水溶性CdSe/CdS量子点的合成及其与牛血清蛋白的共轭作用

用巯基乙酸(TGA)作为稳定剂，合成了水溶性的CdSe和核壳结构的CdSe/CdS半导体量子点。吸收光谱和荧光光谱研究表明，核壳结构的CdSe/CdS半导体量子点比单一的CdSe量子点具有更优异的发光特性。用TEM、电子衍射(ED)和XPS分别表征了CdSe和CdSe/CdS纳米微粒的结构、形貌及分散性。红外光谱和核磁共振谱证实了巯基乙酸分子中的硫原子和氧原子与纳米微粒表面的金属离子发生了配位作用。在pH值为7.4的条件下，将合成的CdSe和CdSe/CdS量子点直接与牛血清白蛋白(BSA)相互作用。实验发现，两种量子点均对BSA的荧光产生较强的静态猝灭作用；而BSA对两种量子点的荧光则具有显著的荧光增敏作用，存在BSA时CdSe/CdS量子点的荧光增强是不存在BSA时体系荧光强度的3倍。     

光谱法研究核壳量子点CdTe/CdS与牛血清白蛋白的相互作用

应用荧光光谱、圆二色光谱和紫外吸收光谱等技术研究核壳量子点CdTe/CdS与牛血清白蛋白(BSA)相互作用的结果表明,CdTe/CdS对BSA的荧光猝灭机理为静态猝灭。根据不同温度下量子点对BSA的荧光猝灭作用计算了结合常数、热力学参数,证明了量子点与BSA相互作用力主要是范德华力或氢键作用力。探讨了量子点对BSA构象的影响。     

光谱法研究巯嘌呤与血清白蛋白的相互作用

利用荧光光谱和紫外-可见光谱法研究了巯嘌呤药物与牛血清白蛋白(BSA)和人血清白蛋白(HAS)分子间的相互结合反应.测得巯嘌呤与BSA、HAS反应的结合平衡常数分别为:2.39×103L/mol、1.28×103L/mol.根据Forster非辐射能量转移理论,求算了给体(BSA和HAS)与受体(巯嘌呤)间的结合距离和能量转移效率.用同步荧光法考察了巯嘌呤对BSA和HAS构象的影响.证实了巯嘌呤药物与牛血清白蛋白和人血清白蛋白的相互结合作用为单一的静态猝灭过程.     

壳寡糖及酰化壳寡糖与钕(Ⅲ)配合物的合成及其与牛血清白蛋白相互作用的对比研究

用壳寡糖及酰化壳寡糖与氯化钕反应,合成了壳寡糖-钕和酰化壳寡糖-钕配合物,利用红外光谱(IR)、紫外光谱(UV)手段对其结构进行了表征。在模拟生理条件下,本文采用紫外光谱和荧光光谱研究了两种配合物与牛血清白蛋白(BSA)的相互作用,计算了配合物与BSA的结合常数、结合位点数。荧光光谱结果表明,配合物均可有规律地猝灭BSA的内源荧光,猝灭方式为静态猝灭,壳寡糖-钕和酰化壳寡糖-钕分别与BSA的结合常数为1.33×104L·mol-1和6.95×104L·mol-1,结合位点数为1.05和1.3,说明配合物与BSA均具有较强的结合作用,能够被BSA储存和运输,并且酰化壳寡糖-钕与BSA的结合能力强于壳寡糖-钕。最后采用紫外光谱法对其作用机理进一步确认。因此,酰化壳寡糖-钕可以被BSA存储和运输,有望成为蛋白质荧光探针。     

Pt/三苯胺烯分子纳米复合物的制备及光催化作用

采用乙醇还原法制备了金属Pt/三苯胺烯共轭分子纳米复合物(Pt@DPSDA),通过UV-vis、TEM、FTIR、XRD、荧光、光电化学等方法对纳米复合物进行了表征.三苯胺烯分子通过分子末端羧基与金属Pt纳米粒子表面原子相互作用,形成以金属Pt纳米粒子为核,三苯胺烯分子为壳的核/壳型纳米复合物.光照下纳米复合物中激发态有机分子与金属Pt纳米粒子之间具有较好的电子转移作用,Pt@DPSDA纳米复合物可以作为催化剂在紫外-可见光照下分解水获得氢气.     

