Preparation and photocatalytic activity of eccentric Au-titania core-shell nanoparticles by block copolymer templates

A novel route for a preparation of eccentric Au-titania core-shell nanoparticles using gold nanoparticles (AuNPs) with block copolymer shells as a template is reported. AuNPs with poly(2-vinyl pyridine)-block-poly(ethylene oxide) (PVP-b-PEO) block copolymer shells are first prepared by UV irradiation of the solution of PVP-b-PEO/HAuCl(4) complexes. Then the sol-gel reaction of titanium tetra-isopropoxide (TTIP) selectively on the surfaces of AuNPs leads to Au-titania core-shell composite nanoparticles. The eccentric Au-titania core-shell nanoparticles are obtained from the Au-titania core-shell composite nanoparticles by removal of organic interlayer by UV treatment. Photocatalytic activities of the resulting eccentric core-shell nanoparticles are investigated in terms of the degradation of methylene blue (MB). The results show that the eccentric core-shell structures endow the catalyst with greatly enhanced photocatalytic activity.     

核壳型纳米粒子合成方法及其性能的研究进展

核壳纳米粒子作为复合纳米粒子一个重要的分支,由于其光、磁和催化等方面的优异性能,近年来引起了人们广泛的关注.本文主要介绍了核壳纳米粒子的制备方法及诸多性能,并对核壳纳米粒子的发展进行了展望.     

Electrosprayed core-shell nanoparticles of PVP and shellac for furnishing biphasic controlled release of ferulic acid

Coaxial electrospraying was explored to organize polymer excipients in a core-shell manner for providing biphasic controlled release of active ingredient. With ferulic acid (FA) as a model drug, and shellac and polyvinylpyrrolidone (PVP) as the core and shell polymeric matrices, core-shell nanoparticles were successfully fabricated. A series of tests were carried out to characterize the prepared core-shell nanoparticles and also the nanoparticles prepared using a single fluid electrospraying of the shell or core fluids alone. The core-shell nanoparticles had an average diameter of 530?±?80 nm with clear core-shell structure. The contained FA was converted to an amorphous state both in the core and the shell parts due to the favorable hydrogen bonding between the components. In vitro dissolution tests demonstrated that the core-shell nanoparticles were able to provide the desired biphasic drug-controlled release profiles. Coaxial electrospraying is a useful tool for the development of novel nanodrug delivery systems from polymers.     

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.     

模板法合成核壳功能材料

模板法制备核壳功能材料是材料科学研究领域的一大热点引起了广泛的关注.本文结合本课题组在有机-无机核壳复合纳米粒子(空心球)领域的研究,较系统地评述了目前国内外利用模板法制备核壳粒子的研究进展,并概述了核壳纳米粒子(空心球)的发展前景和应用领域.     

Preparation of asymmetrically nanoparticle-supported, monodisperse composite dumbbells by protruding a smooth polymer bulge from rugged spheres

A novel method is proposed to create asymmetrically nanoparticle-supported, monodisperse composite dumbbells. The method consists of the three steps of double soap-free emulsion polymerizations before and after a heterocoagulation. In the first step, soap-free emulsion polymerization was conducted to cover silica cores with cross-linked poly(methyl methacrylate) (PMMA) shells. Then, positively or negatively charged silica nanoparticles were heterocoagulated with the silica-PMMA core-shell particles. In the heterocoagulations, the nanoparticles surface-modified with a cationic silane coupling agent, 3-aminopropyltriethoxysilane, were used as the positively charged ones, and silica nanoparticles without any treatment were used as the negatively charged ones. In the third step, soap-free polymerizations at different pH values were performed to protrude a polystyrene (PSt) bulge from the core-shell particles supporting the charged silica nanoparticles. In the polymerization, the core-shell particles heterocoagulated with the positively charged silica nanoparticles were aggregated in an acidic condition whereas the silica nanoparticles supported on the core-shell particles were dissolved in a basic condition. For the negatively charged silica nanoparticle, a PSt bulge was successfully protruded from the core-shell particle in acidic and neutral conditions without aggregation of the core-shell particles. The protrusion of the PSt bulge became distinctive when the number of heterocoagulated silica nanoparticles per core-shell particle was increased. Additional heterocoagulation experiments, in which positively or negatively charged magnetite nanoparticles were mixed with the asymmetrically nanoparticle-supported composite dumbbells, confirmed direct exposure of silica nanoparticles to the outer solvent phase.     

