Silica-based Nanocomposites Research Articles

Congo Red Decolorization Using Textile Filters and Laccase-Based Nanocomposites in Continuous Flow Bioreactors.

Removal of azo and diazo dye content from textile industry wastewaters is crucial due to their environmental impact. Here, we report on the use of the fungal laccase from Pycnoporus sanguineus CS43 immobilized on silica nanoparticles and entrapped in textile-based filters for the degradation of Congo Red. Laccase immobilization and synthesis of the nanocomposites were carried out by two different methods, one in the presence of acetone and the second using water as solvent. This led to a change in the hydrophobicity of the obtained biofilters. Successful preparation of the nanocomposites was confirmed via FTIR spectroscopy. Changes in the secondary structure of the enzyme were inspected through the second derivative of the FTIR spectra. Six different types of filter were fabricated and tested in a continuous flow bioreactor in terms of their decolorization capabilities of Congo Red. The results indicate removal efficiencies that approached 40% for enzymes immobilized on the more hydrophobic supports. Backscattered electron (BSE) images of the different filters were obtained before and after the decolorization process. Percentage of decolorization and activity loss were determined as a function of time until a plateau in decolorization activity was reached. Experimental data was used to recreate the decolorization process in COMSOL Multiphysics® (Stockholm, Sweden). These simulations were used to determine the proper combination of parameters to maximize decolorization. Our findings suggest that the treatment of textile-based filters with immobilized laccase in conjunction with hydrophobic nanocomposites provides a suitable avenue to achieve more efficient laccase dye decolorization (39%) than that obtained with similar filters treated only with free laccase (8%). Filters treated with silica-based nanocomposites and immobilized laccases showed an increase in their decolorization capability, probably due to changes in their wetting phenomena.

Mesoporous silica decorated with platinum nanoparticles for drug delivery and synergistic electrodynamic-chemotherapy

Electrodynamic therapy (EDT) is a conceptually new cancer treatment approach recently proposed by our group. During EDT, the electro-driven catalytic reaction would occur on the surface of platinum nanoparticles (PtNPs) to produce reactive oxygen species (ROS) under the direct current (DC) or square-wave alternating current (AC) electric field. To further extend the potential of EDT, we hereby designed mesoporous silica-based nanocomposites decorated with PtNPs and loaded with anticancer drug doxorubicin (DOX) for synergistic electrodynamic-chemotherapy. Such silica-based nanocomposites could enable homogenous killing of large-sized tumors (over 500 mm3) and realize remarkable tumor destruction efficacy at a relatively low quantity of electricity. To our best knowledge, this is the first study to combine EDT and chemotherapy to develop a synergetic nanoplatform, openning a new dimension for the design of other EDT-based anticancer strategies.

WITHDRAWN: Preparation and characterization of Ce-doped SiO2 nano-materiales as effective photo-catalyst under visible light

A series of silica-based nanocomposites have been synthesised by an impregnation and co-impregnation method, namely, 20 wt% Ti-SiO2, 20 wt% Ce-SiO2, 20Ti-Ce-SiO2 (10:10 wt/wt Ti:Ce), and 40Ti-Ce-Si...

Bioactive antibacterial silica-based nanocomposites hydrogel scaffolds with high angiogenesis for promoting diabetic wound healing and skin repair.

Diabetic wound repair and skin regeneration remains a worldwide challenge due to the impaired functionality of re-vascularization.Methods: This study reports a bioactive self-healing antibacterial injectable dual-network silica-based nanocomposite hydrogel scaffolds that can significantly enhance the diabetic wound healing/skin tissue formation through promoting early angiogenesis without adding any bioactive factors. The nanocomposite scaffold comprises a main network of polyethylene glycol diacrylate (PEGDA) forming scaffolds, with an auxiliary dynamic network formed between bioactive glass nanoparticles containing copper (BGNC) and sodium alginate (ALG) (PABC scaffolds).Results: PABC scaffolds exhibit the biomimetic elastomeric mechanical properties, excellent injectabilities, self-healing behavior, as well as the robust broad-spectrum antibacterial activity. Importantly, PABC hydrogel significantly promoted the viability, proliferation and angiogenic ability of endothelial progenitor cells (EPCs) in vitro. In vivo, PABC hydrogel could efficiently restore blood vessels networks through enhancing HIF-1α/VEGF expression and collagen matrix deposition in the full-thickness diabetic wound, and significantly accelerate wound healing and skin tissue regeneration.Conclusion: The prominent multifunctional properties and angiogenic capacity of PABC hydrogel scaffolds enable their promising applications in angiogenesis-related regenerative medicine.

