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Nanoscale size effects on U(VI) reduction by Fe(II) on hematite were investigated with four aerosol-synthesized hematite nanoparticles (12, 30, 50, 125 nm) and one aqueous-synthesized hematite (70 nm). Batch experiments were conducted at loadings of 0.01 mM U(VI) and 5 mM Fe(II) at pH 7.5 and 9.0. Rate constants for reduction of U(VI) to U(IV) were determined using a pseudo-first order reaction rate law. Reduction was faster at pH 7.5 than at pH 9.0. Rate constants were higher for aerosol-synthesized hematite than for aqueous-synthesized hematite. Rate constants were not significantly different for the 30, 50, and 125 nm particles. However, reduction was two orders of magnitude faster for the 12 nm hematite particles. Possible explanations for the dramatically faster reduction with the 12 nm hematite include the formation of a more reactive solid such as magnetite, effects on electron conduction through hematite, and quantum confinement effects.

The Romanian propolis was extracted in five different media, respectively, in water (pH 6.8), glycine buffer (pH 2.5), acetate buffer (pH 5), phosphate buffer (pH 7.4) and carbonate buffer (pH 9.2). The extracts presented different amounts of flavonoids and phenolic acids, increasing pH leading to higher concentrations of active compounds. Five variants of gold nanoparticles suspensions based on different pH Romanian propolis aqueous extracts were successfully synthesized. The obtained nanoparticles presented dimensions between 20 and 60 nm in dispersion form and around 18 nm in dried form, and different morphologies (spherical, hexagonal, triangular). Fourier transform infrared spectroscopy proved the attachment of organic compounds from propolis extracts to the colloidal gold suspensions and X-ray diffraction certified that the suspensions contain metallic gold. The obtained propolis gold nanoparticles do not exhibit any antibacterial or antifungal activity, but presented different catalytic activities and toxicity on tumour cells.

This paper compares the accuracy of conventional dynamic light scattering (DLS) and atomic force microscopy (AFM) for characterizing size distributions of polystyrene nanoparticles in the size range of 20–100 nm. Average DLS values for monosize dispersed particles are slightly higher than the nominal values whereas AFM values were slightly lower than nominal values. Bimodal distributions were easily identified with AFM, but DLS results were skewed toward larger particles. AFM characterization of nanoparticles using automated analysis software provides an accurate and rapid analysis for nanoparticle characterization and has advantages over DLS for non-monodispersed solutions.

We present a method using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) to determine the chemical composition of bi-metallic nanoparticles. This method, which can be applied in a semi-automated way, allows large scale analysis with a statistical number of particles (several hundreds) in a short time. Once a calibration curve has been obtained, e.g., using energy-dispersive X-ray spectroscopy (EDX) measurements on a few particles, the HAADF integrated intensity of each particle can indeed be directly related to its chemical composition. After a theoretical description, this approach is applied to the case of iron–palladium nanoparticles (expected to be nearly stoichiometric) with a mean size of 8.3 nm. It will be shown that an accurate chemical composition histogram is obtained, i.e., the Fe content has been determined to be 49.0 at.% with a dispersion of 10.4 %. HAADF-STEM analysis represents a powerful alternative to fastidious single particle EDX measurements, for the compositional dispersion in alloy nanoparticles.

To overcome the drawback caused by rapid recombination of photogenerated electron-hole pairs, a novel visible-light-driven Bi2WO6/r-GO/Bi25FeO40 Z-scheme photocatalyst was fabricated through the hydrothermal method. The as-prepared sample was analyzed by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), electrochemical impedance spectra (EIS), and X-ray photoelectron spectrometer (XPS). At the same time, the photocatalytic performance of ternary material was estimated by degradation of methylene blue (MB) aqueous solution under visible-light irradiation. Bi2WO6/r-GO/Bi25FeO40 displayed a superior photocatalytic performance compared with pure Bi2WO6. A dye degradation rate of 98.1% was appeared in ternary material under a 30-min photocatalytic experiment. r-GO plays an important role in ternary material; it acted as a charge-transfer bridge to accelerate electron transfer from Bi2WO6 to Bi25FeO40. Therefore, the recombination of the photogenerated electron holes of the Bi2WO6 itself was effectively suppressed. Most important, the possible photocatalytic mechanism was evaluated on the basis of UV–vis and PL analysis. This work provides a new idea for the synthesis of new photocatalytic materials with enhanced photocatalytic properties.

Water pollution is one of the biggest problems in the world and treatment is very important. ZIF-8 is a promising nanomaterial for water treatment. In this study, zinc imidazolate framework-8 (ZIF-8) nanoparticles were prepared via a solvothermal method. The synthesized were characterized by using several techniques and applied in emulsified oil/water separation and reuse. A combination of techniques (XRD, BET, SEM) showed that the crystalline phase of the ZIF-8 was successfully obtained by the solvothermal method. ZIF-8 exhibits a high surface area of 1146 m2/g and an average nanoparticle size 47 ± 4.6 nm. ZIF-8 exhibits a very high adsorption capacity reached 2811.1 mg/g and it was regenerated by the ethanol-washing method. The process of regeneration of ZIF-8 has proved to be efficient. ZIF-8 was regenerated by a simple ethanol-washing method; the regenerated ZIF-8 exhibited more than 98% of regeneration efficiency over three cycles.

