Silica Framework Research Articles

Effective and safe delivery of GLP-1AR and FGF-21 plasmids using amino-functionalized dual-mesoporous silica nanoparticles in vitro and in vivo

Nanomaterials have attracted increased attention because of their excellent drug-carrying capacity. However, these nanomaterials are rarely used in the treatment of metabolic diseases. Liraglutide, a glucagon-like peptide-1 receptor agonist, has been widely used in the treatment of type 2 diabetes mellitus (T2DM). Furthermore, fibroblast growth factor 21 (FGF-21) has been found to improve glucose metabolism and insulin resistance (IR). To investigate whether these two molecules have synergistic effects in vivo, we developed a novel drug delivery system using amino-functionalized and embedded dual-mesoporous silica nanoparticles (N-EDMSNs) to simultaneously carry liraglutide and FGF-21, and observed their biological effects. The resultant N-EDMSNs possessed unique hierarchical porous structures consisting of open large pores (>10 nm) and small mesopores (~2.5 nm) in the silica framework, highly positively charged surfaces and good disperisity in aqueous solution. We found that N-EDMSNs had a high loading capacity for exogenous genes and low toxicity to Hepa1-6 cells. Moreover, N-EDMSNs can simultaneously carry FGF-21 plasmids and liraglutide and successfully transfect them into Hepa1-6 cells. The transfection efficiency of N-EDMSNs was higher than that of Lipofectamine 2000 in vitro. In mice experiments, N-EDMSNs/pFGF21 treatment resulted in higher FGF-21 expression in the liver than pFGF21 treatment with hydrodynamic delivery. Compared with both pFGF21 and liraglutide, N-EDMSNs/pFGF21/Lira treatment significantly reduced the food intake, body weight, and blood glucose; increased the energy expenditure and improved hepatic IR in high-fat diet (HFD)-fed mice. Our results demonstrated that the biological effects of N-EDMSNs/pFGF21/Lira complexes were better than those of pFGF21 combined with liraglutide in vivo.

The hydrogenation of cycloalkenes over direct-synthetized well-defined zero-valent Pt nanoparticles incorporated TUD-1 mesoporous material

Well-defined Pt nanoparticles were integrated into the mesoporous material TUD-1 by applying one-pot sol–gel methodology and denoted as Pt-TUD-1. The characterization data of Pt-TUD-1 confirmed the presence of highly dispersed nanoparticles of zero-valent platinum (Pt0) of 5–10 nm average size incorporated into the three-dimensional silica framework. Pt-TUD-1 was used to catalyze the liquid-phase hydrogenation of four cycloalkenes; cyclopentene (CPE), cyclohexene (CXE), cyclooctene (COE), and cyclooctadiene (COD) without the use of any solvents in room temperature. The obtained results showed that cyclopentene is the fastest to be hydrogenated where 57.7% was converted within one hour’s reaction. The activity of Pt-TUD-1 benchmarked not only the commercial Pt nanopowder but also the Pt supported SiO2 and SBA-15. Moreover, Pt-TUD-1 showed high stability and it was recycled successfully for four consecutive runs without activity loss.

Preferential Protection of Low Coordinated Sites in Pt Nanoparticles for Enhancing Durability of Pt/C Catalyst

Protecting low coordinated sites (LCS) of Pt nanoparticles, which are vulnerable to dissolution, may be an ideal solution for enhancing the durability of polymer electrolyte fuel cells (PEMFCs). However, the selective protection of LCSs without deactivating the other sites presents a key challenge. Herein, we report the preferential protection of LCSs with a thiol derivative having a silane functional group, (3-mercaptopropyl) triethoxysilane (MPTES). MPTES preferentially adsorbs on the LCSs and is converted to a silica framework, providing robust masking of the LCSs. With the preferential protection, the initial oxygen reduction reaction (ORR) activity is marginally reduced by 8% in spite of the initial electrochemical surface area (ECSA) loss of 30%. The protected Pt/C catalyst shows an ECSA loss of 5.6% and an ORR half-wave potential loss of 5 mV after 30,000 voltage cycles between 0.6 and 1.0 V, corresponding to a 6.7- and 2.6-fold durability improvement compared to unprotected Pt/C, respectively. The preferential protection of the vulnerable LCSs provides a practical solution for PEMFC stability due to its simplicity and high efficacy.

