Preparation of Silver Nanoshells on Silica Particles by a Simple Two-step Process

A simple two-step method was developed to prepare silver nanoshells coated on silica paticles. The method involves two steps: concentration of reaction precursor (AgNO3) on particle surfaces and subsequent reduction by formaldehyde. The obtained composite particles were characterized by TEM, ED, and SEM-EDS measurements. The results show that the silver nanoshell is coated on silica particle surface in the form of a polycrystalline (cubic structure) layer with average thickness of 20 nm and weight percentage of 19%.

Protein Mediated Silica Particles with pH Controlled Porosity and Morphology

Background: The silica leaching activity of some of the mystifying non-pathogenic BKH1 bacteria present in the cluster of hot springs (temperatures range 35°C - 80°C) at Bakreshwar (West Bengal, India, 23°52'48"N;87°22'40"N) has provided some significant advancements in the field of nanotechnology. The present investigation was designed to synthesis the silica particles using bioremediase protein at different pH conditions. Methods: A secretary bacterial protein bioremediase (UniProt Knowledgebase Accession Number P86277) isolated from a thermophilic non-pathogenic bacterium BKH1 (GenBank Accession No. FJ177512) has been used to synthesis the silica particles at different pH conditions (pH at 3.0, 5.0, 8.0, 10.0, and 12.0 respectively). The silica particles were synthesized by the action of bioremediase protein on Tetra-ethyl-orthosilicate (TEOS) under ambient condition. Morphological and compositional studies of the biosynthesized silica particles were characterized by Field emission scanning electron microscope (FE-SEM) equipped with Energy dispersive X-ray analyser (EDX). Results: The Fourier transformed infra-red (FTIR) spectroscopic analysis confirmed the nature as well as occurrence of several functional groups surrounded on the silica particles. The amorphous nature of the prepared silica particles was confirmed by X-ray diffractometer (XRD) study. The Zeta potential (ζ) study revealed the stability of silica particles in neutral pH environment. The Brunauer-Emmett-Teller (BET) surface area measurement confirmed the porosity variation in all biosynthesized silica particles prepared at different pH conditions. Raman spectra analytically depend on their respective specific surface (BET) area. Thermogravimetry tool was used to monitor the effects of the thermal treatment on the surface properties of all the samples. Conclusions: The method for the synthesis of silica particles at different pH condition using the protein bioremediase has a special implication as it is an environmentally benign, cost-effective and facile technique which may have conceivable application in chromatographic packing. In addition, controlling of size as well as porosity of the silica particles can be achievable by pH as an only variable.

Photoacoustic Studies of Colloidal Silica Particles after MeV Ion-Induced Shape Deformation

Ordered arrays of colloidal submicrometer-sized silica particles deposited onto silicon wafers were irradiated with MeV Si ions. The spherical silica particles turned into oblate particles as a result of the increase of the particle dimension perpendicular to the ion beam direction and the decrease in the parallel direction. Pulsed laser photoacoustic spectroscopy was used to study the structural changes of the silica particles after the ion-induced shape deformation. Our purpose is to correlate the mechanical vibrations generated by the pulsed laser as a function of the Si irradiation parameters: ion energy and fluence. Fast Fourier transform analysis of the photoacoustic signal was carried out in order to obtain the normal vibration modes of the system. The size, size distribution and shape of the silica particles were determined by scanning electron microscopy. Our results revealed significant structural differences between the spherical and the deformed silica particles.

Neutralization of interleukin-11 attenuates silica particles-induced pulmonary inflammation and fibrosis in vivo

Environmental exposure to crystalline silica particles can lead to silicosis, which is one of the most serious pulmonary interstitial fibrosis around the world. Unfortunately, the exact mechanism on silicosis is unclear, and the effective treatments are lacking to date. In this study, we aim to explore the molecular mechanism by which interleukin-11(IL-11) affects silica particles-induced lung inflammation and fibrosis. We observed that IL-11 expressions in mouse lungs were significantly increased after silica exposure, and maintained at high levels across both inflammation and fibrosis phase. Immunofluorescent dual staining further revealed that the overexpression of IL-11 mainly located in mouse lung epithelial cells and fibroblasts. Using neutralizing anti-IL-11 antibody could effectively alleviate the overexpression of pro-inflammatory cytokines(i.e., interleukin-6 and tumor necrosis factor-α) and fibrotic proteins(i.e., collagen type I and matrix metalloproteinase-2) induced by silica particles. Most importantly, the expressions of IL-11 receptor subunit α(IL-11Rα), Glycoprotein130(GP130), and phosphorylated extracellular signal-regulated kinase(p-ERK) were significantly increased in response to silica, whereas blocking of IL-11 markedly reduced their levels. All findings suggested that the overexpression of IL-11 was involved in the pathological of silicosis, while neutralizing IL-11 antibody could effectively alleviate the silica-induced lung inflammation and fibrosis by inhibiting the IL-11Rα/GP130/ERK signaling pathway. IL-11 might be a promising therapeutic target for lung inflammation and fibrosis caused by silica particles exposure.

