Mesoporous Silica SBA-15 Research Articles

Probing the Morphology and Mobility of Amines in Porous Silica CO2 Sorbents by 1H T1–T2 Relaxation Correlation NMR

Molecular and oligomeric amines supported in porous oxide supports are a promising class of CO2 sorbent materials studied for CO2 removal from diverse streams such as flue gas and ambient air. Among the various amines investigated, low molecular weight, hyperbranched poly(ethyleneimine) (PEI), and tetraethylenepentamine (TEPA) are among the most extensively studied. While macroscopic structure–performance relationships relating the support structure, amine loading, and other factors affecting CO2 sorption capacities and kinetics have been developed, structural and dynamic information about the organic amine phase in the porous support is less plentiful. The structure and mobility of amines impregnated in the pores of porous supports directly impact gas sorption, as the accessibility of amine sites in the pores directly relates to amine distribution in the pores and overall pore filling as well as the dynamics of the amine chains. Here, we prepare a family of mesoporous silica SBA-15 materials containing varying loadings of oligomeric (PEI) and molecular (TEPA) amines. 1H T1–T2 relaxation correlation solid-state NMR experiments are used to characterize the structural and dynamic properties of the confined amines. Both TEPA and PEI are shown to form multiple different domains in the pores, each with distinguishable dynamic properties. TEPA and PEI form more rigid layers around the silica support walls at lower organic loading fractions, characterized by lower mobilities, followed by the formation of more mobile domains less engaged in pore wall interactions at higher loadings. TEPA shows faster mobilities than PEI because of its lower molecular weight. TEPA also appears to more easily transfer between domains within the pores, leading to generally faster CO2 uptake rates with higher sorption capacities, while PEI located closer to the pore walls remained much less mobile and is thus less engaged in CO2 capture.

Glassy and Rubbery Epoxy Composites with Mesoporous Silica

The reinforcing efficiency of SBA-15-type mesoporous silica, when used as additive in epoxy polymers, was evaluated in this study. The effects of silica loading and its physicochemical characteristics on the thermal, mechanical, and viscoelastic properties of glassy and rubbery epoxy mesocomposites were examined using SBA-15 mesoporous silicas with varying porosities (surface area, pore size, and volume), particle sizes, morphologies, and organo-functionalization. Three types of SBA-15 were used: SBA-15 (10) with 10 nm pore diameters and long particles, SBA-15 (5) with 5 nm pore diameters and short particles, and SBA-15 (sc) with 10 nm pore diameters and short particles (“sc” for short channel). SBA-15 (10) was modified with propyl-, epoxy-, and amino-groups to study the effect of functionalization. The glassy or rubbery epoxy polymers and mesocomposites were produced by the crosslinking of a diglycidyl ether of bisphenol A (DEGBA) epoxy resin with isophorone diamine (IPD) or Jeffaminje D-2000, respectively. Mesoporous silica was uniformly dispersed inside the polymer matrices; however, the opacity levels between the rubbery and glassy samples were different, with completely transparent rubbery composites being prepared with as high as a 9 wt. % addition of SBA-15. The mechanical and thermal performance properties of the mesocomposites were dependent on both the type of the curing agent, which affected the cross-linking density of the pristine polymer matrix, and the characteristics of the mesoporous silica variants, being, in general, improved by the addition of up to 6 wt. % silica for the glassy polymers and up to 9 wt. % for the rubbery polymers.

Effect of CeO2/spherical silica and halloysite nanotubes engineered for targeted drug delivery system to treat breast cancer cells

