Sequestration of CO2 using Cu nanoparticles supported on spherical and rod-shape mesoporous silica

The CO₂ sequestration is one of the most promising solutions to tackle global warming. In this study, spherical mesoporous silica particles (MPS-S) and rod-shaped mesoporous silica particles (MPS-R) loaded with Cu nanoparticles were selectively prepared and employed for CO₂ adsorption. For the first time uniform Cu nanoparticles were incorporated into the rod-shaped mesoporous silica particles by post-synthesis modification using both N-[3-(trimethoxysilyl)propyl]ethylenediamine (PEDA) and ethylenediamine (EDA) as coupling agents. The physiochemical properties of the mesoporous and copper grifted silica composites were investigated by CHN elemental analysis, FTIR spectroscopy, thermogravimetric analysis, X-ray diffraction, energy dispersive X-ray spectroscopy (EDX), surface area analysis, scanning, transmission electron microscopy and gas analysis system (GSD 320, TERMO). The mesoporous silica shows highly ordered mesoporous structures, with the rod-shaped particles having a higher surface area than the spherical ones. Copper nanoparticles with an average diameter of 6.0 nm were uniformly incorporated into the MPS-S and MPS-R. Moreover, Cu-loaded mesoporous silica exhibits up to 40% higher CO₂ adsorption capacity than the bare MPS. The MPS-R modified with Cu nanoparticles showed a maximum CO₂ adsorption capacity of 0.62 mmol/g and the humidity showed a slight negative effect on CO₂ uptake process. The enhancement of CO₂ adsorption onto transition metal/mesoporous substrates provides basis for imminent CO₂ sequestration.     

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.     

Synthesis of novel mesoporous silica spheres with starburst pore canal structure

Novel spherical mesoporous silica materials with uniform diameters and starburst mesopore structures were synthesized by a simple one-step procedure with ethanol as the co-solvent in dilute aqueous solution and their formation mechanism was proposed. The arrangement of the pore canal and the diameter of the sphere could be tailored by altering the concentration of ethanol.     

Emulsion polymerization of ethylene from mesoporous silica nanoparticles with vinyl functionalized monolayers

Emulsion polymerization of ethylene from vinyl functionalized mesoporous silica nanoparticles (V‐MSNs) was reported. V‐MSNs were synthesized via deposition of vinyl monolayers on the pore walls, and the relative surface coverage of the vinyl monolayers was 74%. A fluorinated P‐O‐chelated nickel catalyst coordinated to the vinyl groups. These V‐MSNs hosting catalysts were full dispersed in water assisted by ultrasonic processor in the presence of surfactants. After addition of ethylene, polyethylene (PE) chains grew from the pores of V‐MSNs, formation of stable nanocomposite latices with solid content up to 17.3%. Our method made V‐MSNs well‐dispersed in the PE matrix. Especially, because of a strong interaction between PE and nanoparticles, a stable V‐MSNs core/PE shell structure was formed upon thermal treatment above melting temperature of the PE. Samples were analyzed by a number of techniques including TEM, N₂ adsorption‐desorption, FTIR, and solid state ²⁹Si NMR, DLS, ¹H NMR, GPC, and DSC. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1393–1402, 2009     

P(VPBA-DMAEA) as a pH-sensitive nanovalve for mesoporous silica nanoparticles based controlled release

A pH-sensitive controlled release system was proposed in this work, which consists of mesoporous silica nanoparticles(MSNs) functionalized on the pore outlets with poly(4-vinylphenybronic acid-co-2-(dimethylamino)ethyl acrylate) [P(VPBA-DMAEA)]. Four kinds of P(VPBA-DMAEA)-gated MSNs were synthesized and applied for the p H-sensitive controlled release. The results showed that P(VPBADMAEA) can work as a p H-sensitive nanovalve. The release behavior of the hybrid nanoparticles could be adjusted by changing the mole ratio of VPBA and DMAEA. With the increasing of the mole ratio of VPBA,the leakage of the entrapped molecules in the pores of MSNs could be decreased at neutral and alkaline conditions. By altering the p H of buffer from 4.0 to 8.0, the valve could be switched ‘‘on' and ‘‘off'reversibly. In addition, cells viability results indicated that these P(VPBA-DMAEA)-gated MSNs had good biocompatibility. We believe that these MSNs based p H-sensitive controlled release system will provide a promising nanodevice for sited release of drug delivery.     