Fabrication and characterization of a novel PMO containing riboflavin-5'-phosphate sodium salt for sensitive detection of pesticide ferbam

A highly sensitive and low-cost optical nanosensor of organic-inorganic hybrid material for pesticide ferbam detection was prepared by utilizing a novel organic siloxane precursor obtained from riboflavin-5′-phosphate sodium salt (Rf). A panel of characterizations was carried out to understand the structure, morphology and surface chemistry of the Rf periodic mesoporous organosilica (Rf-PMO) spherical nanosensors. For the Rf-PMO materials, the doped silica nanoparticles exhibit strong fluorescence emission at 520 nm, on account that the greater steric hindrances and the more separated state of π-conjugate planer platforms between Rf molecules embedded within the silica framework can both enhance the fluorescence emission and reduce the self-quenching of fluorescence produced by stacking aggregation of Rf. The electron spin resonance (ESR) spectra prove that the prepared Rf-PMO materials can participate in the redox reaction through electron transfer with the pesticide ferbam. Utilized the reducing reaction mechanism of Rf-PMO, it is applied to detect pesticide ferbam with high sensitivity and selectivity, with the limit of detection (LOD) in aqueous solution as low as 6.97 × 10−9 M. Moreover, the X-ray absorption near-edge spectroscopy (XANES) of Fe K-edge shows a coordination structure through the interaction between iron ions from ferbam and O and N atoms in Rf-PMO. X-ray photoelectron spectroscopy (XPS) further reveals the redox mechanism. Therefore, the designed and prepared Rf-PMO is potentially valuable to food safety monitoring involving ferbam as the nanosensor, due to its hypersensitivity and selectivity.

Development of Pd Supported Catalysts Using Thiol‐Functionalized Mesoporous Silica Frameworks: Application to the Chemo‐ and Regioselective C‐3 Arylation of Free‐Indole

AbstractWe report here the development of Pd‐supported catalysts for the selective C‐3 arylation of free‐indole using thiol‐functionalized silica supports to anchor the palladium centers. The palladium (II) complex, Pd(OAc)2, was efficiently loaded into various thiol‐functionalized mesostructured silicas at room temperature. These materials exhibit different contents of surface SH groups (0.3 to 1.8 SH/nm2) and various SH/Pd molar ratios from 6 to 65. It was found that the catalysts containing the most isolated surface SH groups (0.3 SH/nm2) and the highest loading of Pd were the most active, reaching 70 % of conversion, 1400 as turnover numbers and 100 % selectivity in the C‐3 arylated product using only 0.05 mol % of Pd. However, a leaching of active Pd species (1.7 ppm) was detected. The best compromise was found for a specific solid containing isolated surface thiol groups (0.3 SH/nm2) and a very low loading of Pd (SH/Pd=65). It exhibited a high TON (608) with a very low Pd leaching of 0.5 ppm in the course of the catalytic reaction. These results thus illustrate that both surface SH sites isolation and concentration, as well as the SH/Pd molar ratio are key parameters to access high catalytic performances and very low leaching of metal during catalysis.

Engineered Silicon Carbide Three-Dimensional Frameworks through DNA-Prescribed Assembly.

