infiltration. After 21 d of storage, tan δ generally decreased at Zn-NPs/resin-dentin interface, and augmented when Ca-NPs or non-doped NPs were used. When both Zn-NPs and Ca-NPs were employed, the storage modulus and complex modulus decreased, though both moduli increased at the adhesive and at peritubular dentin after Zn-NPs infiltration. The phosphate and the carbonate peaks, and carbonate substitution, augmented more at interfaces promoted with Ca-NPs than with Zn-NPs after 21 d of storage, but crystallinity did not differ at created interfaces with both ions-doped NPs. Crosslinking of collagen and the secondary structure of collagen improved with Zn-NPs resin-dentin infiltration. Ca-NPs-resin dentin infiltration produced a favorable dissipation of energy with minimal stress concentration trough the crystalline remineralized resin-dentin interface, causing minor damage at this structure.

Cytotoxicity of NiO nanoparticles and its conversion inside Chlorella vulgaris

Cytotoxicity of nickel oxide nanoparticles(NiO NPs) with average diameter of 20 nm were investigated on cultured Chlorella vulgaris. Alga growth-inhibition tests were taken and ultrastructure changes of the microalgae were characterized with transmission electron microscopy(TEM). The biological interface conversion effect between NiO nanoparticles and Chlorella vulgaris were studied by X-ray diffraction(XRD), high-resolution transmission electron microscopy(HRTEM) and X-ray photoelectron spectroscopy(XPS). The results indicated that the NiO nanoparticles had severe inhibitory effect on the growth of microalgae, with a 96 h EC50 value of 31.4 mg/L. Under the exposure to NiO NPs suspensions, Chlorella vulgaris cells showed plasmolysis with a shriveled cell shape, disrupted plasma mem-brane, leaked cytosol and disordered thylakoid grana lamella. The NiO NPs were aggregated and partially reduced to Ni0 inside the Chlorella vulgaris. The bioaccumulation and bio-reduction ability of Chlorella vulgaris provide us with a possible strategy of remediation of aquatic pollution conducted by toxic metal oxide nanoparticles.

Terahertz properties of liquid crystals doped with ferroelectric BaTiO3 nanoparticles

ABSTRACTIn this paper, we present the results of the terahertz measurements of liquid crystal (LC) ferroelectric BaTiO3 nanoparticles (nps) suspensions in the range of frequency from 0.3 up to 3.0 THz. Two different sol-gel methods and the harvesting technique were used to fabricate the nanoparticles. Five LC materials served as hosts for the suspensions: two single compounds: 6CHBT and 2,3′,5′-trifluoro-4-(4-pentylcyclohexyl)-4′-(trifluoromethoxy)-1,1′-biphenyl, and three mixtures: 1867, 2037 and 2020. We characterise, for the first time, the refractive indices and absorption parameters of suspensions with harvested nps in the terahertz range and show how the process of the nps’ preparation affects their response. We observed the increase of birefringence for few LC suspensions in comparison with the pure LCs. The highest increase of birefringence was for 2020 suspension with one kind of ferroelectric nps. On the other hand in most cases the addition of ferroelectric nps to LC causes the increase of its absorption in the THz range. The measurements of LCs terahertz properties by using time-pulsed spectrometer were performed.

Toxicity of CuO Nanoparticles to Structure and Metabolic Activity of Allium cepa Root Tips.

Roots of Allium cepa were exposed to six CuO NPs suspensions (0, 5, 10, 20, 40, 80mgL-1) in this study. Results revealed that with the increase of CuO NPs concentration, the Cu content in roots increased significantly. Compared to control, onion roots treated with CuO NPs (except 5mgL-1 suspension) grew slowly after 24h. The surface of the root cap and meristematic zone were obviously damaged. The apical meristem of roots treated by 10mgL-1 and above concentrations stopped division. The nucleus of meristematic cells deformed, and nucleoli number increased. The plasmolysis occurred, and the cell membrane and nuclear membrane fractured. With the increase of CuO NPs concentration, the MDA content increased, and the root activity decreased. When dealt with 80mgL-1 CuO NPs for 72h, onion roots appeared to be corroded.

