Well‐defined noble metal dendritic structures (see Figure) can be synthesized with the assistance of ultrasonic waves and using a Raney nickel template, as revealed here. Interestingly, Raney nickel is demonstrated to act not only as the template but also as the reducing agent. Advantages of this method include mild reaction conditions and easy removal of the template.
Chalcopyrite quaternary semiconductor CuIn(Se x S 12x ) 2 nanocrystallites (0¡x¡1) were successfully prepared via a relatively simple and convenient solvothermal route. From X-ray data it is found that the cell constants a and c vary linearly with the composition x as: a(A ˚)~5.5299z0.2665x, c(A ˚)~11.1004z0.5139x. The sample CuInSeS was characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and infrared spectroscopy (IR). The optical property of CuIn(Se x S 12x ) 2 nanocrystallites was also recorded by means of UV-Vis absorption spectroscopy. In addition, the effect of different solvents on the formation of the product was studied to indicate that ethylenediamine is the optimal solvent for this reaction. Finally, the reaction mechanism in ethylenediamine was also investigated.
A benzene thermal conversion route has been successfully developed to prepare nanocrystalline indium nitride at 180-200 degrees C by choosing NaNH(2) and In(2)S(3) as novel nitrogen and indium sources. This route has been also extended to the synthesis of other group III nitrides. The product InN was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and high-resolution TEM, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and infrared spectroscopy (IR). The optical properties of nanocrystalline InN were also recorded by means of UV-vis absorption spectroscopy and photoluminescence (PL) spectroscopy, indicating that the as-prepared sample was within the quantum confinement regime. Finally, the formation mechanism was also investigated.
The targeting of a glycosylated antibody Fc fragment to bind to cancer cells by site-selective incorporation of a synthetic ligand is described. Homogeneously glycosylated immunoglobulin G subclass 1 fragment crystallizable (IgG1 Fc) was produced by expression in a glycosylation-deficient yeast strain and subsequent treatment with mannosidase IA. A N-terminal cysteine was generated on the expressed IgG1 Fc by utilizing proteolytic processing enzymes in the yeast secretory pathway. A cyclic RGD peptide thioester 2 was synthesized and then site-selectively attached to the N-terminus of the IgG1 Fc glycoprotein using native chemical ligation. The resulting chemically modified antibody fragment, RGD-Man(5)-IgG1 Fc (5), retained biological activity similar to that of the free cyclic RGD peptide 1 when assayed for its ability to both promote and inhibit the adhesion of alpha(v)beta(3) integrin receptor-expressing WM-115 melanoma cells. In addition, fluorescent microscopy experiments were conducted using FITC-labeled 5 and confirmed binding of 5 to WM-115 melanoma cells. Site-selectively modified antibody fragments such as the one described here may be used to combine the beneficial properties of synthetic receptor ligands with antibody fragments to develop useful biochemical tools and improved therapeutics. The methods described here can also be used to produce glycoprotein fragments for the chemoenzymatic synthesis of homogeneous glycoproteins.
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