Pores Of Mesoporous Silica Research Articles

Immobilization of trypsin onto large-pore mesoporous silica and optimization enzyme activity via response surface methodology

Tannic-acid-templated large pore mesoporous silica nanoparticle (LMSN) was synthesized using one-pot procedure and the external surface was further modified with APTES (LMSN-N) to immobilize trypsin. After modification, trypsin was difficult to be immobilized on the outer surface of the LMSN due to the electrostatic repulsion. Naturally, study of the trypsin immobilized in the interior pores could be implemented solely. Meanwhile, the activity of immobilized trypsin was optimized by response surface method (RSM), and the ANOVA was employed to explore the interaction between independent variables. The maximum enzyme activity (12.28 U/mg) was obtained under a certain condition that the quality of T-LMSN-N-272 was 153 μg, the pH was 7.9, and the temperature was 40.4 °C. Simultaneously, the immobilized enzyme was proved to possess better thermal stability, storage stability and recycling performance than free enzyme.

Characterization of Myoglobin Adsorption into Mesoporous Silica Pores by Differential Scanning Calorimetry.

Adsorption of protein molecules into the pores of a porous material is an important process for chromatographic separation of proteins and synthesis of nanoscale biocatalyst systems; however, there are barriers to developing a method for analyzing the process quantitatively. The purpose of this study is to examine the applicability of differential scanning calorimetry (DSC) for quantitative analysis of protein adsorption into silica mesopores. For this purpose myoglobin, a globular protein (diameter: 35.2 Å) was selected, and its adsorption onto mesoporous silica powders with uniform pore diameters (pore diameters: 39 and 64 Å) was measured by adsorption assay and DSC experiments. Our results confirmed that the adsorption of myoglobin into the silica mesopores induced significant changes in the positions and areas of freezing/melting peaks of the pore water. The decrease in heat of fusion of the pore water after myoglobin adsorption could be utilized to quantify the amount of myoglobin inside the silica mesopores. The advantages of DSC include its applicability to small wet mesoporous silica samples.

Synthesis and characterization of mesoporous Nb Zr/KIT-6 as a productive catalyst for the synthesis of benzylpyrazolyl coumarins

Abstract The direct insertion of niobium(V) and zirconium (IV) into the ordered cubic pores of Ia3d mesoporous silica, KIT-6, was performed by employing a hydrothermal method and utilizing a versatile structure directing agent, Pluronic P123 triblock copolymer, in n-butanol as co-solvent. The effect of simultaneous incorporation of niobium and zirconium on the acidity of KIT-6 nanomaterial was investigated and compared to Nb-KIT-6 and Zr-KIT-6. The prepared mesoporous Nb Zr/KIT-6 was characterized by N2 porosimetry, TEM, FESEM, XRD, NH3-TPD, FT-IR, and ICP-OES. Results displayed that niobium and zirconium ions were well incorporated into the KIT-6 framework and the entire ordered pore structure has been retained. Incorporation of niobium and zirconium ions enhanced the catalytic activity of KIT-6 as strong acid sites. Eventually, the synthesized Nb Zr/KIT-6 was used as an effective, recyclable and green catalyst for the multi-component, one-pot production of some substituted benzylpyrazolyl coumarins via condensation of phenylhydrazine, ethyl acetoacetate, 4-hydroxycoumarin and various aldehydes under mild solvent-free conditions with fair to excellent yields.

