基于SnO2/TiO2/Au NPs纳米复合材料发展光电化学方法特异性检测唾液酸

制备了氧化铟锡（ITO）/二氧化锡（SnO₂）/二氧化钛（TiO₂）/金纳米粒子（Au NPs）纳米复合电极（ITO/SnO₂/TiO₂/Au NPs）,并利用它发展了可以选择性检测唾液酸（SA）的光电化学（PEC）法.采用旋涂法制备了ITO/SnO₂电极,并通过静电纺丝和磁控溅射技术在ITO/SnO₂表面原位合成了TiO₂纳米纤维和Au NPs.与单纯SnO₂比,ITO/SnO₂/TiO₂/Au NPs纳米复合电极的光电性能显著提高.这可能与Au NPs的局域表面等离子体共振效应（LSPR）和TiO₂/SnO₂异质结之间的协同作用密切相关.之后,通过金硫键（Au-S）将四巯基苯硼酸（4-MPBA）修饰在ITO/SnO₂/TiO₂/Au NPs电极表面,利用4-MPBA和SA之间的非特异性酯化反应,发展了可以特异性检测SA的PEC传感平台.     

Au NPs decorated TiO2 nanotubes array candidate for UV photodetectors

This work reports the Au nanoparticles (NPs) deposited on TiO2 nanotubes (NTs) which were successfully synthesized by a simple two-step anodization method. This fabrication process is notable for a simple and inexpensive method for obtaining pure TiO2 NTs and Au NPs deposited TiO2 NTs. The prepared samples were characterized by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and I-V curve. We found that the size of Au NPs can be controlled by changing the bias voltage during the deposition. The photodetectors of Au NPs/TiO2 devices showed good wavelength selectivity with high photocurrent as compared to pure TiO2 NTs devices. Subsequently, Au NPs deposited on TiO2 NTs at bias voltage of 70 V was potentially used in fabrication of UV photodetector. At this applied voltage, a high density of Au NPs was uniformly deposited on TiO2 NTs. As a result, it enables a high photocurrent and great responsivity in UV region. It is suggested that the Au NPs deposited TiO2 NTs device shows good promise for UV photodetectors with possibility to fine-tune properties in both UV and visible regions and is worthy of further investigation.     

Plasmonic coupling in single flower-like gold nanoparticle assemblies

Localized surface plasmon resonance (LSPR) arises when light interacts with metallic nanoparticles (NPs). When nanoparticles (NPs) assemble together, the plasmon coupling effect between the NPs often leads to new features in the LSPR of the assembled structure. Understanding the plasmon coupling in the complex assemblies will greatly benefit the development of new plasmonic devices. Here we demonstrate the fabrication of a 3D structure using two different sized Au NPs as building blocks. This 3D structure was achieved by manipulating the binding efficiency of ligands linking the NPs, and proper choice of the NP size. The assembled structure is flower-like structure, with one 130 nm Au NP in the center, and several 40 nm Au NPs attaching as “petals”. Single particle dark-field scattering measurements of the individual assemblies were performed, together with electrodynamics simulations. The experimental and theoretical studies show that, the plasmonic coupling lead to broadening of the LSPR and additional peaks, depending on the number and 3D arrangement of the 40 nm NPs around the center 130 nm NP.     

单分散Au/ZnO纳米球的可控制备及气敏性能研究

以二水合醋酸锌和二甘醇为原料,采用微波法制备ZnO单分散纳米球;采用柠檬酸还原法制备Au纳米颗粒,并通过静电作用将金纳米颗粒修饰在ZnO纳米球上制备Au/ZnO气敏材料.XRD结果证明了多晶ZnO的形成以及金属Au的成功修饰;FESEM和TEM观察到ZnO单分散纳米球由纳米颗粒组装而成,粒径约280nm;PL光谱对合成材料的晶体缺陷进行了提取,在此基础上深入讨论了Au/ZnO的增敏机理.气敏测试结果显示,Au/ZnO纳米球比未修饰的ZnO纳米球对丙酮具有更好的选择性与更低的检测温度,在体积分数为1×10-6下仍具有较强的气敏响应.     

金/二氧化硅中空核壳纳米球的制备与表征

采用水热反应法和正硅酸乙酯水解法制备出核壳结构的Au/C纳米球颗粒以及夹层结构的Au/C/SiO<,2>纳米球颗粒,在空气中锻烧将Au/C/SiO<,2>夹层结构中的碳层除去,得到内部带有可移动纳米金核、壳层厚度约为20 nM的中空Au/SiO<,2>纳米球颗粒.用透射电子显微镜对所制得的纳米微球的形貌进行表征,并用红...     

