Quantum-dot-embedded silica nanotubes as nanoprobes for simple and sensitive DNA detection

We have developed a new technique using fluorescent silica nanotubes for simple and sensitive DNA detection. The quantum-dot-embedded silica nanotubes (QD-SNTs) were fabricated by a sol-gel reaction using anodic aluminum silica oxide (AAO) as a template. The fluorescent QD-SNTs of different colors were then immobilized with single-stranded DNA and used as nanoprobes for DNA detection. The optical and structural properties of QD-SNT nanoprobes were examined using photoluminescence spectroscopy, confocal microscopy and transmission electron microscopy (TEM). The QD-SNT nanoprobes were applied to detect dye-labeled target DNA in a solution phase. The obvious color change of the QD-SNT nanoprobes was observed visually under a simple microscope after the successful detection with target DNA. The quantitative analyses indicated that ～ 100 attomole of target DNA in one nanoprobe can generate a distinguishable and observable color change. The detection results also demonstrated that our assay exhibited high specificity, high selectivity and very low nonspecific adsorption. Our simple DNA assay based on QD-SNT nanoprobes is expected to be quite useful for the needs of fast DNA screening and detection applications.     

Template synthesis of boron nitride nanotubes in mesoporous silica SBA-15

Nitride nanotubes (BN-NTs) was synthesized by chemical vapor deposition (CVD) using BCl₃ and NH₃ at relatively low temperature within the channels of mesoporous silica SBA-15. TEM images confirmed the existence of BN-NTs. The BN-NTs were of uniform diameter about 7 nm, which was consistent with the channel diameter of the template SBA-15. Using this approach, it is easy to control the diameter of BN-NTs by adjusting the diameter of the channel of mesoporous silica host.     

可控合成空心多孔氧化硅纳米管/CuS体系应用于化疗-光热靶向治疗

多功能药物载体的设计合成并应用于肿瘤的联合治疗得到了研究人员的广泛关注.本文介绍了一种连接靶向基团的化疗-光热联合治疗纳米平台.首先制备了尺寸可控的平均长度为40、55和150 nm的空心多孔氧化硅纳米管,在表面修饰具有光热功能的硫化铜纳米颗粒,然后连接乳糖酸基团实现肝癌细胞靶向功能.平均长度为40 nm、修饰靶向基团的空心多孔材料显示出良好的生物相容性,且具有最大的HepG2细胞吞噬量.负载盐酸阿霉素的纳米复合材料表现出pH和808 nm近红外激光刺激响应的释放效果.将CuS光热治疗和盐酸阿霉素化疗相结合的方法在体外和体内的抑制肿瘤效果都优于单独治疗.研究结果表明,该纳米复合材料在化疗-光热联合治疗方面具有潜在的应用价值.     

Template-directed one-step synthesis of flowerlike porous carbonated hydroxyapatite spheres

Flowerlike porous carbonated hydroxyapatite (CHAp) spheres were first synthesized by the template-directed self-assembly method in a high-pressure system. The product was characterized via Fourier transform infrared (FT-IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that flowerlike porous CHAp spheres were obtained, that the average granularity of porous CHAp spheres is about 20 μm, that the average aperture is about 1 μm, and that the average thickness of flakes is about 50 nm. Great amounts of OH channels, high special surface area and regular spherical shape imply potential applications.     

Comparison of diatoms, exfoliated graphite, single-wall nanotubes, multiwall nanotubes, and silica for the synthesis of the nanomagnet Mn12

We have completed a preliminary series of experiments that compare the silicate shells of the marine organism diatoms to Single-Wall NanoTubes (SWNT), Multi-Wall NanoTubes (MWNT), Exfoliated Graphite (EG), and silica as templates for producing nanostructures of the manganese acetate cluster Mn12 (Mn12[CH3(COO)16(H2O)4O12].(2)CH3COOH.4H2O). Mn12 exhibits magnetic properties because of the molecular arrangement within the cluster and exhibits no exchange couplings between the individual clusters. Data from scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and laser diffraction are discussed in terms of research that can expand the use of diatoms and other materials as templates for nanostructures.     