Cerium oxide nanoparticles (CeO2 NPs) and flavonoid curcumin that has been widely studied for treating diseases involving high reactive oxygen species (ROS). In nanotherapeutics, the particle size, shape, metal oxide dispersity and surface properties of nanocarriers are vital for drug delivery and therapeutic efficiency. Here, cisplatin release behavior on cerium impregnated two different shaped nanocarriers, CeO2/monodispersed spherical silica (Sil) and CeO2/halloysite (Hal) nanotube was studied for potential anti-cancer therapies. For comparison, CeO2 impregnated mesoporous silica MCM-41, SBA-16, Hydroxyapatite and clay were prepared. Subsequently, the nanocomposites were coated with curcumin (25% wt/wt), and cisplatin (Cp) functionalization (5% wt/wt). 5wt%CeO2/Hal/Cp and 5wt%CeO2/Sil/Cp samples were pegylated using lyophilization technique. Physico-chemical analyses revealed the nanosized distribution of CeO2 and functionalization of cisplatin and curcumin. Cp release was studied using automated Franz cell and dialysis membrane techniques. The different structured nanocarriers delivering mechanism was studied by determining the drug kinetic release using four different kinetic models (first order, second order, Higuchi and Korsmeyer-Peppas). In vitro cytotoxicity assay of nano formulations along with free cisplatin and curcumin (Cur) were tested against the breast cancer cell line (MCF-7) for multiple timepoints by MTT assay. The results reveled the efficacy of 5wt%CeO2/Sil/Cp/Cur nanoparticles in delivering cisplatin. On the other hand, 5wt%CeO2/Hal/Cur nanoparticles enhanced the uptake of curcumin in comparison to free curcumin. Overall, pegylated CeO2/Silica nano formulation demonstrated an effective carrier to cisplatin for potential treatment of breast cancer.

Bifunctional acid–base strontium–titanium mixed oxides supported on SBA-15 for selective synthesis of renewable branched bio-jet fuel precursor

Herein, furfural, which is a lignocellulose-derived platform chemical, was converted into a bio-jet fuel precursor via aldol condensation with 2-butanone using strontium (Sr) and titanium (Ti) mixed oxides (STO) loaded onto mesoporous silica SBA-15 (SBA15). A series of acidobasic STO/SBA15 catalysts were prepared via incipient wetness impregnation by systematically varying the mixed oxide loading and Sr:Ti molar ratio of the catalysts. The STO/SBA15 catalysts exhibited a well-mesostructured order, high dispersion of metal oxides, and good textural properties. The acidic and basic properties of the catalysts were facilely controlled by varying the metal oxide composition and amount of STO loaded onto the SBA15 support. The aldol condensation was carried out batchwise under a pressurized nitrogen atmosphere. The products formed in the reaction comprised 9–18 carbon atoms. The yield and selectivity of α,β-unsaturated C9 ketone with branched molecular structure (C9B) were strongly influenced by the acid–base properties of the catalyst and the reaction conditions. 20STO(2:1)/SBA15 was the suitable catalyst, realizing > 99% furfural conversion and 78.3% C9B yield under the following optimized conditions: 4 wt% catalyst loading, 1:5 furfural:2-butanone molar ratio, 180 °C reaction temperature, and 5 h reaction time.

Engineering of Silica Mesoporous Materials for CO2 Adsorption.

Adsorption methods for CO2 capture are characterized by high selectivity and low energy consumption. Therefore, the engineering of solid supports for efficient CO2 adsorption attracts research attention. Modification of mesoporous silica materials with tailor-made organic molecules can greatly improve silica's performance in CO2 capture and separation. In that context, a new derivative of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, possessing an electron-rich condensed aromatic structure and also known for its anti-oxidative properties, was synthesized and applied as a modifying agent of 2D SBA-15, 3D SBA-16, and KIT-6 silicates. The physicochemical properties of the initial and modified materials were studied using nitrogen physisorption and temperature-gravimetric analysis. The adsorption capacity of CO2 was measured in a dynamic CO2 adsorption regime. The three modified materials displayed a higher capacity for CO2 adsorption than the initial ones. Among the studied sorbents, the modified mesoporous SBA-15 silica showed the highest adsorption capacity for CO2 (3.9 mmol/g). In the presence of 1 vol.% water vapor, the adsorption capacities of the modified materials were enhanced. Total CO2 desorption from the modified materials was achieved at 80 °C. The obtained silica materials displayed stable performance in five CO2 adsorption/desorption cycles. The experimental data can be appropriately described by the Yoon-Nelson kinetic model.

Effect of the Structure of Highly Porous Silica Extracted from Sugarcane Bagasse Fly Ash on Aflatoxin B1 Adsorption.

