基于金纳米粒子/聚阿魏酸/多壁碳纳米管修饰电极的DNA计时库仑法生物传感器的制备

构建了基于金纳米粒子/聚阿魏酸/多壁碳纳米管(AuNPs/PFA/MWCNTs)修饰电极的DNA计时库仑法生物传感器.利用循环伏安技术在多壁碳管修饰的玻碳电极表面上聚合一层阿魏酸,在恒电位条件下,在阿魏酸表面沉积金纳米粒子,巯基DNA作为探针通过金硫键固定在金纳米粒子表面.电化学交流阻抗技术(EIS)与扫描电镜(SEM...     

基于表面增强拉曼光谱的重金属离子检测

以对巯基苯甲酸为拉曼标记和自组装修饰分子, 在光亮金基底上修饰后作为检测基底, 在金纳米粒子表面修饰后获得具有表面增强拉曼光谱信号的标记金溶胶. 修饰的基底及纳米离子通过重金属离子与羧基端的配位而发生相互作用, 最终形成“金属基底-对巯基苯甲酸/重金属离子/对巯基苯甲酸-金属纳米颗粒”的三明治结构. 采用扫描电镜表征纳米粒子的组装及以表面增强拉曼光谱检测表面标记分子的信号, 以此实现重金属离子的检测. 以强螯合剂EDTA溶液淋洗三明治结构, 使重金属离子与金属基底以及纳米颗粒上的羧基的配位作用断裂, 获得可再次利用的修饰金基底.     

蜂毒素在功能化金纳米粒子表面的吸附及构象变化

利用硼氢化钠还原法制备了金纳米粒子, 通过在其表面修饰链长不同的巯基羧酸, 得到了功能化纳米粒子. 利用荧光发射、紫外吸收和圆二色谱等手段研究了功能化金纳米粒子与蜂毒素分子之间的相互作用及其所诱导的蛋白质分子的构象变化. 研究结果表明, 功能化修饰的金纳米粒子可通过静电相互作用吸附蜂毒素(Melittin)并诱导其α-螺旋结构的形成, 且这种效应与巯基羧酸分子的链长直接相关.     

金纳米粒子修饰毛细管硅胶整体柱的制备及其电色谱性能研究

通过毛细管硅胶整体柱表面修饰十八烷基硫醇金纳米粒子,制备了一种新型毛细管电色谱固定相.制备金纳米粒子修饰整体柱时,采用溶胶-凝胶法制备毛细管硅胶整体柱,并在其表面化学修饰3-巯基丙基三甲氧基硅烷;通过巯基基团固载金纳米粒子于整体柱上,再共价键合十八烷基硫醇于金纳米粒子表面.以甲苯为探针,对理论塔板高度与流动相线速度之间...     

聚乙二醇功能化程度对纳米金壳夹心二氧化硅载药量及稳定性影响研究

本文系统研究了不同聚乙二醇(PEG)功能化程度对纳米金壳夹心二氧化硅(GSNs)载药量及稳定性的影响.透射电子显微镜(TEM)观察结果表明,GSNs表面经修饰分子量为5 KDa的α-甲氧基-ω-巯基聚乙二醇(mPEG-SH)分子后,PEG分子层平均厚度约为4 nm;随PEG化程度增加,GSNs聚集沉降速度改善,稳定性提高,久置后(35 d)稳定性良好;电感耦合等离子体发射光谱(ICP-OES)测试表明,当PEG与Au反应摩尔比为0.24时,PEG分子层在金壳表面接近饱和;不同PEG化程度对GSNs载药量基本无影响.本研究可为优化无机纳米材料表面PEG修饰过程,发展无机纳米载体材料体内应用提供理论依据.     

纳米金-4,4'-二巯基二苯硫醚自组装膜修饰金电极的制备及其电化学行为

纳米金粒子,因其良好的光学、电学特性和生物相容性,受到分析化学工作者的极大关注.本研究利用4,4'-二巯基二苯硫醚(DMDPSE)中两端巯基的S原子与Au表面强烈作用形成Au-S键,构筑了纳米金-4,4'-二巯基二苯硫醚自组装膜修饰金电极(NG/DMDPSE/Au),然后研究了该电极的电化学行为.这不仅对纳米材料构建在基质表面提供了一个有效途径,而且对纳米粒子制成具有特殊功能的生物传感器具有一定的参考价值.     

