13 research outputs found
Defect-Dominated Shape Recovery of Nanocrystals: A New Strategy for Trimetallic Catalysts
Here we present a
shape recovery phenomenon of Pt–Ni bimetallic
nanocrystals that is unequivocally attributed to the defect effects.
High-resolution electron microscopy revealed the overall process of
conversion from concave octahedral Pt<sub>3</sub>Ni to regular octahedral
Pt<sub>3</sub>Ni@Ni upon Ni deposition. Further experiments and theoretical
investigations indicated that the intrinsic defect-dominated growth
mechanism allows the site-selective nucleation of a third metal around
the defects to achieve the sophisticated design of trimetallic Pt<sub>3</sub>Ni@M core–shell structures (M = Au, Ag, Cu, Rh). Consideration
of geometrical and electronic effects indicated that trimetallic atomic
steps in Pt<sub>3</sub>Ni@M could serve as reactive sites to significantly
improve the catalytic performance, and this was corroborated by several
model reactions. The synthesis strategy based on our work paves the
way for the atomic-level design of trimetallic catalysts
Sustained Codelivery of Cisplatin and Paclitaxel via an Injectable Prodrug Hydrogel for Ovarian Cancer Treatment
The sustained release of both the
hydrophilic drug and hydrophobic drug from one delivery system remains
challenging in pharmaceutics and biomaterials science. The combination
of hydrophilic cisplatin and hydrophobic paclitaxel (PTX) exhibits
a clinical survival advantage compared with the individual drug therapy
against various tumors such as ovarian cancer. In this study, a localized,
long-term codelivery system of cisplatin and PTX was developed using
an injectable and thermosensitive polymer–platinumÂ(IV) conjugate
hydrogel as the carrier. The thermosensitive BiÂ(mPEG-PLGA)–PtÂ(IV)
(PtGel) conjugate was synthesized via covalently linking two mPEG-PLGA
copolymers onto a PtÂ(IV) prodrug, and its concentrated aqueous solution
exhibited a reversible sol–gel transition upon heating. Meanwhile,
the core–corona micelles formed by the amphiphilic conjugates
in water could serve as a reservoir for the solubilization of PTX,
and thus an injectable binary drug-loaded hydrogel formulation was
obtained. We also found that the introduction of PTX into the conjugate
hydrogel decreased its sol–gel transition temperature and improved
its gel strength. In vitro release experiments showed that both of
the loaded drugs were released in a sustained manner for as long as
2.5 months, which was the longest combination delivery of these two
drugs ever reported. In vitro cellular assays revealed that the dual-drug
system exhibited a synergistic anticancer effect against ovarian cancer
cells. Finally, using the SKOV-3 ovarian cancer xenograft mouse model,
we demonstrated that a single injection of the PTX-loaded conjugate
hydrogel system resulted in enhanced anticancer efficacy and significantly
reduced the side effects, when compared with the multiple injections
of the free drug combination
Summary of morphological data and experimental outcomes.
<p>Different from OVX-Saline:</p><p>* <i>P = 0</i>.<i>0004</i></p><p>** <i>P = 0</i>.<i>0024</i></p><p>Summary of morphological data and experimental outcomes.</p
Significant differences were observed in bone mineral density of the humeral head between the <i>Control</i>, <i>OVX-Saline</i> and <i>OVX-PTH</i> groups.
<p>Bone mineral density in the <i>OVX-PTH</i> group was significantly higher than in the <i>OVX-Saline</i> group but similar to that of the <i>Control</i> group.</p
4-layered tendon-bone interface of ISP enthesis: tendon, nonmineralized fibrocartilage (*), mineralized fibrocartilage (▲) (▲), and bone. (↑) indicates the tidemark.