Thioether moiety functionalization of mesoporous silica films for the encapsulation of highly dispersed gold nanoparticles

Highly dispersed gold nanoparticles within mesoporous thin films (MTFs) have been synthesized through a newly developed controllable strategy, in which (1,4)-bis(triethoxysilyl)propane tetrasufide (BPTS) organosiloxane coupling agent was co-assembled with tetraethyl orthosilicate (TEOS) to form organic groups functionalized mesoporous composite films followed with oxidization, ion-exchange with Au(en)₂Cl₃ (en: 1,2-ethanediamine) compound and calcination under hydrogen/nitrogen mixing atmosphere. Small-angle X-ray diffraction (XRD) characterization indicated that up to 10 mol% of BPTS could be incorporated into mesoporous hybrid films, and that would not breakup the structural integrity and long-range periodicity. The loaded gold nanoparticles were uniformly distributed due to the molecular level homogenous mixing of the BPTS precursor with TEOS, and its concentration could be controlled via the original ratio of BPTS to TEOS. The nanoparticles had a narrow size distribution with diameters in the size range of 3-7 nm through transmission electron microscopy (TEM) observation and underwent a slight size increase with the higher gold load level. An overall increase in the absorption intensity, a red shift of absorption peak, together with a comparatively narrower bandwidth could be observed at higher gold concentration within composite films from UV-vis spectra. Wide-angle XRD, TEM, X-ray photoelectron spectroscopy (XPS) and UV-vis spectra characterizations all agreed on the fact that the gold loading level could be controlled by the amount of BPTS in the starting sol for preparing MTFs.     

Facile synthesis of blue-emitting carbon dots@mesoporous silica composite spheres

This paper reported a facile and effective approach towards high-efficient composite luminophores by embedding blue-emitting N-doped carbon dots into spherical SiO₂ matrix (CDs@SiO₂). Mesoporous silica microspheres (r-CDs@MSN) with strong luminescence were synthesized by removing CTAB templates in CDs@SiO₂ using reflux with acetone. The r-CDs@MSN possess a spherical morphology with smooth surface and a diameter of 130 nm, while it exhibits an excitation-independent blue emission peak at 440 nm with an internal quantum yield of 21.5%. BET result shows that the corresponding surface area and adsorption total pore volume are 156.27 m²/g and 0.682 cm³/g, which is suitable for the drugs loading and release. The results indicate that r-CDs@MSN might act as a potential fluorescent drug carrier.     

Aminopyrene functionalized mesoporous silica for the selective determination of resorcinol

Aminopyrene was convalently anchored onto the surface of mesoporous MCM-41 silica by post-grafting. This organic-inorganic hybrid has been applied as sensing material to phenols determination. Experimental results reveal that the functionalized material presents good sensitivity and selectivity towards resorcinol and can be used for resorcinol determination in water at pH 6.0. The fluorescence intensity of aminopyrene functionalized mesoporous silica decreases proportionally to the logarithm of resorcinol concentration in water. The linear range for resorcinol detection lies in 4.79-163 μM with a detection limit of 2.86 μM (S/N = 3).     

Immobilization of ethylene bis-indenyl ligands on functionalized silica gel

Four ethylene bis-indenyl ligands containing tethers of various lengths were successfully immobilized on the surface of functionalized silica gel. The strategy of immobilization was based on catalytic thiol-ene coupling of terminal alkene groups in the tethers with surface thiol groups. Obtained materials have high BET surface area and pore volume. The method developed can be used for immobilization of catalytically active bis-indenyl metallocene complexes, thus preventing their dimerization and deactivation.     

