Mesoporous silica-magnetite nanocomposite synthesized by using a neutral surfactant

Magnetite nanoparticles coated by mesoporous silica were synthesized by an alternative chemical route using a neutral surfactant and without the application of any functionalization method. The magnetite (Fe(3)O(4)) nanoparticles were prepared by precipitation from aqueous media, and then coated with mesoporous silica by using nonionic block copolymer surfactants as the structure-directing agents. The mesoporous SiO(2)-coated Fe(3)O(4) samples were characterized by x-ray diffraction, Fourier-transform infrared spectroscopy, N(2) adsorption-desorption isotherms, transmission electron microscopy, (57)Fe M?ssbauer spectroscopy, and vibrating sample magnetometry. Our results revealed that the magnetite nanoparticles are completely coated by well-ordered mesoporous silica with free pores and stable (～8?nm thick) pore walls, and that the structural and magnetic properties of the Fe(3)O(4) nanoparticles are preserved in the applied synthesis route.     

空心羟基磷灰石亚微球/壳聚糖可注射水凝胶的制备及表征

采用W/O/W复乳法制备空心羟基磷灰石(HAP)亚微球,将空心HAP亚微球均匀分布在壳聚糖/甘油磷酸钠(CS/GP)体系中制备可注射HAP/CS水凝胶(gel 1),同时制备可注射CS水凝胶(gel 2).用X射线衍射仪、场发射透射电镜、红外光谱、扫描电镜对空心HAP亚微球和水凝胶进行了表征,并比较分析了两种溶胶的成胶...     

Magnetic properties of magnetite nanoparticles coated with mesoporous silica by sonochemical method

In this paper we present the magnetic properties of mesoporous silica-coated Fe₃O₄ nanoparticles. The coating of magnetite nanoparticles with mesoporous silica shell was performed under ultrasonic irradiation. The obtained mesoporous silica-coated magnetite nanoparticles were characterized by powder X-ray diffraction, focused ion beam-scanning electron microscopy, nitrogen adsorption-desorption isotherms and vibrating sample magnetometer. The hysteretic behavior was studied using first-order reversal curves diagrams. The X-ray diffraction result indicates that the extreme chemical and physical conditions created by acoustic cavitations have an insignificant effect on crystallographic structural characteristic of magnetite nanoparticles. Changes in the coercivity distributions of the magnetite nanoparticles were observed on the first-order reversal curves diagrams for the samples with coated particles compared with the samples containing uncoated particles of magnetite. The coated particles show an increased most probable coercivity of about 20% compared with the uncoated particles which can be associated with an increased anisotropy due to coating even if the interaction field distribution measured on the diagrams are virtually identical for coated/uncoated samples.     

Synthesis of hollow spheres with mesoporous silica nanoparticles shell

Hollow spheres with mesoporous silica nanoparticles shell were synthesized with the use of cetyltrimethylammonium bromide (CTAB) and polystyrene (PS) hollow spheres as dual templates. The key to this study is that the uneven surface of the template provides nucleation sites for mesoporous nanoparticles, resulting in the formation of hollow spheres with mesoporous silica nanoparticles shell. The final products with hierarchical mesopores can be obtained through a simple one-step approach.     

介孔SiO2负载和包覆的纳米金属颗粒的制备与研究

制备了以SiO2为核、介孔SiO2为壳的核-壳颗粒负载纳米金属颗粒以及介孔SiO2壳层包覆SiO2负载的纳米金属颗粒。结果表明,十六烷基三甲基溴化胺(CTAB)作为模板剂,有助于介孔SiO2壳层包覆SiO2核的结构形成,介孔SiO2壳层的孔径方向垂直于SiO2核的表面;在聚乙烯吡咯烷酮(PVP)的稳定作用下,Pt纳米颗粒能均匀地分布在介孔SiO2壳层的表面。单分散SiO2颗粒经过3-氨丙基三乙氧基硅烷(APS)功能化后,可负载纳米金属颗粒。进一步研究表明,以SiO2负载纳米金属颗粒为核,NH3.H2O,乙醇和水为分散剂,CTAB为模板剂,正硅酸乙酯(TEOS)为硅源,还能制备介孔SiO2壳包覆SiO2负载的纳米金属颗粒,而且介孔SiO2壳层的厚度可通过TEOS的含量调节。     

