5 research outputs found
Structured Assemblages of Single-Walled 3d Transition Metal Silicate Nanotubes as Precursors for Composition-Tailorable Catalysts
Copper silicate has so far been the
only transition metal silicate
that can be synthesized into a single-walled nanotubular structure.
In addition to making single-walled copper silicate nanotubes (CuSiNT)
as hollow spherical or bundle-like assemblages, herein, we developed
a general method to synthesize a series of new single-walled silicate
nanotubes containing other 3d transition metal elements (M = Mn, Fe,
Co, Ni, and Zn). After the controllable synthesis of CuSiNT, up to
80% of Cu in the CuSiNT can be replaced with dopant metals (M) through
complex-assisted ion exchange, while the original tubular structure
remains intact. These metal silicate nanotubes can serve as solid
precursors for design-made nanocatalysts; enhanced catalytic performance
has been demonstrated using CO<sub>2</sub> hydrogenation as a model
reaction
Monodisperse Aluminosilicate Spheres with Tunable Al/Si Ratio and Hierarchical Macro-Meso-Microporous Structure
While tremendous success has been
seen in the development of ordered
mesoporous silica by soft-templated methods, synthesis of hierarchical
structures with controllable multiscale pore networks has remained
a challenging topic. On the other hand, introduction of heteroatoms
as an effective method of chemically functionalizing silica leads
to difficulties in morphological control of the product, and multistep
synthesis has been necessary for functionalized silica particles with
hierarchical pore structure and uniform size. The present work demonstrates
that the conflict between morphological control and heteroatom incorporation
can be resolved in a CTAB-stabilized toluene–water–ethanol
microemulsion system. For the first time, monodisperse macro-meso-microporous
aluminosilicate spheres (MASS) are synthesized in one step at room
temperature. Simultaneous tuning of Al/Si ratio (0–0.35) and
the hierarchical pore structure is realized by Hofmeister anion effects
of the Al source itself, [Al(OH)<sub>4</sub>]<sup>−</sup>,
which change the geometry of CTAB micelles and giant vesicles. The
Al is incorporated purely in a tetrahedrally coordinated status, and
preliminary results from catalytic experiments show improved acidity
of MASS as a catalyst support
sj-doc-1-cnr-10.1177_10547738231194099 – Supplemental material for Implementation of Tunneled Peripherally Inserted Central Catheters Placement in Cancer Patients: A Randomized Multicenter Study
Supplemental material, sj-doc-1-cnr-10.1177_10547738231194099 for Implementation of Tunneled Peripherally Inserted Central Catheters Placement in Cancer Patients: A Randomized Multicenter Study by Yuan Sheng, Li-Hong Yang, Yan Wu, Wei Gao and Sheng-Yi Dongye in Clinical Nursing Research</p
Acid-Sensitive Peptide-Conjugated Doxorubicin Mediates the Lysosomal Pathway of Apoptosis and Reverses Drug Resistance in Breast Cancer
The extended use of doxorubicin (DOX)
could be limited because
of the emergence of drug resistance associated with its treatment.
To reverse the drug resistance, two thiol-modified peptide sequences
HAIYPRHGGC and THRPPMWSPVWPGGC were, respectively, conjugated
to DOXO-EMCH, forming a maleimide bridge in this study (i.e., T10-DOX
and T15-DOX). The structures and properties of peptide–DOX
conjugates were characterized using <sup>1</sup>H NMR, <sup>13</sup>C NMR, mass spectrometry, and high-performance liquid chromatography.
Their stability was also evaluated. By using MCF-7/ADR cells as an <i>in vitro</i> model system and nude mice bearing MCF-7/ADR xenografts
as an <i>in vivo</i> model, the ability of these novel peptide–DOX
conjugates to reverse drug resistance was accessed as compared with
free DOX. As a result, the IC<sub>50</sub> values for T10-DOX and
T15-DOX significantly decreased (31.6 ± 1.6 μM and 27.2
± 0.8 μM), whereas the percentage of apoptotic cell population
increased (35.4% and 39.3%). The <i>in vivo</i> extent of
inhibition was more evident in the mice groups treated with peptide–DOX
conjugates (59.6 ± 8.99% and 46.4 ± 6.63%), which had DOX
primarily accumulated in tumor. These conjugates also showed a longer
half-life in plasma and cleared much more slowly from the body. Furthermore,
T10-DOX may be more effective than T15-DOX with a higher efficacy
and a lower side effect. Most importantly, evidence was provided to
support the enhanced intracellular drug accumulation and the induction
of lysosomal pathway of apoptosis underlying the drug resistance.
As an endosomal/lysosomal marker, cathepsin D permealized the destabilized
organelle membrane and was detected in the cytoplasm, leading to the
activation of the effector caspase-3 in cell apoptosis. This report
is among the first to demonstrate that peptide–DOX-like conjugates
promote apoptosis through the initiation of the lysosomal pathway
Simultaneous Quantification of Protein Phosphorylation Sites using Liquid Chromatography–Tandem Mass Spectrometry-Based Targeted Proteomics: A Linear Algebra Approach for Isobaric Phosphopeptides
As one of the most studied post-translational
modifications (PTM),
protein phosphorylation plays an essential role in almost all cellular
processes. Current methods are able to predict and determine thousands
of phosphorylation sites, whereas stoichiometric quantification of
these sites is still challenging. Liquid chromatography coupled with
tandem mass spectrometry (LC–MS/MS)-based targeted proteomics
is emerging as a promising technique for site-specific quantification
of protein phosphorylation using proteolytic peptides as surrogates
of proteins. However, several issues may limit its application, one
of which relates to the phosphopeptides with different phosphorylation
sites and the same mass (i.e., isobaric phosphopeptides). While employment
of site-specific product ions allows for these isobaric phosphopeptides
to be distinguished and quantified, site-specific product ions are
often absent or weak in tandem mass spectra. In this study, linear
algebra algorithms were employed as an add-on to targeted proteomics
to retrieve information on individual phosphopeptides from their common
spectra. To achieve this simultaneous quantification, a LC–MS/MS-based
targeted proteomics assay was first developed and validated for each
phosphopeptide. Given the slope and intercept of calibration curves
of phosphopeptides in each transition, linear algebraic equations
were developed. Using a series of mock mixtures prepared with varying
concentrations of each phosphopeptide, the reliability of the approach
to quantify isobaric phosphopeptides containing multiple phosphorylation
sites (≥2) was discussed. Finally, we applied this approach
to determine the phosphorylation stoichiometry of heat shock protein
27 (HSP27) at Ser78 and Ser82 in breast cancer cells and tissue samples