Liuqing Huang

Methotrexate-Loaded PEGylated Chitosan Nanoparticles: Synthesis, Characterization, and in Vitro and in Vivo Antitumoral Activity

Cancer nanotherapeutics are rapidly progressing and being implemented to solve several limitations of conventional drug delivery systems. In this paper, we report a novel strategy of preparing methotrexate (MTX) nanoparticles based on chitosan (CS) and methoxypoly(ethylene glycol) (mPEG) used as nanocarriers to enhance their targeting and prolong blood circulation. MTX and mPEG-conjugated CS nanoparticles (NPs) were prepared and evaluated for their targeting efficiency and toxicity in vitro and in vivo. The MTX-mPEG-CS NP size determined by dynamic light scattering was 213 ± 2.0 nm with a narrow particle size distribution, and its loading content (LC %) and encapsulation efficiency (EE) were 44.19 ± 0.64% and 87.65 ± 0.79%, respectively. In vitro release behavior of MTX was investigated. In vivo optical imaging in mice proved that MTX was released from particles subsequently and targeted to tumor tissue, showing significantly prolonged retention and specific selectivity. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay obviously indicated that the higher inhibition efficiency of MTX-mPEG-CS NPs meant that much more MTX was transferred into the tumor cells. A significant right-shift in the flow cytometry (FCM) assay demonstrated that MTX-loaded nanoparticles were far superior to a pure drug in the inhibition of growth and proliferation of Hela cells. These results suggest that MTX-mPEG-CS NPs could be a promising targeting anticancer chemotherapeutic agent, especially for cervical carcinoma.

Sonocrystallization of ZIF-8 on Electrostatic Spinning TiO2 Nanofibers Surface with Enhanced Photocatalysis Property through Synergistic Effect

Semiconductor-metal-organic framework (MOF) hybrid photocatalysts have attracted increasing attention because of their enhanced photocatalytic activity. However, the effect of the interface reaction between semiconductor and MOFs is rarely studied. In this work, we studied the synthesis and photocatalytic activity of zeolitic imidazolate framework-8 (ZIF-8) decorated electrostatic spinning TiO2 nanofibers (TiO2 ESNFs). TiO2/ZIF-8 hybrid photocatalysts were prepared via a facile sonochemical route. It was crucial that the ZIF-8 was assembled homogeneously on the surface of TiO2 ESNFs and formed a N-Ti-O bond under sonochemical treatment, which may result in reducing recombination of the electron-hole pairs. The chemically bonded TiO2/ZIF-8 nanocomposites displayed excellent performance of thermal stability, controllable crystallinity, and great enhancement of photocatalytic activity in Rhodamine B (Rh B) photodegradation. Furthermore, the UV-vis light adsorption spectra of TiO2/ZIF-8 nanocomposites showed that the ZIF-8 photosensitizer extended the spectral response of TiO2 to the visible region. The new strategy reported here can enrich the method for designing new semiconductor-MOF hybrid photocatalysts.

Fabrication of SiO2@silicalite-1 and its use as a catalyst support

SiO2@silicalite-1, using silica sol (pH = 9.47, SiO2 ≈ 30 wt%) as the silica source, was directly synthesized in a eutectic mixture where silicalite-1 grains were formed in the three-dimensional net structure of silica gel, grown in situ by transforming amorphous SiO2 into an MFI-type structure and coated with amorphous SiO2. The alkalinity, template agent, and crystallization time strongly affect the physicochemical properties of SiO2@silicalite-1. The physicochemical properties of these samples were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra and nitrogen adsorption. The results show that the SiO2@silicalite-1 is synthesized in a eutectic mixture and its physicochemical properties can be tuned by controlling the content of sodium hydroxide and tetrapropyl ammonium bromide (TPABr). A time-dependent study reveals that the formation process obeys an in situ epitaxial growth and phase transformation mechanism. Finally, SiO2@silicalite-1 was used as the support to prepare TiO2-loaded SiO2@silicalite-1 (TiO2@SiO2@silicalite-1). After five loading procedures, it could load 0.44% TiO2 nanoparticles, which is higher than the TiO2 nanoparticle loading in traditional silicalite-1 (0.13%). When the catalysts were used as a catalyst for the degradation of rhodamine B (RhB) aqueous solution under UV light, the photocatalytic efficiency of TiO2@SiO2@silicalite-1 (89.2%) is higher than TiO2@silicalite-1 (only 34.6%). The rate of degradation using TiO2@SiO2@silicalite-1 is 4.3 times faster than that using TiO2@silicalite-1. Furthermore, SiO2@TiO2@silicalite-1 exhibits high stability of photocatalytic performance. After five repeated cycles, the photocatalytic efficiency of TiO2@SiO2@silicalite-1 is 88.09%, which reduces only by 1.1%.

Effects of Slag Refining on Boron Removal from Metallurgical-Grade Silicon Using Recycled Slag with Active Component

A new slag refining method to remove boron from metallurgical silicon (MG-Si) by mixed reused slag and active component was proposed. The silicon was refined with CaCl2-CaO-SiO2 slag system in this work. The boron removal efficiency under different temperature and holding time was investigated, particularly for the recycle of the used slag mixed with different amount of CaCl2 in the 2nd and the 3rd run. The multiple slag refining was adopted to test the effect of reused slag; the boron removal ratio was 96% and 94% at 1923 K and 1873 K, respectively. These methods could significantly reduce the slag amount in refining. The total transfer coefficient of boron was also derived by the boron content. The overall boron removal mechanism and effect of slag recycle on boron removal was also discussed.

