阴离子表面活性剂作为添加剂种子生长法制备尺寸可调的单分散金纳米棒

以不同阴离子表面活性剂作为添加剂种子生长法制备金纳米棒, 并考察阴离子表面活性剂种类对金纳米棒形貌及光学性质的影响。在十二烷基苯基磺酸钠(SDBS)存在下, 金纳米棒的产率明显高于使用十二烷基磺酸钠的反应体系。对添加SDBS的种子生长法制备金纳米棒的反应条件进行优化, 得到十六烷基三甲基溴化铵、SDBS、抗坏血酸和硝酸银的最佳浓度分别为0.04 mol·L^-1、2.4 mmol·L^-1、1.2 mmol·L^-1和0.08 mmol·L^-1。在此条件下, 金纳米棒的生长在30 min内完成, 所制备的金纳米棒表面等离子共振吸收峰位于823 nm, 其横纵比为(5±0.03)。当改变生长液中硝酸银浓度时, 金纳米棒的尺寸也随之发生改变。此外, 我们还探讨了SDBS的作用机理。相对于经典种子生长法, 新方法制备纳米金棒在尺寸可调性、单分散性和生物毒性方面明显改善, 可广泛应用于各种光学及生物分析。     

抗坏血酸还原法制备金纳米花的机理

研究了以抗坏血酸和氯金酸为生长溶液制备金纳米花的反应机理. 结果表明, 通过改变生长溶液中抗坏血酸浓度可以调节小尺寸的初级金粒子在种子表面的聚集方式及金纳米花的熟化速度, 从而影响金纳米花的形貌和光学性质. 协同改变抗坏血酸浓度和pH值, 可实现对金纳米花形貌及光学性质的有效调控. 表面增强拉曼散射(SERS)性能评价结果表明, 抗坏血酸还原法制备的金纳米花表面较清洁, 对罗丹明6G有较好的拉曼增强效果.     

一种制备高长径比金纳米棒的新方法

报道了一种制备高长径比金纳米棒的新方法. 在25 ℃条件下, 采用种子介导生长法, 通过优化表面活性剂十六烷基三甲基溴化铵(CTAB)的浓度, 制备了长度(200±18.62) nm, 长径比大于10的金纳米棒, 并讨论了金纳米棒的形成机制. 结果表明, 金纳米棒的长径比和纵向吸收波长与CTAB的浓度有关. 此外, 通过提高反应液的离子强度, 利用制备的金纳米棒与球形颗粒不同的静电作用将金纳米棒分离纯化. 运用透射电子显微镜(TEM)和扫描电子显微镜(SEM)对金纳米棒的表面形貌进行表征.     

二苯胺磺酸钠还原法制备粒径可控的金纳米粒子

采用二苯胺磺酸钠还原四氯合金酸的方法,在室温条件下,用SDS(十二烷基硫酸钠)、SDBS(十二烷基苯磺酸钠)作表面活性剂,成功地合成了金纳米粒子.分别讨论了还原剂二苯胺磺酸钠、表面活性剂(SDS、SDBS)及四氯台金酸的浓度等对金纳米粒子的粒径和形貌的影响.通过控制反应条件,可以合成出平均粒径大约为10、14、30、36nm的金纳米粒子.利用透射电镜(TEN)、紫外-可见(UV-Vis)吸收光谱对金纳米粒子进行了表征.研究结果表明不同的SDS或SDBS/HAuCl4的摩尔比,对金纳米粒子的尺寸大小有影响.     

小尺寸金纳米棒的快速制备及影响因素的研究

通过研究十六烷基三甲基溴化铵、抗坏血酸、NaBH4和AgNO3的用量,以及搅拌时间、反应时间对无种子生长法制备金纳米棒的影响,筛选出了最佳制备条件,以及各成分对金纳米棒生长过程中的作用.采用可见吸收光谱和透射电镜图对不同条件下所制备出的金纳米棒进行了表征.在室温为28℃,CTAB浓度为0.1 mol/L、AgNO3浓度为96μmol/L、AA浓度为0.97 mmol/L、NaBH4浓度为1.5μmol/L,搅拌25 s等最佳条件下,只需反应6h就能够成功制备出长径比为5且形貌均匀、分散性和稳定性良好、轴宽较小的金纳米棒,且有望应用于水环境中Hg2+的检测.     

