离子液体/金纳米粒子自组装介孔材料及其增强的细胞色素c直接电化学(英文)

室温离子液体作为一种软模板用来组装介孔材料,这种材料是由表面覆盖有半胱氨酸的自组装巨型金纳米粒子构成的.首先,由于静电作用或者配体末端的羧基和氨基基团之间的缩合反应,覆盖有半胱氨酸的金纳米粒子能够自组装形成纳米线和亚微米球形粒子.其次,球形自组装粒子在和疏水性室温离子液体1-辛基-3-甲基咪唑鎓六氟磷酸盐相互研磨时能形成一种准固态凝胶.最后,将复合凝胶涂在玻碳电极上,然后在PH=7.4的磷酸缓冲溶液中用循环伏安法进行极化,由于富余的室温离子液体分散在溶液中,形成了一种介孔组装结构.该材料具有良好的导电性和生物大分子亲和性.由于比表面积大和介孔内部的"薄层"效应,细胞色素c的氧化还原反应显著增强.实验结果表明,这种介孔材料在生物传感器和生物燃料电池等电化学器件方面具有潜在的应用前景.     

聚离子液负载金纳米粒子水凝胶的制备及阴离子响应性

通过咪唑基离子液单体与二乙烯苯的自由基聚合制备了聚离子液水凝胶,并通过一步还原得到了离子液水凝胶负载金纳米粒子的复合材料。用UV-Vis光谱和透射电子显微镜研究了金纳米粒子在离子液水凝胶内部的分散状态及阴离子响应性聚集。结果表明,由于空间位阻和静电作用,制得的金纳米粒子的表面等离子共振吸收峰为527 nm,在离子液水凝胶中呈均匀分散的球形(2～5 nm);在PF6-阴离子的作用下,形成了疏水性水凝胶,使凝胶收缩,凝胶内部的金纳米粒子发生聚集,其吸收峰红移到532 nm,初步证实了此水凝胶具有阴离子响应性。     

基于纳米自组装技术的功能化溶胶-凝胶过氧化氢生物传感器

结合功能化溶胶-凝胶(sol-gel)网络结构、自组装技术和纳米粒子效应,提出一种生物传感界面构建方法.利用自组装技术在玻碳电极表面组装氨基化sol-gel膜,通过与自组装膜间的强烈作用将纳米金粒子固定于sol-gel网络中,再通过静电吸附作用实现辣根过氧化物酶(HRP)在纳米金粒子表面的固定化,构建纳米自组装HRP传感界面.将制备的传感器用于对H2O2的催化还原,很好地保持了酶的生物活性,改善了传感器的灵敏度.     

离子液体包裹纳米金修饰金电极用于鲁米诺电致化学发光的研究

室温离子液体是由有机阳离子和无机阴离子或有机阴离子组成的室温熔融盐,由于其优异的化学催化、生物催化和化学反应性能而在化学和工业方面受到广泛的关注和运用.离子液体也应用于合成纳米金属材料特别是纳米金~([1～3]),纳米金作为一种化学和生物催化性能良好的纳米金属材料也应用于鲁米诺的液相电致化学发光研究~([4]).本研究将巯基功能化离子液体应用于纳米金的合成,并将不同粒径的离子液体包裹的纳米金修饰金电极然后用于鲁米诺电极化学发光的研究.     

气-液界面Au纳米粒子网状结构薄膜的制备及SERS性能研究

本研究通过自组装法在气-液界面得到Au纳米粒子网状结构,并通过进一步生长得到连续的Au纳米粒子网状结构薄膜.该方法无需加入任何诱导剂,在室温条件下即可得到稳定性良好的纳米金薄膜.通过改变HAuCl_4和AgNO_3相对用量、陈化时间等条件对网状结构薄膜的形成机理进行了研究.结果发现,AgNO_3用量对Au纳米粒子薄膜的形成至关重要,通过调控AgNO_3用量可以促进纳米金粒子间的融合并形成纳米链、进一步演化为纳米链网状结构.在初步形成的Au纳米粒子网状结构表面通过抗坏血酸还原进一步生长纳米金粒子,有利于形成较大面积、较好稳定性的纳米Au粒子网状结构薄膜.以对氨基苯硫酚(4-ATP)作为探针分子,研究表明,与未发生组装的金纳米粒子相比,自组装形成的Au纳米粒子网状结构薄膜对4-ATP具有较强的表面增强拉曼效应.     