PH responsive selective protein adsorption by carboxylic acid functionalized large pore mesoporous silica nanoparticles SBA-1

Cubic mesoporous silica nanoparticles (MSNs) with the SBA-1 moiety, functionalized with carboxylic acid (COOH) groups as well as enlarged mesopores, are successfully synthesized using tetraethyl orthosilicate (TEOS) and carboxyethylsilanetriol sodium salt (CES) as silica sources, complexes formed by polyacrylic acid (PAA) and hexadecylpyridinium chloride (CPC) as templates, and trimethylbenzene (TMB) as pore expander. The successful incorporation of organic functionalities are confirmed by 13C and 29Si solid-state NMR. The structural properties of cubic mesostructures are characterized by powder XRD, N2 adsorption-desorption isotherms, and TEM measurements. The prepared MSNs exhibit a remarkably high adsorption capacity of 1138 mg g−1 at pH 8.2 when they are used as the supports to immobilize papain. Both factors of the large pore size of the support and the favorable electrostatic attractions between the carboxylate groups on the adsorbent surface and the papain molecules play important roles in reaching such a high adsorption capacity. The immobilized papain possesses better thermal stability, pH tolerance, and heat resistance in comparison to the free papain. The materials are also used for selective adsorption of a single protein (papain) from the binary mixture of two different types of proteins (papain and hemoglobin). Our results demonstrate that proteins such as papain and hemoglobin with different isoelectric points and shapes can be effectively separated from their binary mixture by simply tuning the pH of the buffer.

Effect of size on the magnetic properties and crystal structure of magnetically frustrated DyMn2O5 nanoparticles

We synthesized magnetically frustrated ${\mathrm{DyMn}}_{2}{\mathrm{O}}_{5}$ nanoparticles in pores of mesoporous silica, with particle sizes ranging from 7 to 20 nm, and investigated their magnetostructural correlation. We found that the lattice constants of the ${\mathrm{DyMn}}_{2}{\mathrm{O}}_{5}$ nanoparticles deviated from those of the bulk crystal below $\ensuremath{\sim}12$ nm and their crystallographic structures at the unit cell level were distorted. The size dependences of the blocking temperature and coercive field drastically change at $\ensuremath{\sim}12$ nm. In addition, the Weiss temperature depends strongly on particle size, and its sign changes at $\ensuremath{\sim}12$ nm. It is considered that such features can be realized owing to the distortion caused by the ligand atoms at the surface. The orbital structures of the magnetic sites are easily modified due to the distortion of the ligand ions at the surface, so that the correlation between the crystal structure and magnetic properties can be enhanced. Moreover, magnetization of the nanoparticle results in quasi-superparamagnetic behavior. Monte Carlo calculation of the nanoparticles indicates that such a feature is realized due to the quasi-free spins induced at the surface by magnetic frustration.

Optoacoustic imaging identifies ovarian cancer using a microenvironment targeted theranostic wormhole mesoporous silica nanoparticle

At the intersection of the newly emerging fields of optoacoustic imaging and theranostic nanomedicine, promising clinical progress can be made in dismal prognosis of ovarian cancer. An acidic pH targeted wormhole mesoporous silica nanoparticle (V7-RUBY) was developed to serve as a novel tumor specific theranostic nanoparticle detectable using multispectral optoacoustic tomographic (MSOT) imaging. We report the synthesis of a small, < 40 nm, biocompatible asymmetric wormhole pore mesoporous silica core particle that has both large loading capacity and favorable release kinetics combined with tumor-specific targeting and gatekeeping. V7-RUBY exploits the acidic tumor microenvironment for tumor-specific targeting and tumor-specific release. In vitro, treatment with V7-RUBY containing either paclitaxel or carboplatin resulted in increased cell death at pH 6.6 in comparison to drug alone (p < 0.0001). In orthotopic ovarian xenograft mouse models, V7-RUBY containing IR780 was specifically detected within the tumor 7X and 4X higher than the liver and >10X higher than in the kidney using both multispectral optoacoustic tomography (MSOT) imaging with secondary confirmation using near infrared fluorescence imaging (p < 0.0004). The V7-RUBY system carrying a cargo of either contrast agent or an anti-neoplastic drug has the potential to become a theranostic nanoparticle which can improve both diagnosis and treatment of ovarian cancer.