Halide ion-induced formation of single crystalline mesoporous PtPd bimetallic nanoparticles with hollow interiors for electrochemical methanol and ethanol oxidation reaction

We demonstrate a facile hydrothermal one-pot synthesis method for producing single crystalline mesoporous PtPd bimetallic nanopartides with a hollow interior and porous surface structure in the presence of Br-and I-ions.The formation process analysis indicated that the coexistence of Br-and I-ions is responsible for the formation of the novel bimetallic nanoparticles.The changes in the reduction potential of Pt and Pd metal ions achieved by the coordination with different halide ions resulted in the formation of hollow interiors as a galvanic reaction between Pd2+ and Pt4+ ions occurred.In addition,the size of the mesoporous PtPd nanoparticles can be well controlled by slightly changing the amount of I-ions used.The electrochemical tests indicated that the assynthesized single crystalline mesoporous PtPd hollow nanoparticles exhibited enhanced catalytic properties toward methanol and ethanol oxidation reactions as compared with the commercial Pt black and Pt/C materials.     

高分散AlMCM-41纳米硅铝介孔分子筛的制备

以正硅酸乙脂（TEOS）为硅源,十六烷基三甲基溴化铵（CTAB）为表面活性剂,添加聚乙二醇（PEG）和聚乙烯吡咯烷酮（PVP）为分散剂,合成了A1MCM-41纳米硅铝介孔分子筛,运用XRD、N2吸脱附、TEM对所得样品进行表征,结果表明,添7DPEG和PVP均能显著改善A1M—CM-41纳米硅铝介孔分子筛的分散性,但是PVP的分散效果明显好于PEG,这是因为,PVP链上吡咯基中电负性的氧原子与分子筛颗粒表面的羟基形成氢键,更易吸附在颗粒的表面,提高颗粒的分散性。     

Introducing CTAB into CdTe/PVP nanofibers enhances the photoluminescence intensity of CdTe nanoparticles

The major objective of this work is focused on the preparation and characterization of the photoluminescence (PL) property of poly(vinyl pyrrolidone) (PVP) embedding CdTe nanoparticles. The CdTe nanoparticles were generated via the reaction of Cd²⁺ with NaHTe and then stabilized by thiolglycolic acid (TGA). In the process of preparing CdTe/PVP nanofibers by electrospinning, a surfactant, cetyltrimethylammonium bromide (CTAB), was introduced to prevent CdTe nanoparticles from congregating inside the PVP nanofibers. Then the results of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED) showed that the average diameter of CdTe/PVP nanofibers was 300 (± 61) nm, in which the CdTe nanoparticles were incorporated into the PVP nanofibers homogeneously. Finally, the PL spectra proved that the photoluminescence intensity of CdTe/PVP nanofibers was enhanced by the addition of CTAB.     

Effects of PVP and KCl concentrations on the synthesis of gold nanoparticles using a solution plasma processing

Application of plasma in an aqueous environment, so called Solution Plasma Processing (SPP) is a recent development. Solution plasma processing for the synthesis of gold nanoparticles by reducing HAuCl₄ in the presence of Polyvinylpyrrolidone (PVP) and potassium chloride (KCl) was investigated in this work. Effects of PVP and KCl concentrations on the size and the shape of the gold nanoparticles in SPP were studied using a UV-vis nir spectrophotometer, and high resolution transmission electron microscopy (HRTEM). The results showed that the shape and size of the nanoparticles were affected by various KCl and PVP concentrations. The average particle size of the gold nanoparticles synthesized by SPP decreased with an increase in PVP concentration and the particle shape became more spherical with the addition of KCl. The HRTEM results indicated that gold nanoparticles with a diameter less than 10 nm were single crystals, while particles with a diameter greater than 15 nm were polycrystalline.     

