聚甲基丙烯酸钠辅助的金纳米颗粒的绿色制备

利用聚甲基丙烯酸钠的弱还原性和螯合作用,建立了一种水溶性金纳米颗粒合成的新方法.借助紫外可见分光光度计和透射电子显微镜对金纳米颗粒进行了表征,初步讨论了反应物浓度以及反应温度对产物的影响.     

Photochemical synthesis of gold nanoparticles in latexes

Gold nanoparticles in aqueous dispersions of 100-nm polystyrene microspheres were prepared by photochemical synthesis under exposure to monochromatic light with an excitation wavelength of 254 nm. The kinetic relationships in formation of gold nanoparticles were examined in relation to the H[AuCl₄] and polymer concentration in the photolyte.     

Surfactant-free synthesis and functionalization of gold nanoparticles

A new, facile and generally applicable synthesis of functionalized gold nanoparticles is presented. It is based on the surfactant-free generation of weakly stabilized nanoparticles by the reduction of HAuCl4 with sodium naphthalenide in diglyme. These nanoparticles were found to lack long-term stability. However, stabilization in both unpolar and polar solvents could straightforwardly be achieved by subsequent addition of various capping ligands. The resulting ligand-capped gold nanoparticles were investigated by TEM microscopy, UV-vis, and FT-IR spectroscopy. Particle core size can be tuned by the amount of reduction agent. The strict separation of the reduction step and the functionalization step in this one-pot synthesis offers an easy and fast access to highly functionalized gold nanoparticles.     

Photochemical synthesis and self-assembly of gold nanoparticles

Colloidal gold was prepared by UV light irradiation of the mixture of HAuCl₄ aqueous solution and poly(vinyl pyrrolidone) (PVP) ethanol solution in the presence of silver ions. The resulting sheet-like nanoparticles were found to self-assemble into nanoflowers by a centrifuging process. The results of control experiments reflected that only suitable size sheet-like nanoparticles could assemble into the flower-like structures. The presence of Ag ions and PVP are essential for the formation process of nanoflowers. They perform their function by serving as structure-directing agents to produce the sheet-like particles. The appearance of the flower-like assemblages is attributed to the combination of Van der Waals force and the anisotropic hydrophobic attraction between the nanoparticles. The flower-like assemblages films can be used as surface-enhanced Raman spectroscopy (SERS) substrates with 4-aminothiophenol (4-ATP) molecule as a test probe.     

Size-controlled synthesis and characterization of thiol-stabilized gold nanoparticles

Size-controlled synthesis of nanoparticles of less than a few nanometers in size is a challenge due to the spatial resolution limit of most scattering and imaging techniques used for their structural characterization. We present the self-consistent analysis of the extended x-ray absorption fine-structure (EXAFS) spectroscopy data of ligand-stabilized metal nanoclusters. Our method employs the coordination number truncation and the surface-tension models in order to measure the average diameter and analyze the structure of the nanoparticles. EXAFS analysis was performed on the two series of dodecanethiol-stabilized gold nanoparticles prepared by one-phase and two-phase syntheses where the only control parameter was the gold/thiol ratio xi, varied between 6:1 and 1:6. The two-phase synthesis resulted in the smaller particles whose size decreased monotonically and stabilized at 16 A when xi was lowered below 1:1. This behavior is consistent with the theoretically predicted thermodynamic limit obtained previously in the framework of the spherical drop model of Au nanoparticles.     

Facile photochemical synthesis of unprotected aqueous gold nanoparticles

Aqueous, unprotected gold nanoparticles were prepared from HAuCl4 using a water-soluble benzoin (Irgacure-2959) as a photochemical source of strongly reducing ketyl radicals. This rapid method provides spatiotemporal control of nanoparticle generation, while light intensity can be used to control particle size. The particles are stable for months and do not require any of the conventional (S, N, or P) stabilizing ligands, although these can be readily incorporated if required.     

One-step synthesis and characterization of dendrimer-protected gold nanoparticles

We proposed an economic, convenient, and mild synthesis of dendrimer-protected gold nanoparticles by exposing a third-generation poly(propyleneimine) dendrimer-HAuCl₄ aqueous solution to sunlight without the additional step of introducing other reducing agents and protective agents. Most importantly, it is found that the size of the gold nanoparticles thus formed can be controlled by the molar ratio of the dendrimer to gold. The text was submitted by the author in English.     

