Preparation of luminescent and mesoporous Eu3+/Tb3+ doped calcium silicate microspheres as drug carriers via a template route

Luminescent and mesoporous Eu(3+)/Tb(3+) doped calcium silicate microspheres (LMCS) were synthesized by using mesoporous silica spheres as the templates. The LMCS and drug-loaded samples were characterized by means of X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), N(2) adsorption/desorption, and photoluminescence (PL) spectra. The results reveal that the LMCS have uniform spherical morphology with a diameter around 400 nm and the mesopore size of 6 nm. The prepared samples exhibit little cytotoxicity at concentrations below 5 mg mL(-1) via MTT assay. In addition, drug storage/release properties of the LMCS were demonstrated for ibuprofen (IBU). The obtained LMCS can be used to encapsulate drugs and release them. Under excitation by UV light, the IBU-loaded samples still show the characteristic (5)D(0)-(7)F(1-3) emission lines of Eu(3+) and the characteristic (5)D(4)-(7)F(3-6) emission lines of Tb(3+). The PL intensity of Eu(3+) in the drug carrier system increases with the cumulative released amount of IBU, making the drug release able to be tracked or monitored by the change of luminescence of Eu(3+). The LMCS reported here with mesoporous structure, good biocompatibility and luminescent property can be a promising drug delivery carrier.     

pH响应的介孔二氧化硅纳米颗粒的制备及可控释放

选择带负电荷且溶解度和分子结构对pH值非常敏感的聚丙烯酸作为封堵分子, 采用静电吸附的修饰方法, 制备了pH响应的MCM-41型介孔二氧化硅纳米颗粒. 利用高倍透射电子显微镜(TEM)、 X射线衍射(XRD)、 傅里叶变换红外光谱(FTIR)及比表面积分析等手段表征了介孔二氧化硅纳米颗粒的物理化学性质. 以联钌吡啶染料分子作为模式客体分子, 研究了pH调控下的模式客体分子在介孔二氧化硅纳米颗粒中的包裹及释放行为. 结果表明, 该介孔二氧化硅纳米颗粒对pH具有很好的响应性; 在近中性条件下, 带正电的二氧化硅纳米颗粒通过静电吸附作用吸附带负电的聚丙烯酸, 导致介孔封堵, 使包载的染料分子几乎无释放; 客体分子的释放率随着pH值的降低而升高, 当pH≤5时, 染料分子显著释放, pH=1时客体分子的释放率高达98％, 可以实现对包载客体分子的控制释放. 该pH响应的介孔二氧化硅纳米颗粒载体具有制备简便、 价格低廉和包载量大等优点, 有望应用于药物的控制释放.     

High surface area, mesoporous, glassy alumina with a controllable pore size by nanocasting from carbon aerogels

A strategy to synthesize amorphous, mesoporous alumina by nanocasting has been developed, involving carbon aerogel as a hard template and aluminum nitrate solution as an alumina precursor. The alumina generated exhibits small, transparent granules with a 3-6 mm diameter and has inherited the three-dimensional network structure of the carbon template. The mesopore surface area of the alumina can be as high as 365 m2 g(-1), and the pore volume reaches 1.55 cm3 g(-1) after calcination at 600 degrees C in air for 8 h. The pore parameters can be varied within a certain range by variation of the carbon aerogel template and the loading amount of the alumina precursor. At high loadings, the obtained glassy alumina clearly has a bimodal pore size distribution in the mesopore range.     

双中孔SiO_2的合成与表征

在通常用于合成中孔ＭＣＭ－４１分子筛的反应体系中,用氨水、ＮａＯＨ或四乙基氢氧化胺作催化剂,在较低的ｐＨ值下合成出具有独特Ｎ２吸附等温线和狭窄双峰中孔分布的双中孔ＳｉＯ２材料。实验表明,在所使用的反应体系中,双中孔ＳｉＯ２结构是一种必然的物相,且反应体系的ｐＨ值调节在合成中起决定性作用。当反应体系的ｐＨ值从约９．５增加到１１时,相应产物的孔径分布由双中孔转变为单中孔分布。这些结果为进一步深入理解中孔材料的形成机理提供了新的视野。合成样品用ＸＲＤ和Ｎ２吸附等温线进行了表征。     

Mechanism of freezing of water in contact with mesoporous silicas MCM-41, SBA-15 and SBA-16: role of boundary water of pore outlets in freezing

