Silica Hybrid Nanocomposites Research Articles

Synthesis of Polyhedral Metal-Organic Framework@Mesoporous Silica Hybrid Nanocomposites with Branched Shapes.

The structural modulation of multicompartment porous nanomaterials is one of the major challenges of nanoscience. Herein, by utilizing the polyhedral effects/characteristics of metal-organic frameworks (MOFs), we present a versatile approach to construct MOF-organosilica hybrid branched nanocomposites with MOF cores, SiO2 shells, and periodic mesoporous organosilica (PMO) branches. The morphology, structure, and functions of the obtained hybrid nanocomposites can be facilely modulated by varying particle size, shape, or crystalline structures of the MOF cores. Specifically, these branched multicompartment porous nanoparticles exhibit evasion behaviors in epithelial cells compared with macrophage cells, which may endow them great potential as a vehicle for immunotherapy.

Interfacial optimization of quantum dot and silica hybrid nanocomposite for simultaneous enhancement of fluorescence retention and stability

We have demonstrated an improved quantum dot (QD) and silica hybrid nanocomposite by interfacial optimization for simultaneous enhancement of fluorescence retention and stability. This nanocomposite was synthesized by using silica spheres as cores, adsorbing gradient alloy QDs (GA-QDs) as the first shell, and then coating a silica layer as the other outmost shell (termed SiO2-GA-QD-SiO2). The retaining ratio of pristine fluorescence intensity after silica coating was found to be significantly improved by the QDs' shell interfacial optimization due to the suppression of surface defects. The mechanism of the QDs' surface trap states capturing the excitons before and after silica coating was analyzed in detail. The results show that the optimized SiO2-GA-QD-SiO2 nanocomposite provides the highest resulting fluorescence intensity of 70%, which is 62% and 33% higher than those of the other two conventional structures. Photoluminescent liquid crystal display backlight samples were prepared with this hybrid nanocomposite to show the robustness against high temperature and humid environment. Even when immersed in water and heated to 80 °C, the backlight samples still retained 85% of the initial fluorescence, which was 40% higher than that with bare GA-QDs. High fluorescence and long-term stability highlight the potential of using this nanocomposite in displays or lighting applications.

Recent Trends in Nanomaterial-Based Biosensors for Point-of-Care Testing.

In recent years, nanomaterials of different shape, size, and composition have been prepared and characterized, such as gold and silver nanoparticles, quantum dots, mesoporous silica nanoparticles, carbon nanomaterials, and hybrid nanocomposites. Because of their unique physical and chemical properties, these nanomaterials are increasingly used in point-of-care testing (POCT) to improve analytical performance and simplify detection process. They are used either as carriers for immobilizing biorecognition elements, or as labels for signal generation, transduction and amplification. In this commentary, we highlight recent POCT technologies that employ nanotechnology for the analysis of disease biomarkers, including small-molecule metabolites, enzymes, proteins, nucleic acids, cancer cells, and pathogens. Recent advances in lateral flow tests, printable electrochemical biosensors, and microfluidics-based devices are summarized. Existing challenges and future directions are also discussed.

One-pot synthesis of poly(alkyl methacrylate)-functionalized mesoporous silica hybrid nanocomposites for microencapsulation of poorly soluble phytochemicals

Silibinin (SBN), the major active constituent of milk thistle seeds indicated in liver conditions, has low oral bioavailability due to low solubility and degradation in gastric fluid. Hybrid mesoporous silica nanocomposites composed of polymerized alkyl methacrylate monomers (methyl methacrylate, butyl methacrylate or 1:1 mixture of methyl methacrylate and acrylic acid) were developed to enhance dissolution and antioxidant activity of SBN. Samples were worked up by calcination in oven or refluxing with ammonium nitrate. DLS, FE-SEM, AFM, TGA, FTIR, EDS, XRD and BET techniques were employed to characterize unloaded and SBN-loaded particles. Well-tuned hybrid nanoparticles exhibited spherical morphology, small size (~20 nm), large pore volumes (1.6 cm3g−1), high polymer functionality (~50%) and high SBN loading (19%). Importantly, in-vitro dissolution and DPPH antioxidant activity of SBN in acidic gastric medium increased remarkably after loading in the particles. Conclusively, well-tuned hybrid nanocomposites are suggested for modulating the oral bioavailability of poorly sluble phytochemicals.

Synthesis of Fluorescent Au Nanocrystals-Silica Hybrid Nanocomposite (FLASH) with Enhanced Optical Features for Bioimaging and Photodynamic Activity.

