Nanoparticle transmission electron microscopy

Water-soluble calix[n]arenes are powerful receptors for non-polar substrates in aqueous solution. These compounds are promising candidates as carrier molecules for the transport of non-polar substrates through bulk water as well as inverse phase-transfer catalysts, as proven for the Suzuki coupling of iodobenzene with phenyl boronic acid [91]. 1.5-bis(4,4 -bis(perfluorooctyl)penta-l,4-dien-3-one (39) stabilizes palladium 0) nanoparticles (transmission electron microscopy) formed in the reduction of palladium dichloride with methanol. These palladium colloids are soluble in perfluorinated solvents, and they are efficient recoverable catalysts for Suzuki crosscoupling under fluorous biphasic conditions (Equation 69) [92]. 

Multi-walled CNTs (MWCNTs) are produced by arc discharge between graphite electrodes but other carbonaceous materials are always formed simultaneously. The main by-product, nanoparticles, can be removed utilizing the difference in oxidation reaction rates between CNTs and nanoparticles [9]. Then, it was reported that CNTs can be aligned by dispersion in a polymer resin matrix [10]. However, the parameters of CNTs are uncontrollable, such as the diameter, length, chirality and so on, at present. Furthermore, although the CNTs are observed like cylinders by transmission electron microscopy (TEM), some reports have pointed out the possibility of non-cylindrical structures and the existence of defects [11-14]. 

In the transmission electron microscopy (TEM) images, the starch nanoplatelets (SNPs) are believed to aggregate as a result of hydrogen bond interactions due to the surface hydroxyl groups [13] (Fig. lA). Blocking these interactions by relatively large molecular weight molecules obviously improves the individualization of the nanoparticles. The acetylated starch and cellulose nanoparticles (SAcNPs and CelAcNPs) appeared more individualized and monodispersed than their unmodified counterparts with a size of about 50 nm (Fig. IB C). 

Crystalline phases (truncated octahedra) of 5 nm silver particles, thiolate protected as well, have been detected by means of high-resolution transmission electron microscopy (HRTEM) [26-28]. Three-dimensional architectures of 5-6 nm thiolate-stabilized gold particles have also been described [29]. Several other reports on 3D superlattices of metal nanoparticles have become known during the last few years [30-33]. 

Usually bimetallic nanoparticles as well as monometallic ones are characterized by many probing tools such as UV-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), EXAFS, infrared spectroscopy of adsorbed CO (CO-IR), and so on [1,2]. 

Ag-core/Au-shell bimetallic nanoparticles were prepared by NaBH4 reduction method [124]. UV-Vis spectra were recorded and compared with various ratios of AuAg alloy nanoparticles. The UV-Vis spectra of bimetallic nanoparticles suggested the formation of core/shell structure. Furthermore, the high-resolution transmission electron microscopy (HRTEM) image of the nanoparticles confirmed the core/shell type configuration directly. 

In order to obtain Pt nanoparticles, aqueous solution of 10 M K2PtCl4, which contained 10 M (as monomer unit) of poly-NIPA or poly-NEA, was bubbled with Ar gas and then H2 gas. Then the reaction vessel was sealed tightly and kept in a water bath at a suitable temperature. At given reaction times, the vessels were opened and the samples for transmission electron microscopy (TEM) were prepared by soaking a grid (carbon substrate, Oken) in the colloidal solution and then drying it in the air. The TEM (Hitachi H-8100) was operated at 200 kV. 

The synthesis of nanoparticles using plant biomass has been investigated by many [24,26]. Using high resolution transmission electron microscopy (HRTEM), it has been... 

The cores of individual mammalian ferritin molecules are clearly visible by transmission electron microscopy as well defined nanoparticle crystallites encapsulated within the protein shell which can attain a size close to that of the 8 nm interior diameter of the protein shell (Massover, 1993). This is illustrated in Figure 6.13 for a sample of human ferritin. The amount of iron in the core is variable, and can range from zero to a maximum of approximately 4500 atoms (Fischbach and Anderegg, 1965) this corresponds to the capacity of the internal cavity for Fe(III) as... 

