AucoreCoshell纳米粒子的制备、表征及其表面增强拉曼光谱研究

在乙醇体系中和在制备好的Au纳米粒子表面, 用水合肼还原钴盐制备Co壳, 首次通过化学还原法制得核壳结构的Au-Co纳米粒子, 并通过控制钴盐的投料, 得到不同包裹层厚度的AucoreCoshell纳米粒子. 用扫描电子显微镜(SEM)和电化学循环伏安法(CV)等测试方法对其进行表征, 并用吡啶(Py)作为探针分子研究了其SERS效应.     

疏水高分子介导可动芯SiO2杂化纳米粒子的仿生合成

在疏水高分子胶体模板——含氟丙烯酸酯(FA)共聚物乳胶粒中引入能够介导SiO2原位沉积的聚胺催化活性点-甲基丙烯酰氧乙基三甲基氯化铵(DMC),以四甲氧基硅烷(TMOS)为硅源,在环境条件下可控合成了核壳型FA共聚物/SiO2杂化纳米粒子.高温煅烧除去聚合物核质,可得到中空的SiO2纳米粒子,结合FTIR、EDX、TGA以及XPS等表征数据印证了SiO2的沉积主要发生在聚合物模板的表面.进一步考察了反应条件,如聚胺功能单体DMC的浓度、TMOS的浓度以及反应时间对SiO2杂化纳米粒子的形貌与组成的影响.实验结果表明增加DMC或者TMOS的浓度,适当延长反应时间,均可增加SiO2粒子的沉积速率,导致SiO2壳层的厚度增加,并且杂化粒子的形貌由凹陷多褶皱的核壳结构向可动芯结构转变.由于FA共聚物模板的强疏水性,增加有机核层和无机壳层间的不相容排斥,最终导致核壳层间空腔的形成,得到含可动芯的核壳型SiO2杂化粒子.     

吲哚类菁染料Cy3嵌入的核壳荧光纳米颗粒的制备及其性质研究

以蛋白质或多肽修饰的吲哚类菁染料Cy3为内核, 采用实验条件简单的油包水反相微乳液方法成核, 通过正硅酸乙酯水解形成的网状二氧化硅包壳的方法制备吲哚类菁染料Cy3嵌入的核壳荧光纳米颗粒. 考察了以不同等电点的蛋白质和多肽修饰的Cy3为内核材料对吲哚类菁染料Cy3嵌入的核壳荧光纳米颗粒制备的影响. 结果表明, 分别采用人免疫球蛋白(IgG)或多聚赖氨酸修饰的Cy3为内核材料, 都能制备荧光强度高、荧光稳定性强和染料泄漏极少的Cy3嵌入的核壳荧光纳米颗粒. 进一步对Cy3嵌入的核壳荧光纳米颗粒进行了表征, 并将基于这一新型的荧光纳米颗粒建立起来的生物标记方法初步应用于流感病毒DNA的检测, 其检测线性范围为3.18×10-10～1.27×10-9 mol/L, 检测下限为3.51×10-10 mol/L, 相关系数r为0.986 5.     

金@银核壳纳米粒子的制备和形貌的精确控制及其表面增强拉曼光谱性能

用种子生长法制备了金@银核壳结构的纳米粒子。在制备过程中通过控制氯金酸的浓度和硝酸银的体积,得到了不同粒径的金核和不同厚度的银壳构成的核壳纳米粒子。从而得到了具有不同SERS性能的金@银核壳纳米粒子。选取具有最佳SERS性能的金@银核壳纳米粒子实现了对罗丹明6G的微量检测。     

金@银核壳纳米粒子的制备和形貌的精确控制及其表面增强拉曼光谱性能

用种子生长法制备了金@银核壳结构的纳米粒子。在制备过程中通过控制氯金酸的浓度和硝酸银的体积,得到了不同粒径的金核和不同厚度的银壳构成的核壳纳米粒子。从而得到了具有不同SERS性能的金@银核壳纳米粒子。并选取具有最佳SERS性能的金@银核壳纳米粒子实现了对罗丹明6G的微量检测。     

