Facile one-pot synthesis of PEGylated monodisperse mesoporous silica nanoparticles with controllable particle sizes

In this work, we describe the one-pot synthesis of PEGylated mesoporous silica nanoparticles （MSNs） with uniform shape, tunable sizes, and narrow size distributions. The size of these nanoparticles can be controlled from 49 nm to 98 nm by simply varying the concentration oftriethanolamine during the base- catalyzed sol-gel reaction. Particles were characterized by transmission electron microscopy, dynamic light scattering, Fourier transform infrared spectrometry, thermogravimetric analysis, and nitrogen adsorption-desorption measurements. These PEGylated MSNs exhibited excellent long-term stability in biological media, which ensures their potential applications in drug delivery.     

Fabrication linalool-functionalized hollow mesoporous silica spheres nanoparticles for efficiently enhance bactericidal activity

To develop a novel food preservation technology for efficiently enhance bactericidal activity in a long term, hollow mesoporous silica spheres (HMSS) with regular nanostructures were applied to encapsulate natural organic antimicrobial agents. The chemical structures, morphologies and thermal stabilities of linalool, HMSS and linalool-functionalized hollow mesoporous silica spheres (L-HMSS) nanoparticles were evaluated by polarimeter, field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), fourier transform infrared (FT-IR), thermal gravimetric analyzer (TGA), nitrogen adsorption-desorption, zeta potential and small angle X-ray diffraction (SXRD). The results show that the linalool was successfully introduced into the cavities of HMSS, and the inorganic host exhibited a high loading capacity of about 1500 mg/g. In addition, after 48 h of incubation, the minimum bactericidal concentrations (MBC) of L-HMSS against Escherichia coli (E. coli), Salmonella enterica (S. enterica) and Staphylococcus aureus (S. aureus), Listeria monocytogenes (L. monocytogenes) were decreased to be 4 (< 5) mg/mL and 8 (< 10) mg/mL, respectively. These results revealed linalool-functionalized hollow mesoporous spheres could efficiently improve the bactericidal activities of the organic component. Furthermore, SEM images clearly showed that L-HMSS indeed had an extremely inhibitory effect against gram-negative (E. coli) and gram-positive (S. aureus) by breaking the structure of the cell membrane. This research is of great significance in the application of linalool in nano-delivery system as well as food industry.     

A simple method to ordered mesoporous carbons containing nickel nanoparticles

A series of ordered mesoporous carbons containing magnetic Ni nanoparticles (Ni-OMCs) with a variety of Ni loadings was made by a simple one-pot synthetic procedure through carbonization of phenolic resin-Pluronic block copolymer composites containing various amount of nickel nitrate. Such composite materials were characterized by N₂ sorption, XRD, and STEM. Ni-OMCs exhibited high BET surface area, uniform pore size, and large pore volume without obvious pore blockage with a Ni loading as high as 15 wt%. Ni nanoparticles were crystalline with a face-center-cubic phase and observed mainly in the carbon matrix and on the outer surface as well. The average particle size of Ni nanoparticles was dependent on the preparation (carbonization) temperature and Ni loading; the higher the temperature was used and the more the Ni was incorporated, the larger the Ni nanoparticles were observed. One of the applications of Ni-OMCs was demonstrated as magnetically separable adsorbents. Dedicated to Professor Mietek Jaroniec on the occasion of his 60th birthday.     

Preparation of hollow mesoporous silica nanorods for encapsulating and slowly releasing eugenol

Fragrances are widely used in many aspects of our lives.They cannot only make people happy,but also treat many diseases.However,excessively fast evaporation rate is one of the main obstacles to the use of spices.In this study,mesoporous silica nanorods(MSNRs) and hollow mesoporous silica nanorods(HMSNRs) were prepared to encapsulate eugenol.These two nano-fragrances were named eugenol@MSNRs and eugenol@HMSNRs,respectively.The morphologies,size,interior structures and pore performances of MSNRs a...     

