Fluorescence Quenching of Alpha-Fetoprotein by Gold Nanoparticles: Effect of Dielectric Shell on Non-Radiative Decay

Fluorescence quenching spectrometry was applied to study the interactions between gold colloidal nanoparticles and alpha-fetoprotein (AFP). Experimental results show that the gold nanoparticles can quench the fluorescence emission of adsorbed AFP effectively. Furthermore, the intensity of fluorescence emission peak decreases monotonously with the increasing gold nanoparticles content. A mechanism based on surface plasmon resonance–induced non-radiative decay was investigated to illuminate the effect of a dielectric shell on the fluorescence quenching ability of gold nanoparticles. The calculation results show that the increasing dielectric shell thickness may improve the monochromaticity of fluorescence quenching. However, high energy transfer efficiency can be obtained within a wide wavelength band by coating a thinner dielectric shell.     

Interactions Between Gold Nanoparticles and Polymer Bearing 3-Styryl Thiophene Chromophores

The interactions between gold nanoparticles and a novel acrylate copolymer bearing 3-styryl thiophene chromophores were studied spectrally and electrochemically. The emission intensity of the polymer solution can be quenched by gold nanoparticles. Collisional quenching is likely the main mechanism for the deactivation process and heterogeneous electron transfer takes place in the process. For the solid polymer film, the presence of gold nanoparticles reduces the emission intensity of the single chromophore as well as the intensity of the excimers. Cyclic voltammetry (CV) investigations indicate that the polymer solution exhibits no oxidation wave. However, in the presence of gold nanoparticles, either by directly addition to the polymer solution or by deposition on the ITO electrode, the polymer solutions possess distinct CV oxidation peak(s), indicating that the gold nanoparticles may mediate the contact and enhance the electron transfer between the electrode and chromophores.     

Coalescence Behavior of Gold Nanoparticles

The tetraoctylammonium bromide (TOAB)-stabilized gold nanoparticles have been successfully fabricated. After an annealing of the as-synthesized nanoparticles at 300 °C for 30 min, the coalescence behavior of gold nanoparticles has been investigated using high-resolution transmission electron microscopy in detail. Two types of coalescence, one being an ordered combination of two or more particles in appropriate orientations through twinning, and the other being an ordered combination of two small particles with facets through a common lattice plane, have been observed.     

Trapping Iron Oxide into Hollow Gold Nanoparticles

Synthesis of the core/shell-structured Fe₃O₄/Au nanoparticles by trapping Fe₃O₄ inside hollow Au nanoparticles is described. The produced composite nanoparticles are strongly magnetic with their surface plasmon resonance peaks in the near infrared region (wavelength from 700 to 800 nm), combining desirable magnetic and plasmonic properties into one nanoparticle. They are particularly suitable for in vivo diagnostic and therapeutic applications. The intact Au surface provides convenient anchorage sites for attachment of targeting molecules, and the particles can be activated by both near infrared lights and magnetic fields. As more and more hollow nanoparticles become available, this synthetic method would find general applications in the fabrication of core–shell multifunctional nanostructures.     

Tuning Photoswitchable Dual-Color Fluorescence from Core-Shell Polymer Nanoparticles

Core-shell polymeric nanoparticles (NPs) containing photoswitchable spiropyrans (SP) and spirooxazines (SO) within the cores were fabricated. Fluorescence photoswitching studies revealed that the substituent groups on the photochromic SP/SO structures exerted significant influence on the fluorescence photoswitching behaviors of the as-prepared polymeric NPs, such as the reversibly interchangeable fluorescence color and the photoswitching kinetics. The electron-releasing and electron-withdrawing abilities of the substituent groups are believed to play important roles in controlling the electron configuration of the photochromic component and therefore be responsible for the tunable dual-color photoswitching performance.     