Au/Ag核-壳结构纳米粒子的制备及其SERS效应

随着大量有关表面增强拉曼散射 (SERS)的实验和理论研究的开展 ,金属纳米粒子作为一类重要的 SERS增强介质 ,已引起了人们浓厚的研究兴趣 [1] .而 Au和 Ag作为最常用的活性基底物质 ,更是研究的热点 [2 ,3 ] .最近 ,美国印第安那大学的 Nie等 [4 ] 在单个银纳米粒子上 ,观察到高达 1 0 14 ～ 1 0 15的SERS因子 .同时 ,他们的另外一项工作表明银纳米粒子的形状和大小对 SERS活性有很大影响 [5] .但是 ,由于 Ag溶胶制备的重复性较差 ,且粒度分布不均匀 ,通过控制银颗粒大小而调控 SERS活性是相当困难的[6] .与 Ag相比 ,Au在可见光…     

Fluorescence Enhancement of IgG-FITC Based on Surface Plasmon Resonance of Ag@SiO2 Nanoparticles as Application of Biomarker

Ag@SiO₂ nanoparticles with the core-shell structure have been prepared, of which the silver core was about 50 nm and the thickness of silica shell was approximately 10 nm. In slightly alkaline aqueous solution (pH = 8), through electrostatic force between cationic polymer PDDA (i.e., poly-diallyldimethylammonium chloride) and the obtained Ag@SiO₂ nanoparticles, PDDA molecules were fixed on the surface of Ag@SiO₂ nanoparticles. The prepared Ag@SiO₂/PDDA nanoparticles have both rich positive surface charges and rich micro-holes of silica shell. Based on micro-hole adsorption, the small molecule FITC (i.e., fluorescein isothiocyanate) marking on IgG (i.e., immunoglobulin) was adsorbed into the rich microholes of silica shell; at the same time, the negatively charge macromolecule IgG marked by FITC was firmly fixed on the rich positive charges surface of Ag@SiO₂/PDDA nanoparticles by electrostatic interaction. And then, Ag@SiO₂/PDDA/IgG-FITC fluorescent nanoparticles with the SPR fluorescence enhancement were prepared. The shell-type SiO₂/PDDA/IgG-FITC nanoparticles were obtained by dissolving the silver core in the prepared core-shell Ag@SiO₂/PDDA/IgG-FITC nanoparticles by using H₂O₂. Compared with the shell-type nanoparticles, the fluorescence intensity of Ag@SiO₂/PDDA/IgG-FITC was enhanced 1.7 times. The prepared Ag@SiO₂/PDDA/IgG-FITC nanoparticles have both SPR-based fluorescence enhancement ability and the surface distributing IgG–based obvious advantages including good biocompatibility and easy marking with other biomolecules.     

Preparation of Hybrid Nanocapsules

Hybrid nanoparticles with a polystyrene core and a hybrid copolymer shell were used to produce hybrid nanocapsules by dissolving the polystyrene core from the previously elaborated core-shell particles. Following previous works, the core-shell particles were prepared by emulsion polymerization of styrene and subsequent addition of γ-methacryloxy propyl trimethoxy silane (MPS) to produce the shell by copolymerization reaction of MPS with the residual styrene. Core extraction was performed by diluting the core-shell particles in an excess of tetrahydrofuran (THF). Two procedures were investigated to separate the dissolved polymer chains from the nanocapsules. In the first procedure, the polymer was isolated by successive centrifugation and redispersion in THF, whereas in the second procedure, the free polymer chains were removed by dialysis. The polymer molecular weight was optimized in order to promote dissolution of the polymer chains and allow them to diffuse through the shell.     

Aucore Ptshell纳米粒子对甲醇氧化的电催化性能研究

应用两步化学还原法制备不同厚度的AucorePtshell纳米粒子,经紫外可见光谱(UV-V is)、透射电子显微镜(TEM)表征.该金纳米颗粒经化学还原包裹铂后平均粒径明显增大,调节金与铂的含量可获得不同包裹厚度的AucorePtshell纳米粒子.循环伏安法研究表明,粒径为70~80 nm的AucorePtshell纳米粒子对甲醇的氧化具有较好的电催化活性,并且其电催化性能随着电位循环扫描次数的增加而增强.     

