High Surface Area Mesoporous Silica Nanoparticles with Tunable Size in the Sub-Micrometer Regime: Insights on the Size and Porosity Control Mechanisms

Mesoporous silica nanostructures (MSNs) attract high interest due to their unique and tunable physical chemical features, including high specific surface area and large pore volume, that hold a great potential in a variety of fields, i.e., adsorption, catalysis, and biomedicine. An essential feature for biomedical application of MSNs is limiting MSN size in the sub-micrometer regime to control uptake and cell viability. However, careful size tuning in such a regime remains still challenging. We aim to tackling this issue by developing two synthetic procedures for MSN size modulation, performed in homogenous aqueous/ethanol solution or two-phase aqueous/ethyl acetate system. Both approaches make use of tetraethyl orthosilicate as precursor, in the presence of cetyltrimethylammonium bromide, as structure-directing agent, and NaOH, as base-catalyst. NaOH catalyzed syntheses usually require high temperature (>80 °C) and large reaction medium volume to trigger MSN formation and limit aggregation. Here, a successful modulation of MSNs size from 40 up to 150 nm is demonstrated to be achieved by purposely balancing synthesis conditions, being able, in addition, to keep reaction temperature not higher than 50 °C (30 °C and 50 °C, respectively) and reaction mixture volume low. Through a comprehensive and in-depth systematic morphological and structural investigation, the mechanism and kinetics that sustain the control of MSNs size in such low dimensional regime are defined, highlighting that modulation of size and pores of the structures are mainly mediated by base concentration, reaction time and temperature and ageing, for the homogenous phase approach, and by temperature for the two-phase synthesis. Finally, an in vitro study is performed on bEnd.3 cells to investigate on the cytotoxicity of the MNSs.     

Photochemical Preparation of Nanoparticles of Ag in Aqueous-Alcoholic Solutions and on the Surface of Mesoporous Silica

Stable nanoparticle colloids of silver were obtained by irradiation of aqueous-alcoholic solutions of AgNO₃ in the presence of mesoporous SiO₂ powder and films modified with benzophenone (BP/SiO₂). Colloidal solutions of Ludox silica were used to stabilize the photochemically produced nanoparticles of silver in solution. Formation of nanoparticles of Ag on the surface of mesoporous silica occurred on irradiation of SiO₂ modified with silver ions (Ag⁺/SiO₂) in the presence of benzophenone solution.__________Translated from Teoreticheskaya i Eksperimental’naya Khimiya, Vol. 41, No. 2, pp. 100–104, March–April, 2005.     

氨水诱导硅核自组装制备介孔SiO2

在无模板剂的条件下,通过控制氨水用量,利用正硅酸乙酯水解制备了粒径约20 nm的SiO2初级粒子;随后用过量氨水诱导SiO2初级粒子交联生长,得到孔径在10~50 nm、孔容达2.05 cm3.g-1的介孔SiO2;考察了介孔SiO2的吸附性能.结果表明,所制备的介孔SiO2具有优良的吸附性能.     

MCM-41型介孔二氧化硅纳米颗粒的制备及其在DNA生物传感器中的应用

MCM-41型介孔二氧化硅纳米颗粒具有独特的结构特征和理化性质,能够与DNA、信号探针以及多种活性纳米颗粒结合,在DNA生物传感器中得到了广泛应用.其中,球形和薄膜形的MCM-41型介孔二氧化硅具有高负载量、孔口控释和高比表面积等优点,能有效装载各种信号探针、控制粒子的扩散以及固定大量活性纳米颗粒,可大大提高DNA生物...     

高比表面积有序介孔氧化铝的制备与表征

采用溶胶-凝胶法以非离子表面活性剂PEO-PPO-PEO三嵌段共聚物F127为模板剂, 以异丙醇铝为铝源, 以异丙醇为溶剂, 成功地制备出比表面积为485 m2/g、孔径分布窄(2~20 nm)、孔容在1.2 cm3/g以上和孔道呈蠕虫状且具有一定有序性的介孔氧化铝. 采用BET, TEM, XRD和TG多种测试技术对产物性能进行了表征. 探讨了水铝比、醇水混合溶液的滴加速度、反应时间、水浴温度、陈化温度及陈化时间等条件对合成的有序介孔氧化铝结构的影响.     

