Amino-functionalized Mesoporous SBA-15 Research Articles

Screening of α-glucosidase inhibitors in tea by amino-functionalized mesoporous SBA-15 immobilized α-glucosidase microreactor

NH2-SBA-15 was prepared as an enzyme loading microreactor by modifying SBA-15 with 3-aminopropyltriethoxysilane as the functionalizing reagent. After modification, α-glucosidase (α-Glu) can be easily and fast immobilized on the surface and inner wall of the two-dimensional pores of NH2-SBA-15 by electrostatic adsorption in phosphate buffered saline (PBS, pH 7.4). The quantity of immobilized α-Glu by NH2-SBA-15 under the optimum conditions was 39.93 μg mg−1 which was much higher than unmodified SBA-15 (15.92 μg mg−1), and the enzyme activity still retained 76.1% after 7 cycles. In addition, due to the restricted conformational change of the immobilized enzyme in the 2D pore structure, which had some protective effect on the enzyme, the immobilized enzyme had good acid and alkali resistance, and high temperature resistance. The results showed that the relative activity of the immobilized enzyme fluctuated less in the same pH range, and still retained more than 90% of the activity after standing at 40 °C and 60 °C for 24 h. Finally, the NH2-SBA-15-α-Glu microreactors were co-incubated with the tea extract, and the α-Glu inhibitory active components were screened by HPLC. Several chemical components were successfully screened out, verifying the feasibility of the microreactor.

Preparation of Amino-Functionalized Mesoporous SBA-15 Nanoparticles and the Improved Adsorption of Tannic Acid in Wastewater.

Ordered mesoporous Santa Barbara amorphous (SBA-15) materials have high surface areas and are widely used in adsorption, separation, filtration, and heterogeneous catalytic processes. However, SBA-15 surfaces contain hydroxyl groups that are unsuited to the adsorption of organic pollutants; thus, SBA-15 must be chemically modified to promote its adsorption activity. In this study, amino-functionalized nanoporous SBA-15 was fabricated by employing sodium silicate as a precursor. The structural characteristics of the prepared composites were examined using thermogravimetric analysis, X-ray diffraction, Fourier transform infrared spectrometry, field-emission scanning electron microscopy, transmission electron microscopy, and surface area analysis. The prepared SBA-15 had a large pore size (6.46–7.60 nm), large pore volume (1.037–1.105 cm3/g), and high surface area (546–766 m2/g). Functionalization caused a reduction in the SBA-15 pore volume and surface area, whereas amino groups that promoted an interaction between adsorbates and solids facilitated solute adsorption. The adsorption of tannic acid (TA) onto amino-modified silica composites (SBA-15 and 3-aminopropyltriethoxysilane (SBA-15/APTES) and SBA-15 and pentaethylenehexamine (SBA-15/PEHA)) was studied. Their adsorption capacities were affected by solution temperature, solution pH, agitation speed, adsorbent dosage, and initial TA concentration. The maximum adsorption capacities for SBA-15/APTES and SBA-15/PEHA were 485.18 and 413.33 mg/g, respectively, with SBA-15/APTES exhibiting ultrafast removal of TA (98.61% removal rate at 15 min). In addition, this study explored the thermodynamics, adsorption isotherms, and kinetics. A comparison of two types of amino-functionalized SBA-15 was used for the first time to adsorb TA, which providing valuable information on TA adsorption on high adsorption capacity materials in water media.

Selective uptake of La3+ ions with polyoxometalates-functionalized mesoporous SBA-15: An EXAFS study

Abstract In this work, mesoporous materials based on inorganic/organic polyoxometalate (POMs) hybrids with the ability of further incorporating heterometallic lanthanum cations were designed. On the basis of the La3+ coordination to vacant organophosphonyle derivatives of POMs previously studied, herein POMs-grafted onto an amino-functionalized mesoporous SBA-15 ({NH2}-SBA-15) with incorporated La3+ ions were synthesized by varying the amounts of the latter. LIII-edge La EXAFS spectroscopy of the resulting materials provided local structural information around LaIII ions (i.e. number, nature and distances of neighboring atoms), which are comparable to that of the LaIII complexes of POMs hybrids. This technique, in addition with 31P CP-MAS NMR spectroscopy, gave definitive clues for a selective uptake of the incorporated La3+ ions by the POMs grafted onto the {NH2}-SBA-15 supports. This study is a clear demonstration that, due to their chelate effect, POMs hybrids act as efficient ligands for La3+ even in the presence of competitive adsorption sites. Consequently, a regular distribution of the La3+ ions along the channels of the SBA-15 is thus observed in these materials due to the nanostructuration of the POMs onto the support.