Mechanisms underlying the enhancement of toxicity caused by the coincubation of zinc oxide and copper nanoparticles in a fish hepatoma cell line.

Ecosystems are exposed to a wide variety of individual substances, including at the nano-scale; and the potential adverse effects of their interactions are an increasing concern. The purpose of the present study was to determine whether zinc oxide nanoparticles (ZnONPs) at a no-observed-effect concentration modulate the cytotoxicity of copper nanoparticles (CuNPs) in the fish hepatoma cell line PLHC-1 after 48 h of exposure and the contribution of the released ions to these effects. Cells were exposed to 50-nm CuNPs (0.39-25.0 µg/mL), alone or in combination with ZnONPs (25 nm or 100 nm), at 6.25 µg/mL. Cells were exposed to suspensions of NPs or to their supernatants, as well as to their combinations. The effects on cell viability were assessed through cytotoxicity assays. Changes in cell morphology and metal internalization were also evaluated. The cytotoxicity exerted by CuNPs was enhanced in the presence of nontoxic concentrations of ZnONPs. On the contrary, Zn ions protected the cell line from the CuNP toxicity, this effect being related to an increase in the intracellular levels of Zn. This increase of metal was not observed in cells exposed to both ZnONPs and CuNPs, even when they were visualized inside the cell. The results indicated that the internalization of ZnONPs, but not the Zn ions, was responsible for the enhanced toxicity of the CuNPs. Environ Toxicol Chem 2016;35:2562-2570. © 2016 SETAC.

Mineralization of TiO2 nanoparticles for the determination of titanium in rat tissues

In order to draw appropriate conclusions about the possible adverse biological effects of titanium dioxide nanoparticles (TiO2—NPs), the so-called “dose?effect” relationship must be explored. This requires proper quantification of titanium in complex matrices such as animal organs for future toxicological studies. This study presents the method development for mineralizing TiO2—NPs for analysis of biological tissues. We compared the recovery and quantification limits of the four most commonly used mineralization methods for metal oxides. Microwave-assisted dissolution in an HNO3–HF mixture followed by H2O2 treatment produced the best results for a TiO2—NPs suspension, with 96 ± 8% recovery and a limit of quantification as low as 0.9 µg/L. This method was then used for the determination of titanium levels in tissue samples taken from rats. However, our tests revealed that even this method is not sensitive enough for quantifying titanium levels in single olfactory bulbs or hippocampus in control animals.

Size determination and quantification of engineered cerium oxide nanoparticles by flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry

Facing the lack of studies on characterization and quantification of cerium oxide nanoparticles (CeO2 NPs), whose consumption and release is greatly increasing, this work proposes a method for their sizing and quantification by Flow Field-flow Fractionation (FFFF) coupled to Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). Two modalities of FFFF (Asymmetric Flow- and Hollow Fiber-Flow Field Flow Fractionation, AF4 and HF5, respectively) are compared, and their advantages and limitations discussed. Experimental conditions (carrier composition, pH, ionic strength, crossflow and carrier flow rates) are studied in detail in terms of NP separation, recovery, and repeatability. Size characterization of CeO2 NPs was addressed by different approaches. In the absence of feasible size standards of CeO2 NPs, suspensions of Ag, Au, and SiO2 NPs of known size were investigated. Ag and Au NPs failed to show a comparable behavior to that of the CeO2 NPs, whereas the use of SiO2 NPs provided size estimations in agreement to those predicted by the theory. The latter approach was thus used for characterizing the size of CeO2 NPs in a commercial suspension. Results were in adequate concordance with those achieved by transmission electron microscopy, X-ray diffraction and dynamic light scattering. The quantification of CeO2 NPs in the commercial suspension by AF4-ICP-MS required the use of a CeO2 NPs standards, since the use of ionic cerium resulted in low recoveries (99±9% vs. 73±7%, respectively). A limit of detection of 0.9μgL−1 CeO2 corresponding to a number concentration of 1.8×1012L−1 for NPs of 5nm was achieved for an injection volume of 100μL.