Structure\u2212property relationships of polypropylene-based nanocomposites obtained by dispersing mesoporous silica into hydroxyl-functionalized polypropylene. Part 2: Matrix\u2212filler interactions and pore filling of mesoporous silica characterized by evolved gas analysis

Nanocomposites containing mesoporous silica (MPS) materials with various pore structures (SBA-15 and MCM-41 types) melt mixed into polypropylene (PP) or PP functionalized with hydroxyl groups (PPOH) were characterized by analytical pyrolysis techniques, such as evolved gas analysis (EGA)-mass spectrometry (MS) and heart-cut EGA-gas chromatography (GC)/MS, to evaluate the interactions between the polymer matrix and MPS and the pore filling of the MPS in the nanocomposite. The EGA-MS measurements revealed that nanocomposites with MPSs evolve specific degradation products, which can be attributed to strong interactions between the polymer molecules and the internal pores. The amount of these specific products increased upon increasing the pore size of the MPS and the hydroxyl content in the polymer matrix. Sufficiently large pores of MPS and high hydroxyl contents in the matrix appear to provide strong interactions because the MPS pores are well-filled with polymer molecules, which contributes to the improved physical properties of the nanocomposites.

Structural Characterization of Myoglobin Molecules Adsorbed within Mesoporous Silicas

In the present study, we examined the secondary and tertiary structure of myoglobin (Mb) within folded sheets mesoporous material (FSM)- and Santa Barbara amorphous (SBA)-type mesoporous silicas. The Barrett–Joyner–Halenda pore diameters of SBA-type mesoporous silicas were 39, 70, and 75 A, and that of FSM-type mesoporous silica was 40 A. The secondary and tertiary structures of myoglobin were observed by Fourier transform infrared (FTIR) and small-angle neutron scattering (SANS), respectively. The FTIR and SANS results indicated preservation of the secondary and tertiary structures of myoglobin inside the pores of SBA-type mesoporous silicas. Adsorption of myoglobin within FSM-type mesoporous silica, however, resulted in perturbation of the tertiary structure, accompanied by partial unfolding of the secondary structure. Lower structural stability of myoglobin within the FSM-type mesoporous silica was also confirmed. These findings suggest that the Mb structure is more influenced by the inner pore surface...

Structural Organization of Themagnetic Part of Smart Material Based on Nanoparticles of Iron or Magnetite in Pores of Mcm-41 Mesoporous Silica for Target Drug Delivery

Abstract The important stage of the development of smart material for the target drug delivery is the construction of the magnetic part of this material, including mesoporous silica and magnetic nanoparticles (Fe3O4or Fe0). Such a systemwill allow carry outmagnetic decapsulation (excretion) of drug from smart material using the magnetic field of a given value in the right place of the body. The paper considers the features of synthesis mesoporous silica MCM-41 with various pore diameter (33-51 Å) and synthesis of superparamagnetic nanoparticles of magnetite or metallic iron in the pores of mesoporous silica. The dependence of magnetic properties of nanocomposites MCM-41/Fe0 and MCM-41/Fe3O4 from the pore diameters of MCM-41 templates is studied. It was found that the matrix has a decisive influence on the content of iron or magnetite nanoparticles. The saturation magnetization of the material increases with increasing pore size of the mesoporous matrix. Nanocomposites MCM-41/Fe0 and MCM-41/Fe3O4 exhibit superparamagnetism, that allows them to be used as a magnetic material for targeted drug delivery.

