Resistance of POSS Polyimide Blends to Hyperthermal Atomic Oxygen Attack

Copolymers of polyhedral oligomeric silsesquioxane (POSS) and polyimide (PI) have shown remarkable resistance to atomic oxygen (AO) attack and have been proposed as replacements for Kapton on the external surfaces of spacecraft in the harsh oxidizing environment of low Earth orbit (LEO). POSS PI blends would be an economical alternative to the copolymers if they also resisted AO attack. Thus, blends of trisilanolphenyl (TSP) POSS and PI with different weight percentages of the Si₇O₉ POSS cage were cast into films and exposed to a hyperthermal AO beam, and they were characterized in terms of their recession, mass loss, surface morphology, and surface chemistry. In order to compare the AO resistance of the blends with POSS PI copolymers, samples of previously studied copolymers were also investigated in parallel with the blends. For all POSS PI materials, the AO resistance increased with increasing AO fluence and with increasing POSS cage loading. At similar POSS cage loadings and exposure conditions, the TSP POSS PI blends showed comparable erosion yields to the POSS PI copolymers, with specific samples of blends and copolymers achieving erosion yields as low as 0.066 × 10^–24 cm³ atom^–1 with an AO fluence of 5.93 × 10²⁰ O atoms cm^–2. SEM and XPS analyses indicated that passivating SiO_<i>x</i> layers were formed on the surfaces of all POSS-containing polymers during AO exposure. Thus, a TSP POSS PI blend is proposed as a low-cost variant of a POSS polyimide for use in extreme oxidizing environments, such as LEO

NCTD facilitates NF-κB nuclear translocation.

<p>A–B, RAW264.7 cells (A) and peritoneal macrophages (B) were stimulated with 100 ng/ml LPS in absence or presence of 5 µM NCTD that had been added 24 h before. When LPS addition was added for 15 min, subcellular location of NF-κB p65 subunit was detected using immunofluorescence assay. Scale bar, 10 μm. One of three experiments was shown.</p

NCTD enhances LPS induced cytokines expression at mRNA level.

<p>A, The cytotoxicity of NCTD is much lower than CTD. RAW264.7 cells were treated with NCTD or CTD for 24 h and cell viability was tested with MTS assay as described under Materials and Methods. B, Cytokines production was enhanced obviously by NCTD in RAW264.7 cells. The RAW264.7 cells were pretreated with PBS (containing 0.1% DMSO) or 1–10 μM NCTD for 24 h before stimulation with 100 ng/ml LPS for 1 h. Total cellular RNA were collected and subjected to Real time -PCR analysis. C, Only LPS induced cytokine production was enhance by NCTD obviously. The RAW264.7 cells were pretreated with 0.1% DMSO, 5 μM NCTD for 24 h before stimulation with LPS (100 ng/ml), PMA (100nM) or LTA (10 µg/ml) for 1 h. Total cellular RNA were collected and subjected to Real time PCR analysis. Columns, mean from three independent experiments with three duplicates; bars, SE (*, P<0.05; **, P<0.01 versus control).</p

NCTD protects mice from bacterial-induced peritonitis.

<p>A, Chemical structure of NCTD and CTD. B, The survival of peritonitis mouse was increased by NCTD obviously. The mice were treated with NCTD or PBS at 24 h and 6 h before infection. Both NCTD and PBS (containing 0.1% DMSO) treated mice (n = 8) were intraperitoneal injected with <i>E.coli 0111</i> (8*10⁷) and monitored every 3 h for 72 h. C, Serum concentration of IL-6 and TNF-α in mouse model was enhanced by NCTD. The blood was obtained 6 h after infection and the serum concentration of IL-6 and TNF-α was measured by ELISA assay. (<i>*</i>, P<0.0<i>5</i>) Data are representative of three independent experiments with similar results. D, The quantity of bacterial was reduced in NCTD treated mouse. The mice were treated with 1 ml vehicle control (containing 0.1% DMSO), 100 ug/ml Ampicillin or NCTD (10 mg/kg) respectively followed by an i.p injection with 5×10⁷ CFU of <i>E. coil</i>-GFP in 1 ml PBS for 16 h. Then the bacteria resident in abdomen was visualized by fluorescent stereomicroscope. Also, their peritoneal cavities were lavaged with 3 ml PBS, and bacterial counts were determined by plating on agar plates. n = 4 mice per group. E, NCTD has no effects on the growth of <i>E. coil</i>-GFP. E.coli-GFP were cultured with 100 µg/ml Ampicillin (Amp+) and 5 μM NCTD for 24 h respectively. Then the bacteria number was detected by spectrophotometer. Data are representative of three independent experiments with similar results (mean ± s.d. in B, D).</p

Regulation of NCTD on LPS induced NF-κB activation.