Sugarcane bagasse fly ash is industrial waste produced by incinerating biomass to generate power and steam. The fly ash contains SiO2 and Al2O3, which can be used to prepare aluminosilicate. This latter material exhibits high potential as an adsorbent in various applications, including the livestock industry where issues related to contamination of aflatoxins in animal feeds need to be addressed; addition of adsorbents can help decrease the concentration of aflatoxins during feed digestion. In this study, the effect of the structure of silica prepared from sugarcane bagasse fly ash on physicochemical properties and aflatoxin B1 (AFB1) adsorption capability compared with that of bentonite was investigated. BPS-5, Xerogel-5, MCM-41, and SBA-15 mesoporous silica supports were synthesized using sodium silicate hydrate (Na2SiO3) from sugarcane bagasse fly ash as a silica source. BPS-5, Xerogel-5, MCM-41, and SBA-15 exhibited amorphous structures, while sodium silicate possessed a crystalline structure. BPS-5 possessed larger pore size, pore volume, and pore size distribution with a bimodal mesoporous structure, while Xerogel-5 exhibited lower pore size and pore size distribution with a unimodal mesoporous structure. BPS-5 with a negatively charged surface exhibited the highest AFB1 adsorption capability compared with other porous silica. However, the AFB1 adsorption capability of bentonite was superior to those of all porous silica. Sufficient pore diameter with high total pore volume as well as high intensity of acid sites and negative charge on the surface of the adsorbent is required to increase AFB1 adsorption in the in vitro gastrointestinal tract of animals.

Synergistic activation of persulfate by FeS@SBA-15 for imidacloprid degradation: Efficiencies, activation mechanism and degradation pathways.

In this work, FeS supported SBA-15 mesoporous silica catalyst (FeS@SBA-15) was synthesized successfully, characterized and first applied to persulfate (PS) activation for the degradation of imidacloprid in wastewater. The as-prepared 3.5-FeS@SBA-15 presented an impressive imidacloprid removal efficiency of 93.1% and reaction stoichiometric efficiency (RSE) of 1.82% after 5 min, ascribed to the synergetic effects of improved FeS dispersion and abundant surface sites by SBA-15. Electron paramagnetic resonance spectra and quenching experiments proved that both SO4·- and ·OH were produced in FeS@SBA-15/PS system, and SO4·- played a dominant role in the degradation process. The S2- can accelerate the cycling of Fe(III)/Fe(II) during activation and increase the steady-state concentration of Fe(II). More importantly, the constructed heterogeneous system exhibited an efficient and stable catalytic activity over a wide range of pH (3.0-9.0), temperature (283K-313K), inorganic ion (NO3-) and humic acid (1-20 mg/L). Moreover, the density functional theory calculations were conducted to predict the potential reaction sites of imidacloprid. Based on eighteen identified intermediates, four main degradation pathways were proposed: hydroxylation, dechlorination, hydrolysis, and the ring cleavage of the imidazolidine. ECOSAR analysis indicated hydroxylation and dechlorination played a key role in the detoxification of the formed compounds. These findings would provide new insights into the application of FeS@SBA-15 catalyst in wastewater treatment and the removal mechanism of imidacloprid from wastewater.

Polypropylene Nanocomposites Attained by In Situ Polymerization Using SBA-15 Particles as Support for Metallocene Catalysts: Effect of Molecular Weight and Tacticity on Crystalline Details, Phase Transitions and Rheological Behavior.

In this study, nanocomposites based on polypropylene are synthesized by the in situ polymerization of propene in the presence of mesoporous SBA-15 silica, which acts as a carrier of the catalytic system (zirconocene as catalyst and methylaluminoxane as cocatalyst). The protocol for the immobilization and attainment of hybrid SBA-15 particles involves a pre-stage of contact between the catalyst with cocatalyst before their final functionalization. Two zirconocene catalysts are tested in order to attain materials with different microstructural characteristics, molar masses and regioregularities of chains. Some polypropylene chains are able to be accommodated within the silica mesostructure of these composites. Thus, an endothermic event of small intensity appears during heating calorimetric experiments at approximately 105 °C. The existence of these polypropylene crystals, confined within the nanometric channels of silica, is corroborated by SAXS measurements obtained via the change in the intensity and position of the first-order diffraction of SBA-15. The incorporation of silica also has a very significant effect on the rheological response of the resultant materials, leading to important variations in various magnitudes, such as the shear storage modulus, viscosity and δ angle, when a comparison is established with the corresponding neat iPP matrices. Rheological percolation is reached, thus demonstrating the role of SBA-15 particles as filler, in addition to the supporting role that they exert during the polymerizations.