Wrap-bake-peel process for nanostructural transformation from beta-FeOOH nanorods to biocompatible iron oxide nanocapsules

The thermal treatment of nanostructured materials to improve their properties generally results in undesirable aggregation and sintering. Here, we report on a novel wrap-bake-peel process, which involves silica coating, heat treatment and finally the removal of the silica layer, to transform the phases and structures of nanostructured materials while preserving their nanostructural characteristics. We demonstrate, as a proof-of-concept, the fabrication of water-dispersible and biocompatible hollow iron oxide nanocapsules by applying this wrap-bake-peel process to spindle-shaped akagenite (beta-FeOOH) nanoparticles. Depending on the heat treatment conditions, hollow nanocapsules of either haematite or magnetite were produced. The synthesized water-dispersible magnetite nanocapsules were successfully used not only as a drug-delivery vehicle, but also as a T2 magnetic resonance imaging contrast agent. The current process is generally applicable, and was used to transform heterostructured FePt nanoparticles to high-temperature face-centred-tetragonal-phase FePt alloy nanocrystals.     

超顺磁单分散性Fe3O4磁纳米粒的制备及性能表征

具有超顺磁单分散性的Fe₃O₄磁纳米粒在生物医学材料领域有着广泛的用途. 本研究在水、乙醇和甲苯混合体系74℃回流的条件下制备了具有超顺磁性的表面含油酸的Fe₃O₄磁纳米粒,研究了制备过程中OH^-浓度的变化对磁纳米粒的表面性能、粒径、分散性及磁性能的影响, 并对其机理进行了初步探讨. 采用XRD、FTIR、DLS、TEM和VSM等手段对制备的磁纳米粒进行表征. 结果表明, 当NaOH/Fe(Ⅱ)摩尔比＜8时, Fe₃O₄磁纳米粒表面含油酸可良好地分散于非极性溶剂中, NaOH的加入对磁纳米粒的粒径和饱和磁化强度等性能无明显影响;而当NaOH/Fe(Ⅱ)摩尔比≥8时, Fe₃O₄磁纳米粒仅能分散于水等极性溶剂中, 饱和磁化强度虽可增至40A·m²/kg, 但为多分散且易团聚.     

Mesoporous magnetic hollow nanoparticles-protein carriers for lysosome escaping and cytosolic delivery

It is important for a controlled release system to determine whether nanoparticles can penetrate cell membranes and deliver protein into the nuclear or cytosolic compartments of cells, and thus function as carriers. Here, we prepared different functionalized mesoporous magnetic hollow nanoparticles (MMHs) and chose bovine serum albumin (BSA) as a model protein to detect the intracellular trafficking of MMHs. The results showed that MMHs modified with amino groups (AMMHs) were efficient in protein loading and that the loading was dependent on the pH, temperature and ionic strength. Furthermore, we found that the AMMHs not only transported BSA into the cells but also released the BSA carried into the nuclear or cytosolic compartments of the cells. In addition, the nanoparticles were biocompatible, and the encapsulation of BSA in AMMHs did not affect their bioactivity. Taken together, AMMHs are excellent carriers for releasing protein into the cytosol and nucleus, and they have the potential to be used in a controlled release system.     

Hollow CoNi alloy submicrospheres consisting of CoNi nanoplatelets: Facile synthesis and magnetic properties

Magnetic alloy micro/nanostructures with controllable size and morphology have drawn intensive attention due to their interesting physicochemical properties and potential applications in micro/nanodevices. In this letter, CoNi hollow submicrospheres consisting of CoNi nanoplatelets with a thickness of ca. 10 nm have been successfully synthesized via a facile wet-chemical approach free of any template or surfactant. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images indicate that the diameter and shell thickness of the as-prepared hollow submicrosphere are ca. 600 nm and 200 nm, respectively. Elemental maps demonstrate that Co and Ni elements are distributed homogeneously in the CoNi hollow submicrosphere. Magnetic measurement reveals that the hollow submicrospheres display ferromagnetic behaviour with a coercivity of 109.5 Oe.     