HYDROLYTIC HYDROGENATION OF INULIN WITH USE MAGNETIC-SEPARATE Ru-CONTAINING CATALYST

The combined hydrolysis and hydrogenation of inulin was studied on Ru-containing magnetically recoverable catalyst, using subcritical water as solvent. The Ru−Fe3O4−SiO2 catalysts are synthesized by incorporation of magnetite nanoparticles (NPs) in mesoporous silica pores followed by formation of 2 nm Ru NPs. The latter was obtained by thermal decomposition of ruthenium acetylacetonate in the pores. Magnetic properties of Fe3O4−SiO2 are typical for superparamagnetic iron oxide NPs of comparable size and allow to make a fast magnetic separation of the catalyst. The results of liquid nitrogen adsorption measurements are typical for mesoporous materials. The BET surface area of catalyst is 280 m2/g, what is allowed for mesoporous catalytic materials. The XPS spectra of Ru-Fe3O4-SiO2 demonstrate a good homogeneity of the sample. The catalyst was tested in hydrolytic hydrogenation of inulin. Inulin is hydrolyzed with formation of fructose and a small amount of glucose. There is a hydrogenation of fructose and glucose in hydrogen with receiving a mannitol and sorbitol, respectively. Mannitol is widely used in production of medicines and pharmaceutics, liquid fuel, the chemical and food industry, biotechnology and production of cosmetics. Mannitol presents in many plants and seaweeds. However, the extraction of mannitol from these raw materials is not a profitable process. Instead, fermentation and catalytic hydrogenation processes are used industrially. Nowadays, mannitol can be obtained by catalytic hydrogenation of monosaccharides like fructose or from glucose-fructose mixtures, using heterogeneous catalyst. During the researches key parameters of process, such as temperature and time of reaction, partial pressure of hydrogen are varied. At optimum reaction conditions: temperature of 150 °C, partial pressure of hydrogen of 60 bars in 45 min, – conversion of inulin was achieved of 100 %, a mannitol yield was 44.3 %. The used catalyst has shown high activity and stability in hydrothermal conditions. Stable magnetic properties of the catalyst cause his easy separation from reactionary mixture by means of external magnetic field.Forcitation:Ratkevich E.A., Manaenkov O.V., Matveeva V.G., Kislitza O.V., Sulman E.M. The hydrolytic hydrogenation of inulin catalyzed by Ru-containing magnetically recoverable catalyst. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 4-5. P. 76-81

Amphiphilic Block Copolymers Directed Interface Coassembly to Construct Multifunctional Microspheres with Magnetic Core and Monolayer Mesoporous Aluminosilicate Shell.

Core-shell magnetic porous microspheres have wide applications in drug delivery, catalysis and bioseparation, and so on. However, it is great challenge to controllably synthesize magnetic porous microspheres with uniform well-aligned accessible large mesopores (>10 nm) which are highly desired for applications involving immobilization or adsorption of large guest molecules or nanoobjects. In this study, a facile and general amphiphilic block copolymer directed interfacial coassembly strategy is developed to synthesize core-shell magnetic mesoporous microspheres with a monolayer of mesoporous shell of different composition (FDUcs-17D), such as core-shell magnetic mesoporous aluminosilicate (CS-MMAS), silica (CS-MMS), and zirconia-silica (CS-MMZS), open and large pores by employing polystyrene-block-poly (4-vinylpyridine) (PS-b-P4VP) as an interface structure directing agent and aluminum acetylacetonate (Al(acac)3 ), zirconium acetylacetonate, and tetraethyl orthosilicate as shell precursors. The obtained CS-MMAS microspheres possess magnetic core, perpendicular mesopores (20-32 nm) in the shell, high surface area (244.7 m2 g-1 ), and abundant acid sites (0.44 mmol g-1 ), and as a result, they exhibit superior performance in removal of organophosphorus pesticides (fenthion) with a fast adsorption dynamics and high adsorption capacity. CS-MMAS microspheres loaded with Au nanoparticles (≈3.5 nm) behavior as a highly active heterogeneous nanocatalyst for N-alkylation reaction for producing N-phenylbenzylamine with a selectivity and yields of over 90% and good magnetic recyclability.

Extra-Large Pore Mesoporous Silica Nanoparticles Enabling Co-Delivery of High Amounts of Protein Antigen and Toll-like Receptor 9 Agonist for Enhanced Cancer Vaccine Efficacy.