Microporous nanoparticles with ordered zeolitic structure such as Ti-Beta are used for incorporation into walls or deposition into pores of mesoporous materials to form the micro/mesoporous composite materials [1-3], Microporous particles need to be small enough to be successfully incorporated in the composite structure. This means that the zeolite synthesis has to be stopped as soon as the particles exhibit ordered zeolitic structure. To study the growth of Ti-Beta particles we used 29Si solid-state and liquid-state NMR spectroscopy combined with x-ray powder diffraction (XRPD) and high-resolution transmission electron microscopy (HRTEM). With these techniques we monitored zeolite formation from the initial precursor gel to the final Ti-Beta product. 

Study by Transmission Electron Microscopy Tomography of gold nanoparticles in reduced Au/zeolites... 

Tomography was applied during Transmission Electron Microscopy (TEM) analysis of various reduced Au/zeolite samples. The size and location of the gold nanoparticles as a function of the support characteristics and preparation method are discussed. 

The structure of 3 was confirmed by X-ray crystallography (Fig. 1). The morphology of the nanoparticles was examined by transmission electron microscopy (TEM). The two sp2-C palladacycles 1 and 4 gave what appeared to be triangular nanoparticles, in 2D, from 2-12 nm in size while the sp3-C PdCys 5 and 6 and Pd(OAc)2 exhibited more conventional morphology and were faceted palladium particles from 3-10 nm (Fig. 2). 

Ffirai and Toshima have published several reports on the synthesis of transition-metal nanoparticles by alcoholic reduction of metal salts in the presence of a polymer such as polyvinylalcohol (PVA) or polyvinylpyrrolidone (PVP). This simple and reproducible process can be applied for the preparation of monometallic [32, 33] or bimetallic [34—39] nanoparticles. In this series of articles, the nanoparticles are characterized by different techniques such as transmission electronic microscopy (TEM), UV-visible spectroscopy, electron diffraction (EDX), powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) or extended X-ray absorption fine structure (EXAFS, bimetallic systems). The great majority of the particles have a uniform size between 1 and 3 nm. These nanomaterials are efficient catalysts for olefin or diene hydrogenation under mild conditions (30°C, Ph2 = 1 bar)- In the case of bimetallic catalysts, the catalytic activity was seen to depend on their metal composition, and this may also have an influence on the selectivity of the partial hydrogenation of dienes. 

In this study, nanoparticles of titanium dioxide (TiCh) have been successfully synthesized by. reduction method. These nanoparticles were characterized by using X-ray diffraction (XRD) and TEM (transmission electron microscopy). XRD revealed the presence of pure TiCL NPs. XRD studies suggested that the titanium dioxide, TiCL exists in anatase form. The nanostructured character of the produced titania powders was characterised by Scherer method and TEM examinations. The TEM images indicate that the crystalline size of titanium dioxide precipitates varies from 1.81 nm to 13.15 nm This shows that nanoparticles obtained from reduction method are in more nanorange as compared to those obtained for precipitation method. 

SnC>2 nanoparticles have been successfully synthesized by chemical co-precipitation method using ethanol, acetone, tetrahydrofuran (THF) and ether as solvents. X-ray Diffraction (XRD), Field Emission Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) have been used to study the crystallographic and morphological properties of synthesized SnC>2 nanoparticles, while their optical properties have been studied by UV-Visible absorption spectroscopy. UV-Vis absorption spectra shows a weak quantum confinement in all the synthesized SnCL samples. The photo-catalytic activity of as-synthesized SnC>2 nanoparticles under UV irradiation has been evaluated using Methylene Blue (MB) dye as a test contaminant in water. The results showed that solvents played a key role to control the morphology and photo-catalytic activity of SnCE nanoparticles. 

The fluorescent labels reported for investigation of intracellular uptake and distribution by CLSM comprise Nile red [13], Texas Red, and 6-coumarin [14]. Not only for fluorescence microscopy but also for transmission electron microscopy (TEM), the loading of markers proved to be useful. Osmium tetroxid as an electron dense marker and bovine serum albumin (BSA) as a model protein were entrapped in PLGA-nanoparticles to elucidate their uptake and intracellular distribution in human vascular smooth muscle cells [15]. 

---