Two-Layer Model of Colloidal Gold Bioconjugates and Its Application to the Optimization of Nanosensors

An optical model of the conjugates of colloidal gold nanoparticles with biopolymers is analyzed in terms of two-layer spherical particle with the gold core and dielectric coating. The Mie theory was used to study the dependence of variations (caused by the adsorption of a biopolymer on the particle surface) in the extinction and light scattering (at 90°) spectra on the gold core diameter (d = 5–200 nm), the shell refractive index and thickness s (ratio s/d = 0–1). Some theoretical results by Templeton et al. (J. Phys. Chem. B, 2000, vol. 104, pp. 564–570) on the two-layer dipole model were corrected. It is shown that the dependence of spectral shifts of the extinction and scattering peaks on the conjugate structure is adequately described by the dipole approximation. In particular, we found the universal dependence of the normalized spectral shift of extinction maximum on the s/d ratio. Having in mind the optimization of conjugate–nanosensors, we studied the problem of what particle size is optimal for the transformation of biopolymer adsorption event into the variations in the spectral parameters of extinction and light scattering. Based on the calculations of extinction maximum values and positions, as well as on calculated differential extinction spectra, we concluded that a maximal conjugate efficiency corresponds to the core diameters of 40–80 nm. We also discussed the principles of conjugate–nanosensors optimization for the polymer shell structure.     

Effects of Cosolvents and pH on Protein Adsorption on Polystyrene Latex: A Dynamic Light Scattering Study

Dynamic light scattering was used to study the adsorption of two proteins with different surface properties (IgG and HSA) on negatively charged polystyrene latex. The proteins were adsorbed from water and from water/methanol and water/glycerol mixtures at various pH. Some striking differences between the adsorption behaviors of the proteins were observed. Whereas the thickness of the adsorbed layer of HSA was extremely sensitive to pH and solvent composition, that of IgG was not. IgG mainly showed an end-on orientation on polystyrene whereas several different surface orientations are suggested for HSA under different conditions. The addition of methanol inhibited the adsorption of HSA on the latex, but it did not affect the adsorption of IgG. In contrast, the addition of glycerol increased the thickness of the adsorbed layers of both proteins. So, the orientation of IgG on the latex is insensitive to pH but is a function of the kind of solvent whereas both pH and solvent strongly affect the adsorption of HSA. This is a puzzling result since both cosolvents should equally affect the adsorption of both proteins if the dominant forces for adsorption are the same. Therefore, we concluded that, whereas hydrophobic interactions are the dominant force in the adsorption behavior of HSA, van der Waals forces are the main forces involved in the attachment of IgG to the lattices. Copyright 2000 Academic Press.     

镉(Ⅱ)-邻菲罗啉-溴酚蓝体系的共振光散射光谱研究及分析应用

本文建立了一种测定镉(Ⅱ)含量的共振光散射(RLS)光谱法。在pH=9.60的Tris-HCl介质中,镉(Ⅱ)与邻菲罗啉(Phen)形成螯合物后,再与溴酚蓝(BPB)形成离子缔合物,可使溶液的共振光散射显著增强;在波长638 nm处,RLS的增强程度与镉(Ⅱ)浓度呈线性关系。线性范围为0~3.20 mg/L,检出限为4.50μg/L。该方法简便、快速、灵敏度高,用于合成样和水样中镉(Ⅱ)的测定,结果令人满意。     

银纳米粒子探针等离子共振散射光谱法测定抗坏血酸

利用抗坏血酸(VC)还原银氨溶液生成具有强烈等离子体共振散射特性的银纳米粒子,导致体系共振光散射信号的增强,散射最大峰位于544 nm。 在最佳条件下,体系的共振散射强度与抗坏血酸浓度在0.2~7.0 μmol/L范围内呈线性关系,相关系数为0.9988,检出限为8.1 nmol/L。 抗坏血酸的氧化产物能与银纳米粒子相互作用使之分散均匀且保持稳定,因此该体系不需要添加稳定剂或分散剂。 以此建立了用银纳米粒子为探针的测定抗坏血酸的高灵敏、简捷的共振散射新方法。 同时讨论了最佳反应条件和其它影响因素。 该方法用于ＶＣ片及饮料中抗坏血酸的测定,加标回收率在94.5%~97.0%之间。 结果表明,方法具有操作简单,灵敏度高和回收率较好等优点。     

以DDAB为模板的银纳米粒子多层膜制备及其表面增强拉曼效应

通过离子交换和静电相互作用, 将银纳米粒子引入双十二烷基二甲基溴化铵(DDAB)模板中, 获得了有序的银纳米粒子多层膜. 用紫外-可见光谱(UV-Vis)、循环伏安(CV)和原子力显微镜(AFM)对其进行了表征, 并用小角X射线衍射(XRD)研究了DDAB模板和银纳米粒子多层膜的有序性结构. 以4-巯基吡啶(4-MPY)为探针分子研究了银纳米粒子多层膜在表面增强拉曼(SERS)方面的应用, 结果表明, 4-MPY吸附在银纳米粒子多层膜上呈现很强的SERS信号, 说明该多层膜可以用作高活性的SERS基底.     

