Thiol transmission electron microscopy

For example, Wuelfing et al. reported on the synthesis of Au NPs using the thiolated polymer, a-methoxy-co-mercapto-poly(ethylene glycol) (PEG-SH), as stabilizer in a modification of the Brust-Schiffrin method using a 1/12 polymer thiol/ AuC14 ratio. Transmission electron microscopy showed that the product had modestly polydisperse Au cores of average diameter 2.8 1 nm. This nanomaterial led to characteristics uniquely different from alkanethiolate MPCs, notably aqueous solubility, thermal and chemical stability, ligand footprint size, and ionic conductivity [66]. 

In order to assemble gold nanorods (aspect ratio 2.4) by the click reaction, one batch of nanorods capped with 4-azidobutane-l-thiol, A, and another with hex-5-yn-l-thiol, B, were reacted in the acetonitrile-water mixture under standard conditions [12], The occurrence of the click reaction was established by infrared spectroscopy [13], The product of the reaction was investigated by electronic absorption spectroscopy and transmission electron microscopy. Fig. 1 compares the electronic absorption spectra of the gold nanorods before and after the click reaction between the A and B type nanorods. Isolated gold nanorods show transverse and longitudinal plasmon bands around 520 nm and 630 nm, respectively (see Fig. la). 

Numerous examples of ordered 2D structures, especially of thiol-stabilized silver and gold nanoparticles, have become known in the course of the last few years. They usually form spontaneously on Transmission Electron Microscopy (TEM) grids or other surfaces from solution and will not be... 

Transmission electron microscopy (TEM) images showed that GNPs conjugated with Tat peptide (nuclear localization sequence) were mainly located in the nucleus of fibroblast and also revealed no appreciable cytotoxic effects [22]. In contrast, Tkachenko et al. functionalized GNPs with four different nuclear localization peptides ending with a Cys residue (which contains a free thiol) to evaluate the cellular trajectories of peptide gold complexes. Functionalized GNPs were... 

In addition, more sophisticated albumin polycation architectures have been designed. Serum albumins offer a single reactive thiol group that is accessible for site-directed chemistry, e.g., Michael reactions with a maleimide functionality that can react exclusively at this position. Two cBSA-147 molecules have been interconnected by a poly(ethylene oxide) (PEO) polymer linker and the successful formation of the cBSA dimers has been visualized by transmission electron microscopy (TEM). These cBS A-dimers revealed efficient cellular uptake as well as transfection of pDNA-GFP. 

The interaction of MNPs with DNA is a well-known phenomenon [86-89], and single- or double-strand DNA is decorated by MNPs, which can easily be imaged by transmission electron microscopy (TEM) or AFM [90-92]. Various surface-functionalized AuNPs have been prepared to attach AuNPs securely to DNA molecules. In numerous studies, such AuNPs were prepared by surface modifications with cationic thiols [54, 55, 92] or intercalators [93, 94]. The ID chains of AuNPs coated with cationic trimethyl(mercaptoundecyl) ammonium monolayers were electrostatically assembled along DNA molecules in solution by the relative molar quantities of AuNPs and DNA base pairs. Since psoralen acts as a specific intercalator for A-T base pairs, the functionalized AuNPs were assembled onto the pA-pT ds-DNA [93]. Furthermore, UV irradiations induced the reaction between the psoralen units and the thymine of DNA, and then covalently fixed AuNPs to the DNA. 

Allara has demonstrated, using transmission electron microscopy (TEM), that Au films produced with a cystamine adhesive were very smooth in the 5-10 nm range of film thickness (24). Electrical continuity was shown to be a function of crystallite size the films formed on the thiol surface exhibited smaller crystallites due to the inhibition of adatom diffusion by the anchoring agent. The roughness of the AI2O3 substrates was not considered in the discussion of Au film surface roughness (24), but certainly should affect the nature of the Au film. Limitations in the resolution of the electron microscopy used prevented characterization of such films less than 5 nm thick. 

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