Fluorescent Au nanocrystals (AuNCs)-silica hybrid nanocomposite (FLASH) was synthesized by co-condensation of surface-modified AuNCs. Present FLASH nanocomposite exhibited four times the enhanced photoluminescence and photocatalytic activity compared to single nanocrystals. On the basis of these enhanced optical features, we successfully demonstrated in vitro fluorescence bioimaging of introduced FLASH to human cervical cancer cell line (HeLa). Beyond the confirmation of photocatalytic activity from the photodegradation of methylene blue as a model compound, the regional selective photodynamic therapy of HeLa cells under UV irradiation was also presented. Taken together the enhanced optical features and further potential in theranostic applications, we expect that the present FLASH can be a promising tool for nanobiotechnology field.

Dangling ultrafine nano silica on graphene oxide to form hybrid nanocomposite: enhancement of dielectric properties

AbstarctDefects induced graphene oxide-amine functionalized silica hybrid nanocomposite (GO-NH-(CH2)3-SiO2) has been synthesized through sonochemical route with dangling of amine functionalized silica, SiO2-(CH2)3-NH2 on GO. SiO2-(CH2)3-NH2 nanoparticles (dia ∼ 10–15 nm) have been dangled through chemical conjugations at the defective sites of the GO (on one to two layers)/with functional groups to obtain the hybrid nanocomposite. Dielectric properties of defects induced GO-NH-(CH2)3-SiO2 hybrid nanocomposite pellet has been calculated with various frequencies and temperatures. The dielectric constant of the GO-NH-(CH2)3-SiO2 nanocomposite has been encountered to be as high as 730 at 1 KHz which is 36 times higher than that of the free SiO2-(CH2)3-NH2 NPs. The roles of dangling of SiO2-(CH2)3-NH2 on GO and overall functional groups of nanocomposite that lead to such a high dielectric constant have been straightened out. The dielectric constant of the nanocomposite in the range of 20 Hz to 2 MHz and its temperature dependent behaviour in the range of 150 to 400 °C have been elucidated with the apposite governing mechanism. The ac and dc conductivities of the composite have been calculated using impedance measurement and the behaviour observed to be like a semiconducting material. Temperature dependent high dielectric constant of the composite reveals a new era for its use at high temperature. The synthesis method reported here is very easy and economical which can yield large scale production for industrial applications. Further, the findings directed us that the new hybrid composite could be used in designing the high dielectric constant material based electronic and energy storage devices.

Morphology, thermal and mechanical properties of polypropylene/SiO2 nanocomposites obtained by reactive blending

The isotactic polypropylene – modified silica (iPP/SiO2) hybrid nanocomposites, obtained by grafting polypropylene chains on amine-functionalized silica particles during reactive blending, were studied. It was found that use of amine-functionalized silica and PP-g-MA as a compatibilizer improved dispersion of nanoparticles. Nanosilica, especially surface-modified, revealed some nucleation activity towards iPP, manifesting in an increase of the crystallization temperature and reduction of spherulite size. iPP/silica nanocomposites exhibit highly improved thermo-oxidative stability, due to formation of a silica protective layer, limiting the polymer volatilization rate. Nanocomposites demonstrate enhanced stiffness and strength, but at higher silica content the ductility is nearly lost due to presence of big agglomerates, acting as critical-sized structural flaws. At low silica concentrations dispersion was improved and big agglomerates were not observed. Consequently, iPP/PP-g-MA/am-SiO2 nanocomposites with low silica content demonstrate high ductility and enhanced impact resistance, related to reinforcing effect of well dispersed silica particles.

High-Performance Soya Polyurethane Networked Silica Hybrid Nanocomposite Coatings

The projected fossil fuel deposits depletion by near future and detrimental effects of petroleum products on environment has led to the development of volatile organic compound (VOC) free low molecular weight sustainable polymers, with promising applications in field of inks, adhesives, paints, and coatings. In view of this, present study reports synthesis, characterization, and anticorrosive performance of SMG-PU and modified SMG-PU through in situ formed silica networks (SMG-PU-TEOS) OIH polymer nanocomposite coatings on CS. The size of ∼30 nm silica nanonetworks were formed within SMG-PU on addition of TEOS, inducing thermal stability, hydrophobic, improved physicomechanical and corrosion resistant properties to polymer nanocomposite coatings. The corrosion protective performance of these coatings in 5% NaCl (salt mist test), 3.5% NaCl, and 3.5% HCl solutions revealed very lower Icorr values (3.8891 × 10–10 A cm–2 and 6.8756 × 10–9 A cm–2) as compared to SMG-PU (1.8159 × 10–8 A cm–2 and 9.1396 × 10–7 A...

