9 research outputs found
Self-Curing Phthalonitrile Resin with Disulfide Bond as the Curing Group
To further investigate the presence of a radical mechanism
in the
curing process of phthalonitrile resins, a conventional radical initiation
unit (disulfide segment) was introduced into phthalonitrile resins
for the first time. A disulfide-bond-containing phthalonitrile monomer
(DPBPN) was successfully synthesized. Its self-curing reaction could
be promoted by disulfide segments in the precursor. Rheological measurements
and differential scanning calorimetry showed that DPBPN exhibited
a low melting point (124.5 °C) and a wide processing window (120
°C). Infrared spectroscopy confirmed the formation of isoindoline,
triazine, and phthalocyanine structures in the product. Thermal gravimetric
analysis and dynamic mechanical analysis suggested the outstanding
thermal stability and high glass transition temperature (Tg) of the cured resin with a moderate curing process
Self-Assembled DNA Generated Electric Current Biosensor for HER2 Analysis
We have developed
a new DNA self-assembly amplification technology
that generates electric current for electrochemical biosensing. The
new technology was used for detection of human epidermal growth factor
receptor 2 (HER2). In our technology, an aptamer was utilized both
as a ligand for recognition and as a signal generating reporter. The
aptasensor is based on a sandwich format and a DNA primer on
a HER2 aptamer initiates auxiliary DNA self-assembled on the electrode
to form a long one-dimensional DNA. The resulting DNA is then reacted
with molybdate to generate electrochemical current. The sensitivity
of the aptasensor with DNA self-assembly was greater than that of
the aptasensor without DNA self-assembly due to the extended length
of the DNA strand. Aptasensor analysis of HER2 in serum of breast
cancer patients and healthy individuals is highly correlated (<i>R</i><sup>2</sup> = 0.9924) with ELISA measurements, with a <i>p</i> value of 1.37 × 10<sup>–7</sup>. The analysis
of HER2 in serum (confirmed by ELISA) suggests that HER2 levels in
breast cancer patients are much higher than healthy individuals. For
HER2 positive patients, the levels are higher than those of HER2 negative
patients. After surgery, there is a drop of HER2 levels in serum,
suggesting potential clinical applications of the new self-assembled
DNA electric current generating biosensor. Unlike proteins, DNA is
easily amplifiable. The DNA signal amplification method presented
here enables effective current generation, which can find wide range
of biomedical applications for protein detection
Bio-Based Adenine-Derived Polyimide as a Dual-Functional Binder for the Silicon Anode in Lithium-Ion Batteries
Silicon represents one of the most promising candidates
for anode
materials in the forthcoming generation of lithium-ion batteries.
However, the practical implementation of silicon as an anode material
is hindered by the tremendous volume expansion during battery cycling,
ultimately leading to a rapid capacity degradation. The development
of advanced binders stands out as a highly effective strategy for
enhancing the cycling stability of silicon anodes. Herein, we construct
bio-based adenine-containing polyimides (APIs) as a dual-functional
binder for lithium-ion batteries. Due to the dual interfacial interactions
of adenine segments with the silicon and the conductive carbon, the
API can restrain the silicon volume expansion and maintain the electrode
structure integrity, contributing to the stable solid electrolyte
interphase and improved conductivity pathway. Compared with the conventional
polyimides (PI), API exhibits slower capacity decay and excellent
rate performance, as well as better cycling stability than poly(vinylidene
fluoride), sodium carboxymethyl cellulose, and poly acrylic acid binders.
This molecular structure design provides insights for the preparation
of multifunctional high-performance binders for the silicon anode
MOF-Templated Fabrication of Hollow Co<sub>4</sub>N@N-Doped Carbon Porous Nanocages with Superior Catalytic Activity
Metallic
Co<sub>4</sub>N catalysts have been considered as one of the most
promising non-noble materials for heterogeneous catalysis because
of their high electrical conductivity, great magnetic property, and
high intrinsic activity. However, the metastable properties seriously
limit their applications for heterogeneous water phase catalysis.
