Functionalization of mesoporous MCM-41 for the delivery of curcumin as an anti-inflammatory therapy

In this study, mesoporous silica nanoparticles (MSNs) composed of MCM-41 were synthesized and modified with amine groups (i.e., NH₂) to form NH_2/MCM-41, which was loaded with curcumin (CUR) to form CUR@NH₂/MCM-41 to create an efficient carriers in drug delivery systems (DDSs). The three samples (i.e., pure MCM-41, NH₂/MCM-41, and CUR@NH₂/MCM-41) were characterized using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area, Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transition electron microscopy (TEM), and a thermogravimetric analyzer (TGA). The study investigated the effect of the carrier dose, CUR concentration, pH, and contact time on the drug loading efficiency (DLE%) by adsorption. The best DLE% for MCM-41 and NH₂/MCM-41 was found to be 15.78 and 80%, respectively. This data demonstrated that the Langmuir isotherm had a greater correlation coefficient (R²) of 0.9840 for MCM-41 and 0.9666 for NH₂/MCM-41 than the Freundlich and Temkin isotherm models. A pseudo-second-order kinetic model seems to fit well with R² = 0.9741 for MCM-41 and R² = 0.9977 for NH₂/MCM-41. A phosphate buffer solution (PBS) with a pH of 7.4 was utilized to study CUR release behavior. As a result, the full release after 72 h was found to have a maximum of 74.1% and 29.95% for pure MCM-41 and NH₂/MCM-41, respectively. The first-order, Weibull, Hixson-Crowell, Korsmeyer-Peppas, and Higuchi kinetic release models were applied to releasing CUR from CUR@MCM-41 and CUR@NH₂/MCM-41. The Weibull kinetic model fit well, with R² = 0.944 and 0.96912 for pure MCM-41 and NH₂/MCM-41, respectively.     

Synthesis of mesoporous silica materials (MCM-41) from iron ore tailings

Highly ordered mesoporous materials were successfully synthesized by using the iron ore tailings as the silica source and n-hexadecyltrimethyl ammonium bromide as the template. The samples were detail characterized by powder X-ray diffraction, scanning electron microscope, high-resolution transmission electron microscopy and N₂ physisorption. The as-synthesized materials had high surface area of 527 m² g⁻¹ and the mean pore diameter of 2.65 nm with a well-ordered two-dimensional hexagonal structure. It is feasible to prepare mesoporous MCM-41 materials using the iron ore tailings as precursor.     

Preparation and characterization of epoxy composites filled with functionalized nano-sized MCM-41 particles

Mono-dispersed nano-sized MCM-41 (M (with template)) particles were synthesized by sol–gel reaction. The effect of interface modification on the properties of epoxy composites was investigated. Modifications were carried out either by substituting silanol groups on the surface or in the mesopore channels into amine (M-NH₂), calcinating mixture template in the mesopore channels (M(without template)), or recalcinating them at higher temperature to remove silanol groups (–OH) in the mesopore channels or on the surface (CM). Transmission electron micrograph results showed that the dispersing of MCM-41 nanoparticles was not influenced by the modification, while –NH₂ group indeed modified the mesopore channels or the surface of MCM-41 particle by using IR, XRD, and N₂ adsorption–desorption. In addition, tensile tests suggested that M-NH₂ nanoparticles could simultaneously provide epoxy matrix with strengthening and toughening effects. However, due to the different interfacial structures between the fillers and the matrix, the mechanical properties of the composites filled by M-NH₂ were much better than those of composites filled by MCM-41 (without template), MCM-41 (with mixture template), and CM.     

SiC-dopped MCM-41 materials with enhanced thermal and hydrothermal stabilities

SiC-dopped MCM-41 mesoporous materials were synthesized by the in situ hydrothermal synthesis, in which a small amount of SiC was added in the precursor solvent of molecular sieve before the hydrothermal treatment. The materials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N₂ physical adsorption and thermogravimetric analysis, respectively. The results show that the thermal and hydrothermal stabilities of MCM-41 materials can be improved obviously by incorporating a small amount of SiC. The structure collapse temperature of SiC-dopped MCM-41 materials is 100 °C higher than that of pure MCM-41 according to the differential scanning calorimetry analysis. Hydrothermal treatment experiments also show that the pure MCM-41 will losses it's ordered mesoporous structure in boiling water for 24 h while the SiC-dopped MCM-41 materials still keep partial porous structure.     