Cancer vaccine aims to invoke antitumor adaptive immune responses to detect and eliminate tumors. However, the current dendritic cells (DCs)-based cancer vaccines have several limitations that are mostly derived from the ex vivo culture of patient DCs. To circumvent the limitations, direct activation and maturation of host DCs using antigen-carrying materials, without the need for isolation of DCs from patients, are required. In this study, we demonstrate the synthesis of extra-large pore mesoporous silica nanoparticles (XL-MSNs) and their use as a prophylactic cancer vaccine through the delivery of cancer antigen and danger signal to host DCs in the draining lymph nodes. Extra-large pores of approximately 25 nm and additional surface modification of XL-MSNs resulted in significantly higher loading of antigen protein and toll-like receptor 9 (TLR9) agonist compared with conventional small-pore MSNs. In vitro study showed the enhanced activation and antigen presentation of DCs and increased secretion of proinflammatory cytokines. In vivo study demonstrated efficient targeting of XL-MSNs co-delivering antigen and TLR9 agonist to draining lymph nodes, induction of antigen-specific cytotoxic T lymphocytes (CTLs), and suppression of tumor growth after vaccination. Furthermore, significant prevention of tumor growth after tumor rechallenge of the vaccinated tumor-free mice resulted, which was supported by a high level of memory T cells. These findings suggest that mesoporous silica nanoparticles with extra-large pores can be used as an attractive platform for cancer vaccines.

Simultaneous adsorption of silver nanoparticles and silver ions on large pore mesoporous silica

Large pore mesoporous silica was synthesized using citric acid as template and modified with mercaptopropyl trimethoxysilane. The MP-Silica exhibited a surface area of 474 m2 g−1 with an average pore diameter of 11 nm (pore diameter ranging from 2 to 30 nm). The material was used in the adsorption of silver ions, AgNPs and simultaneous adsorption of these silver species was also observed. The adsorption of silver ions occurred rapidly and followed a pseudo-second order kinetic model. The adsorption equilibrium of silver ions could be described with a Langmuir isotherm and the maximum adsorption capacity was found to be 114.9 mg g−1. In the mixture of AgNPs and silver ions, the adsorption of AgNPs followed a pseudo-second order kinetic model and took place more slowly compared to silver ions due to their larger size. The MP-Silica exhibited a maximum adsorption capacity of 91.9 mg AgNPs g−1 in the mixture. The adsorption of silver species on MP-Silica occurred through chemisorption via the coordination of these species with thiol groups on the surface. The removal of silver species from wastewater samples and consumer products by MP-Silica was demonstrated.

Carbon dioxide adsorption properties and adsorption/desorption kinetics of amine-functionalized KIT-6

An amine-functionalized adsorbent was prepared by loading pentaethylenehexamine (PEHA) into the pores of KIT-6 mesoporous silica. Nitrogen adsorption/desorption, thermogravimetric analysis, and X-ray powder diffraction were employed to analyze the structural properties of the prepared adsorbents. The results reveal that the pore size, pore volume, and surface area of the adsorbents decrease after PEHA loading in KIT-6, while the basic KIT-6 pore structure remains unchanged. The CO2 adsorption performance of amine-functionalized KIT-6 was studied by isothermal CO2 adsorption, adsorption/desorption cycle regeneration testing, and multiple cycle tests. The amount of CO2 absorbed increased with increasing temperature in the temperature range of 303–343 K, achieving a maximum adsorption capacity of 3.2 mmol/g-adsorbent at 343 K. For temperatures greater than 343 K, the adsorption capacity decreased with increasing temperature. The amount of CO2 adsorbed remained nearly constant after 10 adsorption/desorption cycles. The CO2 adsorption/desorption kinetics of the PEHA-impregnated KIT-6 were investigated using three kinetics models. The results indicate that the CO2 adsorption process by the amine-functionalized adsorbent is dominated by intra-particle diffusion, and the adsorption rate is restricted by the intra-particle diffusion process. In addition, high CO2 partial pressure facilitates the adsorption of CO2. The CO2 adsorption breakthrough curves obtained by the deactivation model were in good agreement with the results of this study. The adsorbents were regenerated by vacuum and temperature swing adsorption regeneration. The results indicate that increasing the desorption temperature is an effective means of reducing the regeneration time. The absolute value of the activation energy obtained from the Arrhenius equation for CO2 desorption was 81.992 kJ·mol−1, which was greater than that obtained for adsorption.