Charge polarization-modulated Pd-Ni(OH)2 hybrids in mesoporous silica SBA-15 for efficient low-temperature CO2 hydrogenation to formate

Converting CO2 to formic acid/formate is a considerably significant pathway for future energy storage and utilization; however, it is critical to tailor high-performance catalysts for realizing the process. Herein, highly dispersed Pd-Ni(OH)2 hybrids were immobilized in ordered mesoporous silica SBA-15 via a facile impregnation method. The prepared SBA-15-supported Pd-Ni(OH)2 catalyst exhibited extraordinarily high catalytic performance and stability during the hydrogenation of CO2 toward formate. Significantly, Pd5Ni5/SBA-15, an optimized Pd5Ni5/SBA-15 catalyst afforded a superior formate generation rate of 150.5 molformate moltotalPd-1h−1 at a low temperature (40 °C), which was about 3-fold higher than that of monometallic Pd counterpart. Such a catalytic activity outperforms most of the previously reported catalysts because of its charge polarization action and synergy between bimetallic components as well as ultrasmall and well-dispersed metal species with increased accessible active sites. The relevant experimental observations were well supported by density functional theory (DFT) calculations. In addition, the catalytic activity of SBA-15-supported metal catalysts remained unchanged even after the 5th cycle, demonstrating excellent cycling durability due to the confinement effect of mesoporous silica. The facile synthesis strategy and excellent catalytic performance hold great potential applications of the prepared catalysts in CO2 hydrogenation to formate.

New Nanostructured Materials Based on Mesoporous Silica Loaded with Ru(II)/Ru(III) Complexes with Anticancer and Antimicrobial Properties.

A new series of nanostructured materials was obtained by functionalization of SBA-15 mesoporous silica with Ru(II) and Ru(III) complexes bearing Schiff base ligands derived from salicylaldehyde and various amines (1,2-diaminocyclohexane, 1,2-phenylenediamine, ethylenediamine, 1,3-diamino-2-propanol, N,N-dimethylethylenediamine, 2-aminomethyl-pyridine, and 2-(2-aminoethyl)-pyridine). The incorporation of ruthenium complexes into the porous structure of SBA-15 and the structural, morphological, and textural features of the resulting nanostructured materials were investigated by FTIR, XPS, TG/DTA, zeta potential, SEM, and N2 physisorption. The ruthenium complex-loaded SBA-15 silica samples were tested against A549 lung tumor cells and MRC-5 normal lung fibroblasts. A dose-dependent effect was observed, with the highest antitumoral efficiency being recorded for the material containing [Ru(Salen)(PPh3)Cl] (50%/90% decrease in the A549 cells' viability at a concentration of 70 μg/mL/200 μg/mL after 24 h incubation). The other hybrid materials have also shown good cytotoxicity against cancer cells, depending on the ligand included in the ruthenium complex. The antibacterial assay revealed an inhibitory effect for all samples, the most active being those containing [Ru(Salen)(PPh3)Cl], [Ru(Saldiam)(PPh3)Cl], and [Ru(Salaepy)(PPh3)Cl], especially against Staphylococcus aureus and Enterococcus faecalis Gram-positive strains. In conclusion, these nanostructured hybrid materials could represent valuable tools for the development of multi-pharmacologically active compounds with antiproliferative, antibacterial, and antibiofilm activity.

One-pot synthesis of iron oxide - Gamma irradiated chitosan modified SBA-15 mesoporous silica for effective methylene blue dye removal

The development of adsorption technology and the processing of radiation have both been influenced by chitosan adsorbent (γ-chitosan), a raw material with unique features. The goal of the current work was to improve the synthesis of Fe-SBA-15 utilizing chitosan that has undergone gamma radiation (Fe-γ–CS–SBA-15) in order to investigate the removal of methylene blue dye in a single hydrothermal procedure. High-resolution transmission electron microscopy (HRTEM), High angle annular dark field scanning transmission electron microscopy (HAADF-STEM), small- and wide-angle X-ray powder diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR) and Energydispersive X-ray spectroscopy (EDS) were used to characterize γ–CS–SBA-15 that had been exposed to Fe. By using N2-physisorption (BET, BJH), the structure of Fe-γ–CS–SBA-15 was investigated. The study parameters also included the effect of solution pH, adsorbent dose and contact time on the methylene blue adsorption. The elimination efficiency of the methylene blue dye was compiled using a UV-VIS spectrophotometer. The results of the characterization show that the Fe-γ–CS–SBA-15 has a substantial pore volume of 504 m2 g−1 and a surface area of 0.88 cm3 g−1. Furthermore, the maximum adsorption capacity (Qmax) of the methylene blue is 176.70 mg/g. The γ-CS can make SBA-15 operate better. It proves that the distribution of Fe and chitosan (the C and N components) in SBA-15 channels is uniform.

