33 research outputs found
Janus Composite Nanorod from a Molecular Bottlebrush Containing a Block Copolymer
The asymmetric ABC-type
Janus polymer composite nanorods are synthesized
by the in situ preferential growth of functional materials against
the molecular bottlebrush containing a triblock copolymer of poly(ethylene
oxide)-<i>b</i>-poly(2-methacryloyloxyethyl
pentynoate-<i>g</i>-poly(acrylic acid))-<i>b</i>-polystyrene. PEO and PS single chains are terminated onto the opposite
ends of the composite nanorods. The two polymer chains are responsible
for amphiphilic performance, while the composite nanorod is responsible
for the functionality. The Janus nanorods can stand vertically at
an emulsion interface, making the interfaces easily functionalized
and manipulated. Protection of the PAA molecular bottlebrush via electrostatic
interaction is important to obtaining individual nanorods at high
solid contents. A huge family of Janus composite nanorods is expected
by changing the compositions of the two polymer chains and the nanorod
Polymeric Janus Nanosheets by Template RAFT Polymerization
We report a general method to synthesize
polymeric Janus nanosheets
(PJS) by sequential RAFT grafting from a template particle surface.
Layer number and composition of the PJS are tunable by feeding sequence
and type of monomers. The <i>c</i>PNIPAM–PS PJS is
flexible and thermal responsive, which can form a scrolled superstructure.
A dually responsive <i>c</i>PAA–PNIPAM PJS is derived
by hydrolysis of <i>c</i>P<i>t</i>BA–PNIPAM.
Accordingly, stability of the emulsion with the <i>c</i>PAA–PNIPAM PJS is triggered by alternation of pH or/and temperature
Polymer-Fe<sub>3</sub>O<sub>4</sub> Composite Janus Nanoparticles
A Fe<sub>3</sub>O<sub>4</sub> nanoparticle
(NP) based on composite Janus NP with single polymer chain is prepared
by termination of the modified Fe<sub>3</sub>O<sub>4</sub> NP with
the anionic living polymer chain. The requisite that the polymer chain
should be sufficiently large over the NP diameter determines the grafting
of single polymer chain. From the opposite side of the NP surface,
functional species can be selectively grown for example grafting responsive
PNIPAM by ATRP. Besides simple combination of the thermal and magnetic
responsive performances of different components, the PS–Fe<sub>3</sub>O<sub>4</sub>–PNIPAM composite Janus NP shows additional
interactive performance such as NIR-triggered Janus/hydrophobic transition
at low surrounding temperature below LCST ∼ 32 °C
Conelike Janus Composite Particles
Conelike cross-linked PS particles
are polymerized at a patchy emulsion interface. The PS particles synthesized
in the dispersed paraffin phase immigrate toward the interface due
to the Pickering effect. At the triple phase contact line, the particles
are squeezed into cone shape under an outward convex interfacial tension
mismatch. The conelike PS particles are adhered to paraffin sphere
surface and synchronously protected, which allows selective modifications
of the two sides. The Janus particles can self-organize into superstructures
in dispersions. Robust coatings are easily fabricated from the Janus
particles, whose wettability is tunable from highly adhesive for water
to superhydrophobic by simply changing the size distribution of the
Janus particles
Reversible Transformation of Nanostructured Polymer Particles
A reversible
transformation of overall shape and internal structure
as well as surface composition of nanostructured block copolymer particles
is demonstrated by solvent-adsorption annealing. Polystyrene-<i>b</i>-poly(4-vinylpyridine) (PS-<i>b</i>-P4VP) pupa-like
particles with PS and P4VP lamellar domains alternatively stacked
can be obtained by self-assembly of the block copolymer under 3D soft
confinement. Chloroform, a good solvent for both blocks, is selected
to swell and anneal the pupa-like particles suspended in aqueous media.
Reversible transformation between pupa-like and onion-like structures
of the particles can be readily tuned by simply adjusting the particle/aqueous
solution interfacial property. Interestingly, poly(vinyl alcohol)
(PVA) concentration in the aqueous media plays a critical role in
determining the particle morphology. High level of PVA concentration
is favorable for pupa-like morphology, while extremely low concentration
of PVA is favorable for the formation of onion-like particles. Moreover,
the stimuli-response behavior of the particles can be highly suppressed
through selective growth of Au nanoparticles within the P4VP domains.