The ability to create nanoengineered silicon carbide (SiC) architectures is important for the diversity of optical, electronic, and mechanical applications. Here, we report a fabrication of periodic three-dimensional (3D) SiC nanoscale architectures using a self-assembled and designed 3D DNA-based framework. The assembly is followed by the templating into silica and subsequent conversion into SiC using a lower temperature pathway (<700 °C) via magnesium reduction. The formed SiC framework lattice has a unit size of about 50 nm and domains over 5 μm, and it preserves the integrity of the original 3D DNA lattice. The spectroscopic and electron microscopy characterizations reveal SiC crystalline morphology of 3D nanoarchitectured lattices, whereas electrical probing shows 2 orders of magnitude enhancements of electrical conductivity over the precursor silica framework. The reported approach offers a versatile methodology toward creating highly structured and spatially prescribed SiC nanoarchitectures through the DNA-programmable assembly and the combination of templating processes.

Synthesis of Hierarchical Porous Silica by Sol‐Gel of Sodium Silicate and Nanoemulsion Templating: Effective Combination Conditions

AbstractHierarchical porous materials have attracted a considerable attention owing to the increased interest in their applications. Hierarchical Porous Silica (HPS) was synthesized by combining the sol‐gel of sodium silicate (SS) and oil in water nanoemulsion (O/W‐NE) templating. The oil droplets of NE acted as pore forming agent and the sol‐gel built the silica framework. The O/W‐NE was prepared by a low energy method, i. e., the phase inversion composition (PIC) method. The influence of pH of SS and NE on HPS was studied. The volume of ammonia, used to induce gelling, was studied as a factor influencing the HPS. The calcined samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), FTIR, N2 adsorption and small‐angel X‐ray scattering (SAXS). The results show that the microstructure is highly affected by pH and can be; macropores inserted in a dense matrix; a blend of a dense and a porous structure; or fully hierarchical porous silica. HPS has a specific surface area of 240 m2/g and a large pore volume (1.5 cm3/g) and a surface roughness of 2.95.

Mesoporous Methyl-Functionalized Titanosilicate Produced by Aerosol Process for the Catalytic Epoxidation of Olefins

Titanosilicates (Ti-SiO2) are well-known catalysts for the epoxidation of olefins. Isolated Ti inserted in the silica framework in tetrahedral coordination are the active species. Recently, adjusting the hydrophobic/hydrophilic balance of such catalysts’ surfaces has appeared as a promising tool to further boost their performance. However, adjusting the hydrophobic/hydrophilic balance via a one-pot classical sol-gel generally leads to a decrease in the Ti dispersion and/or collapse of the pore network. To overcome this limitation, hydrophobic mesoporous Ti-SiO2 were here synthesized by aerosol-assisted one-pot sol–gel, which allowed the simultaneous control of their Ti loading, degree of methyl-functionalization, and textural properties. Methyl-functionalization was achieved by a partial substitution of tetraethoxy silane (TEOS) by methyltriethoxy silane (MTES) in different ratios. Solid-state 29Si-NMR, FTIR, TGA, and vapor-phase water adsorption showed that methyl moieties were effectively incorporated, conferring a hydrophobic property to the Ti-SiO2 catalysts. ICP-AES, DRUV, XPS, and N2 physisorption demonstrated that Ti dispersion and textural properties were both successfully preserved upon the incorporation of the methyl moieties. In the epoxidation of cyclooctene with tert-butyl hydroperoxide as oxidant, the hydrophobic Ti-SiO2 showed higher catalytic performance than pristine Ti-SiO2 prepared without MTES. In addition to disentangling the positive effect of adjusting the hydrophobic/hydrophilic balance of epoxidation catalysts on their performance, this contribution highlights the advantages of the aerosol procedure to synthesize mesoporous functionalized catalysts with very high dispersion of active sites.