金纳米微粒作探针共振瑞利散射光谱法测定卡那霉素

在一种含柠檬酸盐的溶液中, 柠檬酸根阴离子自组装于带正电荷的金纳米微粒表面, 使金纳米微粒成为一种被柠檬酸根包裹的带负电荷的超分子化合物. 在pH 4.4～6.8的弱酸性介质中, 它可与质子化的卡那霉素(KANA)阳离子借静电引力、疏水作用力结合, 形成粒径更大的聚集体(平均粒径从12增至20 nm), 这种聚集体的形成在引起金纳米的等离子体吸收带明显红移(Δλ＝102 nm)的同时, 共振瑞利散射(RRS)显著增强并且倍频散射(FDS)和二级散射(SOS)等共振非线性散射也有较大的增强, 最大散射峰分别位于280 nm (RRS), 310 nm (FDS)和480 nm (SOS)处. 在适当条件下, 散射强度(ΔI)与卡那霉素的浓度成正比, 其中RRS法灵敏度最高, 因此金纳米微粒可作为测定卡那霉素的高灵敏RRS探针, 它对卡那霉素的检出限为10.52 ng•mL^－1, 方法有较好的选择性, 可用于血液中卡那霉素的测定, 文中还讨论了有关反应机理和RRS增强的原因.     

阿特拉津与DNA作用共振光散射光谱的研究及其应用

首次报道了阿特拉津与ctDNA作用的共振光散射光谱 (RLS)特征和利用小分子农药阿特拉津作为探针测定痕量脱氧核糖核酸的方法。在 pH=1.41的酸度条件下 ,阿特拉津 -ctDNA在319.8nm处有一增强的共振光散射光谱峰 ,且增强的共振光散射强度与ctDNA的浓度成线性关系。在实验确定的优化条件下 ,方法的线性范围为0.05～34μg·mL -1 ,检出限为11.9ng·mL -1(3δ) ,该方法成功地用于人工混合样品中ctDNA的测定     

厚朴酚-结晶紫-十二烷基硫酸钠体系的共振光散射光谱研究及分析应用

在pH=3.5的柠檬酸钠-盐酸缓冲介质中,阳离子染料结晶紫(CV)对厚朴酚/和厚朴酚与十二烷基硫酸钠( SDS)的共振光散射光谱有协同增强作用.在优化的实验条件下,在共振光散射波长为333 nm处,体系的共振光散射增加值与厚朴酚及和厚朴酚在0.02～5.33 μg/mL范围内呈良好的线性关系,检出限为1.88×10-4...     

Study on the Interaction between a Novel Ionic Liquid Probe and Anionic Surfactants Using Resonance Light Scattering Spectra and Its Analytical Application

The interaction between anionic surfactants (AS) and 1‐hexadecyl‐3‐methylimidazolium bromide [C₁₆mim]Br was studied by using resonance light scattering (RLS) technique, UV‐Vis spectrophotometry and fluorometric methods. In Britton Robinson (BR) buffer (pH 6.0), [C₁₆mim]Br reacted with AS to form supermolecular complex which resulted in enhancement in RLS intensity. Their maximum RLS wavelengths were all at 390 nm. Some important interacting experimental variables, such as the solution acidity, [C₁₆mim]Br concentration, salt effect and addition order of the reagents, were investigated and optimized. Under the optimum conditions, quantitative determination ranges were 0.001–7 μg·mL^?1 for dodecyl sodium sulfate (SDS), 0.001–6 μg·mL^?1 for sodium dodecylbenzene sulfonate (SDBS) and 0.005–7 μg·mL^?1 for sodium lauryl sulfonate (SLS), respectively, while the detection limits were 1.3 ng·mL^?1 for SDS, 1.0 ng·mL^?1 for SDBS and 5.1 ng·mL^?1 for SLS, respectively. Based on the ion‐association reaction, a highly sensitive, simple and rapid method has been established for the determination of AS.     

