5 research outputs found
Chemoresponsive Colloidosomes via Ag<sup>+</sup> Soldering of Surface-Assembled Nanoparticle Monolayers
Colloidosomes with a hollow interior
and a porous plasmonic shell
are highly desired for many applications including nanoreactors, surface-enhanced
Raman scattering (SERS), photothermal therapy, and controlled drug
release. We herein report a silica nanosphere-templated electrostatic
self-assembly in conjunction with a newly developed Ag<sup>+</sup> soldering to fabricate gold colloidosomes toward multifunctionality
and stimuli-responsibility. The gold colloidosomes are capable of
capturing a nanosized object and releasing it via structural dissociation
upon responding to a biochemical input (GSH, glutathione) at a concentration
close to its cellular level. In addition, the colloidosomes have a
tunable nanoporous shell composed of strongly coupled gold nanoparticles,
which exhibit broadened near-infrared plasmon resonance. These features
along with the simplicity and high tunability of the fabrication process
make the gold colloidosomes quite promising for applications in a
chemical or cellular environment
Amplification of arsenic genotoxicity by TiO<sub>2</sub> nanoparticles in mammalian cells: new insights from physicochemical interactions and mitochondria
<p>Titanium dioxide nanoparticles (TiO<sub>2</sub> NPs) have shown great adsorption capacity for arsenic (As); however, the potential impact of TiO<sub>2</sub> NPs on the behavior and toxic responses of As remains largely unexplored. In the present study, we focused on the physicochemical interaction between TiO<sub>2</sub> NPs and As(III) to clarify the underlying mechanisms involved in their synergistic genotoxic effect on mammalian cells. Our data showed that As(III) mainly interacted with TiO<sub>2</sub> NPs by competitively occupying the sites of hydroxyl groups on the surface of TiO<sub>2</sub> NP aggregates, resulting in more aggregation of TiO<sub>2</sub> NPs. Although TiO<sub>2</sub> NPs at concentrations used here had no cytotoxic or genotoxic effects on cells, they efficiently increased the genotoxicity of As(III) in human-hamster hybrid (A<sub>L</sub>) cells. The synergistic genotoxicity of TiO<sub>2</sub> NPs and As(III) was partially inhibited by various endocytosis pathway inhibitors while it was completely blocked by an As(III)-specific chelator. Using a mitochondrial membrane potential fluorescence probe, a reactive oxygen species (ROS) probe together with mitochondrial DNA-depleted Ï<sup>0</sup> A<sub>L</sub> cells, we discovered that mitochondria were essential for mediating the synergistic DNA-damaging effects of TiO<sub>2</sub> NPs and As(III). These data provide novel mechanistic proof that TiO<sub>2</sub> NPs enhanced the genotoxicity of As(III) via physicochemical interactions, which were mediated by mitochondria-dependent ROS.</p
Graphene Oxide Attenuates the Cytotoxicity and Mutagenicity of PCB 52 via Activation of Genuine Autophagy
Graphene oxide (GO), owing to its
large surface area and abundance
of oxygen-containing functional groups, is emerging as a potential
adsorbent for polychlorinated biphenyls (PCBs), which accumulate over
time and are harmful to both natural ecosystems and human health.
However, the effect of GO against PCB-induced toxicity remains largely
unexplored. The present study aimed to investigate the protective
effect of GO against PCB 52 induced cytotoxic and genotoxic response
in mammalian cells at various exposure conditions and clarify the
protective role of autophagy. Pretreatment with GO dramatically decreased
PCB 52 induced cytotoxicity and <i>CD59</i> gene mutation
in humanâhamster hybrid (A<sub>L</sub>) cells. The toxic response
in cells either pretreated with PCB 52 and then treated with GO or
concurrently treated with GO and PCB 52 did not differ significantly
from the toxic response in the cells treated with PCB 52 alone. Using
autophagy inhibitors (3-methyladenine and wortmannin) and inducers
(trehalose and rapamycin), we found that genuine autophagy induced
by GO was involved in decreasing PCB 52 induced toxicity. These findings
suggested that GO has an antagonistic effect against the toxicity
of PCB 52 mainly by triggering a genuine autophagic process, which
might provide new insights into the potential application of GO in
PCB disposal and environmental and health risk assessment
Ordered Porous Pd Octahedra Covered with Monolayer Ru Atoms
Monolayer
Ru atoms covered highly ordered porous Pd octahedra have
been synthesized via the underpotential deposition and thermodynamic
control. Shape evolution from concave nanocube to octahedron with
six hollow cavities was observed. Using aberration-corrected high-resolution
transmission electron microscopy and X-ray photoelectron spectroscopy,
we provide quantitative evidence to prove that only a monolayer of
Ru atoms was deposited on the surface of porous Pd octahedra. The
as-prepared monolayer Ru atoms covered Pd nanostructures exhibited
excellent catalytic property in terms of semihydrogenation of alkynes
Uncoordinated Amine Groups of MetalâOrganic Frameworks to Anchor Single Ru Sites as Chemoselective Catalysts toward the Hydrogenation of Quinoline
Here we report a precise control of isolated single ruthenium site
supported on nitrogen-doped porous carbon (Ru SAs/NâC) through
a coordination-assisted strategy. This synthesis is based on the utilization
of strong coordination between Ru<sup>3+</sup> and the free amine
groups (âNH<sub>2</sub>) at the skeleton of a metalâorganic
framework, which plays a critical role to access the atomically isolated
dispersion of Ru sites. Without the assistance of the amino groups,
the Ru precursor is prone to aggregation during the pyrolysis process,
resulting in the formation of Ru clusters. The atomic dispersion of
Ru on N-doped carbon can be verified by the spherical aberration correction
electron microscopy and X-ray absorption fine structure measurements.
Most importantly, this single Ru sites with single-mind N coordination
can serve as a semihomogeneous catalyst to catalyze effectively chemoselective
hydrogenation of functionalized quinolones