Al-modified yolk-shell silica particle-supported NiMo catalysts for ultradeep hydrodesulfurization of dibenzothiophene and 4,6-dimethyldibenzothiophene:Efficient accessibility of active sites and suitable acidity

Yolk-shell SiO2 particles(YP)with center-radial meso-channels were fabricated through a simple and effective method.Al-containing YP-supported NiMo catalysts with different Al amounts(NiMo/AYP-x,x=Si/Al molar proportion)were prepared and dibenzothiophene(DBT)and 4,6-dimethyl-dibenzothiophene(4,6-DMDBT)were employed as the probes to evaluate the hydrodesulfurization(HDS)catalytic performance.The as-prepared AYP-x carriers and corresponding catalysts were characterized by some advanced characterizations to obtain deeper correlations between physicochemical properties and the HDS performance.The average pore sizes of series AYP-x supports are above 6.0 nm,which favors the mass transfer of organic sulfides.The cavity between the yolk and the shell is beneficial for the enrichment of S-containing compounds and the accessibility between reactants and active metals.Aluminum embedded into the silica framework could facilitate the formation of Lewis(L)and Brønsted(B)acid sites and adjust the metal-support interaction(MSI).Among all the as-synthesized catalysts,NiMo/AYP-20 catalyst shows the highest HDS activities.The improved HDS activity of NiMo/AYP-20 catalyst is attributed to the perfect combination of excellent structural properties of the yolk-shell mesoporous silica,enhanced acidity,moderate MSI,and good accessibility/dispersion of active components.

Size control of monodisperse nonporous silica particles by seed particle growth

Monodisperse nonporous silica particles were prepared by sol-precipitation via seed particle growth method, and the particle size, which varied from 1.0 to 4.7 μm, was strictly controlled in our experiment, The formation of secondary particles, which resulted in a multimodaI distribution of particle size, was suppressed by changing tetraethoxysilane （TEOS） concentration and reaction temperature. Furthermore, the effect of adding small amounts of electrolyte to the hydrolysis mixture was examined.

Bioactive injectable composites based on insulin-functionalized silica particles reinforced polymeric hydrogels for potential applications in bone tissue engineering

Novel bioactive injectable composites based on biopolymeric hydrogels reinforced with insulin-functionalized silica particles were synthesized.The insulin(INS)was immobilized on the surface of amine-modifed silica particles employing covalent attachment by EDC/NHS chemistry and via electrostatic interaction.The resulting formulations were examined for the morphology(SEM),chemical composition(FTIR,XPS)as well as protein content.To facilitate the injectability and support the bone regeneration,developed particles were dispersed in biopolymeric sol composed of collagen,chitosan and lysinemodifed hyaluronic acid and crosslinked with genipin.By means of rheological study,the sol-gel in situ transition of obtained systems was verifed.It was found in vitro study that MG-63 cells cultured on the developed composites exhibit signifcantly higher alkaline phosphatase(ALP)activity,compared to the pristine hydrogel.Furthermore,the biomineralization ability in the simulated body fluid(SBF)model was also demonstrated.Our fndings suggest that proposed herein novel hydrogel-based composites might be the promising formulation for regeneration of bone defects,especially as a less-cost effective support/alternative for BMP-2 systems.