Facile synthesis of casein-based silica hybrid nano-composite for coatings: Effects of silane coupling agent

Abstract Silane coupling agents are recognized as efficient coupling agents extensively used in composites and adhesive formulations. In this paper, casein-based silica nano-composite latex for coatings was prepared via double-in situ method stabilized by methyl propyl trimethoxy silane (KH570) – a kind of silane coupling agent. The latex was mainly characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), scanning electron microscopy (SEM), atomic force microscopy (AFM) and thermogravimetry (TGA). Effects of KH570 on the structure and performance of the latex and film, as well as the application performance were discussed systematically. The results showed that the presence of KH570 increased the silica-shell uniformity due to the improvement of the compatibility between the organism and inorganism. Existence of KH570 could endow the hybrid film with enhanced mechanical strength, water resistance and heat resistance. The as-prepared composite may also give finished leather with preferred wet/dry rub resistance, water resistance and tensile strength. Latex particle formation mechanism was proposed accordingly.

A Single-Step Synthesis of Electroactive Mesoporous ProDOT-Silica Structures.

The single-step preparation of highly ordered mesoporous silica hybrid nanocomposites with conjugated polymers was explored using a novel cationic 3,4-propylenedioxythiophene (ProDOT) surfactant (PrS). The method does not require high-temperature calcination or a washing procedure. The combination of self-assembly of the silica surfactant and in situ polymerization of the ProDOT tail is responsible for creation of the mesoporosity with ultralarge pores, large pore volume, and electroactivity. As this novel material exhibits excellent textural parameters together with electrical conductivity, we believe that this could find potential applications in various fields. This novel concept of creating mesoporosity without a calcination process is a significant breakthrough in the field of mesoporous materials and the method can be further generalized as a rational preparation of various mesoporous hybrid materials having different structures and pore diameters.

A Single‐Step Synthesis of Electroactive Mesoporous ProDOT‐Silica Structures

AbstractThe single‐step preparation of highly ordered mesoporous silica hybrid nanocomposites with conjugated polymers was explored using a novel cationic 3,4‐propylenedioxythiophene (ProDOT) surfactant (PrS). The method does not require high‐temperature calcination or a washing procedure. The combination of self‐assembly of the silica surfactant and in situ polymerization of the ProDOT tail is responsible for creation of the mesoporosity with ultralarge pores, large pore volume, and electroactivity. As this novel material exhibits excellent textural parameters together with electrical conductivity, we believe that this could find potential applications in various fields. This novel concept of creating mesoporosity without a calcination process is a significant breakthrough in the field of mesoporous materials and the method can be further generalized as a rational preparation of various mesoporous hybrid materials having different structures and pore diameters.

Efficient and rapid adsorption characteristics of templating modified guar gum and silica nanocomposite toward removal of toxic reactive blue and Congo red dyes

The present study highlights the potentiality of sol–gel synthesized guar gum-graft-poly (acrylamide)/silica (g-GG/SiO2) hybrid nanocomposite toward the rapid removal of toxic reactive blue 4 (RB) and Congo red (CR) dyes from aqueous solution. Various physicochemical characterizations support the feasibility of the functionalized guar gum matrix as efficient template for the formation of homogeneous nanoscale silica particles. The composite demonstrates rapid and superior adsorption efficiency of RB (Qmax: 579.01mgg−1 within 40min) and CR (Qmax: 233.24mgg−1 within 30min) dyes from aqueous environment. Here, the pH driven adsorption process depends strongly on the ionic strength of the salt solution. The adsorption kinetics data predicts that pseudo second-order (surface adsorption) and intraparticle diffusion take place simultaneously. The adsorption equilibrium is in good agreement with the Langmuir isotherm, while the thermodynamics study confirms spontaneous nature of the adsorption process. Desorption study predicts the excellent regenerative efficacy of nanocomposite.