纳米结构的空腔二氧化硅微球的制备与缓释行为

以单分散聚苯乙烯(PS)微球作为胶体模板,采用层层静电自组装技术,交替组装聚电解质聚二烯丙基二甲基氯化铵[poly(diallyldimethylammonium chloride),PDDA]和二氧化硅纳米颗粒(10和20nm),得到核壳型聚苯乙烯/聚电解质/二氧化硅复合微球,高温煅烧除去模板PS和聚电解质,制得空腔二氧化硅微球.TEM观察的结果显示空腔二氧化硅微球呈单分散性且内部空腔呈球形;XRD图谱显示组装的二氧化硅颗粒热处理后晶化的程度很小,仍基本保持着无定形状态;N₂等温吸附-脱附实验测得用10和20nm的二氧化硅组装成的空腔二氧化硅微球的平均孔径和比表面积分别为11nm、282.71m²·g^-1和15nm、158.17m²·g^-1. 染料的装载和释放实验分别验证了空腔二氧化硅微球的腔壁具有可渗透性和缓释性.     

Synthesis of MCM-41 nanoparticles from stem of common reed ash silica and their application as substrate in electrooxidation of methanol

In this work, stem of common reed ash (SCRA) is introduced as a new source of silica in the preparation of mesoporous materials. Mesoporous silicate MCM-41 nanoparticles were synthesized hydrothermally using sodium silicate prepared from SCRA as a silica source. The characterization of MCM-41was carried out by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), N\(_{2}\) adsorption/desorption (BET) and transmission electron microscopy (TEM). SEM shows that MCM-41 nanoparticles are sphere-like with size in the range of 30–50 nm with some degree of agglomeration. TEM image of the synthesized sample shows the open framework structure of MCM-41. A type IV isotherm can be observed from adsorption/desorption curves, which is the characteristic of mesoporous materials. The prepared MCM-41 nanoparticles were used as substrate to facilitate the oxidation of methanol through the modification with an electroactive species. The modification was achieved by impregnation of MCM-41 pores with \(\hbox {Ni}^{2+}\) ions (Ni-doped MCM-41). A modified carbon paste electrode (CPE) was prepared by mixing Ni-doped MCM-41 with carbon paste (NiMCM-41CPE). Cyclic voltammetry of NiMCM-41CPE shows an increment in current density of methanol oxidation in comparison with CPE in alkaline solution. Moreover, a decrease in the overpotential of methanol oxidation occurred on the surface of modified electrode. The effects of some parameters such as scan rate and methanol concentration are also investigated on the behaviour of NiMCM-41CPE. Also, the heterogeneous electron transfer rate for the catalytic reaction (k) of methanol is calculated.     

磁性MCM-41分离回收RT培司废水中四甲基氢氧化铵的研究

硝基苯法合成RT培司(4-氨基二苯胺)的废水色度高、组分复杂、催化剂四甲基氢氧化铵(TMAOH)难以分离回收。提出采用磁性MCM-41对RT培司废水中有机副产物进行选择性吸附分离。制备的磁性MCM-41样品采用X射线衍射仪(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、N₂吸附-脱附和振动样品磁场计(VSM) 等手段进行表征。结果表明, 磁性MCM-41颗粒的粒径范围为200~300 nm, BET比表面积约为655.2 m²/g, 孔径分布为0.5~4 nm, 内核铁酸镍的存在使磁性MCM-41具有超顺磁性。吸附研究表明磁性MCM-41对RT培司废水中吩嗪、偶氮苯和苯胺等有机物具有良好吸附作用, 经5次吸附磁分离后, RT培司废水中四甲基氢氧化铵能够达到回用要求, 吸附后的磁性MCM-41在外加磁场下极易分离。     