Environmentally friendly synthesis of highly monodisperse biocompatible gold nanoparticles with urchin-like shape

We report a facile and environmentally friendly strategy for high-yield synthesis of highly monodisperse gold nanoparticles with urchin-like shape. A simple protein, gelatin, was first used for the control over shape and orientation of the gold nanoparticles. These nanoparticles, ready to use for biological systems, are promising in the optical imaging-based disease diagnostics and therapy because of their tunable surface plasmon resonance (SPR) and excellent surface-enhanced Raman scattering (SERS) activity.     

4-十二烷氧基苄胺在纳米金微粒合成中的应用

以新型表面活性剂4-十二烷氧基苄胺(C12OBA)构成的C12OBA/正丁醇/正庚烷/丙醛/HAuCl4(aq)反相微乳液作为微反应器,利用微波辐射加热-丙醛还原法制备了C12OBA包覆金纳米微粒;利用透射电镜、傅立叶变换红外光谱仪及X射线衍射仪分析了产物的微观形貌、化学键合特征、晶体结构;并测定了其紫外-可见吸收光谱.结果显示,表面活性剂C12OBA既可参与形成稳定的反相微乳液,又可作为金纳米微粒的良好保护剂.反相微乳液液滴的微小水核以及C12OBA/金的物质的量之比对纳米金微粒的尺寸和形貌起到良好的控制作用.     

One-pot synthesis of robust core/shell gold nanoparticles

A one-pot synthesis of thermally stable core/shell gold nanoparticles (Au-NPs) was developed via surface-initiated atom transfer radical polymerization (ATRP) of n-butyl acrylate (BA) and a dimethacrylate-based cross-linker. The higher reactivity of the cross-linker enabled the formation of a thin cross-linked polymer shell around the surface of the Au-NP before the growth of linear polymer chains from the shell. The cross-linked polymer shell served as a robust protective layer, prevented the dissociation of linear polymer brushes from the surfaces of Au-NPs, and provided the Au-NPs excellent thermal stability at elevated temperature (e.g., 110 degrees C for 24 h). This synthetic method could be easily expanded for preparation of other types of inorganic/polymer nanocomposites with significantly improved stability.     

Laser ablation synthesis of gold nanoparticles in organic solvents

Free and functionalized gold nanoparticles are synthesized by laser ablation of a gold metal plate immersed in dimethyl sulfoxide, acetonitrile, and tetrahydrofuran. Functionalized gold nanoparticles are synthesized in a one-step process thanks to the solubility of the ligands in these solvents. It is possible to have significant control of the concentration, aggregation, and size of the particles by varying a few parameters. UV-vis spectroscopy and transmission electron microscopy are used for the characterization of the nanoparticles. The Mie model for spherical particles and the Gans model for spheroids allow a fast and reliable interpretation of experimental UV-vis spectra.     

Green synthesis of well-dispersed gold nanoparticles using Macrotyloma uniflorum

The synthesis of metal nanoparticles of different sizes, shapes, chemical composition and controlled monodispersity is an important area of research in nanotechnology because of their interesting physical properties and technological applications. Present work describes an eco-friendly method for the synthesis of spherical gold nanoparticles using aqueous extract of Macrotyloma uniflorum. The effects of quantity of extract, temperature and pH on the formation of nanoparticles are studied. The nanoparticles are characterized by UV-visible spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. The high crystallinity of nanoparticles with fcc phase is evident from HRTEM images, SAED and XRD patterns. Synthesized nanoparticles have size in the range 14-17nm. FTIR spectrum indicates the presence of different functional groups present in the bio-molecule capping the nanoparticles. The possible mechanism leading to the formation of gold nanoparticles is suggested.     

Reverse microemulsion-mediated synthesis of silica-coated gold and silver nanoparticles

A reverse microemulsion method is reported for preparing monodispersed silica-coated gold (or silver) nanoparticles without the use of a silane coupling agent or polymer as the surface primer. This method enables a fine control of the silica shell thickness with nanometer precision. As compared to the St?ber method reported for direct silica coating, which can only coat large gold particles ( approximately 50 nm in diameter) at low concentrations (<1.5 x 10(10) particles/mL), this new approach is capable of coating gold particles of a wide range of sizes (from 10 to 50 nm) at a much higher concentration ( approximately 1.5 x 10(13) particles/mL). Moreover, it enables straightforward surface functionalization via co-condensation between tetraethyl orthosilicate and another silane with the desired functional groups. The functional groups introduced by this method are readily accessible and thus useful for various applications.     