Preparation of hollow mesoporous silica nanorods for encapsulating and slowly releasing eugenol

Fragrances are widely used in many aspects of our lives. They cannot only make people happy, but also treat many diseases. However, excessively fast evaporation rate is one of the main obstacles to the use of spices. In this study, mesoporous silica nanorods (MSNRs) and hollow mesoporous silica nanorods (HMSNRs) were prepared to encapsulate eugenol. These two nano-fragrances were named eugenol@MSNRs and eugenol@HMSNRs, respectively. The morphologies, size, interior structures and pore performances of MSNRs and HMSNRs. Besides, the performances of encapsulation and fragrance release of eugenol@MSNRs and eugenol@HMSNRs were compared and analyzed. The results showed that eugenol@HMSNRs encapsulated more fragrance and were faster to encapsulate compared with eugenol@MSNRs. Both the release rates of eugenol from eugenol@MSNRs and eugenol@HMSNRs were slow. But the eugenol was released from eugenol@MSNRs more slowly.     

Novel drug delivery system of hollow mesoporous silica nanocapsules with thin shells: preparation and fluorescein isothiocyanate (FITC) release kinetics

Core-shell nanoparticles of Au@silica with a diameter of approximate 45–60 nm and wall thickness in range of 3–10 nm were synthesized by using 40 and 50 nm gold nanoparticles as the templates. The mesoporous particles are regulated by 3-aminopropyltrimethoxysilane addition. Hollow mesoporous silica nanocapsules (HMSNs) were prepared by using sodium cyanide to dissolve the gold cores. The characterization of Au@silica and HMSNs by transmission electronic microscope indicated that the silica shells were uniform and smooth, and also the porosity was proved by fluorescein isothiocyanate (FITC) release experiments. The ratio of hollow core to HMSNs is more than 70%. HMSNs were subsequently used as drug carrier to investigate FITC (as a model drug) release behaviors in vitro. Fluorescent spectrometry was performed to determine the release kinetics from the HMSNs. The release profiles are significantly different as compared with the control (free FITC), which show that HMSNs are good drug carriers to control drug release, and have high potential in therapeutic drugs delivery in future applications.     

Preparation of amino-functionalized mesoporous silica thin films with highly ordered large pore structures

Highly ordered amino-functionalized mesoporous silica thin films have been directly synthesized by co-condensation of tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES) in the presence of triblock copolymer Pluronic P123 surfactant species under acidic conditions by sol-gel dip-coating. The effect of the sol aging on thin films organization is systematically studied, and the optimal sol aging time is obtained. The amino-functionalized mesoporous silica thin films exhibit a long-range ordering of 2D hexagonal (p6mm) mesostructure with a large pore size of 8.3 nm, a large Brunauer–Emmett–Teller (BET) specific surface area of 680 m² g⁻¹ and a large pore volume of 1.06 cm³ g⁻¹ following surfactant extraction as demonstrated by X-ray diffraction (XRD), Transmission electron microscope (TEM), and physical adsorption techniques. Based on BET surface area and weight loss, the surface coverage of amino-groups for the amino-functionalized mesoporous silica thin films is calculated to be 3.2 amino-groups per nm². Moreover, the functionalized thin films display improved properties for immobilization of cytochrome c in comparison with pure-silica mesoporous thin films.     

Green preparation of hollow mesoporous silica nanosphere inside-loaded gold nanoparticles and the catalytic activity

In this work, an active nano-catalyst with gold nanoparticles loaded in hollow mesoporous silica nanospheres (HMSNs/Au) was prepared by a one-pot sol-gel method, in which gold ions were loaded in hollow mesoporous silica spheres followed by sodium alginate reduction. The characterization of the HMSNs/Au were determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), N₂ adsorption–desorption isotherms (BET). The high catalytic activity of HMSNs/Au, denoted as apparent turn-over frequency (TOF), was detected by UV-Vis spectrophotometer for the catalytic reduction of 4-nitrophenol (74.5 h^?1) and 2-nitrophenol (108.7 h^?1) in the presence of sodium borohydride solution due to the small gold nanoparticles size and overall exposure of active sites. It is expected that this ecofriendly approach to prepare inorganic composited nanoparticles as high active catalysts based on hollow mesoporous materials was a promising platform for loading noble metal nanoparticles.     