Drug Encapsulation and Release by Mesoporous Silica Nanoparticles: The Effect of Surface Functional Groups

Mesoporous silica nanoparticles (MSNPs) have been widely used as drug carriers for stimuli‐responsive drug delivery. Herein, a catalysis screening technique was adopted for analyzing the effects of chain length, terminal group, and density of disulfide‐appended functional ligands on the surface of MSNPs on drug‐loading capacity and glutathione‐triggered drug‐release kinetics. The ligand with an intermediate length (5 carbon atoms) and a bulky terminal group (cyclohexyl) that complexes with theβ‐cyclodextrin ring showed the highest drug loading capacity as well as good release kinetics. In addition, decreasing the surface coverage of the functional ligands led to an enhancement in drug release. In vitro drug‐delivery experiments on a melanoma cell line (B16‐F10) by using the functionalized MSNPs further supported the conclusion. The results obtained may serve as a general guide for developing more effective MSNP systems for drug delivery.     

高比表面积TiO_2纳米管的制备与表征

采用一种简单的化学合成方法制备TiO2 纳米管 ,并采用TEM、XRD等分析手段对TiO2 纳米管进行了表征 .考察了不同温度对TiO2 纳米管比表面积及孔体积的影响 .结果表明 ,采用该方法制得的TiO2 纳米管 ,比用模板法制备的TiO2 纳米管的管径小、管形均匀 .此纳米管的比表面积大于 2 0 0m2 /g ,孔体积最大可达 0 .784cm3 /g .     

紫外光辐照下以PAMAM树形分子为模板制备Ag纳米簇及光致发光性能研究

以G5.0-OH PAMAM树形分子为模板,用紫外光辐照法制备银纳米簇.用透射电子显微镜、紫外-可见吸收光谱和共振散射光谱等对所制备的银纳米簇进行了表征.结果表明:用紫外光辐照法可以制备尺寸分布均匀、稳定的银纳米簇;且辐照时间、PAMAM树形分子的浓度及Ag⁺/PAMAM树形分子的摩尔比都会对所制备的银纳米簇产生较大的影响.由于所制备的银纳米簇的粒径小于树形分子的流体力学半径,表明树形分子起到了“内模板”作用.同时研究了银纳米簇的尺寸对其光致发光性能的影响,发现通过调节银纳米簇的尺寸可实现其光致发光的可调性.     

磁性核壳介孔氧化硅微球的制备与应用

磁性核壳介孔氧化硅微球作为一种新型功能复合材料,已成为众多研究领域的一个研究热点。本文综述了近年来利用模板法合成磁性核壳介孔氧化硅微球的研究进展,重点阐述了溶胶-凝胶法和微乳液法在实心微球和中空微球制备中的应用。介绍了磁性介孔二氧化硅微球在蛋白质、DNA分离,靶向药物传输等生物医学上的应用以及磁性酸催化、加氢催化、纳米贵金属催化、光催化等催化领域的应用,并对其未来的发展趋势做了展望。     

高比表面积窄孔分布氧化铝的制备研究 Ⅱ.加硅的影响

 采用pH摆动法，以硫酸铝为铝源，以氢氧化钠为碱沉淀剂，考察了添加SiO2对沉淀氧化铝物性的影响．通过孔结构分析、粒度测定和电镜观察等证实，加入少量SiO2可使沉淀粒子分散、变小，颗粒相对均匀，从而提高了氧化铝的比表面积和孔集中的程度．当加入2．5％的SiO时，pH仅摆动2次，即可使氧化铝粉体的孔体积高达1．2ml／g，比表面积达380m2／g．这类氧化铝的孔结构适宜，粒子小，易直接成型为孔径集中和耐压强度好的载体，故用于重油高压加氢脱氮反应具有较好的性能．沉淀时酸侧pH值降低，尽管沉淀氧化铝的孔径向较小的方面集中，但此时沉淀粒子呈紧密堆积，颗粒变大，比表面积下降，氧化铝沉淀粒子的结构发生改变．不同结构的氧化铝表现出不同的催化活性．     

耐温高比表面氧化锡制备

对比了氨水或NaOH共沉淀和尿素水解均相沉淀三种不同的制备方法,以及NaOH沉淀不 同的老化条件下制备的SnO2粉体材料的比表面以及烧结特性.实验结果表明,减慢成核速度 及在母液中高温老化都有利于提高初始粒子的晶化程度和焙烧后样品的比表面.以NaOH共沉 淀,在100 ℃下回流老化48 h制备的SnO2具有最大的比表面和最好的烧结性能,在500、800 和1000 ℃焙烧后比表面分别为94、75和53 m2穏-1.初始粒子晶化程度的提高以及材料中 硬团聚的减小是改善SnO2烧结性能的主要原因.     