Characterization of gold nanoparticles electrochemically deposited on amine-functioned mesoporous silica films and electrocatalytic oxidation of glucose

This study reports the preparation and characterization of gold nanoparticles deposited on amine-functioned hexagonal mesoporous silica (NH₂–HSM) films and the electrocatalytic oxidation of glucose. Gold nanoparticles are fabricated by electrochemically reducing chloroauric acid on the surface of NH₂–HSM film, using potential step technology. The gold nanoparticles deposited have an average diameter of 80 nm and show high electroactivity. Prussian blue film can form easily on them while cycling the potential between −0.2 and 0.6 V (vs saturated calomel electrode) in single ferricyanide solution. The gold nanoparticles loading NH₂–HSM-film-coated glassy carbon electrode (Au–NH₂–HSM/GCE) shows strong catalysis to the oxidation of glucose, and according to the cathodic oxidation peak at about 0.16 V, the catalytic current is about 2.5 μA mM⁻¹. Under optimized conditions, the peak current of the cathodic oxidation peak is linear to the concentration of glucose in the range of 0.2 to 70 mM. The detection limit is estimated to be 0.1 mM. In addition, some electrochemical parameters about glucose oxidation are estimated.     

A general method for the synthesis of nanostructured large-surface-area materials through the self-assembly of functionalized nanoparticles

A general synthetic method for the preparation of nanostructured materials with large surface area was developed by using nanoparticle building blocks. The preparation route involves the self-assembly of functionalized nanoparticles in a liquid-crystal phase. These nanoparticles are functionalized by using difunctional amino acid species to provide suitable interactions with the template. Optimum interactions for self-assembly of the nanoparticles in the liquid-crystal phase were achieved with one -NH2 group anchored to the nanoparticle surface per 25 A(2). To maximize the surface area of these materials, the wall thicknesses are adjusted so that they are composed of a monolayer of nanoparticles. To form such materials, numerous parameters have to be controlled such as the relative volume fraction of the nanoparticles and the template and size matching between the hydrophilic component of the copolymer and nanoparticles. The surface functionalization renders our synthetic route independent of the nanoparticles and allows us to prepare a variety of nanostructured composite materials that consist of a juxtaposition of different discrete oxide nanoparticles. Examples of such materials include CeO2, ZrO2, and CeO2-Al(OH)3 composites.     

Potentiometric detection of polyions based on functionalized magnetic nanoparticles

A novel potentiometric detection strategy based on functionalized magnetic nanoparticles has been developed for rapid and sensitive sensing of polyions. Highly dispersed magnetic nanoparticles coated with ion exchanger and plasticizer could promote an in situ cooperative ion-pairing interaction between the ion exchanger and the polyion analyte in sample solution by dramatically reducing the mass-transfer distance. With applying a magnetic field, the nanoparticles can be attached to the surface of ion exchanger free polymeric membrane. The observed potential signals are related to the polyion concentrations. The proposed polymeric membrane electrode exhibits a linear relationship between the greatest potential response slope (dE/dt) and the logarithm of protamine concentration in the range of 0.05−5 μg/mL with a lower detection limit of 0.033 μg/mL.     

Interfacing colloidal graphene oxide sheets with gold nanoparticles

Aqueous solutions of graphene oxide (GO) and citrate-stabilised gold nanoparticles (AuNPs) are two classic, negatively charged colloids. Using the surface plasmon resonance spectra of AuNPs as a probe, we illustrate how the two like-charged colloids interact with each other and in so doing, reveal the unique solution behaviour of GO. We demonstrate that the electrical double layer of the GO sheets in water plays a key role in controlling the interaction between GO and AuNPs, which displays a one-way gate effect. It is shown that GO can capture and disperse AuNPs in water in a controllable fashion, without the need for additional chemical linkers. This discovery allows the successful synthesis of uncapped, yet solution-dispersible metal-nanoparticle assemblies. Such metal nanostructures have long been pursued for nano-plasmonics and sensing applications, but have remained difficult to prepare using conventional polymer dispersants. This work also makes clear that the combination of the two-dimensional conformation of GO along with its large molecular size and self-contained functional groups allows it to act as a unique soluble nanocarrier/substrate (the thinnest, functionalised flat substrate possible in nature) for the synthesis of new, soluble functional materials.     