Lipid Pore-Filled Silica Thin-Film Membranes for Biomimetic Recovery of Dilute Carbohydrates.

Selectively permeable biological membranes containing lipophilic barriers inspire the design of biomimetic carrier-mediated membranes for aqueous solute separation. The recovery of glucose, which can reversibly bind to boronic acid (BA) carriers, is examined in lipid pore-filled silica thin-film composite membranes with accessible mesopores. The successful incorporation of lipids (1,2-dipalmitoyl-sn-glycero-3-phosphocholine, DPPC) and BA carriers (4-((N-Boc-amino)methyl)phenylboronic acid, BAMP-BA) in the pores of mesoporous silica (∼10 nm pore diameter) through evaporation deposition is verified by confocal microscopy and differential scanning calorimetry. In the absence of BA carriers, lipids confined inside the pores of silica thin films (∼200 nm thick) provide a factor of 14 increase in diffusive transport resistance to glucose, relative to traditional supported lipid bilayers formed by vesicle fusion on the porous surface. The addition of lipid-immobilized BAMP-BA (59 mol % in DPPC) facilitates the transport of glucose through the membrane; glucose flux increases from 45 × 10-8 to 225 × 10-8 mol/m2/s in the presence of BAMP-BA. Furthermore, the transport can be improved by environmental factors including pH gradient (to control the binding and release of glucose) and temperature (to adjust lipid bilayer fluidity). The successful development of biomimetic nanocomposite membranes demonstrated here is an important step toward the efficient dilute aqueous solute upgrading or separations, such as the processing of carbohydrates from lignocellulose hydrolysates, using engineered carrier/catalyst/support systems.

Metal-Ion Distribution and Oxygen Vacancies That Determine the Activity of Magnetically Recoverable Catalysts in Methanol Synthesis

Here, we report on the development of novel Zn-, Zn-Cr-, and Zn-Cu-containing catalysts using magnetic silica (Fe3O4-SiO2) as the support. Transmission electron microscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy (XPS) showed that the iron oxide nanoparticles are located in mesoporous silica pores and the magnetite (spinel) structure remains virtually unchanged despite the incorporation of Zn and Cr. According to XPS data, the Zn and Cr species are intermixed within the magnetite structure. In the case of the Zn-Cu-containing catalysts, a separate Cu2O phase was also observed along with the spinel structure. The catalytic activity of these catalysts was tested in methanol synthesis from syngas (CO + H2). The catalytic experiments showed an improved catalytic performance of Zn- and Zn-Cr-containing magnetic silicas compared to that of the ZnO-SiO2 catalyst. The best catalytic activity was obtained for the Zn-Cr-containing magnetic catalyst prepared with 1 wt % Zn and Cr each. X-ray absorption spectroscopy demonstrated the presence of oxygen vacancies near Fe and Zn in Zn-containing, and even more in Zn-Cr-containing, magnetic silica (including oxygen vacancies near Cr ions), revealing a correlation between the catalytic properties and oxygen vacancies. The easy magnetic recovery, robust synthetic procedure, and high catalytic activity make these catalysts promising for practical applications.

Extra-Large Pore Mesoporous Silica Nanoparticles for Directing in Vivo M2 Macrophage Polarization by Delivering IL-4.