Surface-functionalization of mesoporous SBA-15 silica materials for controlled release of methylprednisolone sodium hemisuccinate: Influence of functionality type and strategies of incorporation

Mesoporous SBA-15 silica materials functionalized with several organic moieties, that include different polarities and hydrophobicities, were investigated as matrices for controlled drug delivery. The functionalities were incorporated into SBA-15 using two methods: direct synthesis or co-condensation route and post-synthesis grafting. Methylprednisolone sodium hemisuccinate, a synthetic pharmaceutical compound used as anti-inflammatory and immunosuppressant, was loaded onto the pristine and functionalized mesoporous SBA-15 silica materials. The influence of the type of organic moieties as well as their incorporation method onto the inorganic silica framework has been evaluated. The results show that SBA-15 functionalized with aminopropyl trimethoxysilane groups has the largest capacity of drug adsorption, clearly higher than the provided by materials functionalized with other groups, independently of the synthesis route. Additionally, materials synthesized by the co-condensation approach show a lower degree of drug retention than the same material synthesized by grafting technique. This fact is attributed to the distinct localization of the functionality, more accessible in the case of the grafting procedure, and hence suggesting that stronger interactions among the SBA-15 functionalized surfaces and the model drug are established. To ascertain whether other organosilanes containing amino groups can provide more effective loading and controlled drug delivery, at neutral and acidic conditions (pH of 7.4 and 4.6, respectively), it was also investigated the incorporation by grafting of several amino organic moieties onto the SBA-15 silica materials. It was concluded that as the number of amino groups incorporated into SBA-15 material increased, not only the drug loading capacity was higher, but the functionalized silica material vehicles slowed down the drug delivery. Finally, it was confirmed that cell viability was largely unaffected by amino-functionalized mesoporous SBA-15 silica materials after 72 h of incubation time.

Fabrication of Fe-coordinated diamino-functionalized SBA-15 with hierarchical porosity for phosphate removal

Hierarchically macroporous–mesoporous SBA-15 phosphate adsorbent was synthesized via a dual-templating approach, followed by diamino-functionalization and Fe(III) impregnation. The resulting Fe(III)-coordinated diamino-functionalized macroporous–mesoporous adsorbent possessed well-defined and interconnecting macroporous and mesoporous networks. Its maximum adsorption was 12.7mg/g, which was 86.8% greater than that of Fe(III)-coordinated amino-functionalized mesoporous SBA-15. In the kinetic study of macroporous–mesoporous adsorbent, 92.5% of the final adsorption capacity reached in the first 1min; and the adsorption followed the pseudo-second-order equation well, suggesting the presence of chemisorption. The pH ranging from 3.0 to 6.0 favored the high phosphate adsorption of hierarchically porous adsorbent; however, the coexistence of other anions, especially F−, retarded the adsorption.

Effect of amine functionalization of SBA-15 on controlled baicalin drug release

In this paper, we present the release of baicalin from hexagonal periodic mesoporous silica SBA-15 and amino-functionalized mesoporous SBA-15 (A-SBA-15), which serve as drug delivery systems (SBA-15/baicalin and A-SBA-15/baicalin). The modified and drug loaded mesoporous materials were characterized by XRD, SEM, TEM, N2 physisorption, IR, TG and HPLC. The results demonstrated that slightly higher amount of baicalin was loaded in APS-SBA-15, and the dissolution rate of baicalin from the A-SBA-15/baicalin was much faster than from the SBA-15/baicalin. A-SBA-15/baicalin as baicalin delivery system was better than SBA-15/baicalin because the faster dissolution rate compared with SBA-15/baicalin was more conducive to drug absorption.