Designing superhydrophobic surface based on fluoropolymer–silica nanocomposite via RAFT‐mediated polymerization‐induced self‐assembly

Superhydrophobic surfaces (SHS) find versatile applications as coatings due to their very high water‐repellency, self‐cleaning, and anti‐icing properties. This investigation describes the preparation of a SHS from surfactant‐free hybrid fluoropolymer latex. In this case, reversible addition‐fragmentation chain transfer (RAFT) polymerization was adopted to prepare a copolymer of 4‐vinyl pyridine (4VP) and vinyl triethoxysilane (VTES), where the pyridine units were quaternized to make the copolymer soluble in water. The copolymer was further used as a macro‐RAFT agent to polymerize 2,2,2‐trifluoroethyl methacrylate (TFEMA) in a surfactant‐free emulsion via polymerization‐induced self‐assembly (PISA). The macro‐RAFT agent contained a small amount of VTES as co‐monomer which was utilized to graft silica nanoparticles (SNPs) onto the P(TFEMA) spheres. The film prepared using the nanocomposite latex exhibited a nano‐structured surface as observed by SEM and AFM analyses. Surface modification of the film with fluorinated trichlorosilane produced an SHS with a water contact angle (WCA) of 151.5°. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018 , 56, 266–275     

Functionalized mesoporous silica nanoparticles templated by pyridinium ionic liquid for hydrophilic and hydrophobic drug release application

Chemotherapy is the most common treatment for all cancer patients but this treatment poses many side effects due to lack of drug’s selectivity. To overcome this problem, utilizing a better and more effective delivery agent is the solution. Mesoporous silica nanoparticles (MSNs) emerged as a promising platform in development of drug delivery agent. This is due to its desirable properties such as tunable pores, large surface area, good biocompatibility and easy functionalization. Furthermore, these properties can be tuned through the utilization of alternative template such as pyridinium ionic liquid. Besides, by employing surface functionalization, the effectiveness of MSNs as drug delivery agent may also increase. This work reported the usage of 1-hexadecylpyridinium bromide ionic liquid as template for MSNs production and the surface of MSNs was then further functionalized via post – grafting method in order to obtain MSN – NH₂, MSN – SH and MSN – COOH as drug carrier, respectively. These functionalized MSNs were then used to study the drug loading and drug release of hydrophilic drug, gemcitabine and hydrophobic drug, quercetin. For quercetin, MSN-NH₂ had the highest drug loading percentage (72%) and slowest release (14%) in 48 h while for gemcitabine, it was found that MSN-COOH had the highest drug loading percentage (45%) and slowest release (15%) in 48 h. Based on the results, it is suggested that mesoporous silica nanoparticle with surface functionalization has suitable properties for controlled drug release which gives constant release behavior over a period of time to avoid repeated administration of drug where the drug is administered at a fixed dosage and regular time interval.     

Bioresponsive nanogated ensemble based on structure-switchable aptamer directed assembly and disassembly of gold nanoparticles from mesoporous silica supports

By taking advantage of recent advances in aptamer biology and nanotechnology, a general approach was developed for the design and fabrication of bioresponsive controlled delivery system. It utilized the structure-switchable aptamer directed assembly and disassembly of gold nanoparticles from mesoporous silica supports, which enables the control of cargo release from the inside of the mesoporous nanoparticles specifically in the presence of target molecule.     