Room temperature synthesis of Si-MCM-41 using polymeric version of ethyl silicate as a source of silica

Synthesis of mesoporous MCM-41 materials at room temperature using less expensive polymeric version of ethyl silicate (40 wt% SiO₂) as a source of silica was established. The influence of crucial synthesis parameters such as molar ratios of H₂O/NH₄OH, NH₄OH/SiO₂ and CTMABr/SiO₂ in gel on the quality of the phase formed was investigated. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and low temperature N₂ adsorption-desorption isotherms have been employed to characterize the products. The magnitude of orderness, textural properties and thermal stability of the Si-MCM-41 samples prepared under identical judiciously pre-controlled synthesis conditions using ethyl silicate and conventional tetraethyl orthosilicate (TEOS) were assessed. Even though, ethyl silicate has proved to be suitable source for the preparation of MCM-41 at room temperature, there exists an optimum value of H₂O/NH₄OH for different NH₄OH/SiO₂ molar ratios in the gel. Changes in the morphology were observed when NH₄OH/SiO₂, H₂O/NH₄OH molar ratios in the gels were changed.     

Cerium incorporating into MCM-41 mesoporous materials for CO oxidation

Ceria doped MCM-41 materials were synthesized by surfactant-assisted hydrothermal and wet impregnation methods. All the obtained Ce-MCM-41 materials were characterized by N₂ physical adsorption, X-ray diffraction (XRD), diffuse reflectance UV–visible spectroscopy (DRUV–vis), infrared spectroscopy (IR), solid-state cross-polarization magic angle spinning nuclear magnetic resonance spectroscopy (CP/MAS-NMR), and transmission electron microscopy (TEM). The catalytic properties were evaluated in CO oxidation under atmospheric pressure and various temperatures. The results showed that in the materials synthesized by hydrothermal method, most of Ce ions were well incorporated in the tetrahedral coordinated sites into the framework of the MCM-41 as Si/Ce molar ratio is 30 and 50. High cerium content may lead to mesostructure partial collapsing and ceria particles segregation. For CO oxidation, the catalytic activity of Ce-MCM-41 synthesized by hydrothermal method was significantly greater than that of the materials prepared by impregnation route. Over the Ce-MCM-41 materials prepared via hydrothermal technique, 100% CO conversion was achieved at 504, 514 and 528 K, respectively, as the Si/Ce molar ratio decreased from 50 to 30 and 10. For the first time, we found an interesting correlation of Q₃ species relative area in the ²⁹Si CP/MAS-NMR spectra of the Ce-MCM-41materials with the reaction rates of CO oxidation, which indicates that both surface hydroxyls and tetrahedral-coordinated Ce⁴⁺ ions in the MCM-41 take important roles in the CO oxidation.     

The investigation of MCM-48-type and MCM-41-type mesoporous silica as oral solid dispersion carriers for water insoluble cilostazol

Objective: To explore the suitable application of MCM-41 (Mobil Composition of Matter number forty-one)-type and MCM-48-type mesoporous silica in the oral water insoluble drug delivery system.

Methods: Cilostazol (CLT) as a model drug was loaded into synthesized MCM-48 (Mobil Composition of Matter number forty-eight) and commercial MCM-41 by three common methods. The obtained MCM-41, MCM-48 and CLT-loaded samples were characterized by means of nitrogen adsorption, thermogravimetric analysis, ultraviolet-visible spectrophotometry, scanning electron microscopy, transmission electron microscopy, differential scanning calorimetry and powder X-ray diffractometer.

Results: It was found that solvent evaporation method was preferred according to the drug loading efficiency and the maximum percent cumulative drug dissolution. MCM-48 with 3D cubic pore structure and MCM-41 with 2D long tubular structure are nearly spherical particles in 300–500?nm. Nevertheless, the silica carriers with similar large specific surface areas and concentrating pore size distributions (978.66?m²/g, 3.8?nm for MCM-41 and 1108.04?m²/g, 3.6?nm for MCM-48) exhibited different adsorption behaviors for CLT. The maximum percent cumulative drug release of the two CLT/silica solid dispersion (CLT-MCM-48 and CLT-MCM-41) was 63.41% and 85.78% within 60?min, respectively; while in the subsequent 12?h release experiment, almost 100% cumulative drug release were both obtained. In the pharmacokinetics aspect, the maximum plasma concentrations of CLT-MCM-48 reached 3.63?mg/L by 0.92?h. The AUC_0–∞ values of the CLT-MCM-41 and CLT-MCM-48 were 1.14-fold and 1.73-fold, respectively, compared with the commercial preparation.

