Au—聚丙烯酰胺纳米复合物紫外辐照法的制备及表征

在紫外辐照法制备Au-聚丙烯酰胺（PAM）纳米复合物过程中,HAuCl4的光还原和丙烯酰胺（AM）单体的聚合反应同步进行,使得生成的胶态Au纳米粒子均匀分散在聚丙烯酰胺基质中。实验发现金纳米的生成过程可促进AM聚合反应的进行,而PAM的生成则可有效地阻止初始形成的Au纳米粒子发生团聚,从而控制纳米复合物中Au纳米粒子粒径明显小于同样条件下没有AM存在时得到的Au纳米粒子粒径。进一步实验还表明,在紫外辐照法制备Au-PAM纳米复合物过程中的Au纳米粒子形成较快,且粒径大小不随紫外辐照时间而发生变化,仅受HAuCl4初始浓度的影响。该方法可广泛应用于各类金属－有机聚合物纳米复合材料的制备。     

纳米金在DNA电化学传感器中的应用研究

利用自组装单分子膜原理,通过层层组装的方法将金纳米粒子(AuNPs)和DNA探针分别固定到金电极表面制备成探针电极。结果表明纳米金可以使响应电流大大增强,有利于提高检测的灵敏度;同时DNA自组装到纳米金修饰的金电极上,形成一层致密的分子膜,可使响应电流下降。     

金纳米粒子的制备方法及在DNA检测中的应用

综述了金纳米粒子的几种常见制备方法以及这些方法的特点，并归纳为物理法及化学法。前者包括真空蒸镀法、软着陆法及激光消融法；后者又划分为溶胶法、晶种生长法、反胶束法、相转移法及模板法等。不同的方法可获得不同粒径和形状的金纳米粒子，应用时可根据需要选择合适的方法。金纳米粒子特殊的物理及化学性质使其在化学、生物、医学等领域有广泛的用途，尤其在DNA检测中有重要的应用价值。根据方法的特点，DNA检测可分为光学检测法、电化学检测法、压电检测法等。在这些方法中使用金纳米粒子后，检测方法的灵敏度及检测范围有了明显的提高。     

Investigation on composite Au/TiO_2 nanoparticles (Ⅰ)——Synthesis and characterization

Nanometer sized Au/TiO\-2 particles were synthesized by irradiation of a HAuCl\-4 solution containing colloidal TiO\-2 with light of wavelength (λ)>330 nm. The absorption maximum attributed to the surface plasmon band of gold was observed at 540 nm, a red shift of about 20 nm from the position in aqueous solution. The Au clusters are situated on the surface of TiO\-2 in terms of microcrystallite, which was confirmed by HRTEM, EDS and XRD. The electronic interfaction between the metal and the suport was discussed.     

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.     

Phase transfer based synthesis and thermophysical properties of Au/Therminol VP-1 nanofluids

This paper reports a phase transfer based wet chemistry method for the preparation of Au/VP-1 nanofluids.The method involves the transfer of AuCl 4 ions from water to the base liquid Therminol VP-1,followed by the reduction of AuCl 4 ions using NaBH 4.The prepared nanofluids are characterized for their thermophysical properties and stability.The results show that the mass concentration of Au particles has a significant effect on the stability of Au/VP-1 nanofluids.An increase in the Au concentration results in a higher extent of agglomeration among the particles,leading to a decrease in the nanofluid stability.The results also show that the introduction of 0.005-0.05% Au nanoparticles enhances the thermal conductivity of the fluids by up to 6.5%,whereas the viscosity increase is minimal.     