The fabrication of a highly ordered molecularly imprinted mesoporous silica for solid-phase extraction of nonylphenol in textile samples

We integrated molecularly imprinted technology with mesoporous silica to prepare nonylphenol-imprinted mesoporous silica (NPIMS). It is a highly ordered and efficient absorption material, which developed in one-step co-condensation process. N-Phenyl-3-aminopropyltrimethoxysilane was used as the functional monomer to produce imprinted cavities that were distributed within the framework of MCM-41 mesoporous silica. Fourier-transform infrared and solid-state nuclear magnetic resonance spectroscopies, X-ray diffractometry, transmission electron microscopy, were used to characterize the functional groups, porosity and microscopic ordered structure of NPIMS. The Brunauer–Emmett–Teller specific surface area of NPIMS was 990.97 m2 g−1. NPIMS optimized (1:4) template-to-functional-monomer ratio exhibited the best specific binding capacity (56.4 mg g−1) and imprinted factor (IF = 3.22). NPIMS reached adsorption equilibrium within 10 min even at a very high 4-nonylphenol concentration (300 mg L−1) and showed excellent selectivity among several phenols. NPIMS was used as an adsorbent for the solid-phase extraction of real samples; enrichment experiments demonstrated that NPIMS selectively adsorbed 4-nonylphenol with an excellent selectivity and exhibited good enrichment performance for the target substance with a high recovery.

A Salt Stimulus-Responsive Nanohydrogel for Controlled Fishing Low-Density Lipoprotein with Superior Adsorption Capacity.

A salt-responsive nanoplatform is constructed through a simple tactic by tethering zwitterionic nanohydrogels (NGs) on a carboxylated silica (SiO2-COOH) framework. Chondroitin sulfate (CS), with a specific recognition effect for low-density lipoprotein (LDL), is modified to NGs by amidation reaction. Water retention and swelling properties of NGs are greatly enhanced in a saline environment attributed to the anti-polyelectrolyte effect. It endows the SiO2-NGs-CS framework a sensitive salt-responsive property, and thus, more CS moieties are exposed. The controlled adsorption of LDL with an adsorption efficiency of 7.2 to 93% is achieved by adjusting the concentration of MgCl2 from 0 to 0.1 mol L-1. SiO2-NGs-CS exhibits excellent adsorption capacity for fishing LDL, acquiring the highest adsorption capacity of 898.1 mg g-1. Moreover, SiO2-NGs-CS shows superior selectivity to the other three proteins with similar isoelectric points (pIs) to LDL. The captured LDL is readily stripped by 0.2% (m/m) SDS with a recovery of 95.4%. The superior separation performance of SiO2-NGs-CS is demonstrated by the isolation and selective discrimination of LDL from the simulated serum of hypercholesterolemia patients, as illustrated by sodium dodecyl sulfate polyacrylamide gel electrophoresis assays.

Synthesis and characterization of boron‐acrylate/Santa Barbara Amorphous‐15 polymer composite

AbstractIn the present work, boron‐acrylate/Santa Barbara Amorphous (SBA)‐15 polymer composite was synthesized using free radical polymerization method. Firstly, SBA‐15 was functionalized with 3‐(trimethoxysilyl)propyl methacrylate to obtain chemically bonded boron acrylate (BAc) polymer on the SBA‐15 surface. The structural analysis was evaluated via Fourier‐transform infrared spectroscopy and solid‐state nuclear magnetic resonance 13C. Samples were also characterized by using scanning electron microscopy, X‐ray powder diffraction, N2 adsorption/desorption and thermogravimetric analysis. In order to examine the BAc polymers in the mesopores, the silica framework was removed via hydrofluoric acid etching process. The results indicated that the synthesis of boron‐acrylate/SBA‐15 polymer composite was performed successfully. Thermal stabilities of the composites were higher with greater amounts of BAc polymer in mesopores under oxidative conditions.

Control of the hydration layer states on phosphorus-containing mesoporous silica films and their reactivity evaluation with biological fluids.

