Scalable Synthesis of Defect Abundant Si Nanorods for High-Performance Li-Ion Battery Anodes

Microsized nanostructured silicon–carbon composite is a promising anode material for high energy Li-ion batteries. However, large-scale synthesis of high-performance nano-Si materials at a low cost still remains a significant challenge. We report a scalable low cost method to synthesize Al/Na-doped and defect-abundant Si nanorods that have excellent electrochemical performance with high first-cycle Coulombic efficiency (90%). The unique Si nanorods are synthesized by acid etching the refined and rapidly solidified eutectic Al–Si ingot. To maintain the high electronic conductivity, a thin layer of carbon is then coated on the Si nanorods by carbonization of self-polymerized polydopamine (PDA) at 800 °C. The carbon coated Si nanorods (Si@C) electrode at 0.9 mg cm^–2 loading (corresponding to area-specific-capacity of ∼2.0 mAh cm^–2) exhibits a reversible capacity of ∼2200 mAh g^–1 at 100 mA g^–1 current, and maintains ∼700 mAh g^–1 over 1000 cycles at 1000 mA g^–1 with a capacity decay rate of 0.02% per cycle. High Coulombic efficiencies of 87% in the first cycle and ∼99.7% after 5 cycles are achieved due to the formation of an artificial Al₂O₃ solid electrolyte interphase (SEI) on the Si surface, and the low surface area (31 m² g^–1), which has never been reported before for nano-Si anodes. The excellent electrochemical performance results from the massive defects (twins, stacking faults, dislocations) and Al/Na doping in Si nanorods induced by rapid solidification and Na salt modifications; this greatly enhances the robustness of Si from the volume changes and alleviates the mechanical stress/strain of the Si nanorods during the lithium insertion/extraction process. Introducing massive defects and Al/Na doping in eutectic Si nanorods for Li-ion battery anodes is unexplored territory. We venture this uncharted territory to commercialize this nanostructured Si anode for the next generation of Li-ion batteries

Video1_Single neurons on microelectrode array chip: manipulation and analyses.MP4

Chips-based platforms intended for single-cell manipulation are considered powerful tools to analyze intercellular interactions and cellular functions. Although the conventional cell co-culture models could investigate cell communication to some extent, the role of a single cell requires further analysis. In this study, a precise intercellular interaction model was built using a microelectrode array [microelectrode array (MEA)]-based and dielectrophoresis-driven single-cell manipulation chip. The integrated platform enabled precise manipulation of single cells, which were either trapped on or transferred between electrodes. Each electrode was controlled independently to record the corresponding cellular electrophysiology. Multiple parameters were explored to investigate their effects on cell manipulation including the diameter and depth of microwells, the geometry of cells, and the voltage amplitude of the control signal. Under the optimized microenvironment, the chip was further evaluated using 293T and neural cells to investigate the influence of electric field on cells. An examination of the inappropriate use of electric fields on cells revealed the occurrence of oncosis. In the end of the study, electrophysiology of single neurons and network of neurons, both differentiated from human induced pluripotent stem cells (iPSC), was recorded and compared to demonstrate the functionality of the chip. The obtained preliminary results extended the nature growing model to the controllable level, satisfying the expectation of introducing more elaborated intercellular interaction models.</p

DataSheet1_Single neurons on microelectrode array chip: manipulation and analyses.docx

Chips-based platforms intended for single-cell manipulation are considered powerful tools to analyze intercellular interactions and cellular functions. Although the conventional cell co-culture models could investigate cell communication to some extent, the role of a single cell requires further analysis. In this study, a precise intercellular interaction model was built using a microelectrode array [microelectrode array (MEA)]-based and dielectrophoresis-driven single-cell manipulation chip. The integrated platform enabled precise manipulation of single cells, which were either trapped on or transferred between electrodes. Each electrode was controlled independently to record the corresponding cellular electrophysiology. Multiple parameters were explored to investigate their effects on cell manipulation including the diameter and depth of microwells, the geometry of cells, and the voltage amplitude of the control signal. Under the optimized microenvironment, the chip was further evaluated using 293T and neural cells to investigate the influence of electric field on cells. An examination of the inappropriate use of electric fields on cells revealed the occurrence of oncosis. In the end of the study, electrophysiology of single neurons and network of neurons, both differentiated from human induced pluripotent stem cells (iPSC), was recorded and compared to demonstrate the functionality of the chip. The obtained preliminary results extended the nature growing model to the controllable level, satisfying the expectation of introducing more elaborated intercellular interaction models.</p

