87 research outputs found
Preparation and Characteraction of New Magnetic Co–Al HTLc/Fe3O4Solid Base
Novel magnetic hydrotalcite-like compounds (HTLcs) were synthesized through introducing magnetic substrates (Fe3O4) into the Co–Al HTLcs materials by hydrothermal method. The magnetic Co–Al HTLcs with different Fe3O4contents were characterized in detail by XRD, FT-IR, SEM, TEM, DSC, and VSM techniques. It has been found that the magnetic substrates were incorporated with HTLcs successfully, although the addition of Fe3O4might hinder the growth rate of the crystal nucleus. The morphology of the samples showed the relatively uniform hexagonal platelet-like sheets. The grain boundaries were well defined with narrow size distribution. Moreover, the Co–Al HTLcs doped with magnetic substrates presented the paramagnetic property
Multifunctional bismuth ferrite nanocatalysts with optical and magnetic functions for ultrasound-enhanced tumor theranostics
Ultrasound (US)-assisted oncotherapy has aroused extensive attention due to its capacities to conquer significant restrictions covering short tissue penetration depth and high phototoxicity in photoinduced therapy. We herein developed a class of pure-phase perovskite-type bimetallic oxide, namely, bismuth ferrite nanocatalysts (BFO NCs), for multimodality imaging-guided and US-enhanced chemodynamic therapy (CDT) against malignant tumors. As-prepared BFO nanoparticles with poly(ethylene glycol)-grafted phosphorylated serine (pS-PEG) modification exhibit satisfactory physiological stability and biocompatibility. The BFO NCs also present high fluorescence emission within the second near-infrared region when irradiated with an 808 nm laser. Intriguingly, the BFO NCs demonstrate highly efficient US-enhanced generation of hydroxyl free radicals, as the cavitation bubbles produced by US trigger partial grievous turbulence and promote the transfer rate of the Fenton reagents. Thus, the BFO NCs enable effective inhibition of tumor growth assisted by external US, and the treatment efficacy can be monitored by computer tomography, magnetic resonance, and fluorescence imaging. Meanwhile, H2O2 and US, as a double logic gate, activate the BFO NCs to trigger the iron-catalyzed and US-enhanced CDT with high specificity and treatment efficiency. Therefore, the BFO NCs as a theranostic agent with an enhanced chemodynamic therapeutic effect assisted by external US and a multimodality imaging capacity are put forward, which show a promising prospect for noninvasive chemodynamic oncotherapy.National Research Foundation (NRF)Accepted versionThe work was financially supported by the National Natural Science Foundation of China (51972075, 51772059, and 51972076), the Natural Science Foundation of Shandong Province (ZR2019ZD29), the Heilongjiang Province Postdoctoral Foundation (LBH-Z19129), and the Fundamental Research Funds for the Central Universities. The work was also supported by the Singapore National Research Foundation Investigatorship (NRF-NRFI2018-03)
Theoretical and experimental studies of palladium-catalyzed site-selective C(sp3)−H bond functionalization enabled by transient ligands
Transition
metal-catalyzed selective C–H bond functionalization enabled by transient
ligands has become an extremely attractive topic due to its economical and
greener characteristics. However, catalytic pathways of this reaction process
on unactivated sp3 carbons of reactants have not been well studied
yet. Herein, detailed mechanistic investigation on Pd-catalyzed C(sp3)–H
bond activation with amino acids as transient ligands has been systematically
conducted. The theoretical calculations showed
that
higher angle
distortion of C(sp2)-H
bond
over C(sp3)-H
bond
and stronger
nucleophilicity of benzylic anion over its aromatic counterpart, leading to
higher reactivity of corresponding C(sp3)–H bonds; the angle strain
of the directing rings of key intermediates determines the site-selectivity of
aliphatic ketone substrates; replacement of glycine with β-alanine as the
transient ligand can decrease the angle tension of the directing rings. Synthetic experiments have confirmed that
β-alanine is indeed a more efficient transient ligand for arylation of
β-secondary carbons of linear aliphatic ketones than its glycine counterpart.<br /
Multifunctional Theranostics for Dual-Modal Photodynamic Synergistic Therapy via Stepwise Water Splitting
Combined therapy
using multiple approaches has been demonstrated to be a promising
route for cancer therapy. To achieve enhanced antiproliferation efficacy
under hypoxic condition, here we report a novel hybrid system by integrating
dual-model photodynamic therapies (dual-PDT) in one system. First,
we attached core–shell structured up-conversion nanoparticles
(UCNPs, NaGdF<sub>4</sub>:Yb,Tm@NaGdF<sub>4</sub>) on graphitic-phase
carbon nitride (<i>g-</i>C<sub>3</sub>N<sub>4</sub>) nanosheets
(one photosensitizer). Then, the as-fabricated nanocomposite and carbon
dots (another photosensitizer) were assembled in ZIF-8 metal–organic
frameworks through an in situ growth process, realizing the dual-photosensitizer
hybrid system employed for PDT via stepwise water splitting. In this
system, the UCNPs can convert deep-penetration and low-energy near-infrared
light to higher-energy ultraviolet–visible emission, which
matches well with the absorption range of the photosensitizers for
reactive oxygen species (ROS) generation without sacrificing its efficacy
under ZIF-8 shell protection. Furthermore, the UV light emitted from
UCNPs allows successive activation of <i>g</i>-C<sub>3</sub>N<sub>4</sub> and carbon dots, and the visible light from carbon
dots upon UV light excitation once again activate <i>g</i>-C<sub>3</sub>N<sub>4</sub> to produce ROS, which keeps the principle
of energy conservation thus achieving maximized use of the light.
This dual-PDT system exhibits excellent antitumor efficiency superior
to any single modality, verified vividly by in vitro and in vivo assay
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