A phase-transfer identification of core-shell structures in Ag-Pt nanoparticles

Ag-Pt nanoparticles with a confirmed core-shell structure could only be formed by the successive reduction method using Ag nanoparticles as the seeds. The core-shell structure could be conveniently inferred from the transferability of the particles from water to toluene. Independent measurements by UV-vis spectroscopy, transmission electron microscopy, energy-dispersive X-ray analysis, and X-ray photoelectron spectroscopy were used to validate the experimental results. The reverse order of synthesis using Pt nanoparticles as the seeds did not result in any core-shell product. Instead a physical mixture of Ag nanoparticles and the original Pt seeds was obtained under the same experimental conditions.     

Redox-transmetalation process as a generalized synthetic strategy for core-shell magnetic nanoparticles

Although multicomponent core-shell type nanomaterials are one of the highly desired structural motifs due to their simultaneous multifunctionalities, the fabrication strategy for such nanostructures is still in a primitive stage. Here, we present a redox-transmetalation process that is effective as a general protocol for the fabrication of high quality and well-defined core-shell type bimetallic nanoparticles on the sub-10 nm scale. Various core-shell type nanomaterials including Co@Au, Co@Pd, Co@Pt, and Co@Cu nanoparticles are fabricated via transmetalation reactions. Compared to conventional sequential reduction strategies, this transmetalation process has several advantages for the fabrication of core-shell type nanoparticles: (i) no additional reducing agent is needed and (ii) spontaneous shell layer deposition occurs on top of the core nanoparticle surface and thus prevents self-nucleation of secondarily added metals. We also demonstrate the versatility of these core-shell structures by transferring Co@Au nanoparticles from an organic phase to an aqueous phase via a surface modification process. The nanostructures, magnetic properties, and reaction byproducts of these core-shell nanoparticles are spectroscopically characterized and identified, in part, to confirm the chemical process that promotes the core-shell structure formation.     

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。     

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.     

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。     

A two-color-change, nanoparticle-based method for DNA detection

Herein, we describe the detailed synthesis of Ag/Au core-shell nanoparticles, the surface-functionalization of these particles with thiolated oligonucleotides, and their subsequent use as probes for DNA detection. The Ag/Au core-shell nanoparticles retain the optical properties of the silver core and are easily functionalized with thiolated oligonucleotides due to the presence of the gold shell. As such, the Ag/Au core-shell nanoparticles have optical properties different from their pure gold counterparts and provide another “color” option for target DNA-directed colorimetric detection. Size-matched Ag/Au core-shell and pure gold nanoparticles perform nearly identically in DNA detection and melting experiments, but with distinct optical signatures. Based on this observation, we report the development of a two-color-change method for the detection and simultaneous validation of single-nucleotide polymorphisms in a DNA target using Ag/Au core-shell and pure gold nanoparticle probes.     

CeO2@Au核壳结构纳米粒子的合成与性质研究

采用沉淀法制备了球形CeO2纳米粒子,将其作为核粒子溶液,然后向其中滴加四氯合金酸溶液,在CeO2胶体表面利用柠檬酸钠还原[AuCl4]-离子,得到了CeO2@Au核壳结构纳米粒子。TEM分析表明,CeO2纳米粒子分散效果好,粒径为5 nm;CeO2@Au核壳粒子为球形,无团聚,平均粒径为15 nm。XRD分析表明,CeO2@Au核壳粒子为晶型结构,属于立方晶系,CeO2空间群为O5H-FM3M,Au的空间群为Fm-3m。UV-vis分析发现,CeO2@Au核壳粒子在300和520 nm处呈现出两个比较强的吸收峰,分别对应于CeO2胶体溶液的吸收峰和金粒子的表面等离子共振吸收峰。EDS分析了核壳结构CeO2@Au纳米粒子中存在Ce,O和Au 3种元素。XPS分析表明,Ce3d3/2和Au4f电子结合能与标准结合能相比发生了变化,说明CeO2与Au之间存在着相互作用。     

Facile fabrication of AgCl@polypyrrole-chitosan core-shell nanoparticles and polymeric hollow nanospheres

A one-step sequential method for preparing AgCl@polypyrrole-chitosan core-shell nanoparticles and subsequently the formation of polypyrrole-chitosan hollow nanospheres is reported. The formation of the core and the shell is performed in one reaction medium almost simultaneously. Transmission electron microscopy (TEM) images show the presence of core-shell nanoparticles and hollow nanospheres. Ultraviolet-visible (UV-vis) studies reveal that AgCl was formed first followed by polypyrrole. X-ray diffration (XRD) and UV-vis studies show that AgCl was present in the core-shell nanoparticles and could be removed completely from the core.     