DNA-programmable nanoparticle crystallization

It was first shown more than ten years ago that DNA oligonucleotides can be attached to gold nanoparticles rationally to direct the formation of larger assemblies. Since then, oligonucleotide-functionalized nanoparticles have been developed into powerful diagnostic tools for nucleic acids and proteins, and into intracellular probes and gene regulators. In contrast, the conceptually simple yet powerful idea that functionalized nanoparticles might serve as basic building blocks that can be rationally assembled through programmable base-pairing interactions into highly ordered macroscopic materials remains poorly developed. So far, the approach has mainly resulted in polymerization, with modest control over the placement of, the periodicity in, and the distance between particles within the assembled material. That is, most of the materials obtained thus far are best classified as amorphous polymers, although a few examples of colloidal crystal formation exist. Here, we demonstrate that DNA can be used to control the crystallization of nanoparticle-oligonucleotide conjugates to the extent that different DNA sequences guide the assembly of the same type of inorganic nanoparticle into different crystalline states. We show that the choice of DNA sequences attached to the nanoparticle building blocks, the DNA linking molecules and the absence or presence of a non-bonding single-base flexor can be adjusted so that gold nanoparticles assemble into micrometre-sized face-centred-cubic or body-centred-cubic crystal structures. Our findings thus clearly demonstrate that synthetically programmable colloidal crystallization is possible, and that a single-component system can be directed to form different structures.     

Investigation on composite Au /TiO2 nanoparticles (I)

Nanometer sized Au/TiO₂, particles were synthesized by irradiation of a HAuCl₄ solution containing colloidal TiO₂ with light of wavelength (λ) > 330 nm. The absorption maximum attributed to the surface plasmon band of gold was observed at 540 nm, a red shift of about 20 nm from the position in aqueous solution. The Au clusters are situated on the surface of TiO₂ in terms of microcrystallite, which was confirmed by HRTEM, EDS and XRD. The electronic interfaction between the metal and the suport was discussed.     

唾液中HIV抗体快速检测诊断胶体金免疫层析试纸条的研制

制备一种适于早期HIV的大范围筛查使用的检测人唾液中抗HIV-1抗体的胶体金免疫层析试纸条.采用柠檬酸三钠还原法制备直径为19nm的胶体金颗粒,标记HIV-1gp41抗原,制备胶体金免疫复合物,按常规组装成免疫层析检测试纸条.结果表明:阳性HIV患者唾液中的抗HIV抗体与测试条上金标记物结合后沿着硝酸纤维素膜移动,与膜上的固相抗原结合形成肉眼可见的红色圆点.胶体金颗粒粒径均一,胶体金免疫复合物性能稳定,特异性强,试纸条检测时间只需10～20min.制备的胶体金免疫层析试纸条检测唾液中HIV抗体,使用安全,简便快速,结果准确,适用于基层医疗单位使用和对大量人群的规模筛查等.     

低热固相反应表面活性剂模板法制备纳米硒

以几种表面活性剂为软模板,用亚硫酸钠作还原剂还原二氧化硒,利用低热固相反应技术制备了多种形貌的纳米硒。研究了表面活性剂种类、用量对反应及产物形貌的影响,并采用透射电镜、X射线衍射对产物进行了表征。     

Synthesis of γ-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript>/SiO<Subscript>2</Subscript>/Au magnetic composites for immobilization of bovine serum albumin

A method for the two-step synthesis of magnetic composites with a γ-Fe₂O₃ core, silica inner layer and numerous gold nanoparticles supported on the surface of the silica (γ-Fe₂O₃/SiO₂/Au) is described. First, thiol-functionalized γ-Fe₂O₃/SiO₂ composites and gold colloids are prepared by modifying γ-Fe₂O₃/SiO₂ composites with mercaptosilane and reduction of Au³⁺ to Au⁰ with citrate, respectively. Gold nanoparticles are then assembled on the surface of the thiol-functionalized γ-Fe₂O₃/SiO₂ composites to form γFe₂O₃/SiO₂/Au composites. The structure of the composite particles is confirmed by transmission electronic microscopy and powder X-ray diffraction. Immobilization studies with bovine serum albumin (BSA) demonstrate that the γ-Fe₂O₃/SiO₂/Au composites can be used to immobilize BSA, making them useful for biomedical and biological applications.     

