Dispersion of silica nanoparticles bearing perfluorohexyl units into fluorinated copolymers

This study aims at determining the compatibility behavior of nanoparticles surface with fluorinated matrices to obtain a homogenous dispersion and better composites properties. First, modified silica nanoparticles by C₆F₁₃I and C₆F₁₃‐C₂H₄‐SH led to various fluorinated silica of different massic concentrations and grafting rates. The dispersion of these nanoparticles (in 5 wt %) into molten poly(VDF‐co‐HFP) and poly(TFE‐co‐HFP) matrices were studied as well as the hydrophobic, mechanical, and thermal properties of both fluorinated copolymers and resulting composites. In both series, the storage modulus of nanocomposites increased while the melting (T_m) and decomposition (T_10%) temperatures varied with the polymer matrix. They increased for poly(VDF‐co‐HFP) composites (T_m= 134 to 144 °C and T_10%= 441 to 464 °C) but decreased for poly(TFE‐co‐HFP) nanocomposites (T_m= 276 to 268 °C and T_10%= 488 to 477 °C). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 1512–1522     

The interaction between silica flat substrate and functional group–modified nanoparticles

Inspired by nature, the research of functionalized nanoparticles and nanodevices has been in-depth developed in recent years. In this paper, we theoretically studied the interaction between functional polyelectrolyte brush layer–modified nanoparticles and a silica flat substrate. Based on the Poisson–Nernst–Planck equations, the mathematical model is established. The changes of the volume charge density and electric field energy density when the nanoparticle interacts with the silica flat substrate under multi-ions regulation were investigated. The results show that when there is a strong interaction between the silica flat substrate and nanoparticles, such as the distances between the nanoparticle and silica flat substrate, which are 2 or 5 nm, the isoelectric point shift under the influence of silica flat substrate and the total charge density in the brush layer is jointly controlled by the cations in the solution and the volume charge density of the brush layer. With the increase of the distances between the nanoparticle and silica flat substrate, the regulation of the volume charge density of the brush layer dominates. These results will provide guidance for the movement mechanism of functionalized nanoparticles in silica nanochannels.     

Ag nanoparticles immobilized on guanidine modified-KIT-5 mesoporous nanostructure: Evaluation of its catalytic activity for synthesis of propargylamines and investigation of its antioxidant and anti-lung cancer effects

The current study involves the novel synthesis of Ag nanoparticles (Ag NPs) decorated biguanidine modified mesoporous silica KIT-5 following post-functionalization approach (KIT-5-bigua-Ag). The tiny Ag NPs were being stabilized over the in situ prepared biguanidine ligand. The high surface area material was characterized using advanced analytical methods like Fourier Transformed infrared (FT-IR) spectroscopy, N₂-adsorption–desorption isotherm, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDS), and X-ray Diffraction study (XRD). The material was having large pore cage like structure with pore diameter of 8–10 nm. TEM study displayed the particles size of deposited Ag NPs were 10–15 nm. The KIT-5-bigua-Ag nanocomposite had a significantly high surface area of 318 m²/g (BET analysis). Towards the chemical applications of the material, we headed the three-component reaction of aldehydes, amines and alkynes (A³ coupling) with good to excellent yields (70–98%) of diverse Propargylamines. The catalyst was easily isolable and reused in 8 cycles without any leaching and considerable change in its reactivity. In addition, the KIT-5-bigua-Ag nanocomposite was engaged in biological assays like study of anti-oxidant properties by DPPH mediated free radical scavenging test using BHT as a reference molecule. Thereafter, on having a significant IC50 value in radical scavenging assay, we extended the bio-application of the desired nanocomposite in anticancer study of A549 cell of human lung in-vitro conditions. In the cytotoxicity and anti-human lung studies, the nanocomposite was treated to lung cancer A549 cell line following MTT assay. The cell viability of malignant lung cell line reduced dose-dependently in the presence of KIT-5-biguanidine-Ag nanocomposite. IC50 values of the nanocomposite were observed to be 915.22 μg/mL against A549 cell line. So, these results suggest that KIT-5-bigua-Ag as a novel chemotherapeutic nanocomposite have a suitable anticancer activity against lung cell lines.     

