Morphology,in vivo distribution and antitumor activity of bexarotene nanocrystals in lung cancer

Abstract

The objective of this study was to develop and evaluate the morphology, biodistribution and antitumor activity of bexarotene nanocrystals delivery system. The morphology was investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscope and bexarotene nanocrystals exhibited the advantages of making the efficacy more steady and durable compared with control group in lung with less cardiac accumulation as shown by biodistribution studies in vivo. In addition, MTT assay, flow cytometry analysis, observation of morphological changes and apoptotic body demonstrated that bexarotene nanocrystals could significantly enhance the in vitro cytotoxicity and induced G1 cycle arrest and apoptosis against A549 cells. Also, bexarotene nanocrystals had significant antitumor activity in mice bearing A549 cell line. This finding was correlated with both in vitro and in vivo. Thereby, the overall results suggest that the bexarotene nanocrystals represent a potential source of medicine, which made bexarotene nanocrystals a promising candidate for the treatment of lung cancer.     

A Silicon Nanocrystal Schottky Junction Solar Cell produced from Colloidal Silicon Nanocrystals

Solution-processed semiconductors are seen as a promising route to reducing the cost of the photovoltaic device manufacture. We are reporting a single-layer Schottky photovoltaic device that was fabricated by spin-coating intrinsic silicon nanocrystals (Si NCs) from colloidal suspension. The thin-film formation process was based on Si NCs without any ligand attachment, exchange, or removal reactions. The Schottky junction device showed a photovoltaic response with a power conversion efficiency of 0.02%, a fill factor of 0.26, short circuit-current density of 0.148 mA/cm², and open-circuit voltage of 0.51 V.     

In situ-grown hexagonal silicon nanocrystals in silicon carbide-based films

Silicon nanocrystals (Si-NCs) were grown in situ in carbide-based film using a plasma-enhanced chemical vapor deposition method. High-resolution transmission electron microscopy indicates that these nanocrystallites were embedded in an amorphous silicon carbide-based matrix. Electron diffraction pattern analyses revealed that the crystallites have a hexagonal-wurtzite silicon phase structure. The peak position of the photoluminescence can be controlled within a wavelength of 500 to 650 nm by adjusting the flow rate of the silane gas. We suggest that this phenomenon is attributed to the quantum confinement effect of hexagonal Si-NCs in silicon carbide-based film with a change in the sizes and emission states of the NCs.     

Efficient generation of hydrogen from biomass without carbon monoxide at room temperature – Formaldehyde to hydrogen catalyzed by Ag nanocrystals

In this paper, we present a new route for hydrogen generation from biomass at room temperature without any carbon monoxide over nano-metal-catalysts. It has been found that the Ag nanocrystals are highly efficient and stable catalysts for the CO-free hydrogen production from formaldehyde (HCHO), a model compound of biomass, at room temperature and at atmospheric pressure. By optimizing the structure and component of catalysts, reaction parameters such as temperature, catalyst amounts, oxygen, formaldehyde concentrations, and NaOH concentrations, the hydrogen generation rate has been maintained for hours without any decay. Furthermore, the apparent activation energy of the Ag catalyzed hydrogen production reaction is determined to be 11.8 kJ mol⁻¹, which was much lower than that of the literature results (65 kJ mol⁻¹) without catalyst. Because of its high hydrogen generation rate, hydrogen generation efficiency, lower activation energy, and the low cost, we speculate that this novel Ag catalyst based hydrogen generation reaction should be a promising candidate for providing hydrogen in PEMFCs at room temperature.     

Growth and Optical Properties of Quantized CdS Crystallites in TEOS Silica Xerogels

Quantized CdS crystallite-doped tetraethylorthosilicate (TEOS) silica xerogels are prepared by the sol-gel method. In this method, cadmium acetate [Cd(CH₃COO)₂2H₂O]-doped TEOS alcogel is formed by the hydrolysis and polycondensation of ethanolic TEOS in the presence of hydrochloric acid (HCl) and ammonium hydroxide (NH₄OH) catalysts and Cd(CH₃COO)₂.2H₂O. The CdS crystallites are formed in the alcogel by the reaction of Cd(CH₃COO)₂.2H₂O present in the gel and methanolic sodium sulfide (Na₂S), which is added over the alcogel. The effect of CdS/TEOS, EtOH/TEOS, S/Cd molar ratios, and temperature on the optical properties and CdS crystallite sizes in the xerogels are studied. A blue shift is observed in optical absorption spectra by decreasing the CdS/TEOS molar ratio from 2 × 10^–2 to 1 × 10^–4. It is observed that the crystallite size is increased from 1.6 to 3.4 nm by increasing the EtOH/TEOS molar ratio from 2 to 20, respectively, for a constant CdS/TEOS molar ratio of 5 × 10^–4. Emission spectra of xerogels are measured and found that the emission peak maxima shifted toward lower energies (higher wavelengths) by increasing the CdS/TEOS molar ratio in the xerogels. It is known from the X-ray diffraction (XRD) measurements of CdS-doped xerogels that the CdS crystallite structure in the xerogels is hexagonal wurtzite. The crystallite sizes were calculated from the XRD patterns and tight bonding calculations. There is a significant change in the color and size of CdS crystallite in the xerogels with a variation in temperature from 200 to 400°C.     