Enhancement of Heat-Resistance of Carbonyl Iron Particles by Coating with Silica and Consequent Changes in Electromagnetic Properties

Silica-coated carbonyl iron particles （CIPs） are fabricated with the Stober method to improve their heat-resistance and wave-aSsorption properties. The morphology, heat-resistance, electromagnetic properties and microwave absorption of raw-CIPs and silica-coated CIPs are investigated using a scanning electron microscope, an energy dispersive spectrometer, a thermal-gravimetric analyzer, and a network analyzer. The results show that the heat-resistance of silica-coated CIPs is better than that of raw CIFs. The reflection losses exceeding -lOdB of silica-coated CIPs are obtained in the frequency range 9.5-12.4 GHz for the absorber thickness of 2.3 mm, and the same reflection losses of uncoated CIPs reach the data in the lower frequency range for the same thickness. The enhanced microwave absorption of silica-coated CIPs can be ascribed to the combination of proper electromagnetic impedance match and the decrease of dielectric permittivity.

In Situ Monitoring of the Generation of Monodisperse Silica Particles during the Hydrolysis of Tetraethyl Orthosilicate with Piezoelectric Quartz Crystal Impedance Analyzer

The piezoelectric quartz crystal (PQC) impedance analyzer was used to monitor in situ the generation of monodisperse silica particles during the hydrolysis of tetraethyl orthosilicate (TEOS) and their adsorption onto an Au electrode in alcohol solutions containing water (6-15 mol/L) and ammonia (0 2-2 0 mol/L). The equivalent circuit parameters, the resonance frequencies and the half peak width values of the conductance spectra of the PQC resonance were obtained. The resonant frequency decreased notably while the motional resistance changed very slightly (within 1 Ω) during the hydrolysis reaction, suggesting that the mass effect do^minated the adsorption of generated monodisperse silica particles on the gold electrode in this system. Changes in f 0 indicated that the ammonia concentration affected the hydrolytic reaction obviously, and the influence of water concentration on the reaction was small while the water was significantly excessive. Kinetics of monodisperse silica particle adsorption occurring at the electrode|solution interface was analyzed using a first order reaction scheme. In addition, the electrolyte induced precipitation of the monodisperse silica particles was monitored and discussed. The mean size, the number of adsorbed particles per area and the converge of monodisperse silica particles were obtained from scanning electron microscope (SEM) observations.

Morphologies and Superhydrophobicity of Hybrid Film Surfaces Based on Silica and Fluoropolymer

Fluoropolymer and different kinds of silica particles were used for controlling surface chemistry and morphology, respectively. A superhydrophobic surface originated from strawberry-like or quincunx-shaped composite silica particles was obtained. The dual size particles are obtained by utilizing the graft of different modified silica particles with epoxy functional group and amine functional group, This makes the surface of film form a composite interface to have irregular binary structure which plays an essential role in trapping air between the substrate surface and the liquid droplets to be necessary for high contact angle and low contact angle hysteresis. The maximum contact angle for water on the hybrid film is about 174±2° and the contact angle hysteresis is less than 2°. The surface morphologies, roughness and the wettability on the surface of films containing different structural silica particles were compared. It was shown that the hierarchical irregularly structure with a low roughness factor and high air-trapped ratio is indispensable for superhydrophobic surface. Although this structural surfaces based on composite silica particles play a vital role in governing the surface wettability, it is necessary to combine with a low surface energy to make the surface superhydrophobic.

剖析液相色谱柱技术的复杂状况(英文)

Column packings continue to evolve as the needs of users for high efficiency,high resolution and highly sensitive high performance liquid chromatographic(HPLC) analysis drive further developments.In comparing and contrasting modern HPLC columns technologies,diameters of column packings and particle materials are covered.Some products and applications of modern HPLC columns are provided.Future directions in packing developments are predicted in this introductory article.

不同粒径的介孔纳米硅材料对小鼠的急性毒性研究

目的介孔二氧化硅纳米粒（mesoporoussilicananoparticles，MSN）是一种新型、潜在的药物纳米载体。为探索其可能存在的毒性，本研究采用小鼠进行急性毒性研究，分析毒性与材料粒径的关系。方法使用上下法主试验，经静脉注射途径将3种不同粒径（80、200、1000nm）及二氧化硅粉（20nm）分别给予小鼠，观察动物的毒性反应，存活动物观察14d，计算半数致死量（LD50）。观察期结束后，取血进行血生化检测，并对其进行大体解剖，摘取心、肝、脾、肺、肾和大脑，称重并计算脏器系数，制片及进行病理组织学检查。结果MSNs对小鼠有明显的急性毒性，20、80、200、1000nm给予小鼠静脉注射的LD50范围分别为：（26．3～32．8）、（100～125）、（304．7～381）、（80～100）mg·kg^-1；即毒性大小为20nm〉1000nm〉80nm〉200nm。结论MSNs会对小鼠造成急性毒性，并且毒性强弱与其粒径密切相关。

Dual template approach for the synthesis of hierarchically mesocellular carbon foams

We demonstrated a simple and effective dual-templating approach for the synthesis of hierarchically mesocellular carbon foams by using nonionic surfactant of sorbitan monooleate and silica colloid particles as sacrificial templates, and resorcinol/ formaldehyde as carbon source. The representative carbon foam has dual mesopore sizes of 4 and 10 nm, and possesses the specific surface area of 580 m^2/g and the total pore volume of 0.80 cm^3/g.