电化学置换法制备高Pt利用率的类核壳型Ni-Pt电催化剂(英文)

采用电化学置换法,在VulcanXC-72表面制备得到了活性高和分散性好的纳米Ptshell-Nicore电催化剂.该方法先以NaH2PO2为还原剂,化学沉积得到Ni核,Pt在Ni核表面通过原位置换形成Ni-Pt类核壳型结构.通过透射电镜(TEM)、X射线衍射(XRD)、紫外-可见光光谱(UV-Vis)和循环伏安(CV)测试证明了Pt壳层完全包覆在Ni核的表面.电化学氢吸/脱附测试结果显示,Ptshell-Nicore/XC-72的电化学活性面积为Pt/C(JM)的1.2倍,而其理论Pt担载量只为Pt/C(JM)的40%.这表明,核壳型Ni-Pt纳米粒子可以显著提高Pt的催化活性和利用率.     

不同Pt壳厚度Au_(core)@Pt_(shell)纳米粒子SERS效应

以Au粒子(55nm)为核,抗坏血酸为还原剂,将不同量的Pt沉积在Au核上,制得可控壳层厚度(0.3～6nm)的Pt包Au纳米粒子(Aucore@Ptshell).用紫外-可见吸收光谱、扫描电镜(SEM)、透射电镜(TEM)和电化学循环伏安法等观测Aucore@Ptshell纳米粒子的表面形貌、结构和性能.另以SCN-为探针,考察了Pt壳厚度对Aucore@Ptshell纳米粒子SERS信号的影响.结果表明,SCN-离子的SERS信号强度随Pt壳厚度的增加呈指数衰减,当Pt壳厚度为1.4nm时,Aucore@Ptshel纳米粒子表现出铂良好的电化学性能,又具有较强的SERS活性.     

纳米二氧化硅粒子的制备及对BSA结构的影响

在碱性条件下水解正硅酸乙酯(TEOS)制备纳米二氧化硅(SiO_2)粒子,并采用同步荧光光谱和紫外可见分光光度法探讨了SiO_2对牛血清白蛋白(Bovine Serum Albumin,BSA)结构的影响。结果显示,SiO_2纳米粒子对BSA的结构没有发生显著的影响,这说明在实验条件下,SiO_2不会改变BSA分子的结构和微环境。     

阳离子卟啉与牛血清白蛋白相互作用的光谱研究

采用紫外-可见吸收光谱、圆二色谱和荧光光谱等方法对一系列阳离子卟啉与牛血清白蛋白的相互作用情况进行了研究.研究表明,阳离子卟啉通过静电引力与牛血清白蛋白(BSA)作用,作用位点位于BSA表面.较高的正电荷有利于增强卟啉与BSA的作用力.     

(AgBr)_核·(Ag)_壳纳米粒子的制备及其共振散射光谱研究

以 (AgBr) m 团簇作晶种 ,在柠檬酸钠存在条件下 ,(AgBr) m 团簇表面结合的Ag+被光化学还原而获得土红色的液相 (AgBr) 核·(Ag) 壳 纳米粒子 .研究了 (AgBr) 核·(Ag) 壳 纳米粒子的光谱特性 ,在 51 2nm处有最强共振散射峰 ,在41 0nm处产生一个吸收峰 .结果表明 ,(AgBr) 核·(Ag) 壳 纳米粒子的形成是导致51 2nm共振光散射的根本原因 .     

Characterization of Ag/Pt core-shell nanoparticles by UV-vis absorption, resonance light-scattering techniques

The water-soluble Ag/Pt core-shell nanoparticles were prepared by deposition Pt over Ag colloidal seeds with the seed-growth method using K2PtCl4 with trisodium citrate as reduced agent. The Ag:Pt ratio is varied from 9:1 to 1:3 for synthesizing Pt shell layer of different thickness. A remarkable shift and broadening of Ag surface plasmon band around 410 nm was observed. The contrast of TEM images of Ag/Pt colloids has been obtained. Various techniques, such as transmission electron microscopy (TEM), UV-vis absorption and resonance light-scattering spectroscopy were used to characterize nanoparticles. The data of TEM, UV-vis and resonance light-scattering spectrum all confirm formation of Ag/Pt core-shell nanoparticles. Resonance light-scattering and emission spectrum show the Ag and Ag/Pt core-shell nanoparticles have a nonlinear light-scattering characteristic.     