A FITC-doped silica coated gold nanocomposite for both in vivo X-ray CT and fluorescence dual modal imaging

Dual-modal imaging contrast agents with unique X-ray computed tomography (CT) and optical imaging capabilities have attracted much attention in recent years. Herein, the new silica hybrid nanocomposites containing Au nanoparticles and FITC dyes (FITC–Au@SiO2) were investigated as this kind of contrast agent. TEM characterization showed that the as-synthesized FITC–Au@SiO2 nanoprobes were uniform in morphology with the average size of 90 nm. After the PEGylation, the obtained FITC–Au@SiO2@PEG exhibited good dispersion stability under different conditions. The MTT assay suggested that FITC–Au@SiO2@PEG didn't show appreciable toxicity toward KB cells even at high concentration of up to 1000 μg mL−1. In addition, it was found that FITC–Au@SiO2@PEG could cross the cell membrane and enter into the cytoplasm during the incubation with cells. In vivo dual modal optical/CT imaging of C57BL/6J mice uncovered that within 2 h post-injection FITC–Au@SiO2@PEG nanoprobes preferred to accumulate in the liver and were gradually cleared through the enterohepatic circulation system, which could bring novel opportunities to the next generation of dual-modality contrast agents.

Synthesis of cellulose-L-tyrosine-silica hybrid nanocomposites by sol-gel process for high performance applications.

Cellulose is the most abundant bio-renewable materials with a long and well established technological base products and important applications such as fiber and paper materials. The one dimensional nano-materials such as nanotubes, nanowires and nano-rods have been widely studied for their potential applications in the field of nano-devices and nano-sensors due to their excellent electronic, optical properties. In this present work, the homogeneous cellulose-L-tyrosine-silica hybrid materials is prepared by in-situ sol-gel process using TEOS and γ-aminopropyltriethoxysilane (γ-APTES) as coupling agent. The silica nano-materials could be attached to the surface of amino functionalized cellulose-L-tyrosine matrices. The covalent bonding behavior of silica were characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), X-ray diffraction analysis (XRD) and transmission electron Microscopy (TEM).

Linseed polyurethane/tetraethoxyorthosilane/fumed silica hybrid nanocomposite coatings: Physico-mechanical and potentiodynamic polarization measurements studies

• Linseed polyurethane/tetraethoxyorthosilane/fumed silica hybrid nanocomposites. • Formed transparent, glossy, scratch-resistant, impact –resistant, flexible coatings. • At ambient temperature through simple curing route. The work presents the physico-mechanical properties and potentiodynamic polarization measurements studies of linseed oil based polyurethane/tetraethoxyorthosilane [LPU/TEOS] hybrid and polyurethane/tetraethoxyorthosilane/fumed silica NC [LPU/TEOS/FS] hybrid nanocomposite coatings. The best coating performance was obtained by the inclusion of 2 wt% FS in 2-LPU/TEOS hybrid. 2-LPU/TEOS/FS produced glossy, transparent, flexibility retentive, scratch-resistant and impact resistant coatings at ambient temperature relative to LPU/TEOS coatings. 2-LPU/TEOS/FS showed good scratch hardness (5.5 kg), impact resistance (250 lb/in.), flexibility (1/8 in.) as investigated by standard methods with corrosion rate obtained as 3.567 × 10 −4 mm/year and 4.05 × 10 −4 mm/year and inhibition efficiency as 99.816% and 99.710% in 3.5% NaOH and 3.5% HCl, respectively.

Tailoring carboxymethyl guargum hydrogel with nanosilica for sustained transdermal release of diclofenac sodium

Abstract Carboxymethyl guar gum (CMG) was structurally tailored with aqueous-nanosilica sol for controlled transdermal release of diclofenac sodium. Nanosilica was administered in low to moderately high concentration range to synthesize various, novel CMG–silica hybrid nanocomposites. Spectroscopy together with thermogravimetry, morphology, swelling and rheological studies proved that 1 wt% nanosilica content was the best physical formulation. The drug release studies from different hydrogel nanocomposites exhibited slower release than neat CMG. 1 wt% nanosilica loaded hydrogel nanocomposite gave slowest but steady release profile among all other nanocomposites due to its highly viscous nature owing to most compact microstructure.

Polybenzoxazine–silica (PBZ–SiO2) hybrid nanocomposites through in situ sol–gel method

New type of Polybenzoxazine–silica (PBZ–SiO2) hybrid nanocomposites was prepared through in situ sol–gel method. Benzoxazine was synthesized using bisphenol-A, trans-4-aminocyclohexanol hydrochloride and formaldehyde solution through Mannich condensation reaction and was characterized by FT-IR, 1HNMR and 13CNMR spectroscopy. The methodology adopted in the present study involves to formation of hydrogen bond interaction between the benzoxazine monomer and the silica matrix, followed by the ring opening polymerization of benzoxazine monomer through thermal curing to obtain a red brown transparent PBZ–SiO2 hybrid. The formation of hybrid nanocomposites was confirmed by FT-IR. Thermal and morphological properties of the hybrid materials were investigated by the differential scanning calorimetry (DSC), thermo gravimetric analysis (TGA), scanning electron microscopy (SEM). The PBZ–SiO2 hybrids show improved thermal properties and glass transition (Tg) temperature. The nitrogen porosimetry study was carried out to confirm the nanometer level integration of polybenzoxazine in the PBZ–SiO2 hybrid nanocomposites.