A strategy to incorporate monodispersed PbS nanoparticles into ordered mesoporous silica monolith

A new synthetic procedure has been developed for the preparation of ordered mesoporous silica monoliths doped with uniform PbS nanoparticles (NPs). Ordered mesoporous silica monoliths functionalized with thiol groups have been synthesized through co-condensation method in a lyotropic liquid crystalline system. Thiol groups on the interior wall facilitate the incorporation of Pb²⁺ cations and the formation of PbS NPs inside the ordered mesopores. Combined analysis results indicate that the PbS NPs with a uniform particle size of about 2.5 nm are mostly confined inside the ordered pores of hosts. A great blue shift in the absorbance spectrum has been observed, which shows an obvious quantum confinement effect.     

Copper/Schiff-base complex immobilized on amine functionalized silica mesoporous magnetic nanoparticles under solvent-free condition: A facile and new avenue for the synthesis of thiazolidin-4-ones

A copper/Schiff-base complex supported on amine-functionalized silica mesoporous magnetic nanoparticles was prepared as novel magnetically interphase nanoparticles and its morphology and structure were evaluated using Fourier transform infrared spectroscopy, X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, thermogravimetric analysis, zeta potential, and a vibrating sample magnetometer. The catalytic activity of the synthesized nanoparticles was evaluated for the synthesis of thiazolidine-4-ones.     

Synthesis, characterization, and electrochemical properties of ordered mesoporous carbons containing nickel oxide nanoparticles using sucrose and nickel acetate in a silica template

New ordered mesoporous carbons containing nickel oxide nanoparticles have been successfully synthesized by carbonization of sucrose in the presence of nickel acetate inside SBA-15 mesoporous silica template. The obtained samples were characterized by X-ray diffraction (XRD), nitrogen adsorption-desorption, and transmission electron microscopy (TEM). The NiO nanoparticles were embedded inside the mesoporous carbon framework due to the simultaneous pyrolysis of nickel acetate during carbonization. The electrochemical testing of the as-made nanocomposites showed a large specific capacitance of 230 F g⁻¹ using 2 M KOH as the electrolyte at room temperature. This is attributed to the nanometer-sized NiO formed inside mesoporous carbons and the high surface area of the mesopores in which the NiO nanoparticles are formed. Furthermore, the synthetic process is proposed as a simple and general method for the preparation of new functionalized mesoporous carbon materials, for various applications in catalysis, sensor or advanced electrode material.     

Stepwise synthesis, characterization, and electrochemical properties of ordered mesoporous carbons containing well-dispersed Pt nanoparticles using a functionalized template route

A stepwise method is described for the accurately controlled growth of Pt nanoparticles supported on ordered mesoporous carbons (Pt-OMC) by the nanocasting of carbon and metal precursors in the pore channels of mesoporous silicas functionalized with Si-H groups. Results obtained from N₂ adsorption/desorption isotherms and transmission electron microscopy showed well-dispersed Pt nanoparticles (2-3 nm) on Pt-OMC with high surface area (837 m² g⁻¹) and regular pore channels (2.9 nm), which facilitate reactant/product diffusion. X-ray diffraction and X-ray photoelectron spectroscopy indicated that Pt nanoparticles in the Pt-OMC sample were mostly present in the metallic form of a face-centered cubic (fcc) crystalline structure. The Pt-OMC catalyst was found to have superior electrocatalytic properties during oxygen reduction reaction as compared to typical commercial electrocatalysts.     

A simple method to prepare titania nanomaterials of core-shell structure, hollow nanospheres and mesoporous nanoparticles

A simple method to prepare titania nanomaterials of core-shell structure, hollow nanospheres and mesoporous nanoparticles has been developed. The core-shell nanostructures with NH4Cl as core and TiO2·xH2O-NH4Cl as shell were prepared in nonaqueous system by the deposition on the surface of the aggregated NH4Cl crystals, which could be transformed into mesoporous anatase nanoparticles or hollow nanospheres by calcination at 500℃ or extraction with methanol, respectively. The hierarchical mesoporous nanostruc...     

