Selective enrichment of phosphoproteins or phosphopeptides from complex mixtures is essential for MS-based phosphoproteomics, but still remains a challenge. In this article, we described an unprecedented approach to synthesize magnetic mesoporous Fe(3)O(4)@mTiO(2) microspheres with a well-defined core/shell structure, a pure and highly crystalline TiO(2) layer, high specific surface area (167.1 m(2)/g), large pore volume (0.45 cm(3)/g), appropriate and tunable pore size (8.6-16.4 nm), and high magnetic susceptibility. We investigated the applicability of Fe(3)O(4)@mTiO(2) microspheres in a study of the selective enrichment of phosphopeptides. The experiment results demonstrated that the Fe(3)O(4)@mTiO(2) possessed remarkable selectivity for phosphopeptides even at a very low molar ratio of phosphopeptides/non-phosphopeptides (1:1000), large enrichment capacity (as high as 225 mg/g, over 10 times as that of the Fe(3)O(4)@TiO(2) microspheres), extreme sensitivity (the detection limit was at the fmol level), excellent speed (the enrichment can be completed in less than 5 min), and high recovery of phosphopeptides (as high as 93%). In addition, the high magnetic susceptibility allowed convenient separation of the target peptides by magnetic separation. These outstanding features give the Fe(3)O(4)@mTiO(2) composite microspheres high benefit for mass spectrometric analysis of phosphopeptides.
The heterostructure Ag–Au bimetallic nanocrystals
supported on Fe3O4@carbon composite microspheres
were synthesized by one facile and controllable approach, wherein
the Ag nanocrystals attached on the Fe3O4@carbon
microspheres were prepared first and served as reductant for the galvanic
replacement reaction with the Au precursor (HAuCl4). Upon
varying the feeding amounts of the Au precursor, the bimetallic compositions
on the Fe3O4@carbon microsphere could be readily
tuned resulting in a series of composite microspheres with different
Au-to-Ag molar ratios. Subsequently, we thus investigated the catalytic
activity and selectivity of the magnetic composite catalysts from
two sides. First, 4-nitrophenol (4-NP) was applied as a model molecule
to study the effect of different Au-to-Ag molar ratios on catalytic
capabilities of the resulting composite microspheres. It was found
that upon the addition of NaBH4 the catalytic capability
was markedly enhanced when the Au content was increased. The maximum
activity parameter value reached 1580 s–1 g–1, which is far higher than those of known monometallic
composites. Also, they could give the equally high yields for other
nitroaromatic compounds with various substituents, irrespective of
the linked electron-donating or electron-withdrawing groups. Second,
the synergistic effects of the carbon substrate in the catalysis reaction
were demonstrated. When compared with colloidal SiO2, TiO2, and poly(styrene-co-acrylic acid) substrates,
the carbon support not only facilitated the enhancement of the catalytic
performance of the noble metal nanocrystals but was also more suitable
for the in situ preparation of Au–Ag bimetallic
nanocrystals using the GRR. Besides, the particles’ convenience
in terms of their magnetic separability and outstanding reusability
was validated through many successive reduction reaction cycles. In
light of these unique characteristics, the Fe3O4@C@Ag–Au composite microspheres show promising and great potential
for practical applications.
Killing tumor cells with a visualized system is a promising strategy in tumor therapy to achieve minimal side effects and high efficiency. Herein, a theranostic nanomedicine (AuNCs-Pt) is developed based on nanocarrier gold nanoclusters (AuNCs) with bifunctions of both NIR-I/NIR-II imaging and glutathione-scavenging abilities. AuNCs-Pt possesses NIR-II imaging capability on a fatal highgrade serous ovarian cancer (HGSOC) model in the deep abdomen, thus facilitating it to be a promising tool for monitoring platinum transportation. Meanwhile, AuNCs-Pt depletes intracellular glutathione to minimize platinum detoxification, effectively maximizing the chemotherapeutic efficacy of platinum. AuNCs-Pt is used to eradicate the tumor burden in this study on a HGSOC model and a patient-derived tumor xenograft model of hepatocellular carcinoma, suggesting great potential for clinical visualized therapy and platinum drug sensitization.
The ferroptosis effect has been illuminated with a clear Fenton reaction mechanism that converts endogenous hydrogen peroxide (H 2 O 2 ) into highly oxidative hydroxyl radicals (•OH) in ROS-amplified tumor therapy. This ferroptosis-related oxidation effect was then further enhanced by the enzyme-like roles of cisplatin (CDDP). This CDDP-induced apoptosis was promoted in reverse by ferroptosis via the depletion of glutathione (GSH) and prevention of DNA damage repair. Here, we have developed degradable metallic complexes (PtH@FeP) containing an Fe(III)-polydopamine (FeP) core and HA-cross-linked CDDP (PtH) shell, exaggerating in situ toxic ROS production via the synergistic effect of CDDP and Fe(III). Taken together, the rationally designed PtH@FeP provided a new strategy for self-amplified synergistic chemotherapy/ferroptosis/photothermal therapy (PTT) antitumor effects with a reduced dosage that facilitates clinical safety.
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