<p>In the <i>Control</i> and <i>OVX-PTH</i> groups, well-organized ISP enthesis could be observed with a clear tidemark (A, D). Arrangement of nonmineralized fibrocartilage aligned well, nonmineralized and mineralized fibrocartilage were stained deeply and with abundant cells (B, E). In the <i>OVX-PTH</i> group, the nonmineralized and mineralized fibrocartilage were thicker with a more compact structure (E, F). In <i>OVX-Saline</i> group, a relative thinner tendon-bone interface was observed, as well as a less clear tidemark in the enthesis (G). The cell deposition in the area was less compared to the other groups, and osteoclast number and bone lacuna in the mineralized fibrocartilage seemed to have increased compared to both <i>Control</i> and <i>OVX-PTH</i> groups (H, I).</p
The humerus was placed in a custom made fixture and the tendon attached to a cryo-clamp for testing.
<p>Failure was tested at 1 mm/s and the direction of pull of the tendon was directly superior and along the axes of the ISP tendon fibers.</p
Failure Stress vs. BMD.
<p>A positive linear correlation was observed between failure stress and bone mineral density measured at the humeral head.</p
Thermoresponsive Polymeric Nanoparticles as Efficient Pickering Interfacial Catalysts for Selective Oxidation of Sulfides
Pickering emulsions provide a versatile platform for
liquid–liquid
two-phase reactions; however, the separation and recovery of solid
catalysts have always been plagued by strong adsorption at the interfaces.
In this study, we developed thermoresponsive polymeric nanoparticles
by simply copolymerizing the monomers of N-isopropylacrylamide
(NIPAM) and 2,2,6,6-tetramethyl-4-piperidinyl methacrylate (TMPM)
and oxidizing the precursor to 2,2,6,6-tetramethylpiperidine-1-oxyl
(TEMPO). Structural design and molecular modulation give the polymeric
catalysts excellent amphiphilicity, which allows them to be tightly
adsorbed at the interfaces, thus stabilizing oil-in-water (O/W) Pickering
emulsions in biphasic reaction systems. Such emulsion systems with
abundant interfacial areas can enhance reaction mass transfer and
promote catalytic transformation. More importantly, modulating the
wettability of the polymers leads to an oriented distribution of the
catalysts at the interfaces, which in turn affects the contact between
the substrate molecules and catalyst centers, avoiding overoxidation
of the sulfides and improving the selectivity of sulfoxides. As expected,
the selectivity of methyl phenyl sulfoxide in Pickering emulsion microreactors
was 97.8% with a turnover frequency (TOF) of 10.0 mol mol–1 min–1, which is higher than previously reported
results. When the systems warm to 37 °C at the end of the reactions,
the amine groups of NIPAM immobilized on the polymer catalysts shrink,
causing the particles to become hydrophobic and thus spontaneously
desorbed from the interfaces, resulting in demulsification. After
recycling ten runs, the polymeric nanocatalysts showed no loss on
either conversion or selectivity and maintained stable catalytic activity.
The conceptually temperature-responsive Pickering emulsions provide
a clean and effective channel to efficiently recycle the polymeric
catalysts and promote the catalytic activity of biphasic reactions
Calcitonin-Loaded Thermosensitive Hydrogel for Long-Term Antiosteopenia Therapy
Effective
antiosteopenia therapy can be achieved by designing long-term protein/peptide
drug delivery systems for bone trabecula restoration. Here we show
that a complex of salmon calcitonin and oxidized calcium alginate
(sCT-OCA) was prepared and loaded into a thermosensitive copolymer
hydrogel for long-term antiosteopenia treatment. The triblock copolymer,
polyÂ(d,l-lactic acid-<i>co</i>-glycolic
acid)-<i>b</i>-polyÂ(ethylene glycol)-<i>b</i>-polyÂ(d,l-lactic acid-<i>co</i>-glycolic acid)
(PLGA-PEG-PLGA) exhibited sol–gel transition at body temperature.
The sustained release of sCT from the in situ gelling system was determined
by both the degradation of the hydrogel and the decomposition of the
sCT-OCA complex. This system showed sustained effects in reducing
serum calcium and bone trabecula reconstruction in the treatment of
glucocorticoid-induced osteopenia in rats for approximately 30 days
after a single subcutaneous injection, which may shed light on antiosteopenia
therapy in the future
Additional file 2 of High leukocyte mitochondrial DNA copy number contributes to poor prognosis in breast cancer patients
Supplementary Material