Facile synthesis of gold nanoparticles in aqueous acrylamide solution

A method is advanced for preparing gold nanoparticles (NPs) at 50°C in aqueous acrylamide (AAm), which has the dual function of a reducing agent for HAuCl₄ and a protective ligand for NPs. Nanoparticles have gold cores with the average size d_Au = 20.9 ± 3.6 nm. The growth kinetics of NPs has been studied. Films of NPs have been produced on glass, silica, silicon, and polyethylene terephthalate (PET) substrates. The NPs and films have been characterized by UV-Vis and IR spectroscopy, X-ray powder diffraction, transmission and scanning electron microscopy, and atomic-force microscopy.     

Microwave synthesis of core-shell gold/palladium bimetallic nanoparticles

The microwave-assisted polyol reduction method was applied to the synthesis of core-shell gold/palladium bimetallic nanoparticles by the simultaneous reduction of the AuIII and PdII ions. The thickness of the palladium shell was calculated to be approximately 3 nm, and the gold core diameter is 9 nm. The structure and composition of the bimetallic particles were characterized by high-resolution transmission electron microscopy equipped with a nanoarea energy-dispersive X-ray spectroscopy attachment, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy.     

Green synthesis of gold nanoparticles using glycerol-incorporated nanosized liposomes

There has been enormous interest in the last decade in development methods for the inorganic synthesis of metallic nanoparticles of desired sizes and shapes because of their unique properties and extensive applications in catalysis, electronics, plasmonics, and sensing. Here we report on an environmentally friendly, one-pot synthesis of metallic nanoparticles, which avoids the use of organic solvents and requires mild experimental conditions. The developed method uses liposomes as nanoreactors, where the liposomes were prepared by encapsulating chloroauric acid and exploited the use of glycerol, incorporated within the lipid bilayer as well as in its hydrophilic core, as a reducing agent for the controlled preparation of highly homogeneous populations of gold nanoparticles. The effects of temperature, the presence of a capping agent, and the concentration of glycerol on the size and homogeneity of the nanoparticles formed were investigated and compared with solution-based glycerol-mediated nanoparticle synthesis. Well-distributed gold nanoparticle populations in the range of 2-8 nm were prepared in the designed liposomal nanoreactor with a clear dependence of the size on the concentration of glycerol, the temperature, and the presence of a capping agent whereas large, heterogeneous populations of nanoparticles with amorphous shapes were obtained in the absence of liposomes. The particle morphology and sizes were analyzed using transmission electron microscopy imaging, and the liposome size was measured using photon correlation spectroscopy.     

Biocatalytic synthesis of gold nanoparticles with cofactor regeneration in recombinant Escherichia coli cells

Here we report the enzymatic synthesis of gold nanoparticles (Au NPs) by an engineered Escherichia coli harboring an NADH cofactor regeneration system coupled with glycerol dehydrogenase, which can be triggered by the addition of exogenous glycerol.     

Facile synthesis of gold nanoparticles capped with an ammonium-based chiral ionic liquid crystal

Herein, we describe a facile synthesis of stable chiral ionic liquid crystal (ILC)-capped gold nanoparticles. A new ILC containing a chiral cholesterol moiety having a terminal triethylammonium group was synthesised which exhibited an enantiotropic lamellar mesophase. Stable, monodisperse citrate-stabilised gold nanoparticles having a size of ~60 nm were prepared and the citrate ligands on the gold nanoparticles were replaced with chiral ILC through a two-phase ligand exchange process. The resulting chiral ILC-stabilised particles were characterised using UV–visible (UV–Vis) and transmission electron microscopy (TEM) studies. Different from the citrate-stabilised nanoparticles, the ligand exchanged gold nanoparticles were dispersible in organic solvent and resulting dispersion was stable for more than observed period of 3 months. Furthermore, the chiral ILC-decorated gold nanoparticles were found to be well dispersible in a nematic host without any aggregation and induced a vertical alignment of the nematic director.