<p>A. Little influence was observed by NCTD on IκBα and MAPK signaling pathway. RAW264.7 cells were treated with PBS (containing 0.1% DMSO) or 1–10 μM NCTD for 24 h and then stimulated with 100 ng/ml LPS for different time. The protein levels of IκBα and MAPK signaling pathway in RAW264.7 cells were determined using western blotting. B. The translocation of p65 to nucleus was increased in NCTD treated macrophages. Cells (2×10⁶ cells/ml) were incubated with PBS (containing 0.1% DMSO) or 1–10 μM NCTD for 24 h and treated with 100 ng/ml LPS for 15 min. Cytoplasmic extracts (CE) and nuclear extract (NE) were prepared and analyzed by western blot analysis using specific antibodies. And the translocation of p65 to nuclear was also quantitatively analyzed. C. LPS induced DNA binding ability of NF-κB was enhanced by NCTD in a dose dependent manner. Cells were treated with PBS (containing 0.1% DMSO) or 1–10 μM NCTD at 37°C for 24 h and then activated with 100 ng/ml LPS for 30 min. Finally, nuclear extracts were prepared and then assayed for NF-κB activation by EMSA as described under Materials and Methods. Three independent experiments were performed. D, Diagram of NCTD facilitates LPS-mediated immune responses by up-regulation of AKT/NF-κB associated signaling pathway.</p

Mesoporous Carbon Nanospheres Featured Fluorescent Aptasensor for Multiple Diagnosis of Cancer <i>in Vitro</i> and <i>in Vivo</i>

Multiple diagnosis of cancer by a facile fluorescent sensor is extremely attractive. Herein, a Cy3-labeled ssDNA probe (P₀-Cy3) was π–π stacked on the surface of oxidized mesoporous carbon nanospheres (OMCN) to construct the fluorescent “turn-on” aptasensor. Attributing to the intrinsic properties of OMCN, the OMCN-based aptasensor not only can be used to detect mucin1 protein in liquid with a wide range of 0.1–10.6 μmol/L, a low detection limit of 6.52 nmol/L, and good selectivity, but also can quantify the cancer cells in solution with the linear range of 10⁴–2 × 10⁶ cells/mL and a detection limit of 8500 cells/mL. Fascinatingly, this OMCN-based aptasensor was exploited to image cancer via solid tissues such as cells, tissue sections, and <i>ex vivo</i> and <i>in vivo</i> tumors, in which the obvious distinguishability between cancer and normal tissues was clearly demonstrated. This is a robust and simple detection technique, which can well achieve the multiple diagnosis of cancer <i>in vitro</i> and <i>in vivo</i>

MemHsp70 Receptor-mediated Multifunctional Ordered Mesoporous Carbon Nanospheres for Photoacoustic Imaging-Guided Synergistic Targeting Trimodal Therapy

Integrating multiple discrete function-related theranostic modalities into one platform for effective cancer treatments has been considered to be a challenge for current nanomedicine design. In this work, a “four-in-one” theranostic system was simply prepared and developed for photoacoustic (PA) imaging-guided synergistic targeting chemo-gene-thermo trimodal therapy of breast cancer. In this system, polyethylene glycol (PEG)-bridged polyethylenimine (PEI) and a memHsp70 receptor-targeting peptide (TKD), PPT, was uniformly capped on doxorubicin (DOX)-loaded oxidized mesoporous carbon nanospheres (OMCN) to encapsulate therapeutic genes into cancer cells via active targeting accumulation. Taking both the advantages of OMCN (high photothermal conversion, strong PA contrast, and controllable drug loading) and the hydrophilic polymer (gene vector, switchable pores’ cap, and targeting ability), the “four-in-one” theranostic system exhibited distinct PA imaging visualization, NIR/pH sensitive drug/gene release, and synergistic targeting therapeutic outcome, which were much superior than the single therapy or the combination of two treatments

SSTR2 associated with neuronal apoptosis after intracerebral hemorrhage in adult rats

<p>SSTR2 is a member of superfamily of SST receptor (SSTR), and widely expressed in the brain; however, the knowledge of its functions in area adjacent to hematoma after intracerebral hemorrhage (ICH) is still limited.</p> <p>The role of SSTR2 in the processes of ICH was explored by conducting an ICH rat model. Western blot and immunohistochemistry were employed to examine the level of SSTR2 in area adjacent to hematoma after ICH. Immunofluorescent staining was used to observe the spatial correlation of SSTR2 with cellular types adjacent to hematoma after ICH. RNA interference specific to SSTR2 was adopted in PC12 cells to clarify the causal correlation between SSTR2 and neuronal activities.</p> <p>Increased expression of SSTR2 was observed and restricted to the neurons adjacent to hematoma following ICH. Immunofluorescent staining showed that SSTR2 was significant increased in neurons, but not astrocytes or microglia. Increasing SSTR2 level was found to be accompanied by the up-regulation of activated caspase-3 and the down-expression of p-Akt in a time-dependent manner. What’s more, using SSTR2 RNA interference (SSTR2-RNAi) in PC12 cells, we indicated that SSTR2 might have a pro-apoptotic role in neurons.</p> <p>We speculated that SSTR2 might exert its pro-apoptotic function in neurons through inhibiting Akt activity following ICH.</p

Highly Crystalline Multicolor Carbon Nanodots for Dual-Modal Imaging-Guided Photothermal Therapy of Glioma

Imaging-guided site-specific photothermal therapy (PTT) of glioma and other tumors in central nervous system presents a great challenge for the current nanomaterial design. Herein, an in situ solid-state transformation method was developed for the preparation of multicolor highly crystalline carbon nanodots (HCCDs). The synthesis yields 6–8 nm-sized HCCDs containing a highly crystalline carbon nanocore and a hydrophilic surface, which therefore simultaneously provide strong photoacoustic and photothermal performances as well as tunable fluorescence emission. In vitro and in vivo results demonstrate that the novel HCCDs have high water dispersity and good biocompatibility, but potent tumor cell killing upon near-infrared irradiation. As demonstrated in U87 glioma-bearing mice, HCCDs specifically accumulate in brain tumors and facilitate dual-modal imaging-guided PTT, with therapeutic antitumoral effects without any apparent damage to normal tissues

Additional file 1 of FFAR2 expressing myeloid-derived suppressor cells drive cancer immunoevasion

Additional file 1. Supplementary figures S1–S9