Investigation of Dynamic Behavior of Confined Ionic Liquid [BMIM]+[TCM]- in Silica Material SBA-15 Using NMR.

The molecular dynamics of 1-butyl-3-methyl imidazolium tricyanomethanide ionic liquid [BMIM]+[TCM]- confined in SBA-15 mesoporous silica were examined using 1H NMR spin-lattice (T1) relaxation and diffusion measurements. An extensive temperature range (100 K-400 K) was considered in order to study both the liquid and glassy states. The hydrogen dynamics in the two states and the self-diffusion coefficients of the cation [BMIM]+ above the glass transition temperature were extracted from the experimental data. The results were then compared to the corresponding bulk substance. The effects of confinement on the dynamic properties of the ionic liquid clearly manifest themselves in both temperature regimes. In the high-temperature liquid state, the mobility of the confined cations reduces significantly compared to the bulk; interestingly, confinement drives the ionic liquid to the glassy state at a higher temperature Tg than the bulk ionic liquid, whereas an unusual T1 temperature dependence is observed in the high-temperature regime, assigned to the interaction of the ionic liquid with the silica-OH species.

Repurposing Anthelmintics: Rafoxanide- and Copper-Functionalized SBA-15 Carriers against Methicillin-Resistant Staphylococcus aureus.

The development of materials that can more efficiently administer antimicrobial agents in a controlled manner is urgently needed due to the rise in microbial resistance to traditional antibiotics. While new classes of antibiotics are developed and put into widespread usage, existing, inexpensive compounds can be repurposed to fight bacterial infections. Here, we present the synthesis of amine-functionalized SBA-15 mesoporous silica nanomaterials with physisorbed rafoxanide (RFX), a commonly used salicylanilide anthelmintic, and anchored Cu(II) ions that exhibit enhanced antimicrobial efficacy against the pathogenic bacterium Staphylococcus aureus. The synthesized nanomaterials are structurally characterized by a combination of physicochemical, thermal, and optical methods. Additionally, release studies are carried out in vitro to determine the effects of pH and the synthetic sequence used to produce the materials on Cu(II) ion release. Our results indicate that SBA-15 mesoporous silica nanocarriers loaded with Cu(II) and RFX exhibit 10 times as much bactericidal action against wild-type S. aureus as the nanocarrier loaded with only RFX. Furthermore, the synthetic sequence used to produce the nanomaterials could significantly affect (enhance) their bactericidal efficacy.

Nitrogen Adsorption and Characteristics of Iron, Cobalt, and Nickel Oxides Impregnated on SBA-15 Mesoporous Silica

Hexagonal SBA-15 mesoporous material was used as a catalytic template for impregnation, with the transition metals Fe, Co, and Ni as catalysts for chemical transformation. Nitrogen adsorption/desorption isotherms, scanning electron microscopy, and transmission electron microscopy were conducted to better understand the physicochemical properties of the metal oxide-impregnated SBA-15. The specific surface area of the original SBA-15 was approximately 680 m2/g, and the abundances of the catalysts impregnated ranged from 2 to 8%, corresponding to specific surface areas of 560-470 m2/g for Fe-SBA-15, 440-340 m2/g for Ni-SBA-15, and 410-340 m2/g for Co-SBA-15. The increase in impregnated metal loadings filled the pores and collapsed the silica walls during the metal oxides impregnation on SBA-15 and calcination procedures, resulting in a decrease in the specific surface area and pore volume of the templates. The results showed that the order of nitrogen adsorbed was SBA-15 > Fe-SBA-15 > Ni-SBA-15 > Co-SBA-15 when the metal loading was 5%. In addition, the metal oxides on SBA-15 increased the wall thickness compared with raw SBA-15. Based on the XRD spectrum analysis, Fe2O3, Co3O4, and NiO were the stable crystals on the Fe-SBA-15, Co-SBA-15, and Ni-SBA-15, respectively. The sequence of the average grain size of metal oxides on SBA-15 was Co-SBA-15 > Fe-SBA-15 > Ni-SBA-15, according to XRD spectra and Scherrer's equation. Isopropanol could be decomposed by metal oxide-impregnated SBA-15 to form carbon filament materials. Therefore, these materials have the potential to be employed for pollutant removal, catalytic reactions for organic solvent and bio-oil/biomass reforming, and recycling waste into high-value materials.