Production of uniform-sized polymer core-shell microcapsules by coaxial electrospraying

Spherical polymeric core-shell microcapsules in uniform size were produced by electrospraying with a coaxial nozzle setup. Contrary to the usual coaxial setup, the inner nozzle was slightly bent to touch the inside wall of the outer nozzle. A polymer solution for the core was introduced through the outer nozzle, and the other solution for the shell was supplied through the inner nozzle. The setup greatly increased reproduction of the same results. As a proof of the concept, core-shell microcapsules consisting of a PS or PMMA core and a PCL shell (PS@PCL, PMMA@PCL) were produced. When the volumetric feed rate of the shell-forming PCL solution was higher than that of the core-forming PS or PMMA solution the core-shell structures in uniform size were readily obtained. In contrast, irregular morphologies were observed when the feed rate of the PCL solution was slower or equal to that of the PS or PMMA solution. The size of the colloid was dependent on the relative feed ratio between the polymer solutions as well as the magnitude of applied voltage.     

AucorePtshell础纳米粒子对甲醇氧化的电催化性能研究

应用两步化学还原法制备不同厚度的AucorePtshell纳米粒子，经紫外可见光谱（UV-Vis）、透射电子显微镜（TEM）表征．该金纳米颗粒经化学还原包裹铂后平均粒径明显增大，调节金与铂的含量可获得不同包裹厚度的AucorePtshell纳米粒子．循环伏安法研究表明，粒径为70-80nm的AucorePtshell纳米粒子对甲醇的氧化具有较好的电催化活性，并且其电催化性能随着电位循环扫描次数的增加而增强．     

Characterization and preparation of core–shell type nanoparticle for encapsulation of anticancer drug

The aim of this study is to prepare delivery vehicles of paclitaxel using low molecular weight water-soluble chitosan (LMWSC) and evaluate them as an anticancer drug delivery system. LMWSC was modified with methoxy polyethylene glycol (LMWSC-MPEG, ChitoPEG), and then it was conjugated with cholesterol (LMWSC-MPEG-Chol). Core–shell type LMWSC-MPEG-Chol nanoparticles (LMWSC-NPs) were prepared by the dialysis method, and the core–shell structure was confirmed by ¹H NMR analysis. To this polymer, paclitaxel was encapsulated and core–shell type nanoparticles were prepared. The release tests indicated that release of paclitaxel from the core–shell type nanoparticles and its transport across the dialysis membrane was slower than dialysis of free paclitaxel. In a cytotoxicity study using CT26 cell, the paclitaxel-encapsulated core–shell type nanoparticles (LMWSC-NPs) showed a toxicity against tumor cells similar to paclitaxel itself. The results of a tumor inhibition test with CT26 implanted upon mouse tumor models in vivo indicated that the application of a dose of 10 mg/kg of LMWSC-NPT showed a superior survival rate, and a slower tumor growth than when paclitaxel alone was administered, although the tumor growth and survival rate were not significantly changed at a dose of 2 mg/kg. The LMWSC-NPT dose above 10 mg/kg showed a superior antitumor activity.     

A new simple method to prepare hollow PES microspheres

A new simple method for the formation of hollow polyethersulfone (PES) microspheres was reported in this paper. Coaxial electrospraying equipment and nonsolvent precipitating bath were used to produce hollow microspheres in one step. The properties of the core solution affected the formation of hollow PES microspheres. To form hollow microspheres in one step, the core solution should be removed directly by a nonsolvent. Additionally, the core solution should also be used to occupy the internal space of microspheres and form a supporting layer at the interface between the core solution and the shell solution. The supporting layer formed by the micro-phase that was caused by the phase separation of the core or shell solution was the key factor for the formation of hollow PES microspheres. The performance of hollow microspheres produced by this method was excellent. This method provided a new simple way to form hollow polymer microspheres and can be extended to other polymers to prepare hollow microspheres in one step.     