聚苯胺包裹的金纳米粒子的合成和表征及初步应用

用苯胺作还原剂还原氯金酸合成了金纳米结构. TEM实验表明, 苯胺还原氯金酸能生成苯胺齐聚物或其聚合物包裹的金球形纳米粒子. XPS分析表明, 金纳米粒子包覆的聚合物层带正电荷. 该纳米粒子能用于电极表面纳米结构组装及氧化还原性的生物大分子的电化学研究, 实现了超氧化物歧化酶(SOD)在这种带正电荷的金纳米粒子表面的直接电子转移.     

高分子修饰金纳米粒子的自组装研究进展

近年来,高分子修饰金纳米粒子的自组装行为逐渐成为新的研究热点.当金纳米粒子修饰上高分子后,在维持其自身光电特性的同时展现出了与高分子类似的自组装行为,从而能够在适当的条件下形成结构明确的零维、一维、二维和三维自组装结构.这些自组装结构的出现不仅促进了金纳米粒子组装的基础研究,并且极大地丰富了金纳米粒子的应用潜力,为金/高分子纳米复合材料的发展开拓了新的方向.本文总结了金/高分子纳米复合粒子形成的不同维度组装体,着重讨论了金纳米粒子自组装构筑单元的设计、组装方法以及组装体的性质,分类讨论了相应的自组装材料在环境和生物医药中的应用,并展望了相关研究在未来发展的机遇与挑战.     

聚合物-纳米金在油水界面的自组装及有序结构的构筑

聚合物-纳米金复合物既具有金纳米粒子的光、电及催化性能,又具有聚合物的可加工性及对外界的刺激响应性,因此已成为高分子科学及材料科学研究的热点。本文主要介绍了我们实验室在聚合物-纳米金在油水界面的自组装及有序结构的构筑研究方面的相关工作:(1)利用界面聚合的方法制备侧链接枝亲水性金纳米粒子的聚苯乙烯及杂化聚合物在水溶液中的自组装;(2)亲水性金纳米粒子及疏水性聚合物(或疏水性磁性纳米粒子)在油水界面的自组装研究;(3)利用金纳米粒子为交联点制备具有温度响应性聚合物微凝胶的研究。     

两亲性嵌段共聚物的合成及其在离子液体中的自组装行为

采用阴离子开环聚合法合成了两亲性嵌段共聚物PLA-PEG-PLA.用FT-IR,1H NMR和GPC等手段对嵌段共聚物的结构组成进行了表征.两亲性嵌段共聚物在离子液体1-丁基-3-甲基咪唑六氟磷酸盐中能自组装成胶束,用透射电子显微镜观察了聚合物在离子液体中形成胶束的纳米结构.当疏水链长固定时,胶束的自组装形状主要依赖于亲水链的长度.两亲性共聚物在离子液体中可自组装成可控制结构的纳米胶束,这种纳米结构胶束在很多领域具有广泛的应用前景.     

基于金纳米粒子自组装的分光光度法测定半胱氨酸

在pH 4.56的B ritton-Rob inson(B-R)缓冲溶液中,半胱氨酸的SH和NH3 分别与金纳米粒子表面进行共价结合和静电作用,导致金纳米粒子的长距离自组装,形成网状超分子结构,并使金纳米粒子的最大吸收波长从520 nm红移到660 nm。本实验对半胱氨酸引导的金纳米粒子自组装的作用机制进行了研究,建立了操作简便、高灵敏度测定半胱氨酸的分析方法。其线性范围为0.01~0.20 mg/L;检出限为2.8μg/L(3,σ2.3×10-8mol/L)。在实验条件下,其它常见的氨基酸和谷胱甘肽均不干扰测定。     

