CdS/dendrimer nanocomposites can be synthesized from methanolic Cd(2+) and S(2-) with amine-terminated polyamidoamine dendrimers of generation 8 (G8NH(2)) as stabilizers. By controlling the preparation conditions, nanoparticles with diameters < or = 2 nm can be obtained with a narrow size distribution. They show blue photoluminescence at approximately 450 nm. We studied the effects of various additives on the photoluminescence and elucidated its mechanism. Stable aggregates of two to three G8NH(2) molecules with several CdS nanoparticles form; the particles are located at the surface of the G8NH(2) molecules. The adsorption of the CdS/G8NH(2) nanocomposites on flat substrate surfaces is determined by the substrate chemistry. The hydrophilic nature of G8NH(2) results in weak affinity to graphite but strong affinity to hydroxy-terminated substrates such as mica, oxidized silicon wafers, and carboxylate-terminated monolayers. Patterning of nanocomposites on these hydrophilic substrates is achieved by the microcontact printing method. We propose to use only one molecule, a large dendrimer, to control the nanoparticle formation and also the immobilization of the synthesized nanoparticle/dendrimer composites.
We found a significant increase in G-MDSCs in PHI patients that was related to disease progression and PD-L1 was used by MDSCs to inhibit CD8 T cells in HIV infection. Our data improve the understanding of HIV pathogenesis in PHI.
We describe a simple method for the fabrication of arbitrary submicrometer patterns of cobalt on a nonconducting surface with wet chemical methods and microcontact printing (µCP). A hydroxyl-terminated dendrimer is transferred from a stamp to the surface. The thickness of the dendrimer layer can be tuned by varying the concentration of the dendrimer ink solution. These dendrimer molecules act as host molecules. The guests, palladium ions, sorb into the layer and act as nucleation centers for electroless cobalt plating. We produced cobalt structures down to several hundred nanometers lateral size and up to several tens of nanometer thickness with high spatial selectivity. The printed dendrimers are cage-like molecules with well-defined chemical groups; hence, they can selectively bind guest molecules (here palladium complexes) when the latter possess chemical groups that favor a host-guest interaction. Printing dendrimers therefore points toward a more general method to create patterns with chemical functionality.
Micrometer‐scale patterns of blue photoluminescing CdS nanoparticles can be produced by microcontact printing on a hydroxyl‐terminated silicon wafer surface (see Figure). The CdS nanoparticles were synthesized with amine‐terminated generation eight dendrimers as stabilizers. The resulting CdS/dendrimer composite is directly printable due to hydrogen bonds between dendrimer and surface.
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