巯基苯类为标记分子免疫检测的FT-SERS光谱研究

以对巯基苯甲酸、苯硫酚为标记分子,与金纳米粒子生成具有SERS信号的标记金溶胶．在一定条件下,标记金溶胶与抗体羊抗小鼠IgG形成SERS标记免疫金溶胶．用组装金纳米粒子的玻璃表面吸附抗体,通过对相应抗原小鼠IgG的识别,形成固相抗体/抗原对,再将SERS标记免疫金溶胶组装到固相抗体/抗原对上,形成“固相抗体-待测抗原-标记抗体(即标记免疫金溶胶)”夹心复合物,进而通过拉曼标记分子的SERS信号进行免疫检测．     

空间稳定的SERS标记金纳米棒探针用于免疫检测

报道了空间稳定的表面增强拉曼散射(SERS)标记的金纳米棒探针在免疫检测方面的应用.该探针是将拉曼活性分子4-巯基苯甲酸和生物亲和性高分子α-巯基-ω-羧基聚乙二醇共吸附于金纳米棒表面而制得.其中,聚乙二醇高分子链为探针提供保护作用和空间稳定,使之可以耐受较苛性的条件;其端位的羧基与抗体等靶向实体结合,从而赋予探针检测识别功能.当探针检测待测抗原时(通过固体基底上的捕获抗体、待测抗原和探针上的抗体之间的特异性结合,形成经典“三明治”夹心结构),探针上4-巯基苯甲酸的SERS信号就能示踪出这种识别.该探针对单组分抗原的检出浓度能低至1×10^-9mg·mL^-1.     

界面可控硫醇SAMs纳米金修饰金电极的电化学行为研究

在裸金电极上自组装不同比例的4,4’-二甲基联苯硫醇(MTP)和硫辛酸(TA)混合液,形成自组装膜(MTP+TA/Au SAMs),再修饰纳米金,制得纳米金混合巯基修饰金电极(AuNPs/MTP+TA/Au)。研究了纳米金混合巯基修饰金电极的电化学行为和阻抗行为,结果表明电极表面pH值的改变对电极表面的电子转移有重要影响。对葡萄糖传感器的制备条件、测定条件、抗干扰能力等进行了讨论,结果表明修饰电极的微结构和微环境有必要进一步研究。     

基于金/巯基相互作用的功能分子在磁性高分子复合微球表面可控组装研究

建立了一种基于金纳米粒子与巯基相互作用的在磁性高分子复合微球表面高效组装功能分子的新方法.首先制备了粒径均一的介孔磁性纳米粒子簇(MSP),利用蒸馏沉淀技术在MSP上包覆一层―S―S―键交联的聚甲基丙烯酸壳层(P(MAA-Cy)),并将直径10~30 nm的金纳米粒子沉积在MSP@P(MAACy)复合微球表面,从而获得MSP@P(MAA-Cy)-Au NP复合微球.调控HAu Cl4的投料量可以控制金纳米粒子沉积数量和尺寸.利用金粒子和巯基之间的强相互作用,将巯基修饰的荧光分子快速可控组装在MSP@P(MAA-Cy)-Au NP微球上.作为模型示范,实现了一次在MSP@P(MAA-Cy)-Au NP微球上快速固定单种或多种功能分子,为即时、高效、定量在功能微球(靶向药物载体等)上修饰功能分子提供了一种可选择的解决方案.     

Using selenium-conjugated polyethylene glycol to enhance the stability of gold nanoparticles in biologically relevant samples

Using stabilizing agents to maintain the physicochemical properties of colloids in complex environments is crucial for their realworld applications. In this article, we describe how selenium-(Se-) terminated polyethylene glycol(PEG) can serve as a highaffinity stabilizing agent for gold nanoparticles(AuNPs). Compared to Au NPs modified with standard thiolated PEG(S-PEG),Se-PEG-coated Au NPs are much more stable under extreme conditions such as high/low pH, high salt content, and high temperatures. We demonstrate that the Se anchor can prevent the dissociation of PEG ligands from Au NP surfaces in living cells,where a higher concentration of biothiols is usually present. These results indicate that Se-PEG is an excellent stabilizing agent that may facilitate further studies on metal NPs for various complex and physiological systems.     

Light and neutron scattering study of PEG-oleate and its use in emulsion polymerization

Steric stabilization of colloids forms a robust mechanism to obtain colloids that are stable in a variety of environments, and that can be used to study the phase behavior of hard or soft spheres. We report the synthesis of sterically stabilized colloids in an aqueous environment using readily dissolvable surfactants, with an unsaturated hydrophobic tail. We synthesized a new surfactant by esterification of a poly(ethylene glycol) (PEG) chain of 4.1 kg/mol with oleic acid, called PEG4OA. The micellization of PEG4OA was characterized by light and neutron scattering, which yielded values for the aggregation number and the overall size that are in excellent agreement with a comparable surfactant with a saturated octadecane chain, Brij 700. We successfully used PEG4OA in the emulsion polymerization of polystyrene colloids. In comparison with the smaller surfactant Tween 80, PEG4OA yielded smaller colloids with radii around 50 nm, and the addition of 1-dodecanethiol reduced the formation of aggregates during the synthesis. A contrast variation study with small angle neutron scattering (SANS) showed that a dense PEG layer was grafted to the colloid surface.     