介孔TiO2/WO3空心球的制备及其可见光光催化性能

以硫酸氧钛和偏钨酸铵为前驱体, 以柠檬酸作为络合剂, 采用喷雾干燥-高温煅烧两步法制备了介孔TiO₂/WO₃空心球复合材料。利用SEM、TEM、BET、XRD、UV-Vis DRS等手段对样品的形貌、微结构、比表面积、晶相组成和光学性能进行了表征和分析, 以亚甲基蓝为模拟降解物考察其光催化性能。结果表明: 复合材料为介孔空心球状结构, 球体分散好, 直径主要分布在1 μm左右; 球壁由纳米颗粒和空隙构成, 随着煅烧温度的升高, 颗粒粒径不断增大, 空隙孔径不断增大。性能研究结果表明, TiO₂与WO₃复合后, 样品对光的吸收范围扩展到了可见光区域, 这有利于提高太阳光的利用率; 当前驱体中WO₃含量为3mol%, 样品的煅烧温度为500℃时, 复合材料具有最好的光催化性能: 对亚甲基蓝降解率可达99.1%, 而P25的降解率仅为29.5%。     

Facile synthesis by a covalent binding reaction for pH‐responsive drug release of carboxylated chitosan coated hollow mesoporous silica nanoparticles

In this study, a promising drug nano‐carrier system consisting of mono‐dispersed and pH sensitive carboxylated chitosan‐hollow mesoporous silica nanoparticles (Ccs‐HMSNs) suitable for the treatment of malignant cells was synthesised and investigated. At neutral pH, the Ccs molecules are orderly aggregated state, which could effectively hinder the release of loaded drug molecules. However, in slightly acidic environment, Ccs chains are heavily and flexibly entangled in gel state, which would enhance the subsequent controlled release of the loaded drug. Using doxorubicin hydrochloride (DOX•HCl) as the drug model, their results demonstrated that the system had an excellent loading efficiency (64.74 μg/mg Ccs‐HMSNs) and exhibited a pH‐sensitive release behaviour. Furthermore, confocal laser scanning microscopy revealed that the Ccs‐HMSNs nanocomposite could effectively deliver and release DOX•HCl to the nucleus of HeLa cells, thereby inducing apoptosis. In addition, MTT assay also confirmed that DOX•HCl loaded Ccs‐HMSNs (DOX•HCl@Ccs‐HMSNs) exhibited a good anticancer effect on HeLa cells with a time‐dependent manner. Finally, haemolysis experiment showed Ccs‐HMSNs had no haemolytic activity at all the tested concentrations (5–320 μg/mL). Thus, this biocompatible and effective nano‐carrier system will have potential applications in controllable drug delivery and cancer therapy.Inspec keywords: drug delivery systems, mesoporous materials, silicon compounds, nanoparticles, nanocomposites, nanofabrication, drugs, nanomedicine, biomedical materials, pH, aggregation, gels, optical microscopy, cellular biophysics, cancer, filled polymersOther keywords: facile synthesis, covalent binding reaction, pH‐responsive drug release, carboxylated chitosan coated hollow mesoporous silica nanoparticles, drug nanocarrier system, monodispersed carboxylated chitosan‐hollow mesoporous silica nanoparticles, pH sensitive carboxylated chitosan‐hollow mesoporous silica nanoparticles, malignant cell treatment, neutral pH, orderly aggregated state, loaded drug molecules, acidic environment, gel state, doxorubicin hydrochloride, drug model, confocal laser scanning microscopy, nanocomposite, HeLa cells, apoptosis, MTT assay, anticancer effect, haemolysis experiment, biocompatible nanocarrier system, drug delivery, cancer therapy, SiO₂      

α-Ni(OH)2/SiO2核壳以及α-Ni(OH)2空心微球的制备及表征

采用以正硅酸乙酯(TEOS)水解为基础的硅溶胶种子生长法制备了粒径约为270nm的近单分散二氧化硅球型颗粒.采用一种新的溶液生长法,以氢氟酸作为溶液中镍离子配位剂,加入氨水调节溶液pH值的同时作为镍离子补充配位剂,60℃水浴条件下在已制得SiO2微球表面均匀包覆α-Ni(OH)₂得到Ni(OH)₂/SiO₂核壳结构,Ni(OH)₂壳层厚度约为35nm.结合多步包覆法提高Ni(OH)₂壳层厚度,三次包覆后壳层厚度达到约100nm,四次包覆后约为140nm.采用20wt％的强碱NaOH溶液对三次包覆后的Ni(OH)₂/SiO₂核壳结构进行处理,得到了壳层厚度约为95nm的α-Ni(OH)₂空心微球.空心微球具有较大的比表面积为141.06m²/g.     