Video2_Single neurons on microelectrode array chip: manipulation and analyses.MP4

Chips-based platforms intended for single-cell manipulation are considered powerful tools to analyze intercellular interactions and cellular functions. Although the conventional cell co-culture models could investigate cell communication to some extent, the role of a single cell requires further analysis. In this study, a precise intercellular interaction model was built using a microelectrode array [microelectrode array (MEA)]-based and dielectrophoresis-driven single-cell manipulation chip. The integrated platform enabled precise manipulation of single cells, which were either trapped on or transferred between electrodes. Each electrode was controlled independently to record the corresponding cellular electrophysiology. Multiple parameters were explored to investigate their effects on cell manipulation including the diameter and depth of microwells, the geometry of cells, and the voltage amplitude of the control signal. Under the optimized microenvironment, the chip was further evaluated using 293T and neural cells to investigate the influence of electric field on cells. An examination of the inappropriate use of electric fields on cells revealed the occurrence of oncosis. In the end of the study, electrophysiology of single neurons and network of neurons, both differentiated from human induced pluripotent stem cells (iPSC), was recorded and compared to demonstrate the functionality of the chip. The obtained preliminary results extended the nature growing model to the controllable level, satisfying the expectation of introducing more elaborated intercellular interaction models.</p

Diagnostic Microdosing Approach to Study Gemcitabine Resistance

Gemcitabine metabolites cause the termination of DNA replication and induction of apoptosis. We determined whether subtherapeutic “microdoses” of gemcitabine are incorporated into DNA at levels that correlate to drug cytotoxicity. A pair of nearly isogenic bladder cancer cell lines differing in resistance to several chemotherapy drugs were treated with various concentrations of ¹⁴C-labeled gemcitabine for 4–24 h. Drug incorporation into DNA was determined by accelerator mass spectrometry. A mechanistic analysis determined that RRM2, a DNA synthesis protein and a known resistance factor, substantially mediated gemcitabine toxicity. These results support gemcitabine levels in DNA as a potential biomarker of drug cytotoxicity

Expression levels and mutation status of tumor suppressor pathway genes.

<p>(A) Integrated analysis of <i>mRNA Expression</i>, <i>Mutations</i>, and <i>Copy Number</i> was performed for genes in the <i>TP53</i> and <i>RB1</i> tumor suppressor pathways. Gene-level expression (FPKM) values for pathway member genes are presented and relative gene expression for each gene across the panel of PDX models is indicated by the heatmap (green = lower than the median, red = greater than the median). Mutations (amino acid changes) in <i>TP53</i> and <i>RB1</i> are indicated. Gene copy numbers are presented, and variants indicated as losses (<i>i</i>.<i>e</i>., < 2) or gains (<i>i</i>.<i>e</i>., > 2) shown by darker shades of red and green, respectively. (B) Expression levels (FPKM) of tumor suppressor pathway genes in each PDX are shown in the bar graph.</p

Efficacy test of molecularly guided targeted therapy matched with aberrations.

<p>(A) Efficacy studies of molecularly guided targeted therapy. BL0269 overexpressed HER2 and Src. Compared to the control group of median progression-free survival (PFS) of 13 days, a HER2 inhibitor lapatinib and a Src inhibitor ponatinib had little effect in suppressing tumor growth with a median PFS of 12 (p = 0.16) and 18 (p = 0.11) days, respectively. In contrast, lapatinib was very effective in BL0440 that expressed both HER2 and HER3 with PFS of 25.4 days versus 18.4 days in the control group (p = 0.0007). In BL0269 which also harbored a PIK3CA activation mutation H1047R, a PIK3CA inhibitor BEZ235 significantly suppressed tumor growth (p<0.0001). (B) Studies of efficacy and secondary resistance mechanisms of BGJ398 in BL0293. BL0293 overexpressed FGFR3. Compared to the control group of PFS at 9.5 days, an FGFR3 inhibitor BGJ398 significantly prolonged PFS to 18.5 days (p = 2. 61 X 10⁻⁶). Mice were sacrificed and PDXs were harvested (red arrows) before treatment, at Day 3 and at Day 17 (time of resistance) for western blot. Low levels of p-Akt and p-Erk at the baseline and at Day 3, suggesting low downstream signaling activity of FGFR3. Upon the development of resistance to BGJ398 at Day 17, both p-Akt and p-Erk levels increased, suggesting re-activation of the downstream signaling activity. BGJ398-resistant PDX BL0293 was re-implanted in NSG mice to form xenografts. Mice carrying BGJ398-resistant BL0293 were treated with PBS control, BGJ398, or a Raf inhibitor sorafenib plus a PIK3CA inhibitor BEZ235 combination. Compared to the BGJ398 group, treatment of BGJ398-resistant PDX with sorafenib and BEZ235 significantly prolonged PFS from 12 days to 22 days (p = 0.001). (C) Screening for effective chemotherapeutic agents. The first six PDXs were tested for sensitivity to cisplatin, gemcitabine or combination of both drugs. Only BL0440 was sensitive to cisplatin while only BL0269 and BL0479 were resistant to gemcitabine. Resistance to cisplatin could be overcome by gemcitabine, leaving four of these six PDXs sensitive to the combination therapy.</p

