6 research outputs found
Facile Synthesis of Graphene-Wrapped Honeycomb MnO<sub>2</sub> Nanospheres and Their Application in Supercapacitors
Graphene-wrapped MnO<sub>2</sub> nanocomposites were
first fabricated
by coassembly between honeycomb MnO<sub>2</sub> nanospheres and graphene
sheets via electrostatic interaction. The materials were characterized
by means of X-ray diffraction, scanning electron microscopy, transmission
electron microscopy, atomic force microscopy, and thermogravimetric
analysis. The novel MnO<sub>2</sub>/graphene hybrid materials were
used for investigation of electrochemical capacitive behaviors. The
hybrid materials displayed enhanced capacitive performance (210 F/g
at 0.5 A/g). Additionally, over 82.4% of the initial capacitance was
retained after repeating the cyclic voltammetry test for 1000 cycles.
The improved electrochemical performance might be attributed to the
combination of the pesudocapacitance of MnO<sub>2</sub> nanospheres
with the honeycomb-like “opened” structure and good
electrical conductivity of graphene sheets
Cu<sub>2</sub>O-Catalyzed C(sp<sup>3</sup>)-H/C(sp<sup>3</sup>)-H Cross-Coupling Using TEMPO: Synthesis of 3-(2-Oxoalkyl)-3-hydroxyoxindoles
<div><p></p><p>A simple, convenient and efficient oxidative cross-coupling reaction of oxindoles with ketones toward a variety of 3-(2-oxoalkyl)-3-hydroxyoxindoles in moderate to excellent yields has been developed. This transformation proceeds<i>via</i> a tandem oxidative cross-coupling by using TEMPO in air as an environmentally benign oxidant. This methodology provides an alternative approach for the direct generation of all-carbon quaternary centers at the C3 position of oxindoles.</p></div
Palladium-Catalyzed Synthesis of 1<i>H</i>‑Indenes and Phthalimides via Isocyanide Insertion
A new and versatile multicomponent
domino strategy has been developed
for the synthesis of a series of 1<i>H</i>-indene and phthalimide
derivatives from simple and readily available starting materials.
This process operating under mild conditions shows a broad substrate
scope with moderate to excellent yields
Palladium-Catalyzed Synthesis of 1<i>H</i>‑Indenes and Phthalimides via Isocyanide Insertion
A new and versatile multicomponent
domino strategy has been developed
for the synthesis of a series of 1<i>H</i>-indene and phthalimide
derivatives from simple and readily available starting materials.
This process operating under mild conditions shows a broad substrate
scope with moderate to excellent yields
Metal-Free–Catalyzed Oxidative Trimerization of Indoles Using NaNO<sub>2</sub> to Construct Quaternary Carbon Centers: Synthesis of 2-(1<i>H</i>-Indol-3-yl)-2,3′-biindolin-3-ones
<div><p></p><p>A simple, convenient, and efficient synthesis of 2-(1<i>H</i>-indol-3-yl)-2,3′-biindolin-3-one derivatives via a transition-metal-free-catalyzed oxidative trimeric reaction of indoles has been developed. This transformation may have occurred through a tandem oxidative homocoupling reaction by using NaNO<sub>2</sub> in pyridine as oxidant. This methodology provides an alternative approach for the direct generation of all-carbon quaternary centers at the C2 position of indoles.</p>
</div
Polysaccharide-Based Composite Hydrogel with Hierarchical Microstructure for Enhanced Vascularization and Skull Regeneration
Critical-size skull defects caused by trauma, infection,
and tumor
resection raise great demands for efficient bone substitutes. Herein,
a hybrid cross-linked hierarchical microporous hydrogel scaffold (PHCLS)
was successfully assembled by a multistep procedure, which involved
(i) the preparation of poly(lactic-co-glycolic)/nanohydroxyapatite
(PLGA-HAP) porous microspheres, (ii) embedding the spheres in a solution
of dopamine-modified hyaluronic acid and collagen I (Col I) and cross-linking
via dopamine polyphenols binding to (i) Col I amino groups (via Michael
addition) and (ii) PLGA-HAP (via calcium ion chelation). The introduction
of PLGA-HAP not only improved the diversity of pore size and pore
communication inside the matrix but also greatly enhanced the compressive
strength (5.24-fold, 77.5 kPa) and degradation properties to construct
a more stable mechanical structure. In particular, the PHCLS (200
mg, nHAP) promoted the proliferation, infiltration, and angiogenic
differentiation of bone marrow mesenchymal stem cells in vitro, as
well as significant ectopic angiogenesis and mineralization with a
storage modulus enhancement of 2.5-fold after 30 days. Meanwhile,
the appropriate matrix microenvironment initiated angiogenesis and
early osteogenesis by accelerating endogenous stem cell recruitment
in situ. Together, the PHCLS allowed substantial skull reconstruction
in the rabbit cranial defect model, achieving 85.2% breaking load
strength and 84.5% bone volume fractions in comparison to the natural
cranium, 12 weeks after implantation. Overall, this study reveals
that the hierarchical microporous hydrogel scaffold provides a promising
strategy for skull defect treatment