The freezing mechanism of water contacted with mesoporous silicas with uniform pore shapes, both cylindrical and cagelike, was studied by thermodynamic and structural analyses with differential scanning calorimetry (DSC) and X-ray diffraction (XRD) together with adsorption measurements. In the DSC data extra exothermic peaks were found at around 230 K for water confined in SBA-15, in addition to that due to the freezing of pore water. These peaks are most likely to be ascribed to the freezing of water present over the micropore and/or mesopore outlets of coronas in SBA-15. Freezing of water confined in SBA-16 was systematically analysed by DSC with changing the pore size. The freezing temperature was found to be around 232 K, close to the homogeneous nucleation temperature of bulk water, independent of the pore size when the pore diameter (d) < 7.0 nm. Water confined in the cagelike pores of SBA-16 is probably surrounded by a water layer (boundary water) at the outlets of channels to interconnect the pores and of fine corona-like pores, which is similar to that present at the outlet of cylindrical pores in MCM-41 and of cylindrical channels in SBA-15. The presence of the boundary water would be a key for water in SBA-16 to freeze at the homogeneous nucleation temperature. This phenomenon is similar to those well known for water droplets in oil and water droplets of clouds in the sky. The XRD data showed that the cubic ice I(c) was formed in SBA-16 as previously found in SBA-15 when d < 8.0 nm.     

Luminescent, mesoporous, and bioactive europium-doped calcium silicate (MCS: Eu3+) as a drug carrier

Luminescent, mesoporous, and bioactive europium-doped calcium silicate (MCS: Eu) was successfully synthesized. The obtained MCS: Eu(3+) was performed as a drug delivery carrier to investigate the drug storage/release properties using ibuprofen (IBU) as the model drug. The structural, morphological, textural, and optical properties were well characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N(2) adsorption/desorption, and photoluminescence (PL) spectra, respectively. The results reveal that the MCS: Eu exhibits the typical ordered characteristics of the mesostructure. This composite shows a sustained release profile with IBU as the model drug. The IBU-loaded samples still present red luminescence of Eu(3+) ((5)D(0)-(7)F(1,2)) under UV irradiation. The emission intensities of Eu(3+) in the drug carrier system vary with the amount of released IBU, making the drug release easily tracked and monitored. The system demonstrates a great potential for drug delivery and disease therapy.     

Pore-size tunable mesoporous zirconium organophosphonates with chiral L-proline for enzyme adsorption

Mesoporous zirconium organophosphonates with a tunable mesopore (pore diameter: from 4.8 to 16.3 nm) were synthesized through co-condensation of ZrCl4 and 1-phosphomethylproline (H3PMP) with the aid of organic additives in the presence of an anionic surfactant (sodium dodecyl sulfate) under weak acidic conditions. The organic additives, tetrahydrofuran, can effectively strengthen the assembly of ZrCl4 and H3PMP around the surfactant micelles through decreasing the hydrolysis and condensation rate of ZrCl4. The results of the N2 sorption isotherm and SEM image show that zirconium phosphate with a bimodal structure is formed by calcination of mesoporous zirconium organophosphonate. Mesoporous zirconium organophosphonates can effectively adsorb lysozyme (Lz) and papain, and the adsorption equilibrium for Lz can be reached within 30 min. The adsorption capacity for Lz and papain can reach as high as 438 and 297 mg/g, respectively. Furthermore, Lz adsorbed on mesoporous zirconium organophosphonates can retain its structural conformation as in its free state, and no leaching of Lz from the solid was observed when shaking the Lz-loaded solid in a buffer solution. Also, the existence of L-proline in the mesopore could help the adsorption of papain at a pH value lower than the pI of papain.     

A simple approach to prepare monodisperse mesoporous silica nanospheres with adjustable sizes

A new and facile approach has been developed to prepare monodisperse mesoporous silica nanospheres (MMSNs) with controlled particle sizes and pore structures. In our approach, MMSNs were synthesized simply in a sodium acetate solution without adding any other alkali or alcohol additives. MMSNs have a spherical shape and uniform particle sizes, which can be adjusted from 50 to 110 nm by increasing the reaction temperature from 40 to 80 °C. By performing a subsequent hydrothermal treatment (HT) under basic condition (pH=~11.5) at 130 °C, the mesoporous pore volume and surface area can be enhanced, while keeping the mono-dispersion characteristics and the mesopore size almost unchanged. The pore sizes of MMSNs can be adjusted from 2.8 to 4.0 nm under acidic solutions by changing the HT temperature from 100 to 130 °C. The formation process of MMSNs has been investigated by transmission electron microscopy (TEM) and attenuated total reflection Fourier transform infrared (ATR-FTIR) techniques. A spherical micelle templating mechanism is proposed to explain the formation of MMSNs in our system, which is different from that of traditional highly ordered mesoporous silica nanoparticles (MCM-41).     

