3 research outputs found

    Gold Nanoparticle Inclusion into Protein Nanotube as a Layered Wall Component

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    We describe the synthesis, structure, and catalytic activity of human serum albumin (HSA) nanotubes (NTs) including gold nanoparticles (AuNPs) as a layered wall component. The NTs were fabricated as an alternating layer-by-layer assembly of AuNP and HSA admixture (a negatively charged part) and poly-l-arginine (PLA, a positively charged part) into a track-etched polycarbonate membrane (400 nm pore diameter) with subsequent dissolution of the template. SEM images showed the formation of uniform hollow cylinders of (PLA/AuNP-HSA)<sub>3</sub> with a 426 ± 12 nm outer diameter and 65 ± 7 nm wall thickness. Transmission electron microscopy and energy dispersive X-ray measurements revealed high loading of AuNPs in the tubular wall. HSAs bind strongly onto the individual AuNP (<i>K</i> = 1.25 × 10<sup>9</sup> M<sup>–1</sup>), generating a core–shell AuNP-HSA corona, which is the requirement of the robust NT formation. Calcination of the (PLA/AuNP-HSA)<sub>3</sub> NTs at 500 °C under air yielded red solid NTs composed of thermally fused AuNPs. From the mass decrease by heat treatment, we calculated the weight of the organic components (PLA and HSA) and thereby constructed a six-layer model of the tube. The (PLA/AuNP-HSA)<sub>3</sub> NTs serve as a heterogeneous catalyst for reduction of 4-nitrophenol with sodium borohydrate. Furthermore, implantation of the stiff (PLA/AuNP-HSA)<sub>3</sub> NTs vertically onto glass plate produced uniformly cylindrical tube arrays

    Regioselective Recognition of a [60]Fullerene-Bisadduct by Cyclodextrin

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    The three different regioisomers of bis-<i>N</i>-methylfulleropyrrolidines have been separated by controlling the relative amounts of γ-cyclodextrin and dimethyl sulfoxide (DMSO) contained in solutions of these compounds. When a small amount of γ-CDx was used in a mechanochemical high-speed vibration milling apparatus, the <i>trans-1</i> and <i>trans-2</i>•γ-CDx complexes were separated from the <i>trans-3</i>•γ-CDx complex. In contrast, <i>trans-3</i> was extracted in a relatively high ratio with an excess of γ-CDx. The addition of DMSO to aqueous solutions of the fullerene derivative•γ-CDx complexes allowed for the three regioisomers to be obtained in high purity (>95%). The basis for the observed regioselective separation was a competition between the relative stabilities and solubilities of the complexes in the water and water-DMSO solvents. The stabilities of the complexes in water were assessed by the number of hydrogen bonding interactions between the two γ-CDx units using molecular dynamics simulations. To the best of our knowledge, this is the first reported example of the isolation of the different regioisomers of fullerene derivatives using host–guest complexes

    [70]Fullerenes Assist the Formation of Phospholipid Bicelles at Low Lipid Concentrations

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    The incorporation of neutral [70]­fullerenes (C<sub>70</sub>) led to bicelle formation in a relatively low lipid concentration range from neutral lipid mixtures (DMPC/DHPC). Furthermore, C<sub>70</sub> addition resulted in the formation of large bicelles with a radius of ca. 100 nm, in contrast to C<sub>70</sub>-free bicelles that were formed from anionic lipid mixtures (DMPC/DHPC/DMPG). The stabilization of these bicelles was attributed to C<sub>70</sub> incorporation into the membranes
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