Magnetic properties of monodispersed Ni/NiO core-shell nanoparticles

We have recently developed a method to fabricate monodispersed Ni/NiO core-shell nanoparticles by pulsed laser ablation. In this report, the size-dependent magnetic properties of monodispersed Ni/NiO core-shell nanoparticles were investigated. These nanoparticles were formed in two steps. The first was to fabricate a series of monodispersed Ni nanoparticles of 5 to 20 nm in diameter using a combination of laser ablation and size classification by a low-pressure differential mobility analyzer (DMA). The second step was to oxidize the surfaces of the Ni particles in situ to form core-shell structures. A superconducting quantum interference device (SQUID) magnetometer was used to measure the magnetic properties of nanostructured films prepared by depositing the nanoparticles at room temperature. Ferromagnetism was observed in the magnetic hysteresis loop of the nanostructured films composed of core-shell nanoparticles with core diameters smaller than the superparamagnetic limit, which suggests the spin of Ni core was weakly exchange coupled with antiferromagnetic NiO shell. In contrast, smaller nanoparticles with core diameters of 3.0 nm exhibited superparamagnetism. The drastic change in the hysteresis loops between field-deposited and zero-field-deposited samples was attributable to the strong anisotropy that developed during the magnetic-field-assisted nanostructuring process.     

Tunable Amphiphilic Poly(Ether-Anhydride) Gel Nanoparticles for the Delivery of Hydrophobic Drugs

Summary: Biodegradable amphiphilic poly(ether-anhydride) gel nanoparticles (GNPs) with a hydrophobic crosslinked core and a hydrophilic PEG shell have been prepared from amphiphilic photo-crosslinkable ether-anhydride macromers via microemulsion photo-polymerization. The properties of the GNPs, such as degradability, size and drug-loading capacity, were investigated by tailoring the length of PEG chains in macromers from 400 to 4000 and by the addition of a hydrophobic photo-crosslinkable monomer: stearic monoacrylic anhydride (MSA). TEM showed that the GNPs were spherical in shape with a core-shell structure when MSA was added. The GNPs were used as the carriers to enhance the solubility of hydrophobic drugs. Indomethacin (IND) as a model drug was entrapped in the hydrophobic crosslinked core by an in situ embedding method. Results showed that IND maintained chemically intact during the formulation process, and its dissolution rate were improved compared to those of the pure IND. The GNPs prepared from PEG macromer (molecular weight: 4000) with the addition of MSA exhibited the zero-order release behavior, which is potentially useful to control the release of hydrophobic drugs.     

Boronic Acid functionalized core-shell polymer nanoparticles prepared by distillation precipitation polymerization for glycopeptide enrichment

The boronic acid-functionalized core-shell polymer nanoparticles, poly(N,N-methylenebisacrylamide-co-methacrylic acid)@4-vinylphenylboronic acid (poly(MBA-co-MAA)@VPBA), were successfully synthesized for enriching glycosylated peptides. Such nanoparticles were composed of a hydrophilic polymer core prepared by distillation precipitation polymerization (DPP) and a boronic acid-functionalized shell designed for capturing glycopeptides. Owing to the relatively large amount of residual vinyl groups introduced by DPP on the core surface, the VPBA monomer was coated with high efficiency, working as the shell. Moreover, the overall polymerization route, especially the use of DPP, made the synthesis of nanoparticles facile and time-saving. With the poly(MBA-co-MAA)@VPBA nanoparticles, 18?glycopeptides from horseradish peroxidase (HRP) digest were captured and identified by MALDI-TOF mass spectrometric analysis, relative to eight glycopeptides enriched by using commercially available meta-aminophenylboronic acid agarose under the same conditions. When the concentration of the HRP digest was decreased to as low as 5?nmol, glycopeptides could still be selectively isolated by the prepared nanoparticles. Our results demonstrated that the synthetic poly(MBA-co-MAA)@VPBA nanoparticles might be a promising selective enrichment material for glycoproteome analysis.     