金纳米微粒作探针共振瑞利散射法测定某些蒽环类抗癌药物

在近中性至弱碱性介质中, 金纳米微粒与表柔比星(EPI)、柔红霉素(DNR)和米托蒽醌(MXT)等蒽环类抗癌药物借静电引力、疏水作用力结合, 形成粒径更大的聚集体, 导致共振瑞利散射(RRS)的显著增强并产生新的RRS光谱, 三种结合产物的最大RRS峰均位于313 nm附近, 并在510～610 nm之间有一宽的散射带. 其散射强度(ΔI)与3种抗癌药物的浓度成正比, 对EPI, DNR和MXT的线性范围分别为0.009～0.50, 0.010～0.70 和0.030～1.20 μg•mL^－1, 它们的检出限(3σ)分别为2.7, 3.1和9.0 ng•mL^－1. 研究了反应产物的吸收、荧光和RRS光谱特征, 适宜的反应条件及分析化学性质, 发展了一种用RRS技术灵敏、简便、快速测定蒽环类抗癌药物的新方法.     

Adsorption of 1,4-Benzenedithiol on Gold and Silver Surfaces: Surface-Enhanced Raman Scattering Study

The adsorption behavior of 1,4-benzenedithiol (1,4-BDT) on colloidal gold and silver surfaces has been investigated by means of surface-enhanced Raman scattering (SERS). 1,4-BDT chemisorbed dissociatively on both gold and silver surfaces but as mono- and dithiolate, respectively. Regardless of the bulk concentration of 1,4-BDT, only a monolayer was assembled on the silver surface with a flat orientation by forming two Ag–S bonds. On the gold surface, the monothiolate species,1,4-BDT⁻¹, appeared to assume a rather flat orientation at a very low surface coverage, but as the surface coverage was increased, the adsorbate took a perpendicular orientation. Furthermore, when the bulk concentration of 1,4-BDT was close to that required for a full-monolayer coverage limit, a band assignable to the S–S stretching vibration appeared at 536 cm⁻¹ in the gold sol SERS spectra. A separate ellipsometry measurement performed with vacuum-evaporated gold substrates revealed that up to tetralayers could be assembled on gold in 1 mM n-hexane solution of 1,4-BDT while at best a bilayer formed in either methanol or ethanol solution. The different adsorbate structure of 1,4-BDT on gold and silver was overall quite comparable to that of p-xylene-α,α′-dithiol.     

A Simple Fabrication Method for Three‐Dimensional Gold Nanoparticle Electrodes and Their Application to the Study of the Direct Electrochemistry of Cytochrome c

A simple method for constructing gold nanoparticle‐modified electrodes with three‐dimensional nanostructures is demonstrated. The electrodes were prepared by casting citrate‐reduced AuNPs onto polycrystalline gold electrodes. The resultant electrodes had a large surface area‐to‐volume ratio, adequate for high protein loading and conferring high stability. The gold nanoparticle electrodes were covered with a self‐assembled monolayer of 11‐mercaptoundecanoic acid for electrostatic immobilization of cytochrome c (cyt c). At the electrode, direct, reversible electron transfer from cyt c was observed with remarkable stability. Moreover, an extremely high surface coverage of electrochemically active cyt c, 167 fully packed monolayers, was obtained through use of the electrode.     

A Versatile Dynamic Light Scattering Strategy for the Sensitive Detection of Plant MicroRNAs Based on Click-Chemistry-Amplified Aggregation of Gold Nanoparticles

Plant microRNAs (miRNAs) are naturally 2′-O-methylated at the 3′-terminal; as a consequence, they cannot be efficiently detected by traditional target-triggered polymerization reactions. Here, a simple but robust enzyme-free sensing strategy was developed for plant miRNA analysis by using dynamic light scattering (DLS) to monitor the crosslinking of gold nanoparticles (AuNPs) amplified by click chemical ligation. Combining the enzyme-free cycling chemical-ligation-mediated signal amplification, and the intrinsic outstanding ability of DLS for discriminating the extremely low level of particle aggregation in a large pool of monodisperse AuNPs, high sensitivity was achieved and as low as 78.6 fm plant miRNA could be easily detected.     

Application of Functionalized Ag Nanoparticles for the Determination of Proteins at Nanogram Levels Using the Resonance Light Scattering Method

A novel method for the determination of proteins in aqueous solutions has been developed based on the enhancement of resonance light scattering (RLS) of Ag nanoparticles in the presence of proteins. Factors including acidity of the media, concentration of Ag hydrosol, reaction time, temperature, and interference of non-protein substances were investigated. Under the optimal conditions, with the enhanced RLS signals at 452nm, the linear ranges of calibration curves were 0–0.8µgmL^–1 for bovine serum albumin (BSA), 0–1.2µgmL^–1 for human serum albumin (HSA), and 0–2.5µgmL^–1 for human -IgG (-IgG), respectively. The detection limits were 1.3ngmL^–1 for BSA, 10ngmL^–1 for HAS, and 5.7ngmL^–1 for -IgG.This method has been applied to the analysis of synthetic samples and real human serum samples, and the results were in good agreement with those reported by the hospital, indicating that the method presented here is not only sensitive and simple, but also reliable and suitable for practical applications.     