Mesoporous Hybrid Materials by Simultaneous Pseudomorphic Transformation and Functionalization of Silica Microspheres

Non‐agglomerated amino‐functionalized mesoporous silica microspheres are synthesized by a one‐pot synthesis from a parent silica material. Narrow pore size distributions in the range from 3 to 5 nm are obtained with alkyltrimethylammonium structure‐directing agents (SDAs). By following the pseudomorphic transformation pathway, the particle size distribution and spherical morphology of the parent silica are retained during the synthesis. The products contain accessible and uniformly distributed amino groups. The average pore size and the ratio of small uniform mesopores (<5 nm) to larger mesopores and macropores can be controlled by choosing the appropriate SDA and by adjusting the concentration of the amino‐functionalized alkoxysilane precursor, leading to a variety of meso‐macroporous hybrid materials.     

Cytotoxicity and Cellular Uptake of Amorphous Silica Nanoparticles in Human Cancer Cells

The cytotoxic effects of silica nanoparticles (SNPs) on different human cancer cells, as well as the uptake kinetics and pathways of SNPs have been studied here. SNPs with the diameter of ≈20 nm induced a dose‐dependent cytotoxicity in both gastric cancer cells (MGC80–3) and cervical adenocarcinoma epithelial cells (HeLa), but MGC80–3 cells were more susceptible to the cytotoxic effect induced by SNPs. Changes in the nuclear morphology and flow cytometric analysis with annexin V/PI double staining show that SNPs induced a higher degree of apoptosis in MGC80–3 cells. Accordingly, more remarkable reactive oxygen species (ROS) burst is detected in SNP‐treated MGC80–3 cells. Using fluorescein isothiocyanate (FITC)‐labeled SNPs and flow cytometry, it is found that the uptake of SNPs is more efficient in MGC80–3 than in HeLa cells. SNPs are internalized into both cancer cells through energy‐dependent pathway. Inhibitor studies with dynasore and methyl‐β‐cyclodextrin show that these cancer cells took up 20 nm SNPs mainly through the caveolin‐mediated endocytosis, while in HeLa cells SNPs internalization was also via dynamin‐dependent clathrin‐mediated pathway. These findings indicate that SNPs cause differential cytotoxic effects in different human cancer cells, which might be related to the uptake process and efficiency toward these cancer cells.     

Spherical Polyolefin Particles from Olefin Polymerization in the Confined Geometry of Porous Hollow Silica Particles

Porous hollow silica particles (HSPs) are presented as new templates to control the product morphology in metallocene‐catalyzed olefin polymerization. By selectively immobilizing catalysts inside the micrometer‐sized porous hollow silica particles, the high hydraulic forces resulting from polymer growth within the confined geometries of the HSPs cause its supporting shell to break up from the inside. As the shape of the support is replicated during olefin polymerization, perfectly spherical product particles with very narrow size distribution can be achieved by using HSPs exhibiting a monomodal size distribution. Furthermore, the size of the obtained product particles can be controlled not only by the polymerization time but also by the size of the support material.

     

High Surface Area Mesoporous Silica Nanoparticles with Tunable Size in the Sub-Micrometer Regime: Insights on the Size and Porosity Control Mechanisms