Fabrication and characterization of SiO2@TiO2@silicalite-1 catalyst and its application for degradation of rhodamine B

SiO2@TiO2@silicalite-1 catalyst, with TiO2 (Degussa P25) nanoparticles encapsulated by SiO2 and adhered on the surface of silicalite-1 zeolite, was successfully fabricated by combining pressing, sintering and infiltration methods. The samples were characterized by XRD, SEM, FT-IR, TEM, nitrogen sorption, and UV-vis diffuse reflectance spectra. The photocatalytic properties were investigated by degradation of rhodamine B (RhB) aqueous solution under UV light. The results show that TiO2 nanoparticles are coated with a SiO2 shell and bonded together. The core/shell structure of TiO2@SiO2 is attached to the surface of silicalite-1 particles. The photocatalytic efficiency of TiO2@silicalite-1 is 97.4%. When the catalyst is coated with SiO2, its photocatalytic efficiency is significantly improved to 99.7%. Furthermore, the rate of degradation using SiO2@TiO2@silicalite-1 is 1.54 times faster than that using TiO2@silicalite-1.

Separation of Metal Impurities from Metallurgical Grade Silicon via CaO-SiO2-CaF2 Slag Treatment Followed by Leaching with Hydrochloric Acid

The separation of metal impurities from metallurgical grade silicon by a combination of slag treatment and acid leaching was investigated. Based on a detailed analysis of microstructure evolution in metallurgical grade silicon, the primary precipitated phase in silicon was tended to form Si-Ca system intermetallics after CaO-SiO2-CaF2 slag treatment. Moreover, the extraction efficiency of metal impurities from silicon with slag treatment was higher than that without slag treatment in the leaching process. Some parameters such as acid concentration, temperature, particle size, stirring speed and leaching time were also discussed. The extraction of impurities Fe, Al and Ca increased with increasing acid concentration, leaching time and decreasing particle size. Besides, the leaching kinetics of these metal impurities was confirmed to be controlled by chemical reaction with the application of cracking shrinking model.

Preparation and Characterization of Silicate-1@Kaolin Clay Ceramic with Different Na+ Concentration

In order to explore the synthesis of silicate-1 membrane on kaolin clay ceramic and the effect of Na+ ion substitution on the dielectric properties of ceramic, silicate-1@kaolin clay ceramics containing different content of Na+ were successfully synthesized by combining sintering, sol-gel, and ion exchange method. Samples were analyzed by chemical composition (XRF), X-ray diffraction (XRD), scanning electron microscope (SEM), digital hardness tester, and microwave dielectric measurement system. SEM images exhibited that a layer of silicate-1 was successfully grown on the surface of the kaolin clay ceramic. The energy dispersive spectrometer (EDS) revealed that the content of Na+ in silicate-1 decreased with increase of ion exchange time. The content of Na+ in silicate-1@kaolin clay ceramic decreased from 1.46 to 0.29% when the silicate-1@kaolin clay ceramic was treated by the unsaturated solution of NH3 from zero to two times. In this process, the dielectric constant of the silicate-1@kaolin clay ceramic almost kept the same. But the dielectric loss of silicate-1@kaolin clay ceramic decreased from 0.474 to 0.131. Silicate-1@kaolin clay ceramic is expected to be used as sensor to detect some metal ions.

Effect of solidification rate on representative impurities distribution in Si-Cu alloy

Abstract The main purpose of this article is to demonstrate that solvent refining in combination with directional solidification can be used for preparation of high purity metallurgical grade silicon for solar cells. Silicon was alloyed with copper and grew under different solidification rates from Si–Cu alloy melt. A detailed analysis of the microstructures and morphologies of Si–Cu alloy has been carried out, focusing on the distribution characteristic of representative impurities affected by solidification rate. The experimental results indicated that copper addition promotes segregation of metal impurities Fe, Al and Ca from metallurgical grade silicon, and the purification effect is more pronounced with the solidification rate decreases. It was also determined that the representative non-metallic impurity phosphorus has a remarkable separation performance after alloying with copper, which can be helpful for the phosphorus removal.

Effect of Na2O-SiO2 slag treatment on hydrometallurgical purification of metallurgical grade silicon

The effects of Na2O-SiO2 slag treatment on purification of metallurgical grade silicon by leaching with hydrogen fluoride have been investigated. A comparative analysis of microstructure evolution was carried out to examine the leaching behavior of impurities from metallurgical grade silicon. It was found that the distribution of metal impurities Al, Ca, Ti and Na, which co-deposited with Si and formed different intermetallic phases at grain boundaries, had manifest distinction between precipitated phase and silicon. Moreover, acid corrosion experiment results revealed that slag treatment improved the dissolution rate of metal impurities from metallurgical grade silicon as contrasted to that without slag treatment.

Research on the whitening mechanism of kaolin by chemical bleaching and calcining

Bleaching and calcining are the major whitening process in kaolin industry. However, the whitening mechanism has not been clarified yet. In this paper, the whitening mechanism of kaolin was investigated. Kaolin was bleached with hydrosulfite and calcined under different temperature separately, the whiteness and microstructure were detected throughly by X-ray diffraction and scanning electron microscope. The soluble and insoluble Fe content were determined by phenanthroline spectrophotometry. Effect of chemical bleaching, calcined temperature on mineral characteristics and whiteness was discussed. The mechanism of whitening was analyzed systematically.