抗坏血酸在纳米金/石墨烯复合物修饰电极上的电化学行为研究

根据Hummers方法制备了石墨烯(GR),通过在石墨烯修饰玻碳电极(GR/GCE)表面电沉积纳米金粒子(Au NPs)制备了纳米金/石墨烯复合物修饰电极(Au NPs/GR/GCE),采用扫描电镜表征了电极形貌;并用循环伏安法研究了抗坏血酸(AA)在此修饰电极上的电化学行为,在p H=4.0的磷酸氢二钠-柠檬酸缓冲溶液中,AA在复合物修饰电极上产生一灵敏的氧化峰,氧化峰电流显著高于裸玻碳电极(GCE)和石墨烯修饰玻碳电极(GR/GCE);在优化实验条件下,建立了循环伏安法测定AA的方法,氧化峰电流与AA的浓度在7⁵00μmol/L和1500μmol/L和1³0 mmol/L范围内呈良好的线性,检出限为5μmol/L(信噪比=3);用该方法测定维生素C片中AA的含量,回收率在97.69%30 mmol/L范围内呈良好的线性,检出限为5μmol/L(信噪比=3);用该方法测定维生素C片中AA的含量,回收率在97.69%¹03.5%之间.     

Au, Ag and Au:Ag colloidal nanoparticles synthesized by pulsed laser ablation as SERS substrates

Chemically pure colloidal suspensions of gold and silver nanoparticles were synthesized using pulsed laser ablation.The dependence of laser fl uence on the surface plasmon characteristics of the nanoparticles was investigated.Au:Ag colloidal suspensions were prepared by mixing highly monodisperse Au and Ag nanocolloids.The plasmon band of these mixtures was found to be highly sensitive to Au:Ag concentration ratio and wavelength of the laser beam used in the ablation process.The Au:Ag mixture consists of almost spherical shaped nanostructures with a tendency to join with adjacent ones.The surface enhanced Raman scattering activity of the Au,Ag and Au:Ag colloidal suspensions was tested using crystal violet as probe molecules.Enhancement in Raman signal obtained with Au:Ag substrates was found to be promising and strongly depends on its plasmon characteristics.     

Upconversion luminescence properties of Mn2+-doped NaYF4:Yb/Er nanoparticles

NaYF₄:Yb/Er upconversion nanoparticles doped with Mn²⁺ were synthesized by hydrothermal method. The upconversion photoluminescence measured by 975 nm continuous wave laser indicates that the as-synthesized samples generated green and red color emission with various intensity ratio ranging from 3.25 to 548.35, which is highly correlative to the dopant concentration of Mn²⁺. However, there is no red emission enhancement observed in Cu²⁺-doped NaYF₄:Yb/Er nanoparticles.     

Mesoporous iron oxide-silica supported gold catalysts for low-temperature CO oxidation

Mesoporous iron oxide-silica composite with a high silica content was synthesized by hydrothermal method, and another composite material with a high iron content was obtained by etching part of silica in alkaline solution. Gold catalysts were loaded onto both composites by a deposition-precipitation method, and used for CO oxidation. The samples were characterized by Brumauer- Emmet-Teller （BET）, X-ray diffraction （XRD）, X-ray photoelectron spectra （XPS）, transmission electron micro- scope （TEM） and scanning electron microscope （SEM） techniques. Both composites had high specific surface areas and were amorphous. The Au nanoparticles dispersed on the surface of the composites existed in metallic state. Composite with high silica content was not suitable for Au loading, and its supported gold catalyst showed poor per- formance in catalytic reaction. In contrast, composite with high iron content allowed efficient Au loading, and CO could be oxidized completely at low temperature on its supported gold catalyst. The effects of deposition-precipi- tation pH values on Au loading and activity of the catalyst were investigated, and the results indicated that Au loading was the highest and the catalyst was the most active for CO oxidation when the synthesis pH was adjusted to 8.     

Au纳米粒子对ZnO分级结构的气敏特性影响

采用化学浴法制备了花形ZnO纳米棒簇，将平均粒径约40 nm的Au纳米粒子引入ZnO表面得到不同Au修饰量的Au/ZnO复合结构.Uv-vis吸收光谱表明，在Au和ZnO之间存在着作用力使Au的吸收光谱产生红移，这种作用力的存在使复合结构的气敏性能得到了较显著的改善.当Au修饰的质量分数为6%时，复合材料的气敏性能最高，对丙酮气体的灵敏度较纯ZnO提高了约17倍.     