Assessment of the In Vivo Toxicity of Gold Nanoparticles

The environmental impact of nanoparticles is evident; however, their toxicity due to their nanosize is rarely discussed. Gold nanoparticles (GNPs) may serve as a promising model to address the size-dependent biological response to nanoparticles because they show good biocompatibility and their size can be controlled with great precision during their chemical synthesis. Naked GNPs ranging from 3 to 100 nm were injected intraperitoneally into BALB/C mice at a dose of 8 mg/kg/week. GNPs of 3, 5, 50, and 100 nm did not show harmful effects; however, GNPs ranging from 8 to 37 nm induced severe sickness in mice. Mice injected with GNPs in this range showed fatigue, loss of appetite, change of fur color, and weight loss. Starting from day 14, mice in this group exhibited a camel-like back and crooked spine. The majority of mice in these groups died within 21 days. Injection of 5 and 3 nm GNPs, however, did not induce sickness or lethality in mice. Pathological examination of the major organs of the mice in the diseased groups indicated an increase of Kupffer cells in the liver, loss of structural integrity in the lungs, and diffusion of white pulp in the spleen. The pathological abnormality was associated with the presence of gold particles at the diseased sites, which were verified by ex vivo Coherent anti-Stoke Raman scattering microscopy. Modifying the surface of the GNPs by incorporating immunogenic peptides ameliorated their toxicity. This reduction in the toxicity is associated with an increase in the ability to induce antibody response. The toxicity of GNPs may be a fundamental determinant of the environmental toxicity of nanoparticles.     

Recent Advances in Understanding CO Oxidation on Gold Nanoparticles Using Density Functional Theory

Since the discovery of a series of Au-based catalysts by Haruta et al. considerable progress has been made in understanding the active role of Au in CO oxidation catalysis. This review provides a summary of recent theoretical work performed in this field; in particular it addresses DFT studies of CO oxidation catalysis over free and supported gold nanoparticles. Several properties of the Au particles have been found to contribute to their unique catalytic activity. Of these properties, the low-coordination state of the Au atoms is arguably the most pertinent, although other properties of the Au cluster atoms, such as electronic charge, cannot be ignored. The current consensuses regarding the mechanism for CO oxidation over Au-based catalysts is also discussed. Finally, water-enhanced catalysis of CO oxidation on Au clusters is summarized.     

Biosynthesis of Gold Nanoparticles by Foliar Broths: Roles of Biocompounds and Other Attributes of the Extracts

Biosynthesis of nanoparticles has arisen as a promising alternative to conventional synthetic methodologies owing to its eco-friendly advantages, and the involved bioprotocol still needs further clarification. This research, for the first time from the standpoint of statistics, confirmed an electrostatic force or ionic bond-based interaction between the chloroauric ions and the involved bioconstituents and manifested that reducing sugars and flavonoids were both important reductants responsible for conversion of Au(III) to Au(0). The result also demonstrated that the proteins were not the reducing agents, yet they might be protection agents in biosynthesis of gold nanoparticles (GNPs). Besides, a significant linear relationship was found between the anti-oxidant ability of the foliar broths and their capability to reduce Au(III) into Au(0). Furthermore, the preliminary investigation based on the boxplot on the size/shape distribution of the biosynthesized GNPs revealed that gold nanospheres with higher degree of homogeneity in size tended to be promoted by foliar broths containing higher content of reducing sugars/flavonoids and proteins. Otherwise, i.e., for those broths with lower content of the above biocompounds, sphere GNPs of wider size distribution or even gold nanotriangles tended to be fabricated.     

X-ray Fluorescence Uptake Measurement of Functionalized Gold Nanoparticles in Tumor Cell Microsamples

Quantitative cellular in vitro nanoparticle uptake measurements are possible with a large number of different techniques, however, all have their respective restrictions. Here, we demonstrate the application of synchrotron-based X-ray fluorescence imaging (XFI) on prostate tumor cells, which have internalized differently functionalized gold nanoparticles. Total nanoparticle uptake on the order of a few hundred picograms could be conveniently observed with microsamples consisting of only a few hundreds of cells. A comparison with mass spectroscopy quantification is provided, experimental results are both supported and sensitivity limits of this XFI approach extrapolated by Monte-Carlo simulations, yielding a minimum detectable nanoparticle mass of just 5 pg. This study demonstrates the high sensitivity level of XFI, allowing non-destructive uptake measurements with very small microsamples within just seconds of irradiation time.     