溴甲酚紫分光光度法测定水中的阴离子表面活性剂

在pH=2的酸性条件下,十二烷基苯磺酸钠(SDBS)阴离子表面活性剂能与溴甲酚紫直接缔合,生成浅黄色缔合物;据此建立了测定水中SDBS阴离子表面活性剂的分光光度法.结果表明,生成的浅黄色缔合物的最大吸收波长为436nm,SDBS的表观摩尔吸光系数为1.68×104 L·mol-1·cm-1;SDBS的浓度在0²mg·L-1范围内时遵循比尔定律.该方法可方便地用于测定水样中的痕量阴离子表面活性剂,效果良好.     

三角形银纳米片的合成及其影响因素

报道了一种在不需光照的条件下制备三角形银纳米片的新方法.在表面活性剂BRIJ35存在下,将硝酸银用硼氢化钠和柠檬酸钠还原,在不同温度范围内反应形成各种尺度的三角形银纳米片,探讨了硼氢化钠浓度、BRIJ35浓度和表面活性剂的种类和溶液pH值等因素对银纳米颗粒形貌和尺寸的影响.     

金纳米球和金纳米棒的制备及其光热催化性能

以氯金酸(HAuCl_4)为原料,硼氢化钠(NaBH_4)为还原剂,聚乙烯吡咯烷酮K30(PVP)为稳定剂制备了尺寸5 nm的金纳米球;以阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)为模板剂和油酸钠(NaOL)稳定剂,用种子生长法制备了不同长径比(R=2.5~4)的金纳米棒。在2 W·cm~(-2)的808 nm激光照射10 min条件下,C(0.4 mg·mL~(-1))浓度金纳米球溶液升温10.2℃,该溶液可催化血液中亚硝基硫醇释放NO,最大释放量可达1.42 nmol·L~(-1);相同光热及催化条件下,C(0.4 mg·mL~(-1))浓度金纳米棒(R=3.01)溶液升温41.3℃,该溶液催化血液中亚硝基硫醇释放NO最大释放量可达1.89 nmol·L~(-1)。金纳米球和金纳米棒的光热及催化性能随着浓度增加而增强,金纳米棒的光热及催化性能要优于金纳米球。     

嵌段共聚物反介观液晶相新方法合成多级有序排列的二氧化硅纳米棒

在非极性溶剂体系中,开辟了利用反相液晶法制备多级有序纳米材料的新方法.利用嵌段共聚物表面活性剂在非极性溶剂中形成反相胶束,无机硅物种可以进入胶束的内部,在溶剂挥发后,有机-无机物种进一步组装成为反相六方液晶相.除去模板剂后即制备出尺寸规则的二氧化硅纳米棒材料.由于嵌段高分子的作用,六方排列的二氧化硅纳米棒进一步排列成层状结构(层间距约150nm).通过选择表面活性剂及改变其浓度,纳米棒的尺寸可以在9～15nm范围内调变.该反应途径对于合成其它尺寸均一、多级有序排列的纳米棒材料是非常有意义的.     

金纳米棒的制备、生长机理及纯化

金纳米棒由于其独特物理性质而在众多的各向异性金纳米颗粒中赢得了关注。目前,金纳米棒在纳米电子学、光学、生物医药等研究领域均具有良好的应用前景。对金纳米棒合成的有效调控直接决定着其形状、尺寸和长径比,而这些又进一步影响着金纳米棒的物理性质。本文梳理了金纳米棒制备方法的发展脉络,以模板法、电化学方法、种子生长法以及近年来出现的无种子生长法为主线,系统综述了金纳米棒制备过程实验参数调控对产物结构、物理性质的影响,详细阐述了关于单晶以及孪晶金纳米棒的生长机理,并介绍了提高产物纯度的分离纯化手段。     

Determination of anionic surfactant in surface water by resonance light-scattering technology

A sensitive and rapid method, without any extraction procedure, for the determination of the anionic surfactant expressed in the terms of sodium dodecyl benzene sulfonate (SDBS) by the resonance light scattering (RLS) technique is described in this paper. In the pH value 3.0 Britton-Robinson (BR) buffer, Victoria blue B (VBB) reacted with SDBS and produced large particles which resulted in the remarkable enhancement of the RLS intensity of VBB. The enhanced RLS intensity of the assay system was proportional to the concentration of SDBS in the range of 0.08–3.0 mg L^–1 and the correlation coefficient was r = 0.9996. The detection limit was 0.013 mg L^–1. This method was applied to determine the anionic surfactant in the surface water samples and satisfactory results were obtained. The reaction mechanism was also studied and the interaction between VBB and SDBS was mainly governed by electrostatic effect and the π–π stacking effect.     

