14 research outputs found
Investigation of Silver Nanoparticle Induced Lipids Changes on a Single Cell Surface by Time-of-Flight Secondary Ion Mass Spectrometry
Lipids are the main
component of the cell membrane. They not only
provide structural support of cells but also directly participate
in complex cellular metabolic processes. Lipid signaling is an important
part of cell signaling. Evidence showed that abnormal cellular metabolism
may induce lipids changes. Besides, owing to single cell heterogeneity,
it is necessary to distinguish different behaviors of individual cells.
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is a sensitive
surface analysis technique with high spatial resolution, which is
useful in single cell surface analysis. Herein, we used ToF-SIMS to
investigate silver nanoparticle induced lipids changes on the surface
of single macrophage cells. Delayed extraction mode of ToF-SIMS was
used to simultaneously obtain high mass resolution of mass spectra
and high spatial resolution of single cell chemical imaging. Principle
component analysis (PCA) results showed good agreement with the cytotoxicity
assay results. Clear distinctions were observed between the cell groups
treated with high or low dose of silver nanoparticles. The loadings
plots revealed that the separation was mainly due to changes of cholesterol
and diacylglycerol (DAG) as well as monoacylglycerol (MAG). Meanwhile,
the chemical mapping of single cell components showed that cholesterol
and DAG tend to migrate to the surrounding of the cells after high
dose silver nanoparticles (Ag NPs) treatment. Our results demonstrated
the feasibility of ToF-SIMS for characterizing the changes of the
lipids on a single cell surface, providing a better understanding
of the mechanism of cell–nanoparticle interactions at the molecular
level
Mussel-Inspired Polydopamine Functionalized Plasmonic Nanocomposites for Single-Particle Catalysis
Polydopamine
functionalized plasmonic nanocomposites with well-distributed
catalytically active small gold nanoislands around large gold core
were fabricated without using any chemical reductant or surfactant.
The optical properties, surface molecular structures, and ensemble
catalytic activity of the gold nanocomposites were investigated by
time-of-flight secondary ion mass spectrometry and UV–vis spectroscopy,
respectively. Moreover, the considerable catalytic activity of the
nanocomposites toward 4-nitrophenol reduction was real time monitored
by dark-field spectroscopy techniques at the single-nanoparticle level
avoiding averaging effects in bulk systems. According to the obtained
plasmonic signals from individual nanocomposites, the electron charging
and discharging rates for these nanocomposites during the catalytic
process were calculated. Our results offer new insights into the design
and synthesis of plasmonic nanocomposites for future catalytic applications
as well as a further mechanistic understanding of the electron transfer
during the catalytic process at the single-nanoparticle level
Polydimethysiloxane Modified Silica Nanochannel Membrane for Hydrophobicity-Based Molecular Filtration and Detection
We report in this work the fabrication
of ultrathin silica nanochannel
membranes inhomogeneously modified by polydimethysiloxane (PDMS),
designated as PDMS-SNM, for hydrophobicity-based molecular filtration
and detection. The modification was accomplished by spatially selective
evaporation of hydrophobic PDMS oligomers onto the top surface of
the membrane and orifice of silica nanochannels. Thanks to this hydrophobic
ultrathin layer and beneath ultrasmall channels (2–3 nm in
diameter), only small hydrophobic molecules are able to transport
through the PDMS-SNM, whereas hydrophilic and large ones are remarkably
inhibited. We first employed this PDMS-SNM as the molecular sieving
matrix for selective electrochemical detection of hydrophobic organophosphates
(OPs) in milk samples without pretreatment. The PDMS-SNM modified
electrode displayed an excellent analytical performance and antifouling/anti-interference
ability. We also prepared the free-standing PDMS-SNM consisting of
perforated channels, which could filtrate molecules based on their
hydrophobicity with an excellent selectivity. As demonstrated, 2,4,6-trinitrotoluene
and dopamine could be separated with a selectivity coefficient as
high as 335. Moreover, because of the inhomogeneous nanochannel structure
and ultrasmall thickness, a remarkably high flux of hydrophobic molecules
across the PDMS-SNM was obtained, which was 3–4 orders of magnitude
higher than that reported previously
Image_1_Antibacterial Activity and Mechanism of Action of Aspidinol Against Multi-Drug-Resistant Methicillin-Resistant Staphylococcus aureus.TIF
<p>This study aimed at investigating the antibacterial activity of aspidinol, an extract from Dryopteris fragrans (L.) Schott, against methicillin-resistant Staphylococcus aureus (MRSA). MRSA isolates were treated with aspidinol to determine the differential expression of genes and associated pathways following the drug treatment. Aspidinol displayed significant anti-MRSA activity, both in vivo (minimum inhibitory concentration = 2 μg/mL) and in vitro, and achieved an antibacterial effect comparable to that of vancomycin. In the lethal septicemic mouse study, a dose of 50 mg/kg of either aspidinol or vancomycin provided significant protection from mortality. In the non-lethal septicemic mouse study, aspidinol and vancomycin produced a significant reduction in mean bacterial load in murine organs, including the spleen, lung, and liver. After treatment with aspidinol, we found through RNA-seq and RT-PCR experiments that the inhibition of the formation of ribosomes was the primary S. aureus cell-killing mechanism, and the inhibition of amino acid synthesis and the reduction of virulence factors might play a secondary role.</p
Signal Amplification Cytosensor for Evaluation of Drug-Induced Cancer Cell Apoptosis
Apoptosis is involved in the pathology of a variety of
diseases.