氮掺杂碳纳米粒子荧光共振能量转移测定核黄素

以柠檬酸和乙二胺为前驱体,在油酸介质中通过微波辅助法一步合成了氮掺杂荧光碳纳米粒子,量子产率达41.5%。碳纳米粒子与核黄素可发生有效的荧光共振能量转移,基于此建立了一种定量测定核黄素含量的新方法。测定核黄素含量的线性范围为0~20μg/m L,检出限为68.5 ng/m L。该方法简单、快速、灵敏度高,可用于实际样品中核黄素含量的测定。     

Enhancement of the Antitumour Activity for the Synthesised Dodecylcysteine Surfactant using Gold Nanoparticles

In this paper, the surfactant dodecylcysteine hydrochloride was synthesised. The surface parameters of the synthesised surfactant were studied using a surface tension technique. The surface parameters show a good surface activity of the prepared surfactant in aqueous solution. The self-assembling behaviour of the synthesised surfactant comparing with that of cysteine compound on the prepared gold nanoparticles was confirmed using transmission electron microscope (TEM) measurements. The effect of self-assembling of this surfactant on the size of gold nanoparticles was studied using TEM images. The antitumour activity of the prepared surfactant without and with the gold nanoparticles was investigated. The results show that the antitumour activity of the prepared surfactant was enhanced with the presences of the gold nanoparticles.

Self-organized Multilayer Films and Porous Nanocomposites of Gold Nanoparticles with Octa(3-aminopropyl)octasilsesquioxane

Successive deposition of octa(3-aminopropyl)octasilsesquioxane octahydrochloride and gold nanoparticles coated with carboxylate groups (Au–COO⁻) on glass substrates alternately under mild basic conditions led to systematic buildup of a gold colloidal multilayer. The driving force of the self-assembly was electrostatic interaction between ammonium cations of octa(3-aminopropyl)octasilsesquioxane octahydrochloride and carboxylate anions on Au–COO⁻. A linear increase of surface plasmon resonance of Au–COO⁻ with the deposited bilayers indicated the multilayer manipulation was reproducible. Porous nanocomposites were accomplished by precipitation of octa(3-aminopropyl)octasilsesquioxane octahydrochloride modified polystyrene (PS) latex particles and Au–COO⁻ followed by removal of the PS particles via tetrahydrofuran (THF) extraction. Porous nanocomposite films were obtained by layer-by-layer (LBL) self-assembly of the octa(3-aminopropyl)octasilsesquioxane octahydrochloride modified PS latex particles and Au–COO⁻ followed by removal of the PS particles via THF extraction. Dedicated to Professor Christopher W. Allen for his advances in inorganic ring and polymer chemistry.     

纳米改性聚合物材料研究进展

综述了纳米改性聚合物材料的研究进展,包括纳米粒子的结构与性质,纳米粒子的表面改性,纳米粒子对聚合物的改性机理和方法及纳米技术在高分子材料领域中的应用。     

多孔电聚合膜和纳米金修饰电极阳极溶出伏安法测定痕量铜

使用电聚合2-巯基苯并咪唑膜(PMB I)和纳米金共同修饰玻碳电极。实验发现,多孔PMB I膜可阻止电极表面被共存的污染物污染。方法校正曲线的斜率为0.0464±0.0027μA.L/μg,检测限为0.39μg/L。将该电极用于废水中Cu2+的测定,其结果与原子吸收测定结果接近。     

Facile Synthesis of Gold-nanoparticles-decorated Polymer Assemblies and Core-Shell Gold Nanoparticles Using Pluronic Block Copolymers