Dipole-dipole plasmon interactions in gold-on-polystyrene composites

Red-shifting of the optical absorption spectra of aggregates of gold nanoparticles by dipole-dipole interactions is of considerable interest, both for theoretical reasons and because the phenomenon can be potentially exploited in various applications. A convenient and practical way to control the effect is to assemble the aggregated ensemble of n gold nanoparticles on the outer surface of larger dielectric spheres. Here, we show by experiment and calculation how the spectra of these structures can be systematically morphed from that of isolated gold particles, through the regime of broad absorption dominated by particle-particle interactions, and finally to the limiting case of a continuous nanoshell. The experimental data were produced using the process of deposition-precipitation, which provides a facile method to decorate polystyrene microspheres with gold nanoparticles. There is no need for prior functionalization of the microsphere surface in our method of deposition-precipitation. Calculations were carried out using a code based on the discrete dipole approximation (DDA). The spectra were dominated by three effects. These were a peak absorption at about 540 nm produced by the conventional plasmon resonance of spherical gold nanoparticles, a broad absorption in the range 600-900 nm caused by diverse dipole-dipole interactions between particles, which strengthened as the number of attached gold particles increased and finally, when n was large, an absorption peak due to the onset of nanoshell-like resonances. The experimental spectra could be successfully fitted by spectra calculated using combinations of these effects.     

Spectroscopic identification of S-Au interaction in cysteine capped gold nanoparticles

This study deals with the synthesis of cysteine capped gold nanoparticles with an average size of 12 nm by borohydride reduction and spectroscopic identification of SAu interaction. We have studied the interaction of thiol with gold nanoparticles in aqueous medium by employing UV-vis, Raman, NMR, and FT-IR spectroscopy. The shifting of gold plasmon resonance in the UV-vis spectra shows the stabilization of gold nanoparticles by cysteine. The disappearance of S-H stretching in both the IR and Raman spectra and the shifting of the NMR signals of the protons in close proximity to the metal center supported the existence of the S-Au interaction in cysteine capped gold nanoparticles. The TEM images shows cysteine capped gold nanoparticles as distinct and spherical entities as compared to free colloidal gold nanoparticles.     

Rapid Cationization of Gold Nanoparticles by Two‐Step Phase Transfer

Cationic gold nanoparticles offer intriguing opportunities as drug carriers and building blocks for self‐assembled systems. Despite major progress on gold nanoparticle research in general, the synthesis of cationic gold particles larger than 5 nm remains a major challenge, although these species would give a significantly larger plasmonic response compared to smaller cationic gold nanoparticles. Herein we present the first reported synthesis of cationic gold nanoparticles with tunable sizes between 8–20 nm, prepared by a rapid two‐step phase‐transfer protocol starting from simple citrate‐capped particles. These cationic particles form ordered self‐assembled structures with negatively charged biological components through electrostatic interactions.     

Synthesis of spherical silver nanoparticles by digestive ripening, stabilization with various agents, and their 3-D and 2-D superlattice formation

Capped nanoparticles of silver were synthesized via the solvated metal atom dispersion (SMAD) technique followed by a digestive ripening procedure producing gram quantities of monodisperse spherical nanoparticles. This shows for the first time that a digestive ripening protocol is possible for an element other than gold. The particle size and optical spectra were found to be dependent on the capping agent used. Particles capped with dodecane thiol had a mean diameter of 6.6+/-1 nm, while trioctyl phosphine capped particles were 6.0+/-2 nm determined via TEM microscopy. These particles were found to organize into two- and three-dimensional superlattices with a well defined geometry through self-assembly in a liquid solution, that was dictated by the ligand used resulting in a triangular or circular lattice.     

Regularities of the retention of aminopyridines by silica gel modified with gold nanoparticles

New sorbents based on silica gel and gold nanoparticles stabilized by L-cysteine and its methyl ester are synthesized. Regularities of the retention of various substituted aminopyridines by the synthesized sorbents are examined in the normal-phase mode of high-performance liquid chromatography upon elution by a binary mobile phase (hexane-isopropanol). Quantum-chemical simulations of L-cysteine and its derivative adsorptions on the surface of a gold cluster are performed, along with simulations of subsequent adsorptions of substituted pyridines on the modified gold surface. It is shown that the Snyder-Soczewinski and Scott-Kucera displacement models can be used to describe the experimental data on the synthesized sorbents.     