Lipid,protein and poly(NIPAM) coated mesoporous silica nanoparticles for biomedical applications

In the past decade, mesoporous silica nanoparticles (MSNs) as nanocarriers have showed much potential in advanced nanomaterials due to their large surface area and pore volume. Especially, more and more MSNs based nanodevices have been designed as efficient drug delivery systems (DDSs) or biosensors. In this paper, lipid, protein and poly(NIPAM) coated MSNs are reviewed from the preparation, properties and their potential application. We also introduce the preparative methods including physical adsorption, covalent binding and self-assembly on the MSNs' surfaces. Furthermore, the interaction between the aimed cells and these molecular modified MSNs is discussed. We also demonstrate their typical applications, such as photodynamic therapy, bioimaging, controlled release and selective recognition in biomedical field.     

Synthesis of a trinuclear ruthenium cluster containing pyridine and 4-acetylpyridine ligands and its immobilization on functionalized silica

Summary The trinuclear cluster [Ru₃O(Ac)₆(py)₂(acpy)]PF₆ (py: pyridine;acpy: 4-acetylpyridine) has been synthesized and anchored on functionalized silica. Five successive redox couples exhibitingE°=–1.4, –0.98, 0.21, 1.23, and 2.2 Vvs. SHE have been characterized in acetonitrile solutions based on cyclic voltammetry and spectroelectrochemical measurements. The redox and spectroscopic properties are maintained in the immobilized species, allowing its use in optodes and in electron transfer processes.

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Synthese eines dreikernigen Rutheniumclusters mit Pyridin- und 4-Acetylpyridinliganden sowie seine Fixierung auf funktionalisiertem Kieselgel

Zusammenfassung Der dreikernige Cluster [Ru₃O(Ac)₆(py)₂(acpy)]PF₆(py: Pyridin;acpy: 4-Acetylpyridin) wurde hergestellt und an funktionalisiertem Kieselgel verankert. Mit Hilfe cyclischer Voltammetrie und spektroelektrochemischer Messungen konnten fünf aufeinanderfolgende Redoxpaare beobachtet werden (E ⁰=–1.4, –0.98, 0.21, 1.23 und 2.2 V bezüglich SHE). Die elektrochemischen und spektroskopischen Eigenschaften bleiben in den fixierten Clustern erhalten und erlauben deren Verwendung in Optoden und bei Elektronenübertragungsprozessen.

     

Performance evaluation of functionalized ordered mesoporous silica for VOCs adsorption by molecular dynamics simulation

Volatile organic compounds (VOCs) are growing pollutants now that cause the serious environmental pollution and threaten human health. The functionalized ordered mesoporous silica (FOMS) has attracted considerable attention in adsorbing VOCs. In this paper, the molecular dynamics simulation was used to simulate the adsorption performance of FOMS on VOCs (acetone, ethyl acetate and toluene). After simulating different pore sizes (2 nm, 3 nm and 4 nm) adsorption performances of ordered mesoporous silica (OMS) on VOCs, OMS with a pore size of 4 nm was selected to further study the influence of functional groups (vinyl, methyl, and phenyl). The following law was obtained: the saturated adsorption capacities of vinyl-functionalized OMS (V-FOMS) to acetone, ethyl acetate and toluene were 3.045 mmol.g^?1, 2.568 mmol.g^?1 and 1.976 mmol.g^?1 respectively; the saturated adsorption capacities of methyl-functionalized OMS (M-FOMS) to acetone, ethyl acetate and toluene were 2.798 mmol.g^?1, 2.312 mmol.g^?1 and 1.698 mmol.g^?1 respectively; the saturated adsorption capacities of phenyl-functionalized OMS (P-FOMS) to acetone, ethyl acetate and toluene were 2.124 mmol.g^?1, 1.941 mmol.g^?1 and 1.539 mmol.g^?1 respectively. These results show that the adsorption ability of FOMS for different adsorbates follows the sequence of acetone > ethyl acetate > toluene. Furthermore, the interaction between functional groups (vinyl, methyl and phenyl) in FOMS and VOCs was explored. It is found that the interaction between different functional groups and adsorbates is different (interaction energy effect). This interaction energy effect promotes FOMS to better adsorb VOCs. This work would provide fundamental understanding and guidance for the development of novel adsorption materials for the adsorption of VOCs.