EQCM研究表面活性剂对金电极电化学行为的影响

利用电化学石英微天平（ＥＱＣＭ）,研究了表面活性剂在金电极上的吸附及其对金电极氧化还原过程的影响⒚结果表明：不同的表面活性剂在金电极上吸附能力不同,对金的氧化还原过程产生不同的影响⒚十八烷基三甲基溴化铵易在金电极表面吸附,更易在氧化态金表面吸附,阻碍了金的氧化还原⒚相比之下,十二烷基磺酸钠在金电极上吸附能力较弱,在氧化态金形成后还有些脱落,对金电极的氧化还原影响不大⒚ＴｒｉｔｏｎＸ１００介于以上两种表面活性剂之间⒚还对金电极在磷酸缓冲液中的氧化还原机理作了初步探讨     

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.     

玉米精细胞质膜特异糖蛋白胶体金免疫定位

用亲和层析,SDS-PAGE及印迹技术,从玉米精细胞中分离纯化质膜蛋白。用ConA-HRP检测获得分子量为37和39kD两种糖蛋白特异成分。用它们分别免疫小鼠得到多克隆抗体,以兔抗鼠IgG胶体金(15nm)为探针,检查此两种蛋白在精细胞质膜上的分布。免疫定位表明,37kD, 39kD多肽是玉米精细胞质膜所特异的。有关此多肽的功能有待进一步研究。     

胶体金标记牛血清白蛋白及其在电场中的迁移行为

采用柠檬酸钠还原法制备了不同粒径的胶体金,对牛血清白蛋白(BSA)进行标记,考察了胶体金标记BSA的影响因素.以琼脂糖凝胶为载体介质,研究了三种粒径的胶体金及其BSA复合物在电场中的迁移行为.结果表明,pH值、离子浓度、蛋白量都会影响胶体金对BSA的标记.标记的最适条件是:无盐或极低盐浓度,pH值5.8,蛋白加入量不小于最小稳定蛋白量.胶体金及其BSA复合物在特定电场中的迁移行为类似于火箭免疫电泳,其迁移速度随着金纳米粒子粒径的增大而减小;金纳米粒子与BSA结合后迁移速度减慢,BSA的加入量对复合物的迁移速度无影响.     

Shape control technology during electrochemical synthesis of gold nanoparticles

Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor (HAuCl₄) to an electrolyzed aqueous solution of poly(N-vinylpyrrolidone) (PVP) and KNO₃, which indicates the good reducing capacity of the PVP-containing solution after being treated by electrolysis. Using a catholyte and an anolyte as the reducing agents for HAuCl₄, respectively, most gold nanoparticles were spherical particles in the former case but plate-like particles in the latter case. The change in the pH value of electrolytes caused by the electrolysis of water would be the origin of the differences in shape and morphology of gold nanoparticles. A hypothesis of the H+ or OH? catalyzed PVP degradation mechanism was proposed to interpret why the pH value played a key role in determining the shape or morphology of gold nanoparticles. These experiments open up a new method for effectively controlling the shape and morphology of metal nanoparticles by using electrochemical methods.     

Two-dimensional self-organization of 1-nonanethiol-capped gold nanoparticles

A two-dimensional (2D) ordered hexagonal close-packed structure, formed by 1-nonanethiol-capped gold nanoparticles, is reported. The structure was constructed only by dipping the gold nanoparticle colloidal solution on flat substrate. The gold nanoparticles were synthesized as follows: First, AuCl₄^-1 was transferred from aqueous solution to toluene by the phase-transfer reagent of tetraoctylammonium bromide. Then it was reduced with aqueous sodium borohydride in the presence of a given amount of 1-nonanethiol molecules which was used to control the nucleation and growth of the gold nanoparticles for the desired size. The experimental techniques, such as UV-Vis, FT-IR, and X-ray photoelectron spectroscopy (XPS), were employed to characterize the obtained product. Transmission electron microscopy (TEM) measurement demonstrated the size of the gold nanoparticle and the formation of two-dimensional ordered hexagonal close-packed gold nanoparticle structure.     