Heterogeneous Au-Pt nanostructures with enhanced catalytic activity toward oxygen reduction

Heterogeneous Au-Pt nanostructures have been synthesized using a sacrificial template-based approach. Typically, monodispersed Au nanoparticles are prepared first, followed by Ag coating to form core-shell Au-Ag nanoparticles. Next, the galvanic replacement reaction between Ag shells and an aqueous H(2)PtCl(6) solution, whose chemical reaction can be described as 4Ag + PtCl(6)(2-)→ Pt + 4AgCl + 2Cl(-), is carried out at room temperature. Pure Ag shell is transformed into a shell made of Ag/Pt alloy by galvanic replacement. The AgCl formed simultaneously roughens the surface of alloy Ag-Pt shells, which can be manipulated to create a porous Pt surface for oxygen reduction reaction. Finally, Ag and AgCl are removed from core-shell Au-Ag/Pt nanoparticles using bis(p-sulfonatophenyl)phenylphosphane dihydrate dipotassium salt to produce heterogeneous Au-Pt nanostructures. The heterogeneous Au-Pt nanostructures have displayed superior catalytic activity towards oxygen reduction in direct methanol fuel cells because of the electronic coupling effect between the inner-placed Au core and the Pt shell.     

A bis(p-sulfonatophenyl)phenylphosphine-based synthesis of hollow Pt nanospheres

We report herewith the synthesis of hollow Pt nanospheres by using bis(p-sulfonatophenyl)phenylphosphine to selectively remove the Ag cores of Ag-Pt core-shell nanoparticles. Core-shell Ag-Pt nanoparticles were first obtained by the successive reduction method with a discontinuous Pt shell to allow the BSPP passage. Transmission electron microscopy imaging of the core-shell Ag-Pt nanoparticles before and after BSPP dissolution showed little changes in the particle size, indicating that the removal of the Ag cores had occurred isomorphously. The hollow Pt nanospheres, together with the predecessor Ag-Pt core-shell particles of the same size, were transferred from water to toluene and surface modified by dodecylamine in toluene. This allows the catalytic activities of solid and hollow Pt particles in room temperature methanol oxidation reaction to be compared under conditions of identical particle size and the same surface environment. The measured higher specific activity of the Pt hollow nanospheres could then be attributed unambiguously to the larger specific surface area prevalent in the porous hollow structure.     

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.     

Core-shell Ag–Pt nanoparticles: A versatile platform for the synthesis of heterogeneous nanostructures towards catalyzing electrochemical reactions

Heterogeneous nanostructures that are defined as a hybrid structure consisting of two or more nanoscale domains with distinct chemical compositions or physical characteristics have attracted intense efforts in recent years. In this review, we focus on the introduction of a number of heterogeneous nanostructures derived using core-shell Ag–Pt nanoparticles as starting materials, including hollow, dimeric and composite structures and also highlight their application in catalyzing electrochemical reactions, e.g., methanol oxidation reaction and oxygen reduction reaction. This review not only shows the capability of core-shell Ag–Pt nanoparticles in producing various heterogeneous nanostructures as starting templates, but also highlights the structural design or electronic interaction that endows the heterogeneous nanostructures with enhanced catalytic properties either in methanol oxidation or in oxygen reduction. Further, we also make some perspectives for more heterogeneous nanostructures that may be prepared by using core-shell Ag–Pt particles or their derivatives so as to offer the readers the opportunities and challenges in this field.     

Pt@Au/Al2O3核壳纳米粒子的制备和表征及其在催化氧化甲苯中的应用

Customizing core-shell nanostructures is considered to be an efficient approach to improve the catalytic activity of metal nanoparticles. Various physiochemical and green methods have been developed for the synthesis of core-shell structures. In this study, a novel liquid-phase hydrogen reduction method was employed to form core-shell Pt@Au nanoparticles with intimate contact between the Pt and Au particles, without the use of any protective or structure-directing agents. The Pt@Au core-shell nanoparticles were prepared by depositing Au metal onto the Pt core; AuCl⁴⁻ was reduced to Au(0) by H₂ in the presence of Pt nanoparticles. The obtained Pt@Au core-shell structured nanoparticles were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), high-resolution TEM, fast Fourier transform, powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and H₂-temperature programmed reduction (H₂-TPR) analyses. The EDX mapping results for the nanoparticles, as obtained from their scanning transmission electron microscopy images in the high-angle annular dark-field mode, revealed a Pt core with Au particles grown on its surface. Fourier transform measurements were carried out on the high-resolution structure to characterize the Pt@Au nanoparticles. The lattice plane at the center of the nanoparticles corresponded to Pt, while the edge of the particles corresponded to Au. With an increase in the Au content, the intensity of the peak corresponding to Pt in the FTIR spectrum decreased slowly, indicating that the Pt nanoparticles were surrounded by Au nanoparticles, and thus confirming the core-shell structure of the nanoparticles. The XRD results showed that the peak corresponding to Pt shifted gradually toward the Au peak with an increase in the Au content, indicating that the Au particles grew on the Pt seeds; this trend was consistent with the FTIR results. Hence, it can be stated that the Pt@Au core-shell structure was successfully prepared using the liquid-phase hydrogen reduction method. The catalytic activity of the nanoparticles for the oxidation of toluene was evaluated using a fixed-bed reactor under atmospheric pressure. The XPS and H₂-TPR results showed that the Pt₁@Au₁/Al₂O₃ catalyst had the best toluene oxidation activity owing to its lowest reduction temperature, lowest Au 4d & 4f and Pt 4d & 4f binding energies, and highest Au⁰/Au^δ+ and Pt⁰/Pt²⁺ proportions. The Pt₁@Au₂Al₂O₃ catalyst showed high stability under dry and humid conditions. The good catalytic performance and high selectivity of Pt@Au/Al₂O₃ for toluene oxidation could be attributed to the high concentration of adsorbed oxygen species, good low-temperature reducibility, and strong interaction.     