Application of nanoparticles for the enhancement of latent fingerprints

Two different types of nanoparticles dissolved in organic solution, gold stabilized by n-alkanethiols and CdSe/ZnS stabilized by n-alkane-amine, adhere preferentially to the ridges of latent fingerprints; the gold deposits catalyze silver electroless deposition from "Silver Physical Developer" (Ag-PD), an aqueous solution containing silver colloids stabilized by cationic surfactants, to form dark impressions of the ridge details; the hydrophobic capped gold nanoparticles significantly improve the intensity and clarity of the developed prints compared with Ag-PD alone; finger marks treated with CdSe/ZnS nanoparticles can be viewed directly, due to their fluorescence under UV illumination.     

In situ synthesis of water dispersible bovine serum albumin capped gold and silver nanoparticles and their cytocompatibility studies

A simple and convenient one step room temperature method is described for the synthesis of bovine serum albumin (BSA) capped gold and silver nanoparticles. BSA reduces silver ions to silver nanoparticles but does not directly reduce gold ions to gold nanoparticles at room temperature and varying pH conditions. However, when silver and gold ions are simultaneously added to BSA, silver ions get reduced to metallic silver first and these in turn reduce gold ions to gold nanoparticles through a galvanic exchange reaction. The so synthesized silver and gold nanoparticles are easily water dispersible and can withstand addition of salt even at high concentrations. It is shown that the capped protein retains its secondary structure and the helicity to a large extent on the nanoparticles surface and that the protein capping makes the nanoparticles cytocompatible.     

Effect of polar solvents on the optical properties of water-dispersible thiol-capped cobalt nanoparticles

We were able to stabilize cobalt nanoparticles dispersible in water by optimizing the synthetic procedure using small polar thiol containing compounds as the capping agents. The nanoparticles were found to be spherical. The optical properties of the cobalt nanoparticles were investigated by monitoring the changes in the surface plasmon resonance (SPR) spectrum in various polar solvents. The extent of solvent dependence of the SPR spectrum was found to be dependent on the nature of the capping agent, the size of the cobalt nanoparticles, as well as the nature of the solvent. The Drude model was applicable for the particles capped with mercaptopropionic acid, while the effect of variations in the free electron density in the particles at different solvents became predominant in the nanoparticles capped with mercaptoethanol. The absorption spectra of the Co nanoparticles were simulated with the help of the classical Mie theory, and the results supported the effect of free electron density due to different capping agents on the spectra of the particles.     

Electrophoretic separation of gold nanoparticles according to bifunctional molecules‐induced charge and size

Gold nanospheres modified with bifunctional molecules have been separated and characterized by using agarose gel electrophoresis as well as optical spectroscopy and electron microscopy. The electrophoretic mobility of a gold nanosphere capped with 11‐mercaptoundecanoic acid (MUA) has been found to depend on the number of MUA molecules per gold nanosphere, indicating that it increases with the surface charge of the nanoparticle. The extinction spectrum of gold nanospheres capped with MUA at an MUA molecules per gold nanosphere value of 1000 and connected via 1,6‐hexanedithiol (HDT) decreases by 33% in magnitude and shifts to the red as largely as 22 nm with the increase of the molar ratio of HDT to MUA (R_HM). Gold nanospheres capped with MUA and connected via HDT have been separated successfully using gel electrophoresis and characterized by measuring reflectance spectra of discrete electrophoretic bands directly in the gel and by monitoring transmission electron microscope images of gold nanoparticles collected from the discrete bands. Electrophoretic mobility has been found to decrease substantially with the increment of HDT to MUA, indicating that the size of aggregated gold nanoparticles increases with the concentration of HDT.     

One pot synthesis of polymer protected gold nanoparticles and nanoprisms in glycerol

Uniform and stable polymer protected spherical gold nanoparticles were synthesized using glycerol as reducing agent. Further it was observed that the morphology of the particles varied from spherical to triangular prismatic gold nanoparticles when the reaction was changed from normal mode of reflux condition to microwave mode (MW) of heating. Further a brief mechanism relating the formation of prisms with the orientation of polymer and nucleation period has been discussed. Formation of triangular prismatic and spherical gold nanoparticles were characterised using UV–vis spectroscopy, transmission electron microscopy (TEM) and X-ray diffraction (XRD) analysis.