Synthesis of colloid silica coated with ceria nano-particles with the assistance of PVP

In this paper, a facile synthesis of 100 nm commercial colloid silica coated with nano-ceria core-shell composite particles by the precipitation method using ammonium cerium nitrate and urea as a precipitator with polyvinylpyrrolidone （PVP） as an assistant was briefly introduced. The results showed that the colloid silica was surrounded by nano-ceria uniformly forming the core-shell composite particles. The synthesis process was further discussed and optimized. It was found that the type and quantity of surfactant played a key role in the process. PVP connected the surface of colloid silica and that of the ceria precursor.

Preparation of glucose oxidase electrode containing hydrophobic silica nanoparticles by the sol-gel method

The influences of hydrophobic SiO2 nanoparticles and the contents of glucose oxidase（GOD）upon the response current of enzyme electrode have been investigated by using the sol-gel method,in whichpolyvinylbutyryl（PVB）was used as a matrix.The influenoe of enzymatic activity was measured byelectrochemical method.Experimental data demonstrated that hydrophobic SiO2 particles can immobilizeenzyme well,providing a good and simple method for preparing high quality GOD biosensor.The mechanismhas been discussed.

Natural diatomite particles： Size-, dose- and shape- dependent cytotoxicity and reinforcing effect on injectable bone cement

Natural diatomite （DT） is the ancient deposit of diatom skeleton with many regular pores of 50-200 nm and also an abundant source of biogenic silica. Although silica is considered biologically safe and there is an increasing interest of using natural diatomite for biomedical applications, the toxicity information about natural diatomite is still missing. Here, cytotoxicity of natural diatomite on osteoblasts and fibroblasts were compared to hydroxyapatite and the relationships between cytotoxicity and diatomite sizes, dose, geometry or impurity were systematically investigated. Cell adhesion and interaction with diatomite particles were also fluorescently observed, The results clearly suggested a size-, dose- and shape-dependent cytotoxicity of natural diatomite. Disk-shaped diatomite particles with average size of 30μm in diameter revealed the least toxicity, while the diatomite particles with irregular shapes and sizes less than 10 μm were remarkably toxic. Diatomite particles with proper sizes were then selected to investigate the reinforcing effect on injectable calcium phosphate bone cement. Results showed that diatomite significantly improved the compressive strength of bone cement but did not alter the injectability of the cement, This work provided important biocompatibility information of natural diatomite and demonstrated the feasibility of using selected diatomite as bone implant material.

Determination of Parathion-methyl in Vegetables by Fluorescent-Labeled Molecular Imprinted Polymer

A novel sensor for the determination of parathion-methyl based on couple grafting of functional molecular imprinted polymers （MIPs） was fabricated which is developed by anchoring the MIP layer on surfaces of silica particles embedded CdSe quantum dots by surface imprinting technology. The synthesized molecular imprinted silica nanospheres （CdSe@SiO2@MIP） allow a high selectivity and sensitivity of parathion-methyl via fluorescence intensity decreasing when the MIP material rebinding the parathion-methyl molecule. Compared with the MIP fabri- cated in traditional method, the template of parathion-methyl was easier to remove from the CdSe@SiO2@MIP imprinted material. Under optimal conditions, the fluorescence intensity of parathion-methyl at the imprinted sensor was detected by spectrofluorophotometer. The relative fluorescence intensity of CdSe@SiO2@MIP decreased linearly with the increasing concentration of parathion-methyl ranging from 0.013 mg·kg^-1 to 2.63mg·kg^-1 with a detection limit （3σ） of 0.004 mg·kg^-1 （S/N=3）, which is lower than the MIP in tradition. The imprinted film sensor was applied to detect parathion-methyl in vegetable samples without the interference of other organophosphate pesticides and showed a prosperous application in the field of food safety.