Improved Ionic Diffusion through the Mesoporous Carbon Skin on Silicon Nanoparticles Embedded in Carbon for Ultrafast Lithium Storage

Because of their combined effects of outstanding mechanical stability, high electrical conductivity, and high theoretical capacity, silicon (Si) nanoparticles embedded in carbon are a promising candidate as electrode material for practical utilization in Li-ion batteries (LIBs) to replace the conventional graphite. However, because of the poor ionic diffusion of electrode materials, the low-grade ultrafast cycling performance at high current densities remains a considerable challenge. In the present study, seeking to improve the ionic diffusion, we propose a novel design of mesoporous carbon skin on the Si nanoparticles embedded in carbon by hydrothermal reaction, poly­(methyl methacrylate) coating process, and carbonization. The resultant electrode offers a high specific discharge capacity with excellent cycling stability (1140 mA h g^–1 at 100 mA g^–1 after 100 cycles), superb high-rate performance (969 mA h g^–1 at 2000 mA g^–1), and outstanding ultrafast cycling stability (532 mA h g^–1 at 2000 mA g^–1 after 500 cycles). The battery performances are surpassing the previously reported results for carbon and Si composite-based electrodes on LIBs. Therefore, this novel approach provides multiple benefits in terms of the effective accommodation of large volume expansions of the Si nanoparticles, a shorter Li-ion diffusion pathway, and stable electrochemical conditions from a faster ionic diffusion during cycling

Assignment of metabolites observed by ¹H-NMR in cancer cell lysates.

<p>Assignment of metabolites observed by ¹H-NMR in cancer cell lysates.</p

PCA and PLS-DA for MCF-7, MCF-7/shCK-α, MCF-7/TAM and MCF-7/TAM/shCK-α groups.

<p>(A) PCA for the inspection and overview of the data set. (B) Score plot for the investigation of group differentiation among MCF-7 (MC, n = 4, green), MCF-7/shCK-α (Msh, n = 6, blue), MCF-7/TAM (MT, n = 4, red), and MCF-7/TMA/shCK-α (MTsh, n = 5, yellow) cell groups. (C) VIP values as a measure of the discriminatory potential of the individual metabolites in the group differentiation. (UA: unknown resonance A, lactate, UE: unknown resonance E, glutamine, formate, AXP: AMP/ADP/ATP, UXP: UMP/UDP/UTP, MAU: maleate/AXP/UXP, UC: unknown resonance C, NAG: N-acetyl-aspartate/-amino acid/glutamate, Glx: glutamate/glutamine, LIV: leucine/isoleucine/valine). (D) Loading plot showing the relative contribution of the metabolites to the scores in the score plot. By matching the positions in the score plot and loading plot, the correlations between the individual metabolites and the cell groups were determined.</p

Comparison of the concentrations of the metabolites with VIP>1 among the MCF-7, MCF-7/shCK-α, MCF-7/TAM, and MCF-7/TAM/shCK-α cell groups.

<p>Increased lactate, glycine, phosphocholine, glutamine, and succinate in MCF-7/TAM relative to the other cell groups. Increased myo-inositol in MCF-7/shCK-α relative to the other cells. Non-detectable formate in MCF-7/TAM and MCF-7/TAM/shCK-α. Non-detectable fumarate in 7/shCK-α and MCF-7/TAM and MCF-7/TAM/shCK-α. Decreased AXP in MCF-7/shCK-α cells and MCF-7/TAM/shCK-α relative to MCF-7 and MCF-7/TAM. The spectra were normalized against total intensity and averaged over the samples in MCF-7, MCF-7/shCK-α, MCF-7/TAM and MCF-7/TAM/shCK-α. All values are presented as the mean ± standard error. *<i>p</i><0.05, ** 0.001<i><0.05, *** <i>p</i><0.001.</i></p

Identification of macrophages in the intraperitoneal cells by FACS.

<p>Over 95% of the intraperitoneal cells were F4/80 positive (Black: no staining, Green: F4/80 staining).</p

Downregulation of Choline Kinase-Alpha Enhances Autophagy in Tamoxifen-Resistant Breast Cancer Cells

<div><p>Choline kinase-α (Chk-α) and autophagy have gained much attention, as they relate to the drug-resistance of breast cancer. Here, we explored the potential connection between Chk-α and autophagy in the mechanisms driving to tamoxifen (TAM) resistance, in estrogen receptor positive (ER+) breast cancer cells (BCCs). Human BCC lines (MCF-7 and TAM-resistant MCF-7 (MCF-7/TAM) cells) were used. Chk-α expression and activity was suppressed by the transduction of shRNA (shChk-α) with lentivirus and treatment with CK37, a Chk-α inhibitor. MCF-7/TAM cells had higher Chk-α expression and phosphocholine levels than MCF-7 cells. A specific downregulation of Chk-α by the transduction of shChk-α exhibited a significant decrease in phosphocholine levels in MCF-7 and MCF-7/TAM cells. The autophagy-related protein, cleaved microtubule-associated protein light chain 3 (LC3) and autophagosome-like structures were significantly increased in shChk-α-transduced or CK37-treated MCF-7 and MCF-7/TAM cells. The downregulation of Chk-α attenuated the phosphorylation of AKT, ERK1/2, and mTOR in both MCF-7 and MCF-7/TAM cells. In MCF-7 cells, the downregulation of Chk-α resulted in an induction of autophagy, a decreased proliferation ability and an activation of caspase-3. In MCF-7/TAM cells, despite a significant decrease in proliferation ability and an increase in the percentage of cells in the G0/G1 phase of the cell cycle, the downregulation of Chk-α did not induced caspase-dependent cell death and further enhanced autophagy and G0/G1 phase arrest. An autophagy inhibitor, methyladenine (3-MA) induced death and attenuated the level of elevated LC3 in MCF-7/TAM cells. Elucidating the interplay between choline metabolism and autophagy will provide unique opportunities to identify new therapeutic targets and develop novel treatment strategies that preferentially target TAM-resistance.</p></div

Establishment of choline kinase-α (Chk-α)-downregulated breast cancer cells and analysis of choline-containing metabolites.