Conclusion: Our findings suggest that MCM-41-type and MCM-48-type mesoporous silica have great promise as solid dispersion carriers for sustained and immediate release separately.     

Facile fabrication of ZrO2 hollow porous microspheres with yeast as bio-templates

ZrO₂ hollow porous microspheres have been fabricated successfully using living yeast cells as bio-templates through a facile ageing process at lower crystallizing temperature. XRD, SEM, FT-IR and N₂ adsorption-desorption were used to characterize ZrO₂ hollow microspheres. The results showed that the inorganic-organic hybrid hollow microspheres were fabricated at 100 °C and ZrO₂ hollow microspheres with tetragonal phase and porous structure were obtained at 300 °C. The crystallization temperature of ZrO₂ decreased obviously due to the inducting of bio-molecules. The as-prepared hollow microspheres are approximately ellipsoid. The shells of these hollow microspheres are porous, which are composed of some nanoparticles with size of ∼20 nm. The formation mechanism of ZrO₂ hollow microspheres was proposed and discussed tentatively.     

Laccase immobilized on methylene blue modified mesoporous silica MCM-41/PVA

The mesoporous silica sieve MCM-41 containing methylene blue (MB) provides a suitable immobilization of biomolecule matrix due to its uniform pore structure, high surface areas, good biocompatibility and nice conductivity. Based on this, a facilely fabricated amperometric biosensor by entrapping laccase into the MB modified MCM-41/PVA composite film has been developed. Laccase from Trametes versicolor is assembled on a composite film of MCM-41 containing MB/PVA modified Au electrode and the electrode is characterized with respect to transmission electron microscopy (TEM) and scanning electron microscopic (SEM), Cyclic voltammetry (CV), response time, detection limit, linear range and activity of laccase. The laccase modified electrode remains good redox behavior in pH 4.95 acetate buffer solution, at room temperature in present of 0.1 mM catechol. The response time (t_90%) of the modified electrode is less than 4 s for catechol. The detection limit is 0.331 µM and the linear detect range is about from 4.0 µM to 87.98 µM for catechol with a correlation coefficient of 0.99913(S/N = 3). The apparent Michaelis–Menten (K_M^app) is estimated using the Lineweaver–Burk equation and the K_M^app value is about 0.256 mM. This work demonstrated that the mesoporous silica MCM-41 containing MB provides a novel support for laccase immobilization and the construction of biosensors with a faster response and better bioactivity.     

Amine-impregnated MCM-41 in post-combustion CO2 capture: Synthesis,characterization, isotherm modelling

In this study, a composite mesoporous silica material MCM-41 (Mobil composite matter) is impregnated with monoethanolamine (MEA) as primary linear amine, benzylamine (BZA) as primary cyclic amine and N-(2-aminoethyl) ethanolamine (AEEA) as secondary diamine and the effects of amine loading, amine type, CO₂ partial pressure and adsorption temperatures on the CO₂ adsorption are investigated. The CO₂ adsorption performances of MCM-41 and amine impregnated MCM-41 samples are studied up to 1 bar of CO₂ partial pressure and the temperature range of 25–60 °C. The amine loadings (% impregnation) are optimized for maximum CO₂ uptake. The materials are characterised using N₂ adsorption/desorption isotherm, Fourier Transform Infrared (FT-IR) Spectroscopy, Thermogravimetric (TGA) and Elemental (CHNS) analysis. The materials have shown good structural and thermal stability. The MCM-41-40%AEEA, MCM-41-40%BZA and MCM-41-50%MEA samples are exhibited the CO₂ adsorption capacity of 2.34 mmol/g (102.98 mg/g), 0.908 mmol/g (39.96 mg/g) and 1.47 mmol/g (64.69 mg/g) respectively. The CO₂ uptake of MCM-41-40%AEEA is 3.5 times higher than that of in MCM-41 (0.68 mmol/g) and it is also the highest reported value as di-amine impregnated MCM-41. The results indicated that the adsorption capacities of the materials (MCM-41 and MCM-41-40%AEEA) are decreased with an increase of adsorption temperature in the range of 25–60 °C. The Freundlich, Langmuir, Sips and Toth isotherm models are used to correlate and predict experimental CO₂ adsorption data. The Sips and Toth isotherm models are found to be better fitted with the experimental data. The isosteric heat of adsorption of MCM-41 and MCM-41-40%AEEA samples are also calculated from Van’t Hoff plot using iSorbHP-win instrumental analysis software in the experimental temperature range.     