Transparent phosphorus-containing MPS (PMPS) films were synthesized by the introduction and reaction of phosphoric acid into the silica framework during the sol-gel reaction. We then investigated the hydration layer structures formed on the PMPS films and achieved the selective adsorption of fibronectin (Fn). In particular, the surface analyses indicated that the P atom was distributed at the outermost surfaces of the PMPS films. The PMPS films exhibited a high transparency (e.g., averaged transmittance value in the visible light region: 79%), and the haze value (0.14%) decreased with the increasing P/Si molar concentration. Solid-state 29Si-NMR and Fourier transform infrared spectroscopy (FT-IR) spectra indicated the formation of Si-O-P bonds, suggesting that the condensation reaction between the Si-O- and P-O- groups effectively occurs in the silica framework. The larger amount of P-O- and P[double bond, length as m-dash]O groups at the Si-O-P bonding site on the films affects the water molecular adsorption states (i.e., formation of the hydration layer), which was supported by the Brunauer-Emmett-Teller (BET) surface areas of N2 and water vapor, leading to enhancement of the hydrogen bondability of the PMPS films with the increased formation of Si-O-P bonds. The deconvolution results of the FT-IR spectra demonstrated that the ratio of free water to bonding water increased significantly with an increase in the formation of Si-O-P bonding, and the resulting O-H stretching vibration in the hydration layer became more asymmetric. It is suggested that the water molecules are irregularly hydrogen-bonded with the different functional groups of Si-O-, P-O- and P[double bond, length as m-dash]O. In the immersion experiment of the PMPS films in phosphate buffer, the resultant P/Si molar concentration of the PMPS film decreased upon increasing the immersion time and the mesostructures were preserved. The amount of Fn adsorption significantly increased as the O-H stretching vibration of the water molecules became more asymmetric, whereas the adsorption of fibrinogen was completely suppressed by the films. Therefore, we found that the addition of phosphoric acid in the MPS film synthesis significantly affects the hydration layer structures on the film surfaces to provide the possibility of selective protein adsorption.

Synthesis of antimicrobial siliceous materials by adding sunflowers ashes with silver and copper particles

Microbial contamination of indoor environmental surfaces is a common source for infections. Therefore, bio-deterioration in buildings indoor materials is really important to avoid, due to the negative impact on human health. Consequently, functionalized and sustainable materials are being intensively studied to control the microbial colonization. Firstly, it was possible to obtain silica samples by the sol-gel method with the addition of sunflower residues in the form of ashes together with silver or copper salt to produce antimicrobials solids. Secondly, the synthesized solids were characterized by different techniques. TEM analyses confirmed the successful inclusion of silver and copper nanoparticles into the silica framework mainly spherical in shape, and small size. Both silver and copper as antimicrobial agents reduce the potential for cross-contamination to occur, as it is effective against a wide range of microorganisms, by the addition of ashes into the samples improved the antifungal activity of the solids against both fungal strains tested, Chaetomium globosum and Alternaria alternata.

Sunflower Ashes and Nanoparticles Embedded in Silane Matrix as Bioactive Filler Material

Microbial contamination of indoor environmental surfaces is a common source for infections therefore, bio-deterioration in buildings indoor materials is really important to avoid, due to the negative impact on human health. Consequently, functionalized and sustainable materials are being intensively studied to control the microbial colonization. Firstly, it was possible to obtain silica samples by the sol-gel method with the addition of sunflower residues in the form of ashes together with silver or copper salt to produce antimicrobials solids. Secondly, the synthesized solids were characterized by different techniques. TEM analyses confirmed the successful inclusion of silver and copper nanoparticles into the silica framework mainly spherical in shape, and small size. The antimicrobial activity of the solids was assessed against fungal strains obtained from indoor bio-deteriorated building surfaces, Chaetomium globosum (KU936228) and Alternaria alternata (KU936229). The addition of ashes into the samples improved the antifungal activity of the solids. Both silver and copper as antimicrobial agents reduce the potential for cross-contamination to occur, as it is effective against a wide range of microorganisms.

Encapsulation of gold nanoclusters: stabilization and more.