Magnetic And pH Dual-Responsive Nanoparticles For Synergistic Drug-Resistant Breast Cancer Chemo/Photodynamic Therapy.

BackgroundDrug resistance is one of the prime reasons of chemotherapy failure in breast cancer and is also an important factor affecting prognosis.PurposeIn this study, we constructed a functional magnetic mesoporous silica-based nanocomposite (MMSN) for breast cancer chemotherapy/photodynamic therapy.MethodsMMSN was characterized by scanning electron microscopy and transmission electron microscopy to observe the morphology. The size distribution and zeta potential of the MSNs were determined using Malvern Particle Size Analyzer. Anti-tumor activity in vitro was investigated by CCK-8 assay, flow cytometry and transwell experiment, and the anti-tumor activity in vivo was probed into by magnetic targeting, toxicity, and antitumor effects in breast cancer-bearing BABL/c nude mice.ResultsThe results showed that the release of doxorubicin in the nanocomposites was pH sensitive, and the cumulative release rate reached 80.53% at 60 h under acidic conditions. The nanocomposites had a high cellular uptake ability in MCF-7/ADR cells, and the IC50 value of the nanocomposites on MCF-7/ADR cells was 4.23 μg/mL, much smaller than that of free DOX (363.2 μg/mL). The nanocomposites could effectively reverse resistance and induce apoptosis of MCF-7/ADR cells. The blood biochemistry parameters and H&E staining results showed no serious adverse effects after treatment with the nanocomposites. Prussian blue staining showed that the nanocomposites were able to target tumor tissues in tumor-bearing mice under a magnetic field. The combined chemical/photodynamic therapy significantly inhibited tumor growth in vivo.ConclusionNanocomposites with magnetic and pH dual-responsive performance has shown a promising platform for enhanced drug-resistant breast cancer treatment.

Precise growth of polymer brushes on silica-based nanocomposites via visible-light-regulated controlled radical polymerization

Precise control over molecular variables of grafted polymer brushes is of crucial importance for obtaining polymer nanocomposites with desirable architectures and physicochemical properties, yet it remains a significant synthetic challenge.

Construction of a Glutathione-Responsive and Silica-Based Nanocomposite for Controlled Release of Chelator Dimercaptosuccinic Acid.

Dimercaptosuccinic acid (DMSA) is an oral heavy metal chelator. Although DMSA is the most acceptable chelator in the urinary excretion of toxic elements from children and adults, its defects in plasma binding and the membrane permeability limit its interaction with intracellular elements and affect its efficacy in chelation therapy. Herein, a novel nanocomposite composed of mesoporous silica nanoparticles (MSNs), disulfide bond, and DMSA was synthesized and characterized with a scanning/transmission electron microscope, IR and Raman spectra, and TGA analysis. The in vitro interactions with glutathione (GSH) and cellular uptake assays showed that it was able to be stable in extracellular environments such as in blood, be internalized by cells, and release DMSA inside via GSH-triggered disulfide cleavage reaction. The in vitro adsorption assays showed that MSNs-SH as its intracellular metabolite had strong adsorbability for models of Hg2+ or Pb2+. The hemolysis and cell viability assays showed that it was compatible with blood and cells even at a concentration of 1000 μg·mL−1. All above could not only enable it to be a GSH-responsive drug delivery system (DDS) for DMSA delivery but also to be a solution for its defects and efficacy. Thus, introduction of intelligent DDS might open a new avenue for DMSA-based chelation therapy.

Influence of moisture absorption on electrical properties and charge dynamics of polyethylene silica-based nanocomposites

The use of nanocomposites as dielectric materials is expected to lead to improved electrical performance. However, recent research has shown that moisture absorption can cause a deterioration in the electrical performance of nanocomposites. Although it is generally accepted that hydroxyl groups attached to nanoparticle surfaces are the main cause of moisture absorption, the impact of this absorption on the electrical properties of nanocomposites is still not fully understood. In this paper, a series of measurements, including thermogravimetric analysis, DC breakdown, surface potential decay and space charge, are conducted with the aim of determining the impact of moisture absorption on the electrical properties of polyethylene/silica nanocomposites. The results show that the loading ratio of nanosilica and the humidity of the conditioning environment determine the amount of absorbed moisture. According to the Zhuravlev model, the main contribution to the deterioration in electrical properties of nanocomposites comes from the large amount of moisture absorbed in multilayer form. It is found that the loading ratio of nanosilica is the most significant factor in reducing DC breakdown strength.