Preparation of porous chitosan-poly（acrylic acid）- calcium phosphate hybrid nanoparticles via mineralization

In this work, the preparation of chitosan-poly（acrylic acid）-calcium phosphate hybrid nanoparticles （CS-PAA-CaP NP） based on the mineralization of calcium phosphate （CAP） on the surface of chitosan-poly （acrylic acid） nanoparticles （CS-PAA NPs） was reported. CS-PAA-CaP NPs were achieved by directly adding ammonia to the aqueous solution of CS-PAA nanoparticles or by thermal decomposition of urea in the aqueous solution of CS-PAA nanoparticles, resulting in the mineralization of CaP on the surface of CS-PAA NPs. Through these two routes, especially using urea as a pH-regulator, the precipitation of CS-PAA NPs, a common occurrence in basic environment, was avoided. The size, morphology and ingredient of CS-PAA-CaP hybrid nanoparticles were characterized by dynamic light scattering （DLS）, transmission electron microscope （TEM）, scanning electron microscope （SEM）, thermogravimetry analysis （TGA） and X-ray diffractometer （XRD）. When urea was used as the pH regulator to facilitate the mineralization during the thermal urea decomposition procedure, regular CS-PAA-CaP hybrid nanoparticles with a porosity-structural CaP shells and 400-600 nm size were obtained. TGA result revealed that the hybrid NPs contained approximately 23% inorganic component, which was consistent with the ratio of starting materials. The XRD spectra of hybrid nanoparticles in- dicated that dicalcium phosphate （DCP： CaHPO4） crystal was a dominant component of mineralization. The porous structure of the CS-PAA-CaP hybrid NPs might be greatly useful in pharmaceutical and other medical applications.     

A multiple-labelling method for cells using Au nanoparticles with different shapes

An important and difficult issue is simultaneously identifying the detailed locations of various molecules on the cell surface, as this identification requires a synergistic effect between more than one molecule in a living cell. Au nanoparticles (NPs) with different shapes can be readily recognised under low vacuum scanning electron microscopy (lvSEM). Anisotropic Au nanorods (NRs) possess unique surface plasmon resonance (SPR) properties, which can be further utilised for two photon luminescence (TPL) and other optical imaging techniques. In this paper, Au NRs and Au nanooctahedra (Au NOs) are introduced as biomarkers for ICAM-1 and Integrin β1. Combined with the advantages of lvSEM, this multiple-labelling method is a new method for studying the interactions between specific, functional molecules.     

Synthesis and characterization of red-emitting Yb/Ho-CaSiO3 upconversion phosphors

Host material plays an important role in obtaining efficient photon upconversion and downshifting luminescence. Generally, fluoride and oxyfluoride glasses-based materials are used for high-efficiency photon upconversion. However, the poor thermal stability of fluoride glasses and the toxicity of fluorine ions limit their applications. In this report, Yb/Ho-doped CaSiO₃ wollastonite phosphors have been demonstrated as efficient red-emitting upconversion phosphors. The phosphors have been synthesized by microwave hydrothermal process followed by heat treatment at 1050 ?°C in the air environment. 2M phase of the β-wollastonite has been confirmed by X-ray diffraction and Raman spectroscopy while the existence of the Yb and Ho dopants in the CaSiO₃ lattice has been confirmed by X-ray photoelectron spectroscopy. The synthesized samples showed strong red upconversion emission centered at 662 ?nm and near-infrared downshifting emissions at 2016 ?nm upon 980 ?nm excitation. The emissions were found to depend significantly on the Ho concentration. Temporal evolution of the main emission bands was investigated to show that the energy transfer upconversion from Yb to Ho ions was responsible for the efficient upconversion and downshifting phenomenon.     

连续还原法制备Au/Fe3O4纳米复合粒子

采用共沉淀法制备20～40nm的Fe₃O₄颗粒。在Fe₃O₄悬浮液中分别利用柠檬酸钠单独作为还原剂、四羟甲基氯化磷（THPC）和抗坏血酸共同作为还原剂还原HAuCl₄,生成10～90nm的Au纳米颗粒,形成Au/Fe₃O₄复合颗粒。通过透射电子显微镜和紫外分光光度计对Au/Fe₃O₄进行表征,研究还原剂种类对Au/Fe₃O₄粒径、形貌和分散性的影响,结果表明：柠檬酸钠为还原剂时,生成Au纳米颗粒的反应主要在Fe₃O₄纳米颗粒表面进行,Au纳米颗粒的负载量随柠檬酸钠用量增加而减少,粒径在28.08～77.71nm之间;THPC和抗坏血酸共同作为还原剂时,先在Fe₃O₄ 纳米颗粒表面生成THPC-Au,加入抗坏血酸后生成Au纳米颗粒,粒径在71.44～153.2nm之间。     