Gold nanoparticles with only a few atoms, known as gold nanoclusters (AuNCs), have dimensions below 2 nm and feature singular properties such as size dependent luminescence. AuNCs are also highly photostable and have catalytic activity, low toxicity and good biocompatibility. With these properties, they are extremely promising candidates for application in bioimaging, sensing and catalysis. However, when stabilized only with small capping ligands, their use is hindered by lack of colloidal stability. Encapsulation of the AuNCs can contribute to provide a more robust protection and even to improve their properties. Here, we review the encapsulation of AuNCs in polymers, silica and metal organic frameworks (MOFs) for applications in bioimaging, sensing and catalysis.

Sulfur dioxide removal by mesoporous silica KCC-1 modified with low-coverage metal nitrates

The removal of sulfur dioxide (SO2) from flue gas using fibrous mesoporous silica KCC-1 synthesized via microwave-assisted hydrothermal method was observed. The sorbent was modified by introducing nitrate salts of sodium (Na) and calcium (Ca) at 5 wt. % metal loading via incipient wet impregnation method. The SO2 breakthrough experiment was conducted in a vertical quartz-column reactor at atmospheric pressure and temperature of 323 K in the presence of 0.3 % SO2/N2. The SEM micrograph of KCC-1 exhibited a well-defined fibrous morphology consisting of colloidal spheres of 240–1160 nm in diameter. Addition of metal nitrates resulted in the reduction of surface area, total pore volume and minor breakage of the silica framework. The adsorption capacities of all samples were measured at C/C0 = 0.5, where the addition of sodium (Na5/KCC-1) and calcium (Ca5/KCC-1) enhanced the removal capacity by 1.88 and 2 times higher than the parent KCC-1 respectively. Even though sodium is expected to achieve better removal capacity due to its higher basicity and dispersion related to the lower crystallite size, its performance ultimately suffered from significant agglomeration of sodium oxide which created pore blockage, subsequently resulting in poor accessibility to the active sites.

Hydrocracking of Polyethylene to Jet Fuel Range Hydrocarbons over Bifunctional Catalysts Containing Pt- and Al-Modified MCM-48

A low-density polyethylene was hydrocracked to liquid hydrocarbons in autoclave reactors over catalysts containing Pt- and Al-modified MCM-48. Two kinds of Al-modified MCM-48 were synthesized for the reaction: Al-MCM-48 was synthesized using a sol–gel method by mixing Al(iso-OC3H7)3 with Si(OC2H5)4 and surfactant in a basic aqueous solution before hydrothermal synthesis, and Al/MCM-48 was synthesized using a post-modification method by grafting Al3+ ions on the surface of calcined Al/MCM-48. X-ray diffraction (XRD) patterns indicated that both Al-MCM-48 and Al/MCM-48 had a cubic mesoporous structure. The Brunauer–Emmett–Teller (BET) surface areas of Al-MCM-48 and Al/MCM-48 were larger than 1000 m2/g. 27Al Magic Angle Spinning-NMR (MAS NMR) indicated that Al3+ in Al-MCM-48 was located inside the framework of mesoporous silica, but Al3+ in Al/MCM-48 was located outside the framework of mesoporous silica. The results of ammonia temperature-programmed desorption (NH3-TPD) showed that the acidic strength of various samples was in the order of H-Y &gt; Al/MCM-48 &gt; Al-MCM-48 &gt; MCM-48. After 4 MPa H2 was charged in the autoclave at room temperature, 1 wt % Pt/Al/MCM-48 catalyst showed a high yield of C9−C15 jet fuel range hydrocarbons of 85.9% in the hydrocracking of polyethylene at 573 K for 4 h. Compared with the reaction results of Pt/Al/MCM-48, the yield of light hydrocarbons (C1−C8) increased over Pt/H-Y, and the yield of heavy hydrocarbons (C16−C21) increased over Pt/Al-MCM-48 in the hydrocracking of polyethylene. The yield of C9−C15 jet fuel range hydrocarbons over the used catalyst did not decrease compared to the fresh catalyst in the hydrocracking of polyethylene to jet fuel range hydrocarbons over Pt/Al/MCM-48.