Thorough tuning of the aspect ratio of gold nanorods using response surface methodology

In the present work a central composite design based on response surface methodology (RSM) is employed for fine tuning of the aspect ratios of seed-mediated synthesized gold nanorods (GNRs). The relations between the affecting parameters, including ratio of l-ascorbic acid to Au³⁺ ions, concentrations of silver nitrate, CTAB, and CTAB-capped gold seeds, were explored using a RSM model. It is observed that the effect of each parameter on the aspect ratio of developing nanorods highly depends on the value of the other parameters. The concentrations of silver ions, ascorbic acid and seeds are found to have a high contribution in controlling the aspect ratios of NRs. The optimized parameters led to a high yield synthesis of gold nanorods with an ideal aspect ratio ranging from 1 (spherical particle) to 4.9. In addition, corresponding tunable surface Plasmon absorption band has been extended to 880 nm. The resulted nanorods were characterized by UV–visible spectrometry and transmission electron microscopy.     

Effect of Cyclodextrins on the Interaction Between BSA and Sodium Dodecyl Benzene Sulfonate

Cyclodextrins offer the potential of modulating protein–surfactant interactions. In our work, the effect of cyclodextrin (CD) on the interaction between bovine serum albumin (BSA) and the anionic surfactant sodium dodecyl benzene sulfonate (SDBS) has been studied by isothermal titration calorimetry (ITC), fluorescence spectra and circular dichroism measurements. The presences of cyclodextrin can slightly hinder the strong interactions between BSA and SDBS by the combination of electrostatic and hydrophobic interactions between BSA and SDBS. Furthermore, the effectiveness of α-CD is lower than that of β-CD, due to the lower association constant between α-CD and surfactant. The presence of both α- and β-CD totally hinders the nonspecific interactions between BSA and SDBS, because the hydrophobic interaction between cyclodextrin and surfactant is stronger than that between BSA and surfactant.     

Sensitive Determination of Prulifloxacin by Its Fluorescence Enhancement on Terbium(III)–Sodium Dodecylbenzene Sulfonate System

Abstract

A terbium-sensitized fluorescence spectrophotometry method using an anionic surfactant, sodium dodecyl benzene sulphonate (SDBS), was developed for the determination of prulifloxacin (PUFX). It was found that SDBS significantly enhanced the fluorescence intensity of the PUFX–Tb³⁺ complex (about 13-fold). The optimal experimental conditions were determined as follows: excitation and emission wavelengths of 290 nm and 545 nm, pH 8.0, 4.0 × 10^?5 mol L^?1 terbium(III), and 4.0 × 10^?4 mol L^?1 SDBS. The enhanced fluorescence intensity of the system (ΔF) showed a good linear relationship with the concentration of PUFX over the range 6.0 × 10^?8 to 2.0 × 10^?6mol L^?1 with a correlation coefficient of 0.9991. The detection limit (S/N = 3) was determined as 8.5 × 10^?9 mol L^?1. This method has been successfully applied for the determination of PUFX in pharmaceuticals and human urine/serum samples. Compared with most other methods reported, the rapid and simple procedure proposed here offered higher sensitivity, wider linear range, and good stability. The luminescence mechanism of the system was also discussed in detail. In the fluorescence system of PUFX–Tb³⁺–SDBS, SDBS acted not only as the surfactant but also as the energy donor.     

A novel fused-silica capillary dropping mercury electrode with long drop-time and its application on determination of critical micelle concentration

A novel long drop time mercury electrode has been constructed from common fused-silica capillary (50 μm I.D., 360 μm E.D.). Proposed device provides reproducible mercury drops with typical lifetime 40-120 s. The electrode was used for a set of electrocapillary measurements aimed at determination of critical micelle concentration of anionic surfactants by a convection controlled drop-time technique. A critical micelle concentration of sodium dodecyl sulfate 5.6 ± 0.4 mmol L⁻¹ and 4.3 ± 0.4 mmol L⁻¹ were obtained in 1 mmol L⁻¹ and 5 mmol L⁻¹ phosphate buffer (pH 7.0), respectively. The values were comparable to those obtained from conductometric measurements under the same conditions (7.0 ± 0.1 mmol L⁻¹ and 5.2 ± 0.1 mmol L⁻¹, respectively) and the difference was explained in accordance with theory of hemi-micelle formation.     