不同形状的氧化石墨烯-金纳米粒子对对硝基苯酚的表面增强拉曼活性特性分析

通过种子生长法合成了不同形态的金纳米粒子,之后加入至氧化石墨烯水分散液中超声震荡得到不同形状的氧化石墨烯-金纳米粒子复合物。运用扫描电子显微镜、X射线光电子能谱、拉曼光谱等表征手段,探究复合物的表面结构、结合能与电荷状态,通过对对硝基苯酚的检测以表征其拉曼活性,并分析造成不同增强效果的原因。结果表明,氧化石墨烯-金纳米粒子复合物表现出良好的表面增强拉曼活性,可以成功地检测到10^-5 mol/L的对硝基苯酚,且复合物的表面增强拉曼活性因金粒子的形状不同而有所差异。     

Synthesis and characterization of Au@Pt nanoparticles

Aucore-Ptshell （Au@Pt） nanoparticles were synthesized at room temperature by reducing K2PtCl6 with hydrogen in the solution containing Au colloids and polyvinylpyrrolidone （PVP）. The particles obtained were characterized with UV-Vis, TEM and XPS techniques. UV-Vis spectra show that the surface plasmon absorption feature of Au colloids is significantly reduced with increasing the amount of reduced Pt. TEM images that the metals are found always appear as spherical nanoparticles and their sizes grow apparently due to the reduction of PtCl6^2- ions, indicating that Pt is deposited from solution onto Au particle surface and forms a Pt-layer with uniform thickness. In the XPS spectra, the signals of Au metal decrease due to the reductive deposition of Pt on the surface of the Au colloids. UV-Vis and XPS data are consistent in showing that when the amount of Pt in the AuPt colloids is increased to reach an overall atomic ratio of Pt/Au=2, the Pt deposits form a shell covering completely the surface of Au particles, demonstrating the core-shell structure of the synthesized AuPt particles.     

立方相Lu2O3:Eu3+纳米晶的可控合成和发光性质

采用水热方法, 通过调节前驱体的pH值, 得到不同形貌的立方相Lu₂O₃:Eu³⁺纳米棒、纳米片和纳米颗粒。利用粉末X射线衍射(XRD)、扫描电镜(SEM)、傅里叶变换红外(FTIR)光谱、光致发光(PL)谱和荧光寿命(FL)等技术对所制备的纳米晶进行了系列表征。随着纳米晶尺寸的减少, 样品的荧光强度明显减弱, 这是由于吸附在纳米晶表面的OH^-含量逐渐增加, 加速了非辐射弛豫从而降低了发光效率。此外, 也观测到源于纳米晶表面Eu³⁺离子的逐渐加强的624 nm发射以及在长波侧不断延伸的电荷迁移带长激发尾。     

Synthesis of pH-responsive supramolecular polypeptide nanoparticles from α-amino acids for combined chemo-photothermal therapy

A new smart supramolecular polypeptide copolymer P(Glu-co-Lys) was synthesized by the polymerization of α-amino acids using the N-thiocarboxylic acid anhydride (NTA) method, using the pH dynamic response peptide of L-glutamic acid and L-lysine as a carrier for tumor cells. The drug delivery system activated by external acid can self-assemble (pH 7.4) and disassemble (pH 5.5) under the adjustment of pH to load the drug and control its release. Doxycycline (DOX) and the photothermal reagent hydrophilic quanternary stereo-cyanine (HQS-Cy) were loaded into the peptide copolymer to obtain HQS-Cy/DOX nanoparticles (NPs) for chemo-photothermal therapy. Gentle photothermal heating can enhance the absorption of drugs by cells and enhance the efficacy of chemotherapy. In addition, chemo-photothermal therapy can solve the defect of easy recurrence after single photothermal therapy. The ingenious nanodrug delivery system of HQS-Cy/DOX NPs provides great potential for the improvement of chemo-photothermal therapy and will achieve excellent therapeutic effects in cancer treatment.     

Shape controllable preparations of PbS nanocrystals using cysteine as the precursor of S^2- ions

Flowerlike, spherical and cubic PbS nanoparticles have been successfully synthesized by refluxing cysteine and lead nitrate in an alkaline solu- tion. The influences of the cysteine to Pb2 molar ratio, the pH value of the reaction mixture as well as the refluxing time on the shape of PbS nanoparticles were investigated. Detailed experimental results demonstrated that a higher molar ratio of cysteine to Pb2 (5.2:1) and shorter refluxing time favor the for- mation of flowerlike PbS nanoparticles at pH 9.0. While lower pH value (8.0) favors the formation of spherical PbS nanoparticles, and higher pH value (10.0), however, favors the formation of cubic PbS nanoparticles. The mechanism for the shape control of PbS nanoparticles is discussed.     

纳米银修饰电极的制备及表征

提出一种新颖简单的制备纳米银修饰电极的方法。在金电极表面吸附的氨乙基硫醇(AET)自组装膜固载一价银离子,利用脉冲恒电位法还原制备纳米银修饰电极。从扫描电子显微镜(SEM)可以观察到金电极表面的纳米银颗粒,同时可观察到修饰电极上银的溶出峰。