聚丙烯酸与核酸相互作用的共振光散射光谱研究及其分析应用

研究了聚丙烯酸(PAA)与脱氧核糖核酸(DNA)相互作用的共振光散射(RLS)光谱.实验结果表明,在pH=2.0的B-R缓冲溶液中,PAA与DNA自身的共振光散射峰均较弱,但当二者发生静电作用形成复合物后,体系的共振光散射峰增强,散射增强程度则各不相同,其相对散射强度的顺序是fsDNA＞ctDNA＞yRNA.在一定范围...     

Application of L-Cysteine-Capped ZnS Nanoparticles in the Determination of Nucleic Acids Using the Resonance Light Scattering Method

Nanometer-sized L-cysteine-capped ZnS particles were synthesized by a colloidal aqueous method. The functionalized nanoparticles are water-soluble and suitable for biological applications. In Tris-HCl buffer solution, nucleic acids combine with cysteine-capped nano-ZnS particles by intermolecular forces to form larger nanoparticles. There are two resonance light scattering peaks at 304.5nm and 373.8nm, respectively. The enhanced RLS is related to the concentration of nucleic acids in the range of 0.04 to 1.2µgmL^–1 for calf thymus DNA and 0.2 to 1.0µgmL^–1 for fish sperm DNA. The detection limits (3) are 19ngmL^–1 for calf thymus DNA and 23ngmL^–1 for fish sperm DNA, respectively. Four synthetic samples were analyzed satisfactorily.     

十六烷基溴化吡啶与脱氧核糖核酸作用的共振光散射光谱及其分析应用

在碱性条件下，十六烷基溴化吡啶(CPB)与脱氧核糖核酸(DNA)共存时，体系产生较强的共振光散射，其强度与DNA浓度呈线性关系，据此提出了基于阳离子表面活性剂的共振光散射法定量测定DNA。在最佳实验条件下，测得小牛胸腺DNA(ctDNA)和鱼精子DNA(fsDNA)的线性范围分别为0．2-2．0mg／L和0．2—1．25mg／L，检出限分别为0．07mg／L和0．05mg／L。该方法已应用于合成样品及实际样品中DNA含量的测定。     

共振散射光谱法测定多巴胺的分析应用研究

研究了I3-与孔雀石绿(MG)间的相互作用,并用于共振散射光谱法测定痕量多巴胺。在pH 4.5的柠檬酸-柠檬酸钠缓冲液中,在聚乙烯醇(PVA)与聚乙二醇辛基苯基醚(OP)存在的条件下,孔雀石绿与I3-通过静电作用力生成络合比为1∶2的离子缔合物MG(I3)2,而多巴胺具有还原性,可将I3-还原成I-,从而导致I3--孔雀石绿体系的共振散射强度下降。据此建立了一种灵敏度高、重现性好、快速测定多巴胺的共振散射光谱新方法。在优化的实验条件下,多巴胺的线性范围为2.0×10-7～4.5×10-6mol.L-1,相关系数(r)为0.999 1;检出限(3S/k)为9.5×10-8mol.L-1。将方法应用于针剂和人血清中多巴胺含量的测定,其加标回收率为100.1%～102.4%,相对标准偏差为0.41%～4.8%。     

四磺基铈酞菁共振光散射法测定人血清白蛋白

1　引　　言蛋白质的定量测定是生物化学、药学、食品及临床中常涉及的内容 ,也是临床诊断疾病及检验疾病康复情况的重要指标 ,是许多生化药物分离提纯和质量检验中最常用的手段。其定量分析方法研究在国际上一直非常活跃。本文研究了四磺基铈酞菁 (ＣｅＳ4Ｐｃ)与人血清白蛋白 (ＨＳＡ)作用的共振光散射光谱 ,发现在酸性条件 (ｐＨ =2 .0～ 3 .0 )下 ,在 4 1 2ｎｍ处存在一共振光散射强峰 ,其强度增加值 (ΔＩ)与人血清白蛋白的浓度呈线性关系。据此建立了一种测定微量ＨＳＡ的方法。该方法简便 ,快速 ,灵敏度高 ,用于混合样品中ＨＳＡ的测…     

Determination of Elastic Moduli and Compliances of Viscoelastic Liquids Using the Dynamic Light Scattering Technique

Relations between the dynamic light scattering spectrum and the mechanical compliances and longitudinal stress moduli of viscoelastic liquids are provided. The result provides a basis for determination of mechanical relaxation spectra using the dynamic light scattering technique. The method of Computating the longitudinal modulus and the compliance spectra from the time correlation of density fluctuations of poly (propylene glycol), as determined by the photon correlation spectroscopy technique is illustrated.