Oxovanadium(IV) and dioxomolybdenum(VI) salen complexes tethered onto amino-functionalized SBA-15 for the epoxidation of cyclooctene

Oxovanadium(IV) and dioxomolybdenum(VI) salen complexes were firstly tethered onto amino-functionalized mesoporous SBA-15 materials by a stepwise procedure and were screened as catalysts for the epoxidation of cyclooctene. The mesoporous structural integrity throughout the tethering procedure, the successful tethering of the organometallic complexes, the loadings of metal ions and organic ligands as well as the catalyst surface constitution and location of active organometallic species on the SBA-15 support were determined by comprehensive characterization techniques such as XRD, N 2 adsorption/desorption, FT-IR, UV–vis spectroscopy, ICP-AES, XPS and TG/DTA. Catalytic properties in the epoxidation of cyclooctene demonstrate that both tethered oxovanadium(IV) and dioxomolybdenum(VI) catalysts were more active than their respective homogeneous analogue, and the tethered oxovanadium(IV) complex showed the best activity (64.3%) with H 2O 2 as the oxidant and CH 3CN as the solvent.

Tethering of Cu(II), Co(II) and Fe(III) tetrahydro-salen and salen complexes onto amino-functionalized SBA-15: Effects of salen ligand hydrogenation on catalytic performances for aerobic epoxidation of styrene

A variety of transition metal tetrahydro-salen complexes M-[H 4]Salen (M = Cu, Co and Fe) and the corresponding metal salen complexes M-Salen were firstly tethered onto amino-functionalized mesoporous SBA-15 and screened as heterogeneous catalysts for aerobic epoxidation of styrene. The mesoporous structural integrity throughout the tethering procedure, the successful tethering of the organometallic complexes, the loadings of metal ions and organic ligands as well as the catalyst surface constitution and location of active organometallic species on the SBA-15 support were determined by comprehensive characterization techniques such as XRD, N 2 adsorption/desorption, TEM, FT-IR, UV–vis spectroscopy, ICP-AES, XPS and TG/DSC. The tethered catalyst M-[H 4]Salen-SBA (M = Cu or Co) exhibits improved reactivity than the corresponding M-Salen-SBA catalyst due to the incorporation of a modified coordination environment of the central metal cations by C N bond hydrogenation. However, Fe-[H 4]Salen-SBA shows lower reactivity as compared to Fe-Salen-SBA possibly due to the easy formation of relatively inactive dinuclear iron(III) tetrahydro-salen complexes, verified by XPS and ESR. The recycling results of these heterogeneous catalysts exemplified by Co-Salen-SBA, Co-[H 4]Salen-SBA and Fe-Salen-SBA, show good recoverability without significant loss of activity and selectivity within successive runs. Heterogeneity tests of three sample catalysts confirm the high stability of cobalt catalysts against leaching of active species into solution.

Wet-Chemical Analysis of Surface Concentration of Accessible Groups on Different Amino-Functionalized Mesoporous SBA-15 Silicas

Surface functionalization is one of the key steps toward the utilization of mesoporous materials in different applications. In this study, we characterized amino-functionalized mesoporous SBA-15 silicas that have been prepared by different means; co-condensation, post-grafting of amino-silanes, and surface hyperbranching polymerization of poly(ethylene imine). Special focus is put on the accessibility of the introduced function. The materials are thoroughly characterized both by structural and by surface chemical means. We generally observe a good agreement between the C-value derived from BET surface area analysis, the number of accessible amine groups determined by quantitative imine reaction in solution, and zeta-potential measurements. Furthermore, indirect information about differences in the number of amine groups present on the outside surface of the particles can also be obtained. Our results clearly show that there are large differences between the availability of the amine function for materials...

Design and synthesis of Alq 3-functionalized SBA-15 mesoporous material

A luminescent organic molecule aluminum tris(8-hydroxyquinoline) (Alq 3) has been successfully introduced in the pores of amino-functionalized mesoporous SBA-15 (APS-SBA-15). An obvious blue-shifted photoluminescence (PL) of Alq 3 was observed. In the pores of APS-SBA-15, the Alq 3 organic molecules exhibited efficient and intense PL as monomers and the emission intensities increased with increasing Alq 3 concentration.