Cobalt phthalocyanine conjugated SBA-15 mesoporous silica via the Ugi four-component reaction: A potential heterogeneous catalytic nanocomposite for CO2 fixation reaction

Owing to the porosity, high hydrothermal and mechanical stability of SBA-15, this type of silica mesoporous has attracted significant attention from many researchers for catalytic systems design. Accordingly, SBA-15 was utilized in this work as eco-friendly support to synthesize an effective heterogeneous catalytic nanocomposite based on the conjugation or immobilization of metalophthalocyanines (MPcs). For this purpose, initially, SBA-15 was modified by (3-aminopropyl)triethoxysilane (APTES) as an amination agent to produce SBA-15-NH2 and then participated in a straightforward one-pot Ugi four-component reaction (Ugi-4CR) of cyclohexyl isocyanide, benzaldehyde, and cobalt (II) phthalocyanine tetracarboxylic acid (Co-PcTCA) as an acid component. Afterward, the catalytic activity of the cobalt (II) phthalocyanine immobilized via SBA-15-NH2 (Co-PcTCA/SBA-15-N) was examined in the CO2 fixation reaction for the preparation of cyclic carbonates in water as a green solvent. Interestingly, catalytic experiments revealed that SBA-15 as a porose support could considerably ameliorate the catalytical properties of the Co-PcTCA regarding the CO2 fixation reaction via high CO2 adsorbent capacity in the shortest reaction time.

Transition Metal Single Atoms Constructed by Using Inherent Confined Space.

Single-atom catalysts (SACs) show expressively enhanced activity toward diverse reactions due to maximized atomic utilization of metal sites, while their facile, universal, and massive preparation remains a pronounced challenge. Here we report a facile strategy for the preparation of SACs by use of the inherent confined space between the template and silica walls in template-occupied mesoporous silica SBA-15 (TOS). Different transition metal precursors can be introduced into the confined space readily by grinding, and during succeeding calcination single atoms are constructed in the form of M-O-Si (M = Cu, Co, Ni, and Zn). In addition to the generality, the present strategy is easy to scale up and can allow the synthesis of 10 g of SACs in one pot through ball milling. The Cu SAC has been applied for CO2 cycloaddition of epichlorohydrin, and the activity is obviously higher than the counterpart prepared without confined space and various reported Cu-containing catalysts.

Dual-functional pyrene implemented mesoporous silicon material used for the detection and adsorption of metal ions

A fluorescent active organic–inorganic hybrid material PyN-SBA-15 was synthesized by implementing pyrene derivatives into mesoporous SBA-15 silica. PyN-SBA-15 had detection and removal functionalities toward Al3+, Cu2+, and Hg2+. On the one hand, PyN-SBA-15 was used as a fluorescence sensor and displayed high sensitivity toward Al3+, Cu2+, and Hg2+ cations (limit of detection: 8.0 × 10−7, 1.1 × 10−7, and 2.9 × 10−6 mol·L–1, respectively) among various analytes with “turn-off” response. On the other hand, the adsorption studies for these toxic analytes (Cu2+, Hg2+, and Al3+) showed that the ion removal capacity could reach up to 45, 581, and 85 mg·g−1, respectively. Moreover, the Langmuir isotherm models were better fitted with the adsorption data, indicating that the adsorption was mono-layer adsorption. Kinetic analysis revealed that the adsorption process was well described by the pseudo-second-order kinetic model for Cu2+ and Hg2+ and pseudo-first-order kinetic model for Al3+. The prepared silica material could be reused in four recycles without significantly decreasing its adsorption capacity. Therefore, the PyN-SBA-15 material can serve as a promising candidate for the simultaneous rapid detection and efficient adsorption of metal ions.

Design and Evaluation of Pegylated Large 3D Pore Ferrisilicate as a Potential Insulin Protein Therapy to Treat Diabetic Mellitus.