Preparation and characterization of monolithic column by grafting pH-responsive polymer

A novel modified monolithic column with pH-responsive polymer chains was prepared by grafting methacrylic acid onto the poly(glycidyl methacrylate-co-ethylene dimethacrylate) monolith. The grafting polymerization was achieved in an in situ manner which was performed by pumping methacrylic acid directly through an acidic hydrolysis monolithic column using potassium peroxydisulfate initiated free-radical polymerization. The grafted monolithic column was demonstrated to be the pH-responsive to the pore structure and the chromatographic characterization. The permeability of the column and the retention factors of five benzene homologues decreased due to the conformational changes of the polymer chains when the pH of mobile phase increased from 4.5 to 7.5. Furthermore, the modified monolithic column was used as the pH-responsive stationary phase and exhibited an excellent separation of four basic proteins.     

Dendrimer-like supramolecular nanovalves based on polypseudorotaxane and mesoporous silica-coated magnetic graphene oxide: a potential pH-sensitive anticancer drug carrier

In the present research, two types of drug carriers based on mesoporous silica-coated magnetic graphene oxide, Fe₃O₄@GO@mSiO₂, were synthesised and the pH-responsive behaviour for doxorubicin release was investigated. One type of the carrier was dendrimer-like multi ethylene amine grafted on Fe₃O₄@GO@mSiO₂ and the other was dendrimer-like supramolecular polypseudorotaxane. Herein, α-cyclodextrin was used in the structure of supramolecular nanoparticles as a gatekeeper to inhibit the drug from escaping at neutral pH (the pH of healthy tissue). The drug release profile showed that the supramolecular nanocarrier was more sensitive to the pH changes. The content of drug release was about 100% at pH 5.5 (endosomal pH) during 48 h; but it was zero at pH 7.4. Also, the dendrimer structure facilitated the triggered release of doxorubicin.     

Face-centered-cubic large-pore periodic mesoporous organosilicas with unsaturated and aromatic bridging groups

Large-pore ethenylene-bridged (-CH═CH-) and phenylene-bridged (-C(6)H(4)-) periodic mesoporous organosilicas (PMOs) with face-centered-cubic structure (Fm3m symmetry) of spherical mesopores were synthesized at 7 °C at low acid concentration (0.1 M HCl) using Pluronic F127 triblock copolymer surfactant in the presence of aromatic swelling agents (1,3,5-trimethylbenzene, xylenes-isomer mixture, and toluene). In particular, this work reports an unprecedented block-copolymer-templated well-ordered ethenylene-bridged PMO with cubic structure of spherical mesopores and an unprecedented block-copolymer-templated face-centered cubic phenylene-bridged PMO, which also has an exceptionally large unit-cell size and pore diameter. The unit-cell parameters of 30 and 25 nm and the mesopore diameters of 14 and 11 nm (nominal BJH-KJS pore diameters of 12-13 and 9 nm) were obtained for ethenylene-bridged and phenylene-bridged PMOs, respectively. Under the considered reaction conditions, the unit-cell parameters and pore diameters were found to be similar when the three different methyl-substituted benzene swelling agents were employed, although the degree of structural ordering appeared to improve for phenylene-bridged PMOs in the sequence of decreased number of methyl groups on the benzene ring.     

A simple route utilizing surfactant-assisted templating sol-gel process for synthesis of mesoporous Dy2O3 nanocrystal

A simple route of combined sol-gel process with surfactant-assisted templating technique was successfully employed for the first time to synthesize nanocrystalline mesoporous Dy(2)O(3) with narrow monomodal pore size distribution under mild conditions. The nanocrystalline Dy(2)O(3) with monomodal mesoporous characteristic was ultimately achieved by controlling the hydrolysis and condensation steps of dysprosium n-butoxide modified with acetylacetone in the presence of laurylamine hydrochloride surfactant aqueous solution. The synthesized material was methodically characterized by thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), N(2) adsorption-desorption, Brunauer-Emmett-Teller (BET) surface area analysis, and Barrett-Joyner-Halenda (BJH) pore size distribution analysis. The particle size of the synthesized Dy(2)O(3) in nanosized range obtained from the SEM and HRTEM micrographs was in good accordance with the crystallite size estimated from the XRD result. The N(2) adsorption-desorption result exhibited hysteresis pattern with single loop, indicating the existence of monomodal mesopore. The extremely narrow pore size distribution with mean pore diameter in the mesopore region of the synthesized Dy(2)O(3) was also confirmed by the BJH result.     