The measurement of apoptosis will help us to evaluate the onset of
disease and the effect of therapeutic interventions. In addition,
the increased demand for understanding the early stages of apoptosis
is pushing the envelope for solutions in early instance real-time
monitoring of death kinetics. Here we present a novel electrochemiluminescent
cytosensing strategy to quantitate apoptotic cell numbers, screen
some anticancer drugs, and evaluate their effects on hepatocarcinoma
cell line (HepG2) cells by utilizing the human antiphosphatidyl serine
antibody (APSA) conjugated RuÂ(bpy)<sub>3</sub><sup>2+</sup>-encapsulated
silica nanoparticle (APSA-SiO<sub>2</sub>@Ru) as the detection probe.
HepG2 cells were easily immobilized on the arginine-glycine-aspartic
acid-serine (RGDS)-multiwalled carbon nanotubes (RGDS-MWCNTs) nanocomposite
by the specific combination of RGD domains with integrin receptors
on the cell surface. Then APSA-SiO<sub>2</sub>@Ru was introduced to
the surface of apoptosis cells through the specific interaction between
APSA and phosphatidylserine (PS) that distributed on the outer membrane
of apoptotic cells. On the basis of the signal amplification of the
APSA-SiO<sub>2</sub>@Ru nanoprobe, the cytosensor could respond as
low as 800 cells mL<sup>–1</sup>, showing very high sensitivity.
In addition, the dynamic alterations of surface PS expression on HepG2
cells in response to drugs and the cell heterogeneity were also demonstrated.
The strategy presented a promising platform for highly sensitive cytosensing
and convenient screening of some clinically available anticancer drugs
Image_3_Antibacterial Activity and Mechanism of Action of Aspidinol Against Multi-Drug-Resistant Methicillin-Resistant Staphylococcus aureus.TIF
<p>This study aimed at investigating the antibacterial activity of aspidinol, an extract from Dryopteris fragrans (L.) Schott, against methicillin-resistant Staphylococcus aureus (MRSA). MRSA isolates were treated with aspidinol to determine the differential expression of genes and associated pathways following the drug treatment. Aspidinol displayed significant anti-MRSA activity, both in vivo (minimum inhibitory concentration = 2 μg/mL) and in vitro, and achieved an antibacterial effect comparable to that of vancomycin. In the lethal septicemic mouse study, a dose of 50 mg/kg of either aspidinol or vancomycin provided significant protection from mortality. In the non-lethal septicemic mouse study, aspidinol and vancomycin produced a significant reduction in mean bacterial load in murine organs, including the spleen, lung, and liver. After treatment with aspidinol, we found through RNA-seq and RT-PCR experiments that the inhibition of the formation of ribosomes was the primary S. aureus cell-killing mechanism, and the inhibition of amino acid synthesis and the reduction of virulence factors might play a secondary role.</p
Characterization of CIP and CMX encapsulated PLGA particles.
<p>Characterization of CIP and CMX encapsulated PLGA particles.</p
Surface morphology of CIP encapsulated PLGA magnetic particles by SEM.
<p>(A) CIP encapsulated in PLGA magnetic nanoparticles (B) CIP encapsulated in PLGA magnetic microparticles (C) CMX.</p
Particle size distribution of CIP encapsulated in PLGA magnetic microparticles (A) and nanoparticles (B).
<p>Particle size distribution of CIP encapsulated in PLGA magnetic microparticles (A) and nanoparticles (B).</p
Drug release from PLGA magnetic micro/nanoparticles.
<p>(A) Drug release in PBS buffer from PLGA magnetic micro/nanoparticles at 37°C and shaking at 100rpm. (B) Drug release from PLGA magnetic micro/nanoparticles under OMF and control drug release from PLGA magnetic micro/nanoparticles at 20°C without OMF. (C) Drug release from PLGA magnetic microparticles under OMF for initial 4hours then released in PBS buffer at 37°C and shaking at 100 rpm for another 15 days. (D) Drug release from PLGA magnetic nanoparticles under OMF for initial 4 hours then released in PBS buffer at 37°C and shaking at 100 rpm for another 15days.</p