Versatile nanoadsorbents based on magnetic mesostructured silica nanoparticles with tailored surface properties for organic pollutants removal

This paper addresses the development of new magnetic silica-based nanoadsorbents and evaluates their potential application in the removal of contaminants of emerging concern (CECs), polyaromatic hydrocarbons (PAHs) and aliphatic hydrocarbons. For this purpose, magnetic iron oxide nanoparticles were covered with a hybrid shell of silica and 3-(trimethoxysilyl)propyl-octadecyldimethyl-ammonium chloride (TPODAC) as structure directing agent. The as-prepared hybrid material (MMST) was further modified with trimethoxyphenylsilane, obtaining a phenyl-functionalized nanoadsorbent (MMST-Ph). Both materials were thoroughly characterized with diverse physicochemical techniques, and batch sorption tests with single-contaminant and with mixtures of contaminants were performed. MMST-Ph proved to be more efficient for the adsorption of PAHs and aliphatic hydrocarbons. The presence of TPODAC and phenyl moieties anchored on the mesostructured silica frameworks resulted to be a key factor to obtain high PAHs uptakes from aqueous media. In the case of CECs, ibuprofen (IBU), diclofenac (DCF) and carbamazepine (CBZ) were tested. These experiments demonstrated that even though MMST possesses better adsorption capacities of CECs, MMST-Ph achieved high IBU and DCF uptakes. Regeneration and reuse experiments showed that MMST-Ph can be reused in eight cycles without losing the adsorption capacity of anthracene. In the case of MMST, there was a 42% drop in the adsorption capacity of ibuprofen in the second cycle, whereas in the next seven cycles the adsorption capacity remained constant.The promising results obtained in this work strengthen the potential application of surface-modified magnetic silica nanoparticles for the removal of different types of organic pollutants from waters.

Silica-Supported Phosphine-Gold Complexes as an Efficient Catalytic System for a Dearomative Spirocyclization.

The combination of metal catalyst and inorganic silica frameworks provides a greener approach to recyclable catalysis. In this study, three phosphine-gold chloride complexes have been successfully covalently grafted onto chiral silica nanohelices. The resulting 3D ensembles showed chiroptical properties that allowed the monitoring of the supported ligands. The heterogeneous gold chloride catalysts in cooperation with silver triflate exhibited high reactivity in various reactions, especially in the spirocyclization of aryl alkynoate esters, for which a catalytic loading of 0.05 mol % could be employed. The heterogeneous catalysts could be easily recovered and recycled seven or eight times without any loss of efficiency. By adding more silver triflate, 25 cycles with full conversion were achieved owing to a complex catalytic system based on silica and metallic species.

Controlled release of anticancer drug using o-phenylenediamine functionalized SBA-15 as a novel nanocarrier

In this study, a pH-sensitive drug delivery system was presented by o-phenylenediamine functionalized SBA-15 as a new carrier for controlled release of imatinib mesylate. O-phenylenediamine functionalized SBA-15 mesoporous silica was synthesized and characterized. Powder X-ray diffraction proved the 2D hexagonal mesostructure with p6mm space group for nanoporous materials. The o-phenylenediamine functionalized SBA-15 showed the BET surface area 265 m2g−1 and pore diameter 5.8 nm, based on adsorption–desorption of N2 at 77 oK. The presence of organic groups in the silica framework was demonstrated by FTIR spectrum. Then, the imatinib mesylate was loaded on o-phenylenediamine functionalized SBA-15 in saturated drug aqueous solution at ambient temperature for 1 h. According to the observations on drug release in phosphate buffers, the imatinib mesylate release from o-phenylenediamine functionalized SBA-15 shows a pH-associated behavior, and the rate of imatinib mesylate release was quicker at lower pH than higher pH. In addition, the imatinib mesylate had a slow release pattern in SBF with a constant rate of approximately 1.4 µg h−1 after the first hour. The results illustrated that o-phenylenediamine functionalized SBA-15 is a suitable option for being employed as a new carrier for controlled release of imatinib mesylate.