Silver Nanoparticles Synthesised within the Silica Matrix in Hyperstoichiometrical of Mercury from Aqueous Solutions

Mercury adsorption of silver containing silica-based nanocomposites was evaluated. Maximum adsorption capacity of 0.4 mmol g−1 was achieved at silver loading of 0.5 mmol g−1. Nevertheless, if to calculate in respect to silver content the mercury adsorption capacity was generally elevated along with decreasing silver nanoparticle diameter. It has been demonstrated that silver particle diameters and loading should collectively be taken into consideration in designing the optimal mercury removal process. Further recommendations have been proposed with the aim of increasing the mercury removal efficiency using silver nanoparticles deposited on the surface of silica with lover silver loading, while achieving similar or even higher efficiencies due to observed hyperstoichiometry effect.

Characterization of low-dose doxorubicin-loaded silica-based nanocomposites

In this study, we synthesized multicomponent solid films of low-dose doxorubicin (DOX)-loaded polydimethylsiloxane (PDMS)-SiO2/CaP nanocomposites via sol–gel process combined with the method of evaporation-induced self-assembly (EISA) at low temperature. Nanomechanical properties (elasticity and adhesion) of the synthesized multicomponent films were determined by using atomic force microscopy with a PeakForce™ quantitative nanomechanical mapping imaging technique. Solid state of DOX in the synthesized films was studied by using UV–vis and fluorescence spectroscopy. The release profile of different concentrations of DOX loaded (1, 3, and 5wt%) on the multicomponent films was assessed using USP Apparatus 4 and via UV–vis end analysis. Results indicate drug–component interactions on the overall morphology of domains (size and shape), nanomechanical properties, and release behavior of the DOX-loaded nanocomposites. We observed a progressive increase in surface roughness and mean adhesive value with increasing concentration of DOX loaded (0–5wt%). In addition, for all the different concentrations of DOX-loaded, we observed a diffusion-controlled drug release.

The Effect of Weight Fraction, Silanization and Size of Fillers on the Mechanical Properties of an Experimental SiO2 Dental Composite

Background: This research studied mechanical properties of silica-based nanocomposite as a strong restorative material through flexural test method. Objectives: The purpose of this study was to evaluate the effect of weight fraction, silanization and filler size on the flexural properties of silica-based dental nanocomposite. Methods: The prepared composites were made of light-cured copolymer based on Bisphenol A glycolmethacrylate (Bis-GMA) and Triethylene glycoldimethacrylate (TEGDMA) at proportion of 50:50 which reinforced by silica filler. The effect of silanization and weight fraction of the filler was studied with samples containing 10 wt% (n (10)), 20 wt% (n (20)) and 30 wt% (n (30)) nanosilica filler. Samples silanized with (γ-MPS) were also tested. Flexural properties were evaluated with Three-Point Bending test. Flexural strength of the nano SiO2 based composites were also compared to micro silica glass composites. Flexural data were analyzed with one-way analysis of the variance. Results: The sample with 10 wt% (n (10)) had equal strength as the sample with 30 wt% (n (30)) nanosilica filler. Modulus of the sample n (30) was higher than the other samples, but its toughness was significantly lower. Silanization had not expected positive effect on the flexural properties. Conclusions: Adding low amount of nanosilica improved mechanical properties of the resin composite. Silanization of the particles enhanced workability of the paste, but mechanical properties decreased significantly. Reduction in the size of the filler to nano scale caused better flexural strength in comparison to micro glass silica composites.

Preserving the spin transition properties of iron-triazole coordination polymers within silica-based nanocomposites

Composites integrating one dimensional iron(ii) polymers and silica particles preserve the spin-crossover properties of polymer when the interface polymer-silica is controlled.

Unique properties of silver and copper silica-based nanocomposites as antimicrobial agents

The paper reports a new route for the fabrication and determination of physicochemical properties and biological activity, of metallic silica-based nanostructure (Ag/SiO2, Cu/SiO2).