Organo-functionalized mesoporous supports for Jacobsen-type catalyst: Laponite versus MCM-41

In order to exploit the different textural properties of Laponite and MCM-41, specifically in terms of their external versus internal surface areas, in the covalent anchoring of a chiral Mn(III) salen complex, these materials were functionalized with 3-aminopropyltriethoxysilane (APTES), subsequently activated with sodium ethoxide, and finally used to anchor the Jacobsen catalyst derivative C1. All the materials were characterized by nitrogen elemental analysis, XPS, PXRD, nitrogen adsorption at −196 °C, FTIR and for those with the immobilized complex, they were additionally characterized by Mn AAS. The APTES anchored at the edges of the Laponite single crystals and inside the MCM-41 pores. Moreover, under the same preparative conditions, higher amount of APTES was anchored onto MCM-41 than onto Laponite, which is due to the higher surface area of MCM-41 compared to Laponite, as well as to its more exposed SiO₄ tetrahedra. Activation of the two organo-functionalized materials with sodium ethoxide originated anionic nitrogen groups as deduced by the increase of surface sodium content of these materials and N1s binding energy changes, but led to a small decrease in N bulk content as a result of some APTES leaching. Moreover, for MCM-41 some disruption of the silica framework occurred as a consequence of the basic treatment, as suggested by XPS, PXRD, and nitrogen adsorption study. The APTES functionalized Laponite and MCM-41 materials, as well as the activated analogs, were able to anchor C1 through axial coordination of the metal centre to the grafted surface nitrogen atoms. APTES functionalized MCM-41 presented similar complex content to Laponite analog, what points out for the fact that, at least for the bulky complex used in this work, there was no clear benefit in using a material of high internal area; for the ethoxide activated analogs, Laponite showed the highest complex content of all materials, but MCM-41 was able to anchor the lowest complex quantity, probably as a consequence of damaging effect caused by the basic treatment within its porous structure. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Influence of pH on the sorption behaviour of uranyl ions in mesoporous MCM-41 and MCM-48 molecular sieves

The sorption of uranyl ions in mesoporous MCM-41 and MCM-48 was accomplished with the help of a direct-template-exchange route, and the progress was monitored as a function of pH of the precursor uranyl nitrate solution. Under identical conditions of synthesis, around one and a half times larger amount of uranium was found to be sorbed in MCM-48 (∼12.5 wt.%) as compared to MCM-41 (∼9.5 wt.%). Further, the powder X-ray diffraction (XRD) data revealed that the expansion of unit cell parameters and broadening of reflections of the uranium containing samples depended on the pH of the precursor uranyl solution. Likewise, the Fourier transform infrared spectroscopy (FT-IR) studies showed a progressive decrease in the frequency of the axial OUO asymmetric stretching vibrational band, ν_a(UO) of the anchored uranyl groups with the increase of pH of the exchanging uranyl solution. The presence of two bands at ∼920 and 879 cm⁻¹ for uranyl exchanged samples prepared at pH > 5 indicated the presence of trinuclear (UO₂)₃⁺₅(OH) species. The occlusion of uranium thus depends upon the pore structure of the host material and the nature and dimension of the hydrolysis species formed at a particular pH of uranyl solution. Furthermore, the template-exchange of hexavalent uranium in MCM-41 and MCM-48 not only results in the formation of bulky hydrolysis species in the mesovoids, but also substitutes (isomorphously) in the silicate matrix resulting in the formation of UMCM-41 and UMCM-48.     