An integrated PDX para-clinical platform to improve molecularly guided targeted therapy.

<p>① Patients with muscle-invasive or advanced bladder cancer undergo transurethral or surgery resection. Some tumor specimens are implanted into NSG mice to establish PDXs. ② When the first PDXs (Passage 0 or P0) are established, some PDX specimens are implanted to more NSG mice to establish more PDXs (P1) while some other specimens are submitted for deep sequencing, including whole genome, exome and transcriptome sequencing. ③ Patients and mice carrying P1 PDXs receive the same primary treatment. ④ Computational biology is used to identify genetic aberrations in cancer cells. ⑤ Validation tests, such as direct sequencing, western blot, IHC and immunofluorescence staining, are performed to validate the genetic aberrations as identified in Step ④. ⑥ Because of the subcutaneous location and fast tumor growth in mice, tumor relapses in PDXs will occur sooner than that in human patients. Upon relapse, mice carrying PDXs will be treated with regimens A-D targeting 4 genetic alterations identified in Steps ④ and ⑤. In addition, serial biopsies can be performed during treatment. These biopsy specimens can be studied to decipher the secondary resistance mechanisms and guide the development of further therapy to overcome resistance. ⑦ Since only some of the genetic alterations are driver ones, some medications (Drug B and C) can induce response while PDXs do not respond to some other treatments (Drug A and D). ⑧ Upon cancer relapse in human patients, biopsy can be performed to validate the existence of genetic aberrations in the relapsed cancer, then the effective drug (Drug C) matching to the genetic aberrations in human cancers is used to treat relapsed cancer in patients. ⑨ Drug C can potentially be used while patients are in remission to cure or delay cancer recurrence.</p

Conservation of genomic variants between patient bladder cancer specimens and PDXs.

<p>WES analysis was performed on genomic DNA samples isolated from parental patient tumors and engrafted PDX P0 tumors. WES data was filtered for variants occurring at a frequency of >0.5 and then compared between samples on the basis of variant types. The number and type of variants occurring in each parental tumor and in the P0 PDX tumor were quantified and depicted as percentage of conservation in the graph. For all variants, 91.8% and 97.6% were conserved in BL0429 and BL0440, respectively.</p

Morphology of PDX.

<p>(A) Comparison of morphology between patient specimens and PDXs, subcutaneous and orthotopic PDXs, of PDX BL0293 and BL0440. Hematoxylin and eosin stain (H & E stain) showed that cell morphology was maintained during establishment of PDX and during passaging in mice, both at the subcutaneous site (S.C., at passage 6) and at the orthotopic bladder wall (at passage 4). However, more mitotic cells were observed in PDXs, especially at passage six. (B) Staining of human Ki67. Both PDXs were stained positive with anti-human Ki67, supporting that these PDX cells were indeed of human origin. In PDX BL0440, more cells were stained positive with Ki67 at passage six PDX compared to the human bladder cancer specimen, suggesting more cells were in cell proliferation, and this finding was consistent with the observation of more mitotic cells in Panel A of H & E staining. (C) Staining of human vimentin. Some human bladder cancer cells (left panel) and stromal cells (middle panel) were stained positive for human vimentin in the patient specimens. In the PDX specimen at passage 0, only a few bladder cancer cells were stained positive for human vimentin, suggesting that the stromal cells in PDX were not derived from human stromal cells.</p