Optical and electrical properties of Al2O3 films containing silicon nanocrystals

Optical, electrical, and structural properties of Al₂O₃ films subjected to silicon-ion implantation and annealing were investigated by means of photoluminescence measurements, current-voltage measurements and transmission electron microscopy. Transmission electron microscopy revealed that silicon nanocrystals were epitaxially formed in ϑ-Al₂O₃. Visible photolum inescence was observed, for the first time, from Al₂O₃ films containing silicon nanocrystals. Observed visible photoluminescence seems to be related to quantum size effects in silicon nanocrystals as well as localized radiative recombination centers located at the interface between silicon nanocrystals and matrix, similar to porous Si and other Si nanostructures. The conduction mechanism in the samples was studied by using dc current-voltage measurements. The conduction properties depend on temperature and applied electric fields. The conduction behavior in low electric fields consists of thermally activated region dominated by the Schottky conduction and nonthermally activated region in which carrier transport is controlled by space-charge-limited currents. The conduction behavior under relatively high electric fields is almost independent of temperature and well fitted by space-charge-limited conduction.     

Nanocomposite piezoelectric films of P(VDF‐TrFE)/LiNbO3

Piezoelectric films were prepared by incorporation of lithium niobate (LiNbO₃) nanoparticles into copolymer of vinylidene difluoride and trifluoroethylene. Nanoparticles of LiNbO₃ with ferroelectric phase were successfully synthesized and dispersed homogenously by ultrasonication in the copolymer matrix without any surfactant or surface functionalization. The nanocomposites were fully characterized by electronic microscopy, X‐ray diffraction, differential scanning calorimetry, dynamical mechanical analysis, and piezometer. Surprisingly, the copolymer matrix crystallinity and morphology were not affected by the incorporation of nanoparticles. Therefore the nanocomposites remained good mechanicals properties and high ferroelectricity coupled to nonlinear optical activity thanks to the noncentro symmetric space group of lithium niobate. This could be a novel approach to develop new multifunctional materials. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

A Composite Formation Route to Well‐Crystalline Manganese Oxide Nanocrystals: High Catalytic Activity of Manganate–Alumina Nanocomposites

Manganese oxide nanocrystals are combined with aluminum oxide nanocrystals to improve their crystallinity via calcination without a significant increase of crystal size. A nanocomposite, consisting of two metal oxides, can be synthesized by the reaction between permanganate anions and aluminum oxyhydroxide keggin cations. The as‐prepared manganese oxide–aluminum oxide nanocomposite is X‐ray amorphous whereas heat‐treatment gives rise to the crystallization of an α‐MnO₂ phase at 600 °C and Mn₃O₄/Mn₂O₃ and γ‐Al₂O₃ phases at 800 °C. Electron microscopy and N₂ adsorption‐desorption‐isotherm analysis clearly demonstrate that the as‐prepared nanocomposite is composed of a porous assembly of monodisperse primary particles with a size of ～20 nm and a surface area of >410 m² g^?1. Of particular interest is that the small particle size of the as‐prepared nanocomposite is well‐maintained up to 600 °C, a result of the prevention of the growth of manganate grains through nanoscale mixing with alumina grains. The calcined nanocomposite shows very‐high catalytic activity for the oxidation of cyclohexene with an extremely high conversion efficiency of >95% within 15 min. The present results show that the improvement of the crystallinity without significant crystal growth is very crucial for optimizing the catalytic activity of manganese oxide nanocrystals.     

Preparation of transparent PMMA/Fe(IO3)3 nanocomposite films from microemulsion polymerization

Polymethyl methacrylate (PMMA)/Fe(IO₃)₃ nanocomposite thin films are obtained by in situ particle generation in microemulsions and subsequent photopolymerization of a mixture containing methyl methacrylate, trimethylolpropane triacrylate, and crystallized iron iodate (Fe(IO₃)₃) nanorods. Hyper‐Rayleigh scattering measurements combined with X‐ray diffraction, transmission electron microscopy, and dynamic light scattering are first used to probe in situ the crystallization kinetics of iron iodate nanorods in water‐in‐oil microemulsions prepared with methyl methacrylate as the oil phase and marlophen NP12 as a surfactant. Trimethylolpropane triacrylate is then added as a crosslinker before spin‐coating. Films are deposited on glass substrates for the nonlinear optical characterizations and on silicon wafers for the piezoelectric and mechanical measurements. Nanocomposite films treated by corona discharge are finally characterized through optical microscopy, laser Doppler vibrometry, and Brillouin spectroscopy. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1203‐1211, 2013