浸渍金属盐二次活化制备中孔沥青基球形活性炭的研究

以煤焦油沥青为原料,水蒸气活化法制备具有一定孔隙结构的预活化沥青基球形活性炭:通过在预活化球形活性炭中浸渍Fe(NO3)3、Co(NO3)2、Ni(NO3)2水蒸气二次活化,制备得到具有不同中孔孔径分布和较高强度的球形活性炭;研究了金属Fe、CO、Ni在二次活化过程中对预活化球形活性炭的孔结构参数和VB12吸附性能的影响,实验结果表明,预活化球形活性炭通过浸渍硝酸盐二次活化能够有效提高中孔孔容和中孔含量,其中浸渍CO(NO3)2二次活化对中孔孔容的增加最为明显,其中孔孔容达0.50cm3/g,占总孔孔容的65%.随着浸溃Co(NO3)2二次活化时间的延长,预活化球形活性炭中孔孔容增加,孔径分布变宽.     

介孔分子筛Al-MCM-41接枝三甲基氯化锡的合成、表征及催化性能

将三甲基氯化锡与Al-MCM-41介孔分子筛在N2气气氛中135 ℃回流4.5 h,得到表面键合有机锡的分子筛(CH3)3Sn-O-MCM-41[(CH3)3SnM]。 采用电感耦合等离子体质谱（ICP-MS）、有机元素分析、红外光谱、N2吸附-脱附、热重分析（TG）、NH3程序升温脱附（NH3-TPD）、X射线多晶衍射（XRD）和透射电子显微镜等测试技术对样品的组成、结构和表面物理化学性质进行表征。 结果表明,有机锡接枝率可达14.44%;接枝前后分子筛的NH3-TPD表面酸量(NH3)由0.652 6 mmol/g增加至1.294 4 mmol/g。 接枝后分子筛的比表面积减小,孔容变大,孔径变小,仍保持六方介孔结构;接枝分子筛(CH3)3SnM用于催化合成乙酸异戊酯,当n(异戊醇)∶n（冰乙酸）=1.0∶1.0,w（催化剂）=5%,138 ℃,回流5 h,反应转化率为96%;催化剂重复使用5次,酯化转化率仍可达到86%。     

Double-Mesopore V-MSU-X Silica and its Pure Siliceous Derivative Prepared by One Synthesis System

Since their first disclosure of the M41S family of materials1,2 in 1992, considerable research effort has been developed to prepare the other derivatives of mesoporous materials such as SBA3 and MSU-X4,5 silicates by using different polymeric and oligomeric templates. The later involved different sorts of nonionic poly (ethylene oxide)-based surfactants, which led to the family of MSU-X (X=1-4) and then provided new advantages in either topologies or processing. The interest in these mate…     

有序介孔有机金属Au(I)催化剂催化水相炔烃水合制备甲基酮

采用表面活性剂自组装、有机金属硅烷与苯基硅烷共聚法制备了有机金属Au(I)嵌于介孔材料孔壁的非均相催化剂Au(I)-PPh2-PMO(Ph).结果表明,Au(I)-PPh2-PMO(Ph)催化剂的活性位分散均匀,孔道不易堵塞,对反应物的扩散与传质影响较小,其催化活性不仅明显高于后嫁接法制得的Au(I)-PPh2-PMO(Ph)-G和均相Au(PPh3)Cl催化剂,且可以重复使用,显示出较好的应用前景.     

