MOESM1 of Understanding cellular internalization pathways of silicon nanowires

Additional file 1. Wire characterization including representative TEM of unmodified SiNWs and SiNW-NH2, FTIR analysis of unmodified SiNWs and SiNW-NH2, and wide XPS spectrum for an amine-modified silicon nanowires. Confocal images of SiNW-NH2 after incubation with CHO-β cells at 2 and 5-hour incubation periods and a graph plotting the average number of wires internalized per cell as a function of incubation time at 37 °C. Confocal images of HeLa cells at 2 and 5-h incubation time at 37 and 4 °C with unmodified SiNWs

Fluoride Regulate Osteoblastic Transforming Growth Factor-β1 Signaling by Mediating Recycling of the Type I Receptor ALK5

<div><p>This study aimed to preliminary investigate the role of activin receptor-like kinase (ALK) 5 as one of TGF-βR1 subtypes in bone turnover and osteoblastic differentiation induced by fluoride. We analyzed bone mineral density and the expression of genes related with transforming growth factor-β1(TGF-β1) signaling and bone turnover in rats treated by different concentrations of fluoride with or without