二氧化硅纳米管的制备及表征

用表面活性剂十六烷基三甲基溴化铵(C16TMAB)为模板剂,以原硅酸四乙酯(TEOS)为原料,在酸性介质的催化条件下进行水解、缩合,制得了二氧化硅纳米管(平均管径30～60nm),并用FTIR、XRD、TEM对所制备的二氧化硅纳米管进行了表征。此外,讨论了二氧化硅纳米管的形成机理。     

Metallization of biologically inspired silica nanotubes

The desire and need for various types of nanostructures have been met with challenges of feasibility, reproducibility, and long fabrication time. To work towards improved bottom-up methods of nanofabrication, we use bacterial flagella as bio-templates for fabricating silica-mineralized nanotubes, which are ideal for the formation of metal nanoparticles or metal oxide nanoparticles. In this study, we show that silica nanotubes formed from flagella templates can be coated with gold, palladium, and iron oxide nanoparticles under mild aqueous conditions. The process was accomplished through reactions including reductive metallization or oxidative hydrolysis. Morphology and chemical composition were analyzed by transmission electron microscopy and energy dispersive X-ray spectroscopy, respectively. The results from these studies provide evidence for the complete coating of silica nanotubes with metal nanoparticles using a simple and fast procedure.     

Template-directed preparation of two-layer porous NiO film via hydrothermal synthesis for lithium ion batteries

A two-layer porous NiO film is prepared by hydrothermal synthesis method through self-assembled monolayer polystyrene spheres template. The substructure of the NiO film is composed of ordered close-packed hollow-sphere array and the superstructure is made up of randomly NiO nanoflakes. The electrochemical properties are measured by galvanostatic charge/discharge tests and cyclic voltammetric analysis (CV). As anode material for lithium ion batteries, the two-layer porous NiO film exhibits high initial coulombic efficiency of 75%, high reversible capacity and rather good cycling performance. The discharge capacity of the two-layer porous NiO film is 501 mAh g^?1 at 0.5 C after 50 cycles. The two-layer porous architecture is responsible for the enhancement of electrochemical properties.     

Suspension array with shape-coded silica nanotubes for multiplexed immunoassays

A suspension array for multiplexed immunoassays has been developed using shape-coded silica nanotubes (SNTs) as coding materials. Fabricated by multistep anodization template synthesis, each shape-coded SNT has several segments with different reflectance values depending on their diameters and wall thicknesses. Therefore, the code of each SNT can be "read-out" under a conventional optical microscope. The suspension array with shape-coded SNTs has shown high stability and dispersibility in aqueous buffer media and high detection sensitivity. The SNTs have not shown any visible degradation while submerged in aqueous solution for 7 months, the tubular structure and silanol groups on the inner and outer surfaces allow SNTs to disperse evenly in buffer solution, and the detection limit of an IgG protein is about 6 pM with 1.5 x 10(6) SNTs per mL. We have demonstrated the high selectivity of the SNTs suspension array for the detection of multianalytes in the multiplexed immunoassay experiments.     

荧光材料在爆炸物检测中的应用研究

近年来,全球恐怖事件呈现日益频发的趋势,各个国家与国际组织对安全的要求越来越高.使用各种技术检测爆炸物成为了当今安防领域研究的重点.其中,使用荧光猝灭材料检测爆炸物是一种既简单又快捷的方法.本文总结了国内外各类荧光传感器上所使用的荧光材料,并简要叙述了其在实际应用中的性能.     

Novel fabrication of silica nanotubes using multi-walled carbon nanotubes as template

Silica nanotubes were synthesized using multi-walled carbon nanotubes (MWCNTs) as template. The as-obtained samples were characterized by infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscope (FE-SEM) and photoluminescent (PL) spectroscopy. The results indicate that the thickness of the outer walls is about 10 nm and the inner diameter is completely dependent on the size of MWCNTs. The as-fabricated silica nanotubes emit a strong violet light under excitation of 250 nm.     