Branched mesoporous Mn3O4 nanorods: facile synthesis and catalysis in the degradation of methylene blue

Branched MnOOH nanorods with diameters in the range of 50-150 nm and lengths of up to tens of micrometers were prepared by using potassium permanganate (KMnO(4)) and PEG 400 (PEG=polyethylene glycol) as starting materials through a simple hydrothermal process at 160 °C. After annealing at 300 °C under a N(2) atmosphere for 5 h, MnOOH nanorods became gradually dehydrated and transformed into mesoporous Mn(3)O(4) nanorods with a slight size-shrinking. The as-obtained mesoporous Mn(3)O(4) nanorods had an average surface area of 32.88 m(2) g(-1) and a mean pore size of 3.7 nm. Through tuning the experimental parameters, such as the annealing atmosphere and temperature, β-MnO(2), Mn(2)O(3), Mn(3)O(4), MnO, and Mn(5)O(8) were selectively produced. Among these structures, mesoporous Mn(3)O(4) nanorods were efficient for the catalytic degradation of methylene blue (MB) in the presence of H(2)O(2) at 80 °C.     

介孔分子筛Ti-AlKIT-1的制备、表征与催化性能

分别采用直接(ds)和后合成法(ps)合成含铝的介孔分子筛Al(ds or ps)KIT-1。 以钛酸四丁酯Ti（OEt）4为钛源,将钛嫁接在AlKIT-1表面制备出Ti-AlKIT-1样品。 用傅里叶变换红外光谱、X射线粉末衍射、固体核磁共振(MAS NMR)、固体紫外 可见漫反射光谱（DRS）、能谱(EDS)和N2吸附-脱附对样品进行了表征,并以双氧水氧化环己醇为探针考察了样品的催化活性。 实验结果表明,分子筛Ti-AlKIT-1具有规整的介孔孔道结构,钛进入介孔分子筛骨架而成为四配位的骨架钛,铝的存在形式与样品AlKIT-1的预处理有关,经铵溶液洗涤的Al(ds)KIT-1中没有非骨架铝。 Ti-AlKIT-1在催化双氧水氧化环己醇反应中铝和钛存在明显的协同作用。 样品Ti-Al(ds)KIT-1表现出更高的催化作用,这与其具有较高的比表面积、较大的孔容和较高钛铝比有关,80 ℃反应48 h,重复使用3次后,环己醇的转化率降低至51.3%,仅下降4.31%。     

NPE在有序介孔炭上的吸附行为研究

采用有序介孔硅为硬模板制备了具有不同孔径的有序介孔炭(OMCs). 氮气吸附测试表明, 有序介孔炭具有丰富的介孔表面和集中的介孔分布. 以壬基酚聚氧乙烯醚(NPE)为探针分子, 研究了大分子酚类在有序介孔炭上的吸附行为. 吸附研究表明, NPE在有序介孔炭上的吸附满足Langmuir吸附模型. 孔结构分析表明, 大于1.5 nm的孔的表面积是决定NPE吸附量的关键因素, 而有序介孔炭的最可几孔径决定吸附速率的大小. 与吸附量相比, 吸附速率更容易受环境温度的影响. 动力学研究表明, NPE在有序介孔炭上的吸附满足准二级动力学方程.     

Borate‐Driven Gatelike Scaffolding Using Mesoporous Materials Functionalised with Saccharides

We report the development of an MCM‐41 mesoporous support that is functionalised with saccharides at the pore outlets and contains the dye [Ru(bipy)₃]²⁺ in the pores (solid S1 ; bipy=2,2′‐bipyridyl). For this hybrid system, the inhibition of mass transport of the dye from the pore voids to the bulk solution in the presence of borate is demonstrated in water at neutral pH. The formation of the corresponding boroester derivative is related to the selective reaction of borate with the appended saccharides. This control is selective and only anion borate, among several anions and cations, can act as a molecular tap and inhibit the delivery of the entrapped guest. Additionally, the S1 –borate system behaves as pH‐controlled gatelike scaffolding. This pH‐responsive release can be achieved in an acidic pH (due to hydrolysis of the boroester), whereas the system remains closed at neutral pH. Molecular dynamic simulations using force‐field methods have been made to theoretically study the open/close borate‐driven mechanism. A mesoporous silica structure was constructed for this purpose, taking the plane (1?11) of the β‐cristobalite structure as a base on which hexagonal nanopores and anchored saccharide derivatives were included. The final model shows a highly flexible nanopore diameter of approximately 12.5 Å of similar size to the [Ru(bipy)₃]²⁺ complex (ca. 12 Å). However, the anchoring of borate to the appended saccharides results in a remarkable reduction of the pore size (down to ca. 6.4 Å) and a significant constraint in the flexibility and mobility of the saccharides. The theoretical calculations are in agreement with the experimental results and enable visualisation of the functional borate‐driven dye‐delivery‐inhibition outcome.