Synthesis of gold nanoparticles (AuNPs) and Pluronic triblock copolymer composite in aqueous medium was studied. Gold-polymer nanocomposite with different structures was fabricated by tailoring the molar ratio of gold precursors to Pluronic P123 molecules or pH value of the P123 solution. When a lower volume ratio of [AuCl4-]/[P123] (0.05) was employed at pH 11.1, a nanostructure similar to plum pudding was obtained. AuNPs with an average diameter of 13.1 nm were embedded in Pluronic assemblies, and each one held about 21 single gold nanoparticles. When [AuCl4-]/[P123] was increased to 0.1, core-shell structure was obtained if the pH value was in the range of 10.6~11.6, while gold polyhedra were fabricated when pH value was 8.1. Typical core-shell AuNPs had an average diameter of 9.6 nm with a narrow size distribution, while gold polyhedras with a mean diameter of 12.8 nm was obtained. The specific morphologies of the resultant nanocomposite were presumably obtained due to the synergistic interaction among the reactants.     

一步法制备新型荧光聚合物纳米粒子

采用一步细乳液聚合法将荧光单体4-甲胺基-9-(2-烯丙基)-1,8-萘二甲酰亚胺(MANI)共价键结合进聚合物纳米粒子中.光谱特性研究证明了MANI已经成功结合进人纳米粒子中.更重要的是,因为MANI通过共价键的方式结合进聚合物纳米粒子中,可以有效避免产生染料泄漏现象.并且可以通过控制纳米粒子中MANI的含量,来获得...     

轮状病毒结构蛋白自组装修饰金纳米粒子

通过轮状病毒结构蛋白VP6自组装的方式对金纳米粒子进行了修饰,获得了VP6包覆的金纳米复合材料,改善了金纳米粒子的生物相容性,使其表面带有丰富的化学基团,更易在靶向药物输运、热疗及造影等方面获得新应用。     

聚合物纳米微球分离纯化棘白霉素B母核方法研究

以聚合物纳米微球为层析介质,采用HPLC检测方法,开发高纯度棘白霉素B母核的分离纯化工艺,并对层析条件进行优化。结果表明,当选择Uni PS 30型聚合物纳米微球为层析介质、上样量为1.2g·(100g介质)-1、以体积分数为3%的乙醇进行洗脱、流速为12mL·min-1时,得到的棘白霉素B母核纯度大于98%。建立了高纯度棘白霉素B母核的分离纯化工艺,流程简单、可行,为该产品产业化开发提供了一定的理论基础。     

Methanobactin-Mediated One-Step Synthesis of Gold Nanoparticles

Preparation of gold nanoparticles with a narrow size distribution has enormous importance in nanotechnology. Methanobactin (Mb) is a copper-binding small peptide that appears to function as an agent for copper sequestration and uptake in methanotrophs. Mb can also bind and catalytically reduce Au (III) to Au (0). In this study, we demonstrate a facile Mb-mediated one-step synthetic route to prepare monodispersed gold nanoparticles. Continuous reduction of Au (III) by Mb can be achieved by using hydroquinone as the reducing agent. The gold nanoparticles have been characterized by UV-visible spectroscopy. The formation and the surface plasmon resonance properties of the gold nanoparticles are highly dependent on the ratio of Au (III) to Mb in solution. X-ray photoelectron spectroscopy (XPS), fluorescence spectra and Fourier transform-infrared spectroscopy (FT-IR) spectra suggest that Mb molecules catalytically reduce Au (III) to Au (0) with the concomitant production of gold nanoparticles, and then, Mb statically adsorbed onto the surface of gold nanoparticles to form an Mb-gold nanoparticles assembly. This avoids secondary nucleation. The formed gold nanoparticles have been demonstrated to be monodispersed and uniform by transmission electron microscopy (TEM) images. Analysis of these particles shows an average size of 14.9 nm with a standard deviation of 1.1 nm. The gold nanoparticles are extremely stable and can resist aggregation, even after several months.