无皂乳液聚合法制备聚甲基丙烯酸甲酯包覆厚度可控的纳米核-壳二氧化硅微球

用改进的Stöber法和无皂乳液聚合法制备窄分布的二氧化硅/PMMA核-壳纳米微球. 用改进的Stöber法将3-乙氧基甲基丙烯酸丙基硅烷(MPS)修饰在纳米的二氧化硅表面后, 用无皂乳液聚合法制备核-壳纳米微球. 该法简单有效且得到厚度均匀的聚合物包覆层. 随着单体MMA用量的增加, 用动态光散射法测量, PMMA壳层的厚度从6.4 nm增加到96.3 nm. 热重分析表明, PMMA的含量从22.25%增加到93.41%. 扫描电子显微镜和透射电子显微镜结果表明, 得到的是包覆良好、表面光滑的核-壳无机/聚合物纳米微球.     

Sensoric potential of gold�Csilver core�Cshell nanoparticles

The sensitivities of five different core-shell nanostructures were investigated towards changes in the refractive index of the surrounding medium. The shift of the localized surface plasmon resonance (LSPR) maximum served as a measure of the (respective) sensitivity. Thus, gold-silver core-shell nanoparticles (NPs) were prepared with different shell thicknesses in a two-step chemical process without the use of any (possibly disturbing) surfactants. The measurements were supported by ultramicroscopic images in order to size the resulting core-shell structures. When compared to sensitivities of nanostructures reported in the literature with those of the (roughly spherical) gold-silver core-shell NPs, the latter showed comparable (or even higher) sensitivities than gold nanorods. The experimental finding is supported by theoretical calculation of optical properties of such core-shell NP. Extinction spectra of ideal spherical and deformed core-shell NPs with various core/shell sizes were calculated, and the presence of an optimal silver shell thickness with increased sensitivity was confirmed. This effect is explained by the existence of two overlapping plasmon bands in the NP, which change their relative intensity upon change of refractive index. Results of this research show a possibility of improving LSPR sensor by adding an extra metallic layer of certain thickness.     

An approach to core–shell nanostructured materials with high colloidal and chemical stability: synthesis, characterization and mechanistic evaluation

Silver–polypyrrole (PPy) core–shell nanoparticles have been fabricated by a facile one-step “green” synthesis using silver nitrate as an oxidant and soluble starch as an environmentally benign stabilizer and co-reducing agent. The morphology and optical properties of the particles were significantly affected by the reaction temperature, soluble starch concentration, and ratio of pyrrole monomer to AgNO₃ oxidant. The core–shell nanoparticles exhibited outstanding dispersive properties in deionized water due to residual starch, as compared with PPy nanoparticles in which starch was absent. The mechanism of core–shell nanoparticle formation was elucidated through TEM imaging vs. reaction time. The colloidal and chemical stability of the nanoparticles was demonstrated in a variety of solvents, including acids, bases, and ionic and organic solvents, through monitoring the localized surface plasmon resonance of the nanoparticles. Furthermore, the catalytic properties of these silver–PPy core–shell nanoparticles were also demonstrated.

Preparation and electrochromic property of covalently bonded WO3/polyvinylimidazole core-shell microspheres

Covalently bonded WO3/polyvinylimidazole (C-WO3/PVI) core-shell microspheres in sizes of 250 nm were prepared. The microstructures of C-WO3/PVI core-shell microspheres were characterized by TEM, IR, and XRD. It is found that the chemical and thermal stabilities of C-WO3/PVI core-shell microspheres are higher than those of pure WO3 nanoparticles and noncovalently bonded WO3/polyvinylimidazole (NC-WO3/PVI) core-shell microspheres. This is attributed to the strengthened interaction of the WO3 nanoparticle core and the PVI shell resulting from the interaction of covalent bonds. The electrochromic device made by the C-WO3/PVI core-shell microspheres was studied. It is suggested that the C-WO3/PVI core-shell microspheres exhibit better electrochromic properties than pure WO3 nanoparticles or NC-WO3/PVI core-shell microspheres.