3 research outputs found
Gold Nanoparticle Inclusion into Protein Nanotube as a Layered Wall Component
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
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
The
incorporation of neutral [70]Âfullerenes (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