Over the past decade, mesoporous silica nanoparticles (MSNs) smaller than 200 nm with a high colloidal stability have been extensively studied for systemic drug delivery. Although small molecule delivery via MSNs has been successful, the encapsulation of large therapeutic biomolecules, such as proteins or DNA, is limited due to small pore size of the conventional MSNs obtained by soft-templating. Here, we report the synthesis of mesoporous silica nanoparticles with extra-large pores (XL-MSNs) and their application to in vivo cytokine delivery for macrophage polarization. Uniform, size-controllable XL-MSNs with 30 nm extra-large pores were synthesized using organic additives and inorganic seed nanoparticles. XL-MSNs showed significantly higher loadings for the model proteins with different molecular weights compared to conventional small pore MSNs. XL-MSNs were used to deliver IL-4, which is an M2-polarizing cytokine and very quickly degraded in vivo, to macrophages and polarize them to anti-inflammatory M2 macrophages in vivo. XL-MSNs induced a low level of reactive oxygen species (ROS) production and no pro-inflammatory cytokines in bone marrow-derived macrophages (BMDMs) and in mice injected intravenously with XL-MSNs. We found that the injected XL-MSNs were targeted to phagocytic myeloid cells, such as neutrophils, monocytes, macrophages, and dendritic cells. Finally, we demonstrated that the injection of IL-4-loaded XL-MSNs successfully triggered M2 macrophage polarization in vivo, suggesting the clinical potential of XL-MSNs for modulating immune systems via targeted delivery of various cytokines.

Iron oxide inside SBA-15 modified with amino groups as reusable adsorbent for highly efficient removal of glyphosate from water

Iron oxide clusters were incorporated into amino-functionalized SBA-15 in order to obtain a magnetically recoverable adsorbent. The physical-chemical properties of the material were characterized by FE-SEM, STEM, XRD, TGA, XPS, FT-IR and acid-base titration analysis.Iron oxide nanoparticles were uniformly dispersed into the pore of mesoporous silica and that the adsorbent is characterized high specific surface area (177m2/g) and accessible porosity.The sorbent was successfully tested for the removal of glyphosate in real water matrices. Despite the significant content of inorganic ions, a quantitative removal of the contaminant was found. The complete regeneration of the sorbent after the adsorption process through diluted NaOH solution was also proved.

Benzene, Toluene, m-Xylene Adsorption on Silica-Based Adsorbents

It was proposed that incorporation of nitrogen groups on mesoporous silica pores would enhance its surface polarity and improve adsorption of gaseous BTX (benzene, toluene, and m-xylene). Among the popular list of mesoporous silica adsorbents, KIT-6 and SBA-15 were selected as a result of their superior textural properties, as well as because they are being widely reported in literature. After preliminary screening using toluene test, KIT-6 was chosen to have better affinity and therefore selected for Aptes (3-aminopropyl triethoxysilane) surface modification. Aptes modification was performed through the grafting method utilizing factorial design of experimental techniques to identify the effective process variable covering the parameters: Aptes concentration, reaction temperature, and reaction duration. The results of a statistical design of experiments using Minitab-15 showed that Aptes concentration was the only significant factor which affects the silica adsorbent BET surface area. Benzene adsorption ...

Raman Spectroscopy of Pharmaceutical Cocrystals in Nanosized Pores of Mesoporous Silica.

The Raman spectroscopy of pharmaceutical cocrystals based on caffeine and oxalic acid in nanosized pores of mesoporous silica has been demonstrated at various molar amounts. The Raman peak shifts of caffeine molecules express the existence of pharmaceutical cocrystals in mesoporous silica. The molar amount dependence of the peak shifts describes that caffeine and oxalic acid cocrystallized on the surface of the nanosized pores and piled up layer by layer. This is the first report that shows the Raman spectroscopy is a powerful tool to observe the synthesis of pharmaceutical cocrystals incorporated in the nanosized pores of mesoporous silica. The results indicate a way to control the size of cocrystals on a nanometer scale, which will provide higher bioavailability of pharmaceuticals.