Preparation of hollow TiC nanoparticles by the two-stage refluxing method

The two-stage refluxing method was applied to prepare hollow TiC nanoparticles. In this method, after refluxing the hydrous TiO₂ and ethanol, the precipitate and n-dedocane were refluxed to obtain the refluxing-derived precursor. The precursor was heat-treated at 1300 °C for 1 h and hollow TiC nanoparticles could be achieved. It is found that the pore size of the hollow TiC nanoparticles ranges from 3 to 76 nm and the mean pore size is 26.776 nm. The formation of the hollow structure is due to that the mesoporous channels of the precursor confine the carbide's growth inside it. In comparison with commercial TiC nanocrystals, the hollow TiC nanoparticles have higher specific surface area and pore volume significantly.     

Solid-CdS and hollow-ZnS porous submicrospheres: Direct preparation by C-S decomposition of thiol via solvothermal processing

Porous solid-CdS or hollow-ZnS submicrospheres (SMSs) were prepared by reaction of 2-mercaptoethanol as S-source with Cd²⁺ or Zn²⁺ in ethanol using solvothermal route. Without any alkaline, solid-CdS SMSs with an average diameter of 440 nm were obtained and their size distribution in the range of 390-490 nm is above 80%; With the addition of alkaline, single crystal CdS nanorods with high-temperature-stable hexagonal phase were synthesized. With or without poly(N-vinyl-2-pyrrolidone) (PVP), solid-CdS SMSs can be prepared, but the addition of the PVP leads to the preparation of relative uniform CdS-SMSs. Hollow-ZnS SMSs with an average diameter of 340 nm were obtained under the existence of alkaline. The longer reaction time hardly influences on the size of the hollow-ZnS SMSs. More or less amount of alkaline directly influences the morphology of final product. Close-ring-shaped ZnS was prepared under the existence of less alkaline. With or without PVP under preparation reaction, hollow-ZnS SMSs can also be synthesized. Thus, during preparation of either CdS or ZnS, the PVP function is not as template, but as surfactant. The BET measurement results show that the special surface areas of solid-CdS and hollow-ZnS SMSs are 25.56 and 83.55 m²/g, respectively. The adsorption of methylene blue shows that the hollow-ZnS SMSs have very strong adsorption and decomposition ability.     

微纳分级结构碳酸钙中空微球的可控制备

以CaCl₂和Na₂CO₃为反应原料, 以聚乙烯吡咯烷酮(PVP)和十二烷基磺酸钠(SDSN)为模板剂, 在50℃采用化学沉淀反应, 干燥、煅烧后成功制备了具有微纳分级结构的CaCO₃中空微球。采用扫描电子显微镜、透射电子显微镜和X射线衍射等检测手段对所制备的样品形貌、结构进行了表征, 结果显示：所制备的微纳分级结构CaCO₃中空微球直径为4~6 μm, 壳壁由直径约60 nm的CaCO₃颗粒组成, 壳层厚度约为200 nm, CaCO₃中空微球晶相组成为方解石和球霰石的共混体。同时, 在反应温度为50℃、PVP添加量为0.4 g, SDSN浓度为0.1 mol/L的条件下, 所制备的微纳分级结构CaCO₃中空微球分散性好, 且形貌比较完整。     

Study of mesoporous silica/magnetite systems in drug controlled release

Ordered mesoporous materials like SBA-15 have a network of channels and pores with well-defined size in the nanoscale range. This particular silica matrix pore architecture makes them suitable for hosting a broad variety of compounds in very promising materials in a range of applications, including drug release magnetic carriers. In this work, magnetic nanoparticles embedded into mesoporous silica were prepared in two steps: first, magnetite was synthesized by oxidation-precipitation method, and next, the magnetic nanoparticles were coated with mesoporous silica by using nonionic block copolymer surfactants as structure-directing agents. The materials were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), N(2) adsorption, and scanning electron microscopy (SEM). The influence of magnetic nanoparticles on drug release kinetics was studied with cisplatin, carboplatin, and atenolol under in vitro conditions in the absence and in the presence of an external magnetic field (0.25 T) by using NdFeB permanent magnet. The constant external magnetic field did not affect drug release significantly. The low-frequency alternating magnetic field had a large influence on the cisplatin release profile.