Bimetallic iron and cobalt incorporated MFI/MCM-41 composite and its catalytic properties

The MFI/MCM-41 composite material with bimetallic Fe and Co incorporation was prepared using templating method via a two-step hydrothermal crystallization procedure. The obtained products were characterized by a series of techniques including powder X-ray diffraction, N₂ sorption, transmission electron microscopy, scanning electron microscope, H₂ temperature programmed reduction, thermal analyses, and X-ray absorption fine structure spectroscopy of the Fe and Co K-edge. The catalytic properties of the products were investigated by residual oil hydrocracking reactions. Characterization results showed that the FeCo-MFI/MCM-41 composite simultaneously possessed two kinds of stable meso- and micro-porous structures. Iron and cobalt ions were incorporated into the silicon framework, which was confirmed by H₂ temperature programmed reduction and X-ray absorption fine structure spectroscopy. This composite presented excellent activities in hydrocracking of residual oil, which was superior to the pure materials of silicate-1/MCM-41.     

Synthesis and characterization of super-microporous material with enhanced hydrothermal stability

Super-microporouos silicon material with high hydrothermal stability denoted as MCM-41-T has been prepared from mesoporous MCM-41 by high temperature treatment. The structural and chemical property of MCM-41-T has been characterized by X-ray diffraction, transmission electron microscopy, N₂ adsorption-desorption, infrared spectroscopy and ²⁹Si MAS NMR. The characteristic results show that Si-OH groups are forced to condense by high temperature treatment, and the pore size of MCM-41-T is around 1.5 nm in the super-microporous range. Compared with the original material MCM-41, the hydrothermal stability of MCM-41-T has been significantly enhanced.     

MCM-41 deposition on alumina ceramic foams

Alumina-based macro-porous ceramic foams were successfully coated with MCM-41 meso-porous materials using an in-situ one step hydrothermal synthesis. Low H₂O/NaOH ratio in the starting mixture leads to a not uniform deposition of the meso-porous materials. Using higher H₂O/NaOH ratio and two cycles of deposition, a CF with a continuous and thick layer of well-ordered MCM-41 material coating was produced.     

金属Pt团簇在氧化钛修饰MCM-41中的组装

采用光沉积的合成方法将纳米金属Ｐｔ组装于氧化钛修饰ＭＣＭ－４１孔道中,并对合成的样品进行了ＸＲＤ、ＸＰＳ、ＵＶ－vis、Ｎ₂吸附－脱附等结构表征．光电子能谱表明组装的Ｐｔ呈金属状态;Ｎ_２吸附－脱附数据表明组装于孔道中的Ｐｔ虽然使ＭＣＭ－４１的ＢＥＴ比表面和孔容下降,但是由于Ｐｔ的组装量较小,使其对孔径分布的影响较小．由于Ｐｔ的引入,使其紫外－可见光漫反射吸收光谱与氧化钛修饰的ＭＣＭ－４１不同．     

Gel-like properties of MCM-41 material and its transformation to MCM-50 in a caustic alkaline surround

MCM-41 material, prepared by sol–gel method, reveals gel-like properties in a caustic alkaline environment, i.e., 6 M potassium hydroxide (KOH) electrolyte. The gellation of MCM-41 starts at a KOH weight ratio of 40 wt.%. The structural change of the material is verified with X-Ray diffractograms and supported by observation using Scanning Electron Microscope (SEM). As the KOH weight ratio increases, the MCM-41 hexagonal arrays structure gradually transforms into MCM-50 lamellar structure before disappearing completely at 80 wt.% KOH. The MCM gel phase is further characterized by rotational viscometry and texture analysis. The gel phase shows shear thinning or pseudoplastic behavior and possesses homogeneous matrix structure.