Thermodynamic considerations and computer simulations on the formation of core-shell nanoparticles under electrochemical conditions

We report on thermodynamic modeling and computer simulations on the electrochemical generation of metallic and bimetallic nanoparticles (NPs) by means of quenched molecular dynamics (QMD). The present results suggest that the spontaneous formation of core-shell NPs depends on several factors, i.e. size and shape of the core, chemical composition of the system, and under-/oversaturation conditions. Homo- and heteroatomic prototypical systems were considered. The former systems were Au and Pt. The latter were Ag(core)/Au(shell), Pt(core)/Au(shell), Au(core)/Ag(shell) and Au(core)/Pt(shell).     

Spontaneous formation of core/shell bimetallic nanoparticles: a calorimetric study

We showed recently that low entropy core/shell structured nanoparticles form spontaneously from the physical mixture of a dispersion of Ag nanoparticles and that of another noble metal (Rh, Pd, or Pt) at room temperature. Here we use isothermal titration calorimetry (ITC) and show that the initial step of such a spontaneous process is strongly exothermic. When the alcohol dispersion of poly(N-vinyl-2-pyrrolidone) (PVP)-protected Rh nanoparticles (average diameter 2.3 nm) was titrated into the alcoholic dispersion of PVP-protected Ag nanoparticles, a strong exothermic enthalpy change, DeltaH, was observed: DeltaH = -908 kJ/mol for Ag(S) nanoparticle (average diameter 10.8 nm) and -963 kJ/mol for Ag(L) nanoparticles (average diameter 22.5 nm). The strength of interaction increases in the order of Rh/Ag > Pd/Ag > Pt/Ag. This strong exothermic interaction is considered as a driving force to from low entropy bimetallic nanoparticles by simple mixing of two kinds of monometallic nanoparticles. We show also that exothermic interactions occur between a pair of noble metal nanoparticles themselves by using ITC.     

PMMA纳米球的制备及其银膜包覆技术

采用无皂乳液聚合法制备了单分散、直径为170 nm左右的聚甲基丙烯酸甲酯(PMMA)纳米球, 然后利用3-甲基丙烯酰氧基丙基三甲氧基硅烷(MATS)和3-巯丙基三甲氧基硅烷(MPTMS)对PMMA纳米球进行表面改性, 在其表面包覆一层均匀的巯基, 通过巯基与银离子之间的相互作用, 使银在PMMA纳米球表面成核长大, 从而合成PMMA/Ag纳米球壳粒子. 通过扫描电子显微镜、投射电子显微镜和紫外-可见吸收光谱测试技术对产物性能进行了表征, 研究结果表明, 制备的PMMA/Ag纳米球壳粒子的分散性好、包覆均匀.     

PtRuAgCoNi高熵合金纳米颗粒高效电催化氧化5-羟甲基糠醛

5-羟甲基糠醛(HMF)的电催化氧化被认为是合成2,5-呋喃二甲酸(FDCA)最环保、经济和有效的方法之一,它可作为聚呋喃二甲酸乙二醇酯(PEF)的生物基前体。在这项工作中,我们通过低温溶剂热法合成了PtRuAgCoNi高熵合金纳米颗粒,并在不改变颗粒结构和组成的情况下进行了简易的处理以去除表面活性剂。负载在碳载体上的合金纳米催化剂无论是否含有表面活性剂在HMF电催化氧化为FDCA的过程中都表现出比商业Pt/C更好的催化性能。且表面活性剂的去除可以进一步提高其电催化性能,表明高熵合金纳米粒子在电催化和绿色化学中具有广阔的应用前景。