<p>(A and B) Images of MCF-7-shChk-α and MCF-7/TAM-shChk-α cells transduced with lentivirus containing Chk-α shRNA and GFP. (C and D) RT-PCR analysis of Chk-α and β. A selective and significant decrease in Chk-α mRNA levels was detected in MCF-7-shChk-α and MCF-7/TAM-shChk-α cells. (E and F) Western blot analysis of Chk-α. Chk-α was significantly downregulated in MCF-7-shChk-α and MCF-7/TAM-shChk-α. (G and H) Analysis of 1H-NMR spectra of choline-containing metabolites, choline (Cho), phosphocholine (PC) and glycerophosphocholine (GPC). PC level remarkably decreased in MCF-7-shChk-α and MCF-7/TAM-shChk-α as compared to MCF-7 and MCF-7/TAM cells. Data are presented as the mean ± standard deviation of 5 independent experiments. * <i>p</i><0.05 and ** <i>p</i><0.001. shChk-α transduced vs control.</p

Downregulation of choline kinase-α (Chk-α) expression and activity enhanced the expression of the autophagosome marker, LC3 and P62 and the formation of autophagosomes in MCF-7/TAM cells.

<p>(A and B) Images of autophagic structure in MCF-7-shChk-α and MCF-7/TAM-shChk-α cells. Chk-α downregulation induced autophagic structures (arrow) in MCF-7 cells as well as MCF-7/TAM cells. (C and D) Western blot analysis of LC3. MCF-7-shChk-α and MCF-7/TAM-shChk-α cells exhibited a significantly higher LC3 as compared to MCF-7 and MCF-7/TAM cells. (E and F) Immunofluorescence images for LC3. Chk-α downregulation led to an increase in the number of autophagosomes stained with LC3 antibody. (G and H) Western blot analysis of p62. MCF-7/TAM-shChk-α cells exhibited a significantly higher p62 as compared to MCF-7/TAM cells. (I and J) Western blot analysis of LC3. Inhibition of Chk-α activity by treatment with CK37 significantly increased LC3 expression. (K and L) Immunofluorescence images for LC3. CK37 treatment resulted in an increase in the number of autophagosomes stained with LC3 antibody. (M and N) Western blot analysis of p62. CK37 treatment did not change the level of p62 as compared to untreated cells. Data are presented as the mean ± standard deviation of 5 independent experiments. *<i>p</i><0.05. shChk-α transduced vs control and CK37-treated vs control.</p

The downregulation of Chk-α attenuated the phosphorylation levels of ERK1/2, AKT and mTOR.

<p>(A) Western blot analysis of the phosphorylation of AKT. (B) Western blot analysis of the phosphorylation of ERK1/2 (C) Western blot analysis of the phosphorylation of mTOR. The phoshorylation levels of AKT, ERK1/2 and mTOR decreased MCF-7-shChk-α and MCF-7/TAM-shChk-α cells relative to MCF-7 and MCF-7/TAM cells. Data are presented as the mean ± standard deviation of 5 independent experiments. *<i>p</i><0.05. shChk-α transduced vs control.</p

The downregulation of Chk-α attenuated the cell growth rate and enhanced G0/G1 fraction and in MCF-7/TAM but induced caspase-dependent death in MCF-7 cells.

<p>(A and B) MTT assay in assessing cell viability and growth. MCF-7-shChk-α and MCF-7/TAM-shChk-α cells exhibited the decreased cell viability and growth ability compared to MCF-7 and MCF-7/TAM cells. (C and D) Immunostaing of Ki67. The downregulation of Chk-α led to a decrease in the number of Ki-67 positive cells (red arrow). (E and F) Cell cycle analysis using propidium iodide staining and flow cytometry. The significant increase and decrease in the population in G0/G1 and the S proportion in MCF-7/TAM-shChk-α cells as compared to MCF-7/TAM cells. (G and H) Western blot analysis of the p21. p21 level was higher in MCF-7 and MCF-7-shChk-α cells relative to MCF-7/TAM and MCF-7/TAM-shChk-α cells. The downregulation of Chk-α caused to a significant decrease in p21 level in MCF-7/TAM cells. (I and J) Western blot analysis of the p27. MCF-7/TAM and MCF-7/TAM-shChk-α cells expressed p27 highly as compared to MCF-7 and MCF-7-shChk-α cells. The downregulation of Chk-α caused to a significant decrease in p27 level in MCF-7/TAM cells. (K and L) Immunofluorescence image of cleaved caspase-3. Activated caspase-3 (white arrow) was observed in MCF-7-shChk-α cells but not inMCF-7/TAM-shChk-α cells. Data are presented as the mean ± standard deviation of 5 independent experiments. **<i>p</i><0.001, *<i>p</i><0.05. shChk-α transduced vs control.</p