Growth of gold nanorods and bipyramids using CTEAB surfactant

Gold nanorods and bipyramids have been synthesized using the seed-mediated approach in aqueous cetyltriethylammonium bromide (CTEAB) solutions in the presence of silver nitrate. Gold nanoparticle seeds that are stabilized with either CTEAB or sodium citrate have been used. The use of the CTEAB-stabilized seeds gives gold nanorods in high yield in one step with the longitudinal plasmon wavelength ranging from 750 to 1030 nm, depending on the amount of the seeds. The longitudinal plasmon wavelength can be extended to 1100 nm by the use of a two-step growth method. The growth of gold nanorods in CTEAB solutions takes 5-10 h, more than 5 times slower than that in cetyltrimethylammonium bromide solutions at the same concentration of surfactants. The use of the citrate-stabilized seeds gives both gold bipyramids and a small percentage of gold nanorods. The longitudinal plasmon wavelength of the bipyramids is tunable from 700 to 1100 nm by varying the amount of the citrate-stabilized seeds. The growth of gold bipyramids takes more than 1 day. Transmission electron microscopy characterizations reveal that the gold nanorods grown from both types of gold nanoparticle seeds are single-crystalline and that the gold bipyramids are penta-twinned.     

An original nitrate sensor based on silver nanoparticles electrodeposited on a gold electrode

The electroreduction of nitrate in synthetic seawater was investigated by cyclic voltammetry (CV) at a bare gold electrode modified by electrodeposited silver nanoparticles (AgNPs). The AgNPs were generated by chronoamperometry using a charge, Q, lower than the theoretical one corresponding to a silver monolayer. In these conditions, a linear range for nitrate determination is obtained from 10·10^-6 mol L^-1 to 10·10^-3 mol L^-1. Such a low limit of detection was achieved due to the combination of two chemical reactions coupled with electron transfer.     

Room Temperature Synthesis of Gold Nanokites in Polyvinyl Alcohol‐Sodium Dodecyl Sulfate Aggregations Aqueous Solution

Controlled synthesis of asymmetrical gold nanokites was realized by reducing HAuCl₄ with polyvinyl alcohol (PVA) in PVA‐sodium dodecyl sulfate (SDS) aggregations aqueous solution at room temperature without any additional reducing agents. The crystal structures, optical property and growth process of the gold nanokites were investigated by X‐ray diffraction (XRD), Vis‐NIR spectrum and transmission electron microscope (TEM). HAuCl₄ concentration dramatically influenced the morphologies of the products. When HAuCl₄ concentration was increased from 0.5 mmol·L⁻¹ to 2.2 mmol·L⁻¹, the products changed from network‐like nanostructures to nanokites, nanoleaves and microplates. SDS was indispensable for the formation of gold nanokites and without SDS super‐branched structures became the dominant products.     

Properties and Extraction for [Ni(NH3)6]2+ of ATPS-a Formed by Aqueous Cationic–Anionic Surfactant Mixtures

The properties and extraction for [Ni(NH₃)₆]²⁺ of anionic aqueous two-phase systems (ATPS-a) that formed in mixtures of cetyltrimethylammonium bromide (CTAB) and excess sodium dodecyl sulfate (SDS) aqueous solutions were investigated. The results showed that the properties and extraction effects were strongly affected by the surfactant concentration, the temperature of system, and the mole fraction of surfactants. The increase of temperature induces narrower phase region and larger phase volume ratio. In addition, [Ni(NH₃)₆]²⁺ was extracted into the surfactant-rich phase with higher distribution coefficient when the liquid crystal had the birefringent properties. Moreover, the distribution coefficient can be improved through reducing the concentration of surfactant from 0.15 to 0.05 mol · L^?1 or increasing mole fraction of CTAB from 21.9% to 23.1%. The results showed that ATPS of cationic–anionic surfactants was efficient for [Ni(NH₃)₆]²⁺ extraction with distribution coefficients of 13.5 when the total surfactant concentration was 0.05 mol · L^?1, mole fraction of CTAB was 21%, and temperature was 34°C.