A study of carboxylic-modified mesoporous silica in controlled delivery for drug famotidine

A series of pure silica MSU and carboxylic-modified MSU materials were prepared. The formation of mesoporous silica materials with terminal carboxylic groups on pore surface was performed by the acid-catalyzed hydrolysis of cyano to carboxylic. Then their potential applications in controlled drug delivery carriers were investigated. Drug famotidine was selected as a model molecule out of the consideration of the terminal amino groups in its molecule. The adsorption experiments show significant adsorption of famotidine on the carboxylic-modified MSU materials. And, the functionalization level of carboxylic groups has been found to be the key factor affecting the adsorption capacities of the modified MSU materials for famotidine. Subsequently, three kinds of release fluids, including simulated gastric medium, simulated intestinal medium, and simulated body fluid, were used to test the famotidine release rate from the carboxylic-modified MSU material. Obvious delayed effect has been observed for the famotidine release from the carboxylic-modified mesoporous silica material under the in vitro assays.     

硅酸钠与有机硅氧烷前驱体自组装杂化硅基中孔材料

采用有机硅氧烷(RTES)与硅酸钠(Na2SiO3)共水解缩聚合成有机官能化的MSU型硅基中孔材料.考察了合成体系pH值对材料织构性能的影响以及不同有机硅氧烷与硅酸钠在中性条件下的自组装行为.发现在中性条件下，加入NaF可以有效避免带有较小有机基团的有机硅氧烷进入材料孔壁的可能性，而且合成体系的pH值对材料的孔径有一定的调控作用.     

中孔分子筛MSU及其杂原子衍生物的合成、表征和催化性能研究

以十八烷基聚氧乙烯基醚为模板剂,在ＳiＯ２的等电点（ＰＨ值为２）下,成功地合成了 具有ＭＳＵ结构的中孔ＳiＯ２分子筛及其Ｔｉ、Ｚｒ和Ｖ取代衍生物。用ＸＲＤ、Ｘ２吸 附／脱附、ＤＲＵＶ－Ｖｉｓ和元素分析等手段,对它们的孔道及骨架结构进行了全面表征。催化性能评价结果表明,在乙酸介质中,Ｔｉ、Ｚｒ和Ｖ等过渡金属原子取代的分子筛样品可以催化苯乙烯氧化为苯甲醛的反应,且活笥和选择性较高。     

层状和MSU结构的介孔纳米二氧化锆

在不添加任何结构稳定剂的条件下, 首次用固态反应结构导向法成功地合成了具有层状结构和MSU结构的介孔纳米二氧化锆. 研究发现, 通过有效地控制晶化条件, 二氧化锆的晶相、比表面和孔结构可以方便地得以调变. 晶相的转变由粒度大小控制, 并且构成无机骨架的相态不同, 合成样品的热稳定性存在差异. 结果显示, 介孔纳米二氧化锆的形成仍遵循超分子液晶模板机制, 且由碱锆摩尔比的大小控制介观相的转化, 低碱锆摩尔比条件下形成层状相, 而高碱锆摩尔比条件下为维持整个体系的低能稳定状态, 在电荷作用下形成反棒状胶束结构.     

Discovering New Classes of <Emphasis Type="Italic">Brugia malayi</Emphasis> Asparaginyl-tRNA Synthetase Inhibitors and Relating Specificity to Conformational Change

SLIDE software, which models the flexibility of protein and ligand side chains while docking, was used to screen several large databases to identify inhibitors of Brugia malayi asparaginyl-tRNA synthetase (AsnRS), a target for anti-parasitic drug design. Seven classes of compounds identified by SLIDE were confirmed as micromolar inhibitors of the enzyme. Analogs of one of these classes of inhibitors, the long side-chain variolins, cannot bind to the adenosyl pocket of the closed conformation of AsnRS due to steric clashes, though the short side-chain variolins identified by SLIDE␣apparently bind isosterically with adenosine. We hypothesized that an open conformation of the motif 2 loop also permits the long side-chain variolins to bind in the adenosine pocket and that their selectivity for Brugia relative to human AsnRS can be explained by differences in the sequence and conformation of this loop. Loop flexibility sampling using Rigidity Optimized Conformational Kinetics (ROCK) confirms this possibility, while scoring of the relative affinities of the different ligands by SLIDE correlates well with the compounds’ ranks in inhibition assays. Combining ROCK and SLIDE provides a promising approach for exploiting conformational flexibility in structure-based screening and design of species selective inhibitors.     