An iron-based SBA-16 mesoporous silica (ferrisilicate) with a large surface area and three-dimensional (3D) pores is explored as a potential insulin delivery vehicle with improved encapsulation and loading efficiency. Fe was incorporated into a framework of ferrisilicate using the isomorphous substitution technique for direct synthesis. Fe3+ species were identified using diffuse reflectance spectroscopy. The large surface area (804 m2/g), cubic pores (3.2 nm) and insulin loading were characterized using XRD, BET surface area, FTIR and TEM analyses. For pH sensitivity, the ferrisilicate was wrapped with polyethylene glycol (MW = 400 Daltons) (PEG). For comparison, Fe (10 wt%) was impregnated on a Korea Advanced Institute of Science and Technology Number 6 (KIT-6) sieve and Mesocellular Silica Foam (MSU-F). Insulin loading was optimized, and its release mechanism was studied using the dialysis membrane technique (MWCO = 14,000 Da) at physiological pH = 7.4, 6.8 and 1.2. The kinetics of the drug's release was studied using different structured/insulin nanoformulations, including Santa Barbara Amorphous materials (SBA-15, SBA-16), MSU-F, ultra-large-pore FDU-12 (ULPFDU-12) and ferrisilicates. A different insulin adsorption times (0.08-1 h), insulin/ferrisilicate ratios (0.125-1.0) and drug release rates at different pH were examined using the Korsmeyer-Peppas model. The rate of drug release and the diffusion mechanisms were obtained based on the release constant (k) and release exponent (n). The cytotoxicity of the nanoformulation was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay using human foreskin fibroblast (HFF-1) cells. A low cytotoxicity was observed for this nanoformulation starting at the highest concentrations used, namely, 400 and 800 μg. The hypoglycemic activity of insulin/ferrisilicate/PEG on acute administration in Wistar rats was studied using doses of 2, 5 and 10 mg/kg body weight. The developed facile ferrisilicate/PEG nanoformulation showed a high insulin encapsulation and loading capacity with pH-sensitive insulin release for potential delivery through the oral route.

ENHANCEMENT OF CURCUMIN SOLUBILITY AND DISSOLUTION BY ADSORPTION IN MESOPOROUS SBA-15

Objective: Curcumin belongs to BCS class IV, which has low solubility, around 7.8 µg/ml and its results of low bioavailability. The study aimed to enhance solubility and dissolution rate of curcumin by adsorption in mesoporous silica SBA-15.
 Methods: The synthesis of SBA-15 was done by using tetraethyl orthosilicate (TEOS) as silica precursors and Pluronic P123 (EO20PO70EO20) as template of pore-forming. Impregnation of curcumin in SBA-15 was conducted by evaporation in ethanol solution with 2:1 of curcumin: SBA-15 proportion. Curcumin-SBA-15 were characterized by Nitrogen Adsorption-Desorption Isotherm, Powder X-Ray Diffraction (PXRD), Fourier Transformed Infrared (FT-IR), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM). The solubility test was performed by using an orbital shaker for 24 h in CO2-free distilled water. The dissolution rate was conducted in CO2-free distilled water using USP Type-II dissolution test apparatus.
 Results: Efficiency entrapment of curcumin-SBA-15 was 59.433%. The successful adsorption of curcumin in SBA-15 was confirmed by reducing its surface area (48.165 m2/g) and pore volume (0.073x10-1 cm3/g). The results of PXRD analysis showed that decreased in the intensity of the diffraction peak. In addition, the FTIR spectrum of curcumin-SBA-15 was similar to its intact component. The solubility and dissolution rate test of curcumin-SBA-15 enhanced 2.201 times and 3.214 times at 60 min compared to intact curcumin.
 Conclusion: It can be concluded that the adsorption of curcumin in SBA-15 increased both the solubility and dissolution rate of curcumin.

Architecture of a functionalized SBA-15 (SBA-Pr-N-BFE) chemosensor for the detection of Fe3+ ions in aqueous media

SBA-Pr-N-BFE was designed as a chemosensor starting from mesoporous silica SBA-15, (3-aminopropyl)trimethoxy silane, and 1,2-bis(2-formylphenoxy)ethane (BFE), characterized by various techniques and applied as a selective fluorescent chemosensor. Photoluminescence (PL) spectroscopy has been employed to examine the sensing prowess of the functionalized SBA-Pr-N-BFE, which could selectively detect the Fe3+ ions in H2O over various metal ions; notable quenching in the fluorescence intensity was discerned after adding Fe3+ ions in H2O. Furthermore, the fluorescence studies established the linear correlation of fluorescence intensity of SBA-Pr-N-BFE and the concentration of Fe3+ ions with a detection limit of 1.209 × 10-6 M.