Selective oxidation with dioxygen by gold nanoparticle catalysts derived from 55-atom clusters

Supported gold nanoparticles have excited much interest owing to their unusual and somewhat unexpected catalytic properties, but the origin of the catalytic activity is still not fully understood. Experimental work on gold particles supported on a titanium dioxide (110) single-crystal surface has established a striking size threshold effect associated with a metal-to-insulator transition, with gold particles catalytically active only if their diameters fall below approximately 3.5 nm. However, the remarkable catalytic behaviour might also in part arise from strong electronic interaction between the gold and the titanium dioxide support. In the case of industrially important selective oxidation reactions, explanation of the effectiveness of gold nanoparticle catalysts is complicated by the need for additives to drive the reaction, and/or the presence of strong support interactions and incomplete understanding of their possible catalytic role. Here we show that very small gold entities ( approximately 1.4 nm) derived from 55-atom gold clusters and supported on inert materials are efficient and robust catalysts for the selective oxidation of styrene by dioxygen. We find a sharp size threshold in catalytic activity, in that particles with diameters of approximately 2 nm and above are completely inactive. Our observations suggest that catalytic activity arises from the altered electronic structure intrinsic to small gold nanoparticles, and that the use of 55-atom gold clusters may prove a viable route to the synthesis of robust gold catalysts suited to practical application.     

纳米氢氧化铝稳定泡沫性能研究

通过原位表面活性化可使纳米颗粒变成表面活性颗粒,使其能够吸附在气-液界面上形成颗粒单层,这种颗粒单层类似于表面活性剂在气-液界面上的吸附单分子层,有起泡和稳泡的作用.研究了纳米氢氧化铝与表面活性剂SDS及OP-10复配产生的泡沫的性能.结果表明,以水为溶剂时,OP-10基本不能使纳米氢氧化铝颗粒原位表面活性化,不能在起泡和稳泡方面产生协同效应.而阴离子表面活性剂SDS能够通过静电作用吸附在纳米氢氧化铝颗粒表面,使颗粒表面覆盖一层烷基链而亲水性减弱,从而能以颗粒单层形式吸附在气-液界面上起到起泡和稳泡的作用.当SDS质量分数大于0.6%后,表面活性剂分子在颗粒表面形成双层或多层吸附,打破了活性颗粒的亲水-亲油平衡,纳米颗粒重新转变为强亲水颗粒,起泡、稳泡能力下降.质量分数0.1%纳米Al(OH)3+SDS体系的泡沫封堵性能明显优于单一SDS体系,文中实验条件下阻力因子可达100以上.     

Properties and characterization of Au3+-adsorption by mycelial waste ofStreptomyces aureofaciences

Mycelial waste of Streptomyces aureofaciences procured from the aureomycin fermentation industry is used as biosorbent for Au³⁺  The properties of Au³⁺ adsorption by the mycelial waste are studied. The results indicate that the optimum pH value of Au³⁺ adsorption is 3.5. The biosorption is a rapid and non-temperature-dependent process. The bio-sorptive capacity with 45.6 mg/g and efficiency with 91.2% are achieved under the conditions of pH 3.5 and 30 ℃ for 45 min, in which the ratio is 50 mg/g dry weight for the concentrations of initial Au³⁺ and the mycelial waste. The Au³⁺ ions adsorbed on the mycelial waste can be eluted. The observation in a transmission electron microscope shows that the Au³⁺ ions can be reduced to Au particles by the mycelial waste and the Au⁰ can become gold crystals with differentforms and sizes. X-ray photoelectron spectroscopy analysis further proves that the Au³⁺ can be reduced to Au⁰ by the mycelial waste.