Poly(ethylene oxide)–silica hybrids entrapping sensitive dyes for biomedical optical pH sensors: Molecular dynamics and optical response

Polymer–silica hybrid nanocomposites prepared by sol–gel process based on triethoxisilane-terminated poly(ethylene oxide) chains and tetraethoxysilane as silica precursor, doped with organic pH sensitive dyes, have been prepared and their suitability for use as sensors coupled with plastic optic fibers has been evaluated. Sensors were prepared by immobilizing a drop of the hybrid materials onto the tip of a multi-mode poly(methyl methacrylate) optical fiber. The performance of the optical sensor in terms of sensitivity and response time was tested in different experimental conditions, and was found to be markedly higher than analogous sensors present on the market. The very fast kinetic of the hybrid’s optical response was supported by studies performed at the molecular level by broadband dielectric relaxation spectroscopy (DRS), investigated over a wide range of frequency and temperature, showing that poly(ethylene oxide) chains maintain their dynamics even when covalently bonded to silica domains, which decrease the self-association interactions and promote motions of polymer chain segments. Due to the fast response kinetic observed, these pH optical sensors result suitable for the fast-detection of biomedical parameters, i.e. fast esophageous pH-metry.

Advanced anticorrosive coatings prepared from electroactive epoxy–SiO 2 hybrid nanocomposite materials

A series of electroactive epoxy/amino-SiO 2 nanocomposite materials containing conjugated segments of electroactive amino-capped aniline trimer (ACAT) unit were successfully prepared. First of all, the amino-modified silica (AMS) particles of ∼50 nm in diameter were synthesized by performing the conventional base-catalyzed sol–gel reactions of tetraethyl orthosilicate (TEOS) in the presence of (3-aminopropyl)-trimethoxysilane (APTES) molecules. Subsequently, the AMS nanoparticles were blended into the epoxy ring-opening polymerization reactions between amino-terminated aniline trimer (ACAT)/T-403 and DGEBA, leading to the formation of electroactive epoxy resin–silica hybrid nanocomposites (EES). Furthermore, the redox behavior of as-prepared EES materials was identified by the electrochemical cyclic voltammetry studies. It should be noted that the as-prepared electroactive hybrid materials in the form of coating on cold-rolled steel (CRS) electrode were found to be much superior in corrosion protection over those of non-electroactive epoxy (NEE) and electroactive epoxy (EE) materials based on a series of electrochemical corrosion measurements in saline. The possible mechanism for the advanced enhancement of corrosion protection of EES coatings on CRS electrode could be interpreted as follows: (1) electroactive epoxy coatings may act as physical barrier coating; (2) redox catalytic capabilities of ACAT units existed in electroactive epoxy may induce the formation of passive metal oxide layers on CRS electrode, as further evidenced by SEM and ESCA studies; (3) well-dispersed AMS nanoparticles in EES matrix could act as effective hinder to enhance the oxygen barrier property of electroactive epoxy matrix, the result could be demonstrated by gas permeability analysis (GPA). Electroactive epoxy/SiO 2 nanocomposites were identified by a series of electrochemical measurements such as corrosion potential ( E corr ), polarization resistance ( R p ), corrosion current ( I corr ) and electrochemical impedance spectroscopy (EIS) studied in 5 wt% NaCl electrolyte.

A facile synthesis of cyanate ester silica hybrid nanocomposites by in situ sol-gel method

High performance cyanate ester—silica hybrid nanocomposites were prepared using the sol—gel method through in situ reaction. The methodology adopted here was the formation of a covalent bond between the bisphenol-A cyanate ester (CE) and silica matrix utilizing γ-aminopropyltriethoxysilane (γ-APS) as coupling agent. The covalent bond formation in the hybrid was confirmed by Fourier transform infrared analysis and solvent extraction. Thermal and morphological properties of the hybrid materials were investigated by differential scanning calorimetry, thermogravimetric analysis and scanning electron microscopy. The CE—silica hybrids show improved thermal properties. The double degradation curves observed from thermogravimetric analysis may be due to the weak adduct linkage and the cleavage of the triazine ring in the hybrid. The nitrogen porosimetry study confirmed the molecular level dispersion of cyanate ester in the cyanate ester—silica hybrid nanocomposites.