Mesoporous silica nanostructures (MSNs) attract high interest due to their unique and tunable physical chemical features, including high specific surface area and large pore volume, that hold a great potential in a variety of fields, i.e., adsorption, catalysis, and biomedicine. An essential feature for biomedical application of MSNs is limiting MSN size in the sub-micrometer regime to control uptake and cell viability. However, careful size tuning in such a regime remains still challenging. We aim to tackling this issue by developing two synthetic procedures for MSN size modulation, performed in homogenous aqueous/ethanol solution or two-phase aqueous/ethyl acetate system. Both approaches make use of tetraethyl orthosilicate as precursor, in the presence of cetyltrimethylammonium bromide, as structure-directing agent, and NaOH, as base-catalyst. NaOH catalyzed syntheses usually require high temperature (>80 °C) and large reaction medium volume to trigger MSN formation and limit aggregation. Here, a successful modulation of MSNs size from 40 up to 150 nm is demonstrated to be achieved by purposely balancing synthesis conditions, being able, in addition, to keep reaction temperature not higher than 50 °C (30 °C and 50 °C, respectively) and reaction mixture volume low. Through a comprehensive and in-depth systematic morphological and structural investigation, the mechanism and kinetics that sustain the control of MSNs size in such low dimensional regime are defined, highlighting that modulation of size and pores of the structures are mainly mediated by base concentration, reaction time and temperature and ageing, for the homogenous phase approach, and by temperature for the two-phase synthesis. Finally, an in vitro study is performed on bEnd.3 cells to investigate on the cytotoxicity of the MNSs.     

Ru助剂对Co/SiO2催化剂费托合成反应性能的影响

 考察了 Ru 助剂 (0.17%?9.96%) 对 Co/SiO2 催化剂结构及其费托合成反应性能的影响. 结果表明, Ru 助剂可降低 Co/SiO2 催化剂的还原温度, 从而提高其还原度. 光电子能谱和扩展 X 吸收射线精细结构研究表明, 即使 Ru 含量高达 9.96%, 在 Co/SiO2 催化剂焙烧过程中也未观察到 Ru 物种与 Co 物种作用形成的化合物. 还原后催化剂中 Ru 趋向于与 Co 物种紧密接触且分散在催化剂表面. H2 程序升温脱附结果表明, 随着 Ru 含量的增加, 位于反应温度附近的 H2 脱附峰面积增加, 即此时催化剂吸附 H2 能力提高, 因此反应活性单调增加, 但存在最佳 Ru 含量, 此时 C5+选择性最高.     

Electrochemiluminescence immunosensor for ultrasensitive detection of biomarker using Ru(bpy)3-encapsulated silica nanosphere labels

Here, we describe a new approach for electrochemiluminescence (ECL) assay with Ru(bpy)₃²⁺-encapsulated silica nanoparticle (SiO₂@Ru) as labels. A water-in-oil (W/O) microemulsion method was employed for one-pot synthesis of SiO₂@Ru nanoparticles. The as-synthesized SiO₂@Ru nanoparticles have a narrow size distribution, which allows reproducible loading of Ru(bpy)₃²⁺ inside the silica shell and of α-fetoprotein antibody (anti-AFP), a model antibody, on the silica surface with glutaraldehyde as linkage. The silica shell effectively prevents leakage of Ru(bpy)₃²⁺ into the aqueous solution due to strong electrostatic interaction between the positively charged Ru(bpy)₃²⁺ and the negatively charged surface of silica. The porous structure of silica shell allowed the ion to move easily through the pore to exchange energy/electrons with the entrapped Ru(bpy)₃²⁺. The as-synthesized SiO₂@Ru can be used as a label for ultrasensitive detection of biomarkers through a sandwiched immunoassay process. The calibration range of AFP concentration was 0.05-30 ng mL⁻¹ with linear relation from 0.05 to 20 ng mL⁻¹ and a detection limit of 0.035 ng mL⁻¹ at 3σ. The resulting immunosensors possess high sensitivity and good analytical performance.     

Novel inorganic morphologies formed in polyimide/silica hybrid films

2-(4-Aminophenyl)-5-aminobenzimidazole was used to prepare polyimide/silica hybrid films via sol-gel process. At 40 wt.% silica content, hybrid films were still translucent. No noticeable silica particle has been observed. Unexpectedly, after treating at 800 °C, novel morphologies of silica were observed on the surface of inorganic films, which changed from homogeneous to sea-island and to co-continuous structure with increasing silica content in the matrix. Hydrogen bonding between NH in imidazole and silanol group results that silica tends to linear structures, which is considered as the main reason for this morphological change.