A facile synthesis of highly water-soluble, core–shell organo-silica nanoparticles with controllable size via sol–gel process

A series of highly water-soluble organo-silica nanoparticles, ranging from 2 to 10 nm in diameter, were synthesized by the cohydrolysis and copolycondensation reactions. ω-methoxy(polyethyleneoxy)propyltrimethoxysilane (PEG6-9) and hydroxymethyltriethoxysilane (HMTEOS) mixtures were catalyzed by sodium hydroxide in the presence of surfactant benzethonium chloride (BTC) with various ratios of PEG6-9/HMTEOS at room temperature. The synthesized organo-silica nanoparticles possess a core–shell structure with a core of organo-silica resulting from HMTEOS and a monolayer shell of PEG6-9. The chemo-physical characteristics of the particles were studied by gel permeation chromatography (GPC), Fourier transform infrared (FTIR) spectroscopy, ²⁹Si nuclear magnetic resonance (NMR), dynamic light scattering (DLS), transmission electron microscopy (TEM), and thermogravimetric analysis (TGA). The molecular weight and particle size of the particles increased with increasing HMTEOS molar ratios. The richest HMTEOS composition for the water-soluble particles was found to be HMTEOS:PEG6-9 = 80:20, where the particles had a 6 nm diameter core and a 0.8 nm thick shell. We propose that these water-soluble organo-silica nanoparticles will be suitable for biomedical applications.     

A facile approach to synthesize uniform hydrogel shells with controllable loading and releasing properties

We present a facile and straightforward method to synthesize uniform poly(vinyl amine) hydrogel shells with excellent loading capability for active materials and controllable responsiveness to applied stimuli, providing tunable releasing properties.     

A scanning electron microscopy study on hollow silica microspheres: defects and influences of the synthesis composition

Defects on hollow silica spheres synthesized in a tetraethylorthosilicate-octylamine-HCl-H₂O system were recorded by scanning microscope. Based on the results, influences of synthesis composition on the formation of these defects are discussed. It is evidenced that products prepared with different octylamine-to-tetraethylorthosilicate ratios may have surface depressions, cracks and non-hollow microspheres. However, by changing water and acid additions, these defects could be reduced or eliminated. Generally, samples synthesized with a large octylamine addition commonly exhibit surface depressions. A small octylamine or a large water addition benefits the formation of solid silica microspheres among the product. Acid, although is not indispensable for the formation of hollow spheres, helps to eliminate or reduce depressions on the hollow shells. It is explained that the added acid gives rise to a relative localized fast hydrolysis versus condensation, facilitating an easy mobility of hydrolyzed silica species, and consequently the shell surface is smoothened.     

A general approach to mesoporous metal oxide microspheres loaded with noble metal nanoparticles

Catalytic microspheres: A general approach is demonstrated for the facile preparation of mesoporous metal oxide microspheres loaded with noble metal nanoparticles (see TEM image in the picture). Among 18 oxide/noble metal catalysts, TiO(2)/0.1?mol?% Pd microspheres showed the highest turnover frequency in NaBH(4) reduction of 4-nitrophenol (see picture).     

Step-by-step synthesis of copper(I) complex supported on platinum nanoparticle-decorated mesoporous silica hollow spheres and its remarkable catalytic performance in Sonogashira coupling reaction

In this study, a step-by-step method for the synthesis of platinum nanoparticles and copper(I) complex supported on mesoporous silica hollow spheres (Pt-MSHSs-Cu) is introduced. Scanning electron microscopy, transmission electron microscopy, powder X-ray diffraction, Fourier transform infrared spectroscopy, nitrogen adsorption–desorption, energy-dispersive X-ray spectrometry, X-ray photoelectron spectroscopy, and elemental and thermogravimetric analyses were applied for characterization of the surface, structure, size, phase composition, and morphology of the synthesized materials. The characterized material, Pt-MSHSs-Cu, was used as an efficient and heterogeneous catalyst in the Sonogashira coupling reaction under different reaction conditions. In comparison with MSHSs, Cu(I)-functionalized MSHSs (MSHSs-Cu), and Pt-MSHSs samples, the Pt-MSHSs-Cu catalyst exhibited significantly increased catalytic performance with 91.50% yield. Therefore, the results obtained suggested a synergistic effect derived from platinum nanoparticles, MSHSs substrate, and copper(I) complex, which enhanced the rate of the Sonogashira coupling reaction.