高温高表面氧化铝新材料的制备化学研究——La、Ba共添加对氧化铝热稳定性的影响

本文用镧、钢共同添加并使用溶胶－凝胶法制得改性氧化铝,详细研究了在保持La含量为5．2 wt%时,Ba添加量的改变对氧化铝热稳定性的影响,实验结果表明镧,钡元素的共添加能大大增加氧化铝的热稳定性,从而使氧化铝在高温下保持高比表面积,体相中同时添加5．2wt%La和2wt?以及5．2wt%La和7wt?能使氧化铝保持较好的热稳定性,样品经1100℃煅烧20h后,比表面分别达100．8m^2.g^-1和92．3m^2.g^-1.通过对添加物与氧化铝保持高温高表面能力的内在联系的探讨,得出Ba、La元素的添加提高氧化铝热稳定性的原因主要表现在两方面,一是抑制氧化铝的微孔烧结速度,二是阻止了氧化铝向α相的转变。     

具有高比表面的介孔Co-SiO2微球的合成与表征

在碱性条件下,利用十六烷基三甲基溴化铵(CTAB)为结构导向剂,以含氨基有机硅烷与过渡金属离子Co(Ⅱ)形成的配合物Co(Ⅲ)-APTMOS为金属离子前驱体,合成了含金属元素钴的介孔Co-SiO₂微球.运用XRD,TEM以及N₂-吸附等技术对所制备的产物进行了表征.结果表明,产物为具有高比表面、孔道无序的介孔微球.同时阐述了金属离子以配合物Co-APTMOS形式加入反应体系的优越性.     

高比表面积磷化钼的制备

 利用柠檬酸与钼的螯合作用,采用柠檬酸-程序升温还原联合法制备了高比表面积的磷化钼,并考察了制备条件的影响. 结果表明,当柠檬酸与钼的摩尔比为2.0时,得到的磷化钼比表面积高达122.0 m2/g. 采用该方法还可制得较高比表面积的磷化镍和磷化钴.     

制备高比表面积碳化硅的几种影响因素

采用溶胶凝胶法，以蔗糖和正硅酸乙酯(TEOS)为原料，草酸为TEOS水解的催化剂，制备均相碳化硅前驱体，在氩气氛和高温条件下(1 350～1 600 ℃)将碳化硅先驱体进行碳热还原，制备出高比表面积的SiC。考察了水/TEOS物质的量的比、碳/硅物质的量的比及镍盐等因素对碳化硅比表面积的影响。结果表明，当n_water/n_TEOS=7.5，n_C/n_Si=4时，适宜的镍催化剂(n_Ni/n_TEOS=0.005)，凝胶形成的时间最短，镍盐的加入可使碳热还原温度降低200 ℃。     

Preparation and Biosafety Evaluation of the Peptide Dendron Functionalized Mesoporous Silica Nanohybrid

Mesoporous silica nanoparticles (MSNs) have been extensively studied and proposed as promising candidates for numerous biomedical applications.In this study,we report the design,preparation,characterization and biosafety evaluation of peptide dendron functionalized mesoporous silica nanohybrid.This nanohybrid was prepared by surface modification of MSNs via click reaction of azido-MSNs with alkynyl peptide dendrons,and characterized by TEM,SEM,TGA,dynamic light scattering (DLS).In vitro cytotoxicity of the nanohybrid was evaluated against different cell lines by CCK-8 assay.The in vivo toxicity evaluation was measured by body weight shift,blood routine test and histological analysis,suggesting that the peptide functionalized nanohybrid possessed good biocompatibility due to the non-observed significant side effects to normal organs of healthy mice.Overall,considering our results we believe that the peptide dendron functionalized mesoporous silica nanohybrid is very promising in further biomedical applications.     

Facile Fabrication of Well‐Dispersed Pt Nanoparticles in Mesoporous Silica with Large Open Spaces and Their Catalytic Applications

In this paper, a facile strategy is reported for the preparation of well‐dispersed Pt nanoparticles in ordered mesoporous silica (Pt@OMS) by using a hybrid mesoporous phenolic resin‐silica nanocomposite as the parent material. The phenolic resin polymer is proposed herein to be the key in preventing the aggregation of Pt nanoparticles during their formation process and making contributions both to enhance the surface area and enlarge the pore size of the support. The Pt@OMS proves to be a highly active and stable catalyst for both gas‐phase oxidation of CO and liquid‐phase hydrogenation of 4‐nitrophenol. This work might open new avenues for the preparation of noble metal nanoparticles in mesoporous silica with unique structures for catalytic applications.     

介孔氧化铝的制备及应用

本文介绍了介孔氧化铝(MA)的各种制备方法,概括了MA制备的分析表征方法,如TEM、SAED、XRD、LAXRD、气体吸附-脱附、DT-TGA等。通过平均孔径、比表面积、MA形貌等因素,讨论和总结了制备方法、铝源、模板剂、反应物配比、pH值和后处理方法等对MA制备和热稳定性的影响,综述了近年来MA的研究和应用进展,并对今后的研究方向进行了展望。