Atom Transfer Radical Polymerization of Styrene and Methyl Methacrylate from Mesoporous Ordered Silica Particles

Summary: Mesoporous silica was used as substrate for the grafting of alkyl halides initiators. The control over the surface‐initiated polymerization of styrene and MMA, in terms of molar mass and molar mass distribution, was successfully achieved using an ATRP mechanism. The occurrence of the polymerization inside the mesopores was confirmed by thermogravimetric analysis.

Transmission electron microscopy and schematic representation of mesoporous silica functionalized by the anchored iniator (left) and the grafted polymer (right).     

氯苄基官能化和氯苄基甲基双官能化介孔分子筛MCM-41的合成与表征

首先比较了氯苄三乙氧基硅烷和氯苄基三氯硅烷硅烷化介孔分子筛MCM-1的差异性,进而采用氯苄基三氯硅烷和甲基三氯硅烷混合试剂硅烷化介孔分子筛,一步得到氯苄基甲基双官能化介孔分子筛MCM-41,并用固体核磁予以证实.发现甲基三氯硅烷一方面可以作为一种“稀释剂”调节氯苄基的负载量,另一方面甲基的引入可增强介孔分子筛的水热稳定性.     

Comparative Evaluation of Steam Stability and Catalytic Properties of Four Common Aluminosilicate Mesostructures Prepared by Post‐Grafting Method

Four common mesostructured aluminosilicates (e.g. AlMCM‐41, AlMCM‐48, AlMSU‐1 and AlSBA‐15, Si/Al = 7.5) with different pore framework structures were prepared via post‐synthetic method utilizing aluminum isopropoxide as the aluminating agent and characterized by ²⁷Al MAS NMR, XRD, N₂‐adsorption isotherm and NH₃‐TPD. It was found that, on the basis of the above analysis results, AlMCM‐41, AlMSU‐1 and AlSBA‐15 retained more mesoporosity than cubic Al/MCM‐48 after exposure to pure steam at 800 °C, which may be responsible for their much higher activities in bulky 1,3,5‐triisopropylbenzene (TIPB) conversion.     

苯及苯磺酸基官能化的中孔分子筛的合成及催化应用

近年来 ,通过对介孔分子筛 (如 MCM,HMS,MSU-X)结构及组成的化学“裁剪”,制备具有特定结构和表面性质的催化材料成为该领域的研究热点之一 [1～ 5] .许多文献报道了 MCM-4 1的有机官能化中孔材料的制备技术 [5～ 8] ,并将其应用于有机合成反应 ,取得了较好的结果 [7,8] .其中 MSU-X介孔分子筛结构具有三维排列“Worm-like”孔道特征 ,有利于物料传输 ;相对于 MCM-4 1分子筛在合成方面具有以中性表面活性剂作模板剂且模板剂容易去除等诸多优点[9] .本文采用非离子表面活性剂 C11— 15H2 3— 31(CH2 CH2 O) 9H(AEO9)为模板剂 ,…     

新型钴基介孔分子筛催化剂F-T合成性能和烃分布研究

采用介孔分子筛MSU－1，SBA－12和HMS为载体，制得含钴质量分数为15％的催化剂。在原料气V（H2）／V（CO）＝2．0，T＝473－513K,p=2.0MPa,GHSV=500H^-1的F－T合成条件下，反应活性依Co/HMS,Co/SBA-12,Co/MSU-1顺序降低，高碳烃（C19^ )选择性以Co/HMS最低；Co/MSU-1和Co／SBA-12催化剂介孔结构在反应中相对稳定，Co/HMS介孔结构在反应后完全塌陷。