We investigate formation of unique quantum states (metastates) in quantum dot-metallic nanoparticle systems via self-induced coherent dynamics generated by interaction of these systems with a visible and an infrared laser fields. In such metastates, the quantum decoherence rates of the quantum dots can become zero and even negative while they start to rapidly change with time. Under these conditions, the energy dissipation rates and plasmon fields of the nanoparticle systems undergo undamped oscillations with gigahertz frequency, while the amplitudes of both visible and the infrared laser fields are considered to be time-independent. These dynamics also lead to variation of the plasmon absorption of the metallic nanoparticles between high and nearly zero values, forming electromagnetically induced transparency oscillations. We show that under these conditions, the effective transition energies and broadening of the quantum dots undergo oscillatory dynamics, highlighting the unique aspects of the metastates. These results extend the horizon for investigation of light-matter interaction in the presence of zero or negative polarization dephasing rates with strong time dependency.

Single-walled carbon nanotubes (SWNT) possess high-near-infrared absorption coefficient, large surface area, and have great potential in drug delivery. In this study, we obtained ultrashort oxidized SWNT (OSWNT) using mixed acid oxidation method. Then, docetaxel (DTX) and folic acid (FA) are conjugated with OSWNT via π–π accumulation and amide linkage, respectively. A targeting and photothermal sensitive drug delivery system FA–DTX–OSWNT–SLN was prepared following a microemulsion technique. The size and zeta potential of FA–DTX–OSWNT–SLN were 182.8 ± 2.8 nm and −34.59 ± 1.50 mV, respectively. TEM images indicated that FA–DTX–OSWNT–SLN was spherical and much darker than general solid lipid nanoparticles (SLN). Furthermore, OSWNT may wind round, insert into or be encapsulated into the nanocarriers. Compared with free DTX, FA–DTX–OSWNT–SLN could efficiently cross cell membranes and afford higher antitumor efficacy in MCF-7 cells in vitro. Meanwhile, the combination of near-infrared laser (NIR) irradiation at 808 nm significantly enhanced cell inhibition. In conclusion, FA–DTX–OSWNT–SLN drug delivery system in combination with 808 nm NIR laser irradiation may be promising for targeting and photothermal cancer therapy with multiple mechanisms in future.

The present study aimed to synthesize multifunctional ZnO-NP samples, namely ZnO-20, ZnO-40, and ZnO-80 nm, using different approaches, to be used as efficient anticancer agents. Systematic characterizations revealed their particle sizes and demonstrated nanostructures of nanorods (ZnO-80 nm) and nanogranules (ZnO-20 and ZnO-40 nm). They exhibited significant (p < 0.05) toxicity to HeLa cancer cells. HeLa cell viabilities at 1 mM dose reduced to 37, 32, 15 %, by ZnO-80, ZnO-40, and ZnO-20 nm, respectively, at 48 h. However, the same dose exerted different effects of 79.6, 76, and 75 % on L929 normal cells at 48 h. Measurement of reactive oxygen species (ROS) showed a considerable ROS yields on HeLa cells by all samples with a pronounced percentage (50 %) displayed by ZnO-20 nm. Moreover, ROS-mediated apoptosis induction and blocked cell cycle progression in the S, G2/M, and G0/G1 phases significantly (p < 0.05). Apoptosis induction was further confirmed by DNA fragmentation and Hoechst–PI costained images viewed under fluorescence microscope. Additionally, morphological changes of HeLa cells visualized under light microscope showed assortment of cell death involved shrinkage, vacuolization and apoptotic bodies’ formation. Most importantly, results exposed the impact of size and morphology of ZnO samples on their toxicity to Hela cells mediated mainly by ROS production. ZnO-20 nm in disk form with its nanogranule shape and smallest particle size was the most toxic sample, followed by ZnO-40 nm and then ZnO-80 nm. An additional proposed mechanism contributed in the cell death herein was ZnO decomposition producing zinc ions (Zn2+) into the acidic cancer microenvironment due to the smaller sizes of ZnO-NPs. This mechanism has been adopted in the literatures as a size-dependent phenomenon. The emerged findings were suggested to provide new platforms in the development of therapeutics as selective agents to the fatal cervical cancer, and to benefit from the synergistic influence of size and nanostructure when designing anticancer agents. Mechanism of cell death by ZnO-NPs, displaying ROS formation and Zn2+ release that induced apoptosis and arrested cell cycle progression. Apoptosis involved DNA fragmentation, chromatin condensation, membrane shrinkage, and formation of apoptotic bodies. The synergistic effect of ZnO-NPs size (20, 40, 80 nm) and nanostructure (nanorods, nanogranules) impacted the inhibition of HeLa cells growth and eventually death.