水溶性的CdSe/ZnS纳米微粒的合成及表征

用L-半胱氨酸(Cys)作为稳定剂，合成了水溶性的CdSe/ZnS核壳结构的半导体纳米微粒。吸收光谱和荧光光谱表明，CdSe/ZnS纳米微粒比单一的CdSe纳米粒子具有更优异的发光特性。透射电子显微镜（TEM）、ED和XPS表征了CdSe/ZnS纳米微粒的结构、分散性及形貌。红外光谱证实半胱氨酸分子中的硫原子和氧原子参加了与纳米粒子表面的金属离子的配位作用。     

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.     

DNA-embedded Au/Ag core-shell nanoparticles

Here, we synthesized highly stable DNA-embedded Au/Ag core-shell nanoparticles (NPs) by a straightforward silver-staining of DNA-modified Au nanoparticles (AuNPs); unlike conventional DNA-surface modified NPs that present particle stability issues, DNA-embedded core-shell NPs offer an extraordinary stability with nanoscale controllability of silver shell thickness; these DNA-embedded core-shell NPs show excellent biorecognition properties and Ag shell-thickness-based optical properties, distinctively different from those of a mixture of AuNPs and AgNPs or Ag/Au alloy nanoparticles.     

基于介孔纳米粒子模板合成兼有荧光和近红外发光的稀土核-壳结构纳米材料

利用单分散性良好介孔SiO2纳米粒子为模板,选择Y2O3为基底,同时掺杂可见区红光中心Eu3+和近红外区Er3+(1.54 μm)发光中心,成功制备特殊结构的核壳多功能发光纳米材料. 光谱测试表明这种核壳材料同时具有可见区发光和近红外发光的双重性质. 表明Y2O3可作为红光Eu和近红外发光Er的良好基底材料. 该方法可以大大降低纳米发光材料中稀土元素的使用量,降低发光材料的成本,并且该核壳结构材料密度相对较低,易于分散在有机溶剂或者水中,在药物释放和多功能生物标记等方面有着潜在的应用价值.     

Preparation and electrochemical properties of core-shell Si/SiO nanocomposite as anode material for lithium ion batteries

The Si/SiO nanocomposite was synthesized by a sol–gel method in combination with a following heat-treatment process. It was analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), cyclic voltammetry (CV) and capacity measurement as anode material for lithium ion battery. Si nanoparticles were coated with SiO and a core-shell structured nanocomposite was formed. The core-shell Si/SiO nanocomposite displays better reversibility of lithium insertion/extraction and higher coulomb efficiency than virginal Si nanoparticles. The SiO shell envelops the Si nanoparticles to suppress the aggregation of the nanoparticles during cycling. As a result, the core-shell Si/SiO nanocomposite exhibits better capacity retention than virginal Si nanoparticles, indicating that this is a promising approach to improve the electrochemical performance of nano anode materials for lithium ion battery.     

核壳纳米粒子与牛血清白蛋白表面增强拉曼光谱的研究

本文用表面增强拉曼光谱(SERS)系统地研究了牛血清白蛋白(BSA)与Ag/Pt核壳纳米粒子的相互作用,特别是核壳纳米粒子与被吸附的牛血清白蛋白分子之间的界面作用,并用紫外可见光谱、圆二色光谱(CD)作为辅助手段进一步证实了BSA与核壳纳米粒子的作用状况.通过紫外光谱研究发现,核壳纳米粒子的特征吸收峰的消失表明纳米粒子完全被牛血清白蛋白包覆.用近紫外CD光谱探讨了血清白蛋白的芳基氨基酸(苯丙氨酸、酪氨酸)残基微环境的变化.为探讨牛血清白蛋白与Ag/Pt核壳纳米粒子的作用机理及纳米尺寸的生物效应奠定了理论基础.