This strategy provides a new concept for the reversible transformation
of nanostructured polymer particles, which will find potential applications
in the field of sensing, detection, optical devices, drug delivery,
and smart materials fabrication
Janus Nanocage toward Platelet Delivery
The
platelet-shaped Janus nanocages with a mesoporous silica shell are
prepared. PEG moiety onto the exterior surface is responsible for
good dispersity in water. The graphene sheet inside the cavity is
responsible for hydrophobic performance to selectively capture hydrophobic
species, and photothermal effect by NIR irradiation. As a biocompatible
DOX-loaded Janus platelet delivery, HeLa cell cytotoxicity is greatly
enhanced under NIR irradiation. There exists a synergetic effect between
the chemotherapy and photothermal therapy
Robust Reactive Janus Composite Particles of Snowman Shape
We present a facile approach toward
snowman-like silica@PDVB/PS
Janus particles by seed emulsion polymerization using a gelable monomer
MPS against a PDVB/PS hollow particle. Individual silica bulge is
protruded from the seed particle surface, whose size is tunable. The
silica@PDVB Janus particles are derived after dissolution of PS, which
are robust to tolerate against organic solvents. Both sides are reactive
for selective modifications to grow desired materials with tunable
wettability and functionality. As solid emulsifiers, the Janus balance
of the particles is tunable from more hydrophobic to more hydrophilic
by changing either aspect size ratio or composition of the two sides
Coral-like Janus Porous Spheres
A Janus
porous sphere with a coral-like microstructure is prepared by stepwise
dealloying a metallic alloy sphere and sequential modification (for
example, using silanes and polymers). Nanoscale coral-like microstructure
of the internal skeleton gives remarkable capillary force, thus accelerating
the mass transportation. Starting from the outer layer of the sphere,
stepwise dealloying can achieve different layers inwardly, thus introducing
different composition and performance. As an example, poly(ethylene
glycol)–poly(<i>N</i>-isopropylacrylamide) (PEG–PNIPAM)-
and poly(ethylene glycol)–poly(<i>N</i>,<i>N</i>-diethylamino-2-ethylmethacrylate) (PEG–PDEAEMA)-responsive
Janus porous spheres can quickly capture oil by simply changing temperature
or pH. Similarly, release is also triggered
Light-Triggered Responsive Janus Composite Nanosheets
We report the synthesis of light-triggered
Janus composite nanosheets and their Janus performance. Onto the amine-group
terminated side of silica Janus nanosheets, a photo-responsive spiropyran-containing
polymer (PSPMA) brush has been prepared by ATRP, while the other side
terminated with hydrophobic octyl groups is preserved. Upon UV irradiation,
the hydrophobic PSPMA side becomes hydrophilic since the hydrophobic
spiropyran changes to the hydrophilic zwitterionic merocyanine form
(or vice versa with visible light). Consequently, the PSPMA/silica
composite nanosheets become Janus from hydrophobic or vice versa.
The Janus composite nanosheets can serve as a responsive solid emulsifier,
thus the stability of the emulsions can be remotely triggered with
light. Unlike those pH- or temperature-responsive Janus materials,
the light-triggering process requires no additional input of chemicals
or thermal energy
Table1_Screening of anti-heart failure active compounds from fangjihuangqi decoction in verapamil-induced zebrafish model by anti-heart failure index approach.DOCX
Heart failure is the end stage of various cardiovascular diseases. Fangjihuangqi Decoction (FJHQD) is a famous traditional Chinese medicine (TCM) formula, which is clinically effective in the treatment of chronic heart failure. However, the anti-heart failure ingredients of FJHQD have not been clarified, and the related mechanisms of action are rarely studied. In the present study, through quantification analysis of heart rate and ventricular area changes, a heart failure model and cardiac function evaluation system in cardiomyocytes-labelled Tg (cmlc2: eGFP) transgenic zebrafish larvae were constructed, and the anti-heart failure index (AHFI) that can comprehensively evaluate the cardiac function of zebrafish was proposed. Based on this model, FJHQD, its mainly botanical drugs, components and ingredients were evaluated for the anti-heart failure effects. The results showed that FJHQD and its botanical drugs exhibited potent anti-heart failure activity. Furthermore, total alkaloids from Stephania tetrandra S. Moore, total flavonoids from Astragalus mongholicus Bunge and total flavonoids from Glycyrrhiza uralensis Fisch. ex DC. were identified to be the main components exerting the anti-heart failure activity of FJHQD. Then, we screened the main ingredients of these components, and glycyrrhizic acid, licochalcone A and calycosin were found to exhibit excellent cardioprotective effects. Finally, we found that FJHQD, glycyrrhizic acid, licochalcone A and calycosin may improve cardiac function in zebrafish by regulating oxidative stress, inflammatory response and apoptosis-related pathways. Taken together, our findings offer biological evidences toward the anti-heart failure effect of FJHQD, and provide guidance for the clinical application of FJHQD.</p