Controlling Interfacial Dynamics: Covalent Bonding versus Physical Adsorption in Polymer Nanocomposites.

It is generally believed that the strength of the polymer-nanoparticle interaction controls the modification of near-interface segmental mobility in polymer nanocomposites (PNCs). However, little is known about the effect of covalent bonding on the segmental dynamics and glass transition of matrix-free polymer-grafted nanoparticles (PGNs), especially when compared to PNCs. In this article, we directly compare the static and dynamic properties of poly(2-vinylpyridine)/silica-based nanocomposites with polymer chains either physically adsorbed (PNCs) or covalently bonded (PGNs) to identical silica nanoparticles (RNP = 12.5 nm) for three different molecular weight (MW) systems. Interestingly, when the MW of the matrix is as low as 6 kg/mol (RNP/Rg = 5.4) or as high as 140 kg/mol (RNP/Rg= 1.13), both small-angle X-ray scattering and broadband dielectric spectroscopy show similar static and dynamic properties for PNCs and PGNs. However, for the intermediate MW of 18 kg/mol (RNP/Rg = 3.16), the difference between physical adsorption and covalent bonding can be clearly identified in the static and dynamic properties of the interfacial layer. We ascribe the differences in the interfacial properties of PNCs and PGNs to changes in chain stretching, as quantified by self-consistent field theory calculations. These results demonstrate that the dynamic suppression at the interface is affected by the chain stretching; that is, it depends on the anisotropy of the segmental conformations, more so than the strength of the interaction, which suggests that the interfacial dynamics can be effectively tuned by the degree of stretching-a parameter accessible from the MW or grafting density.

Carbon functionalized mesoporous silica-based gas sensors for indoor volatile organic compounds

Indoor organic gaseous pollution is a global health problem, which seriously threats the health and life of human all over the world. Hence, it is important to fabricate new sensing materials with high sensitivity and efficiency for indoor volatile organic compounds. In this study, a series of ordered mesoporous silica-based nanocomposites with uniform carbon coatings on the internal surface of silica mesopore channels were synthesized through a simple template–carbonization strategy. The obtained mesoporous silica–carbon nanocomposites not only possess ordered mesostructures, high surface areas (up to ∼759m2g−1), large and tunable pore sizes (2.6–10.2nm), but also have the improved hydrophobicity and anti–interference capability to environmental humidity. The sensing performances of the mesoporous silica–carbon nanocomposites to volatile organic compounds, such as ethylbenzene, methylbenzene, benzene, methanol, acetone, formaldehyde, dichloromethane and tetrahydrofuran, were systematically investigated. The relationships between the sensing performances and their properties, including mesostructures, surface areas, pore sizes, carbon contents and surface hydrophilic/hydrophobic interactions, have been achieved. The mesoporous silica–carbon nanocomposites with hexagonal mesostructure exhibit outstanding performance at room temperature to benzene and acetone with high responses, short response (2–3s) and recovery (16–19s) time, strong anti–interference to environmental humidity, and long–term stability (less than ∼5% loss of the frequency shifts after 42days). Therefore, the obtained mesoporous silica–carbon nanocomposites have a hopeful prospect in the field of environmental air quality monitoring.

ChemInform Abstract: Preparation and Characterization of a Silica‐Based Magnetic Nanocomposite and Its Application as a Recoverable Catalyst for the One‐Pot Multicomponent Synthesis of Quinazolinone Derivatives.

An environmentally benign magnetic silica-based nanocomposite (Fe3O4/SBA-15) as a heterogeneous nanocatalyst was prepared and characterized using Fourier transform infrared and ultraviolet–visible diffuse reflectance spectroscopies, scanning electron microscopy, X-ray diffraction, vibrating sample magnetometry and Brunauer–Emmett–Teller multilayer nitrogen adsorption. Its catalytic activity was investigated for the one-pot multicomponent synthesis of 2,3-dihydroquinazolin-4(1H)-ones starting from isatoic anhydride, ammonium acetate and various aldehydes under mild reaction conditions and easy work-up procedure in refluxing ethanol with good yields. The nanocatalyst can be recovered easily and reused several times without significant loss of catalytic activity. Copyright © 2015 John Wiley & Sons, Ltd.

Separation of Microcystin-LR by Cyclodextrin-Functionalized Magnetic Composite of Colloidal Graphene and Porous Silica.