pH诱导两性离子配体修饰的金溶胶的浓缩与保存

研究了两性离子配体修饰的金纳米颗粒在酸性和碱性溶液中的稳定性和可逆聚集性. 测量了金溶胶在不同条件下的UV-Vis 吸收光谱, 通过光谱的变化揭示其稳定性和可逆聚集性. 结果表明: 经配体修饰的金纳米颗粒在酸性和碱性溶液中的稳定性有了很大的提高; 强酸性条件可诱导金溶胶失稳聚沉, 回调pH值又可使其重新分散. 利用这种pH依赖的可逆聚集特性, 可以将稀溶胶浓缩成浓溶胶或固体保存, 一旦需要又可加水恢复到分散的状态.     

One-pot preparation of mono-dispersed and physiologically stabilized gold colloid

We have developed a rapid and simple method for the preparation of nearly mono-dispersed gold colloids with a fairly high concentration above 10 mM using hydroxylamine as the reducing agents, in the presence of α-methoxy-ω-mercaptoethyl-poly(ethylene glycol)(MeO-PEG-SH). It was found that a hydroxylamine acted not only as a reducing agent, but also as a nucleation agent under alkaline reaction conditions. Though the colloid concentration was fairly high, the dispersion stability was remarkably improved even in a high ionic strength in the range greater than 1 M NaCl, in which conventional citrate gold colloids immediately flocculate and precipitate. The obtained colloid was successfully re-dispersed in aqueous media after lyophilization. In addition, the prepared gold colloid reduced a protein adsorption significantly on its surface. Concerning these results, the obtained colloidal dispersion may be suitable for biological applications, since a regionally concentrated colloidal dispersion with dispersion stability is required for bio-labeling and bio-imaging systems.Electronic Supplementary Material Supplementary material is available for this article at     

Ultrahigh nanoparticle stability against salt, pH, and solvent with retained surface accessibility via depletion stabilization

For many applications, it is desirable to stabilize colloids over a wide range of buffer conditions while still retaining surface accessibility for adsorption and reaction. Commonly used charge or steric stabilization cannot achieve this goal since the former is sensitive to salt and the latter blocks the particle surface. We use depletion stabilization in the presence of high molecular weight polyethylene glycol (PEG) to stabilize a diverse range of nanomaterials, including gold nanoparticles (from 10 to 100 nm), graphene oxide, quantum dots, silica nanoparticles, and liposomes in the presence of Mg(2+) (>1.6 M), heavy metal ions, extreme pH (pH 1-13), organic solvents, and adsorbed nucleosides and drugs. At the same time, the particle surface remains accessible for adsorption of both small molecules and macromolecules. Based on this study, high loading of thiolated DNA was achieved in one step with just 2% PEG 20,000 in 2 h.     

Stability of thiol-passivated gold particles at elevated temperatures studied by X-ray photoelectron spectroscopy

The thermal stability of thiol-passivated gold colloids has been studied by means of X-ray photoelectron spectroscopy. Different colloids were chemically synthesized with thiol lengths from 3 to 8, and 16 carbon atoms. Depending on the synthesis parameters, the mean gold particle size varied from 1.6 to 4.9 nm for the particular colloid. Temperature-dependent measurements revealed a general tendency of shells with longer thiol chains (>5 carbon atoms) to be more stable in terms of desorption but to show a X-ray radiation-induced damage, which was absent with shorter thiols. Additionally, the self-assembling properties of the colloids were characterized by TEM, showing differences as a function of the chain lengths.     

Stability of gold nanorods passivated with amphiphilic ligands

The stability of gold nanorods (NRs) coated with amphiphilic ligands (ALs) was investigated. NRs coated with cetyltrimethylammonium bromide (CTAB) were ligand exchanged with polyoxyethylene [10] cetyl ether (Brij56), Oligofectamine (OF), and phosphatidylserine (PS). An aggregation index based on the longitudinal surface plasmon resonance peak broadening was used to measure stability of the NR-ALs under different conditions including the number of washes, pH, ionic concentration, and temperature. The aggregation index was also used to measure the stability of the NR-ALs under ultrafast laser irradiation and in the presence of proteins commonly used in cell culture. Differences in NR-AL stability were found, which were due to differences in the physical and chemical properties of the ALs. Apart from the charge on the AL headgroup, we suggest the Gibbs free energy of passivation (ΔG(p)) and enthalpy of passivation (ΔH(p)) of the AL could potentially aid in the selection of amphiphiles that can effectively passivate NRs for stability and optimize their properties and desired biological impact.     