Molecular imprinting at walls of silica nanotubes for TNT recognition

This paper reports the molecular imprinting at the walls of highly uniform silica nanotubes for the recognition of 2,4,6-trinitrotoluene (TNT). It has been demonstrated that TNT templates were efficiently imprinted into the matrix of silica through the strong acid-base pairing interaction between TNT and 3-aminopropyltriethoxysilane (APTS). TNT-imprinted silica nanotubes were synthesized by the gelation reaction between APTS and tetraethylorthosilicate (TEOS), selectively occurring at the porous walls of APTS-modified alumina membranes. The removal of the original TNT templates leaves the imprinted cavities with covalently anchored amine groups at the cavity walls. A high density of recognition sites with molecular selectivity to the TNT analyte was created at the wall of silica nanotubes. Furthermore, most of these recognition sites are situated at the inside and outside surfaces of tubular walls and in the proximity of the two surfaces due to the ultrathin wall thickness of only 15 nm, providing a better site accessibility and lower mass-transfer resistance. Therefore, greater capacity and faster kinetics of uptaking target species were achieved. The silica nanotube reported herein is an ideal form of material for imprinting various organic or biological molecules toward applications in chemical/biological sensors and bioassay.     

Cellular uptake and cytotoxicity of silica nanotubes

"Template synthesized" silica nanotubes (SNTs) provide unique features such as end functionalization to control drug release, inner voids for loading biomolecules, and distinctive inner and outer surfaces that can be differentially functionalized for targeting and biocompatibility. Very limited information is available about their biological interactions. This work evaluates the influence of size and surface charge of SNTs on cellular toxicity and uptake. Results additionally indicate endocytosis to be one possible mechanism of internalization of SNTs.     

Secondary electrospray ionization-ion mobility spectrometry for explosive vapor detection

The unique capability of secondary electrospray ionization (SESI) as a nonradioactive ionization source to detect analytes in both liquid and gaseous samples was evaluated using aqueous solutions of three common military explosives: cyclo-1,3,5-trimethylene-2,4,6-trinitramine (RDX), nitroglycerin (NG) and pentaerythritol tetranitrate (PETN). The adducts formed between the compounds and their respective dissociation product, RDX.NO(2)(-), NG.NO(3)(-), and PETN.NO(3)(-), gave the most intense signal for the individual compound but were more sensitive to temperature than other species. These autoadducts were identified as RDX.NO(2)(-), NG.NO(3)(-), and PETN.NO(3)(-) and had maximum signal intensity at 137, 100, and 125 degrees C, respectively. The reduced mobility values of the three compounds were constant over the temperature range from 75 to 225 degrees C. The signal-to-noise ratios for RDX, NG, and PETN at 50 mg L(-1) in methanol-water were 340, 270, and 170, respectively, with a nominal noise of 8 +/- 2 pA. In addition to the investigation of autoadduct formation, the concept of doping the ionization source with nonvolatile adduct-forming agents was investigated and described for the first time. The SESI-IMS detection limit for RDX was 116 microg L(-1) in the presence of a traditional volatile chloride dopant and 5.30 microg L(-1) in the presence of a nonvolatile nitrate dopant. In addition to a lower detection limit, the nitrate dopant also produced a greater response sensitivity and a higher limit of linearity than did the traditional volatile chloride dopant.     

一维SiO_2纳米管研究进展

主要综述了SiO2纳米管合成的方法及研究进展,重点介绍模板法合成取得的成果及优势,论述了SiO2纳米管在不同领域的应用,并展望了它的发展前景。     

A facile method to fabricate silica-coated carbon nanotubes and silica nanotubes from carbon nanotubes templates

Silica-coated multiwalled carbon nanotubes (MWCNTs) have been prepared by the sol–gel polymerization of tetraethoxysilane (TEOS) in the presence of the acid-oxidized MWCNTs at room temperature, followed by oxidizing the MWCNTs templates at high temperature in air to produce hollow silica nanotubes. The thickness and architectures of silica shell were well controlled by rationally adjusting the concentration of TEOS, and by adding cationic surfactant as a structure-directing agent. These results also give a clear answer to prove the fact that the structures of spherical silica particles can be fully “copied” to the coating shell and the wall of silica nanotubes when prepared by the same method as the synthesis of silica particles in the presence of templates.