Microcystin-LR belongs to the family of microcystins produced by cyanobacteria and known to be the most toxic of this family. Existence of cyanobacteria in water bodies leads to the contamination of drinking water with microcystin-LR and thus their separation is essential for an advanced water purification system. Here we report functional nanocomposite-based selective separation of microcystin-LR from contaminated water. We have synthesized cyclodextrin-functionalized magnetic composite of colloidal graphene and porous silica where the cyclodextrin component offers host-guest interaction with microcystin-LR and the magnetic component offers easier separation of microcystin-LR from water. High surface area and large extent of chemical functional groups offer high loading (up to 18 wt %) of cyclodextrin with these nanocomposites, and the dispersible form of the nanocomposite offers easier accessibility of cyclodextrin to microcystin-LR. We have shown that microcystin-LR separation efficiency is significantly enhanced after functionalization with cyclodextrin, and among all the tested cyclodextrins, γ-cyclodextrin offers the best performance. We have also found that graphene-based nanocomposite offers better performance over porous silica-based nanocomposite due to better accessibility of cyclodextrins for interaction with microcystin-LR. The proposed graphene-based functional nanocomposite is environment friendly, reusable, and applicable for advanced water purification.

Multifunctional silica-based nanocomposites for cancer nanotheranostics.

Nanotheranostics have recently attracted increasing attention for their simultaneous drug delivery and diagnostic imaging of diseases, particularly in cancer treatment. Among various nanomaterials, silica nanoparticles are one the most popular models for nanotheranostics. With a tailored mesoporous structure and high surface area, silica nanoparticles show significant advantages over traditional drug nanocarriers as drug delivery systems. With versatile silicone chemistry, silica nanoparticles can incorporate multiple components with optical, magnetic, and electrical properties for imaging and therapy. In this review, we give an overview of the recent progress in the synthesis and biomedical application of multifunctional silica nanoparticles for multimodal imaging, combination therapy, and the nanotheranostics of cancer. We also include our personal perspectives on the direction in which future work in this field might be focused.

Mechanical and impact performance of three-phase polyamide 6 nanocomposites

• Secondary nanofillers enhance the polyamide-6 nanocomposite properties. • Highly sensitive to the percentage and type of filler selection. • Optimum filler content for polyamide-6 nanocomposite found. • Nanoclay (OMMT) improved energy absorption and crash behaviour. • Polyamide-6/glass fibre/3 wt.% SiO 2 , enhanced mechanical properties. In this work, three-phase nanocomposites using multiscale reinforcements were studied to evaluate the influence of nanofillers on static and dynamic mechanical properties at varying temperature conditions. In particular, short-fibres reinforced polyamide 6 (30 wt.%) composites with various weight fractions of montmorillonite (OMMT) and nanosilica (SiO 2 ), manufactured and investigated. Quasi-static tensile properties were investigated at room temperature and also at 65 °C just above the polyamide 6 (PA6) glass transition temperature. The low velocity impact tests were conducted on the manufactured cone-shaped structures to evaluate the crash behaviour and energy absorption capability. The study results shows that the increase of the weight percentage level of OMMT in PA6/glass fibre (30 wt.%) composite made the nanocomposites more brittle and simultaneously deteriorated the tensile properties. SiO 2 nanofiller at 1 wt.% was found to be the optimum ratio for improving tensile properties in silica-based nanocomposites studied. It was further noted that for both types of nanofillers, the crashing behaviour and energy absorption in dynamic properties were improved with increase in nanofillers weight percentage in the composites. The study also shows that the brittleness behaviour of the nanocomposites investigated is associated to the fibre/matrix interaction which is dependent on the nanofiller type and has significant effect on crash modes observed.

Silica-based nanocomposites via reverse microemulsions: classifications, preparations, and applications

Silica-based nanocomposites with amorphous silica as the matrix or carrier along with a functional component have been extensively investigated. These nanocomposites combine the advantages of both silica and the functional components, demonstrating great potential for various applications. To synthesize such composites, one of the most frequently used methods is reverse microemulsion due to its convenient control over the size, shape, and structures. The structures of the composites have a decisive significance for their properties and applications. In this review, we tried to categorize the silica-based nanocomposites via reverse microemulsions based on their structures, discussed the syntheses individually for each structure, summarized their applications, and made some perspectives based on the current progress of this field.