A Simple Protocol to Stabilize Gold Nanoparticles using Amphiphilic Block Copolymers: Stability Studies and Viable Cellular Uptake

Di‐ and triblock non‐ionic copolymers based on poly(ethylene oxide) and poly(propylene oxide) were studied for the stabilization of nanoparticles in water at high ionic strength. The effect of the molecular architecture (di‐ vs. triblock) of these amphiphilic copolymers was investigated by using gold nanoparticles (AuNPs) as probes for colloidal stability. The results demonstrate that both di‐ and triblock copolymers can provide long term stability, and that in both cases AuNPs are individually embedded within globules of polymers. However, in the case of diblock copolymers, the colloidal stability was related to the formation of micelles, in contrast with the case of triblock copolymers, which were previously shown to provide good stability even at concentrations at which micelles do not form. Quartz crystal microbalance (QCM) experiments showed that the presence of the hydrophobic block in the structure of the polymer is important to ensure quantitative adsorption upon a gold surface and to limit desorption. We demonstrate that with an appropriate choice of polymer, the polymer/AuNP hybrids can also undergo filtration and freeze‐drying without noticeable aggregation, which can be very convenient for further applications. Finally, preliminary studies of the cytotoxicity effect on fibroblast cells show that the polymer/AuNP hybrids were not cytotoxic. TEM micrographs on ultrathin sections of cells after incubation with the colloidal solutions show that the nanoparticles were internalized into the cells, conserving their initial size and shape.     

Gold nanoparticles decorated with oligo(ethylene glycol) thiols: protein resistance and colloidal stability

The interactions between proteins and gold colloids functionalized with protein-resistant oligo(ethylene glycol) (OEG) thiol, HS(CH2)11(OCH2CH2)6OMe (EG6OMe), in aqueous solution have been studied by small-angle X-ray scattering (SAXS) and UV-vis spectroscopy. The mean size, 2R, and the size distribution of the decorated gold colloids have been characterized by SAXS. The monolayer-protected gold colloids have no correlations due to the low volume fraction in solution and are stable in a wide range of temperatures (5-70 degrees C), pH (1.3-12.4), and ionic strength (0-1.0 M). In contrast, protein (bovine serum albumin) solutions with concentrations in the range of 60-200 mg/mL (4.6-14.5 vol %) show a pronounced correlation peak in SAXS, which results from the repulsive electrostatic interaction between charged proteins. These protein interactions show significant dependence on ionic strength, as would be expected for an electrostatic interaction (Zhang et al. J. Phys. Chem. B 2007, 111, 251). For a mixture of proteins and gold colloids, the protein-protein interaction changes little upon mixing with OEG-decorated gold colloids. In contrast, the colloid-colloid interaction is found to be strongly dependent on the protein concentration and the size of the colloid itself. Adding protein to a colloidal solution results in an attractive depletion interaction between functionalized gold colloids, and above a critical protein concentration, c*, the colloids form aggregates and flocculate. Adding salt to such mixtures enhances the depletion effect and decreases the critical protein concentration. The aggregation is a reversible process (i.e., diluting the solution leads to dissolution of aggregates). The results also indicate that the charge of the OEG self-assembled monolayer at a curved interface has a rather limited effect on the colloidal stabilization and the repulsive interaction with proteins.     

Improving Lanthanide Nanocrystal Colloidal Stability in Competitive Aqueous Buffer Solutions using Multivalent PEG-Phosphonate Ligands

The range of properties available in the lanthanide series has inspired research into the use of lanthanide nanoparticles for numerous applications. We aim to use NaLnF(4) nanoparticles for isotopic tags in mass cytometry. This application requires nanoparticles of narrow size distribution, diameters preferably less than 15 nm, and robust surface chemistry to avoid nonspecific interactions and to facilitate bioconjugation. Nanoparticles (NaHoF(4), NaEuF(4), NaGdF(4), and NaTbF(4)) were synthesized with diameters from 9 to 11 nm with oleic acid surface stabilization. The surface ligands were replaced by a series of mono-, di-, and tetraphosphonate PEG ligands, whose synthesis is reported here. The colloidal stability of the resulting particles was monitored over a range of pH values and in phosphate containing solutions. All of the PEG-phosphonate ligands were found to produce non-aggregated colloidally stable suspensions of the nanoparticles in water as judged by DLS and TEM measurements. However, in more aggressive solutions, at high pH and in phosphate buffers, the mono- and diphosphonate PEG ligands did not stabilize the particles and aggregation as well as flocculation was observed. However, the tetraphosphonate ligand was able to stabilize the particles at high pH and in phosphate buffers for extended periods of time.