In this work, a novel Co-metal–organic framework (MOF)-derived
hollow porous nanocages (PNCs) composed of metallic Co<sub>4</sub>N and N-doped carbon (NC) were synthesized for the first time. This
hollow three-dimensional (3D) PNC catalyst was synthesized by taking
advantage of Co-MOF as a precursor for fabricating 3D hollow Co<sub>3</sub>O<sub>4</sub>@C PNCs, along with the NH<sub>3</sub> treatment
of Co-oxide frames to promote the in situ conversion of Co-MOF to
Co<sub>4</sub>N@NC PNCs, benefiting from the high intrinsic activity
and electron conductivity of the metallic Co<sub>4</sub>N phase and
the good permeability of the hollow porous nanostructure as well as
the efficient doping of N into the carbon layer. Besides, the covalent
bridge between the active Co<sub>4</sub>N surface and PNC shells also
provides facile pathways for electron and mass transport. The obtained
Co<sub>4</sub>N@NC PNCs exhibit excellent catalytic activity and stability
for 4-nitrophenol reduction in terms of low activation energy (<i>E</i><sub>a</sub> = 23.53 kJ mol<sup>–1</sup>), high
turnover frequency (52.01 × 10<sup>20</sup> molecule g<sup>–1</sup> min<sup>–1</sup>), and high apparent rate constant (<i>k</i><sub>app</sub> = 2.106 min<sup>–1</sup>). Furthermore,
its magnetic property and stable configuration account for the excellent
recyclability of the catalyst. It is hoped that our finding could
pave the way for the construction of other hollow transition metal-based
nitride@NC PNC catalysts for wide applications
Oxygen Vacancy-Reinforced Water-Assisted Proton Hopping for Enhanced Catalytic Hydrogenation
Water-assisted
proton hopping (WAPH) has been intensively
investigated
for promoting the performance of metal oxide-supported catalysts for
hydrogenation. However, the effects of the structure of the metal
oxide support on WAPH have received little attention. Herein, we construct
oxygen vacancy-bearing, MoO3–x-supported
Pd nanoparticle catalysts (Pd/MoO3–x-R), where the oxygen vacancies can promote WAPH,
thereby facilitating catalytic hydrogenation. The experimental results
and theoretical calculations show that the oxygen vacancies favor
the adsorption of water, which assists the proton hopping across the
surface of the metal oxide, enhancing the catalytic hydrogenation.
Our finding will provide a potential approach to the design of metal
oxide-supported catalysts for hydrogenation
Effect of suppressed PGC-1α expression on OA-induced VSMC proliferation and migration.
<p>VSMCs were transfected with siRNA S1 or the negative control (siRNA N). The interference effect was assessed by quantitative PCR (A) and western blot (B). Effects of decreased PGC-1α on OA-induced VSMC proliferation were determined by MTT assay (C) and cell counting (D). Effects of decreased PGC-1α on OA-induced VSMC migration were determined by wound healing (E) and transwell analysis (F). Data in VSMC proliferation and migration detections represent the means±SEM of 18 determinants from 3 independently prepared samples each with 6 measurements. Data in PGC-1α mRNA level detections are expressed as means±SEM of five different experiments normalized to β-actin levels. Data in PGC-1α protein level detections are expressed as means±SEM of four different experiments normalized to GAPDH levels. **P<0.01, #P<0.001 vs. control or N group.</p
Effects of PGC-1α on OA-induced p-ERK activity in VSMCs.
<p>PDGF-BB and pharmacological ERK-MAPK inhibitor PD98059 were chosen as positive and negative controls of ERK phosphorylation, respectively. VSMCs were made quiescent by serum-starvation for 24 h and then stimulated with PDGF-BB (100 ng/ml) for 30 min, PD98059 (50 uM) for 1 h before stimulation with PDGF-BB (100 ng/mL), or 0.4 mmol/L OA for 2 h. Proteins extracted following these treatments and phosphorylation of ERK was determined by western blot (A). VSMCs were also treated with 48 h adenovirus infection and then incubated with 0.4 mmol/L OA for 24 h. Phosphorylation of ERK was also analyzed with elevated PGC-1α level by western blot (B). Data were shown as the ratio of p-ERK/total ERK. The ratios of control were designated as 1.0. Individual data in this chart represent the mean±SEM of 4 determinants. #P<0.001 vs. control or positive/negative group.</p
Effect of overexpressed PGC-1α on OA-induced VSMC proliferation and migration.
<p>VSMCs were treated with 48 h adenovirus infection, then incubated with 0.4 mmol/L OA for 24 h. PGC-1α expression was analysised by quantitative PCR (A) and western blot (B). Effects of PGC-1α overexpression on OA-induced VSMC proliferation were determined by MTT assay (C) and cell counting (D). Effects of PGC-1α overexpression on OA-induced VSMC migration were determined by wound healing (E) and transwell analysis (F). Data in VSMC proliferation and migration detections represent the means±SEM of 18 determinants from 3 independently prepared samples each with 6 measurements. Data in PGC-1α mRNA level detections are expressed as means±SEM of five different experiments normalized to β-actin levels. Data in PGC-1α protein level detections are expressed as means±SEM of four different experiments normalized to GAPDH levels. *P<0.05, **P<0.01, #P<0.001 vs. control or GFP group.</p
Changes of PGC-1α expression and VSMC proliferation/migration in response to increased proportion of PA in fatty acid mixtures.
<p>VSMCs were incubated with various FFAs for 24 h before analysis. Effects of PA on PGC-1α expression was determined by quantitative PCR (A) and western blot analysis (B). Effects of increased PA on PGC-1α expression were determined by quantitative PCR (C). Effects of increased PA on OA-induced VSMC proliferation were determined by MTT assay (D) and cell counting (E). Effects of increased PA on OA-induced VSMC migration were determined by wound healing (F) and transwell analysis (G,H). Data in VSMC proliferation and migration detections represent the means±SEM of 18 determinants from 3 independently prepared samples each with 6 measurements. Data in PGC-1α mRNA level detections are expressed as means±SEM of five different experiments normalized to β-actin levels. Data in PGC-1α protein level detections are expressed as means±SEM of four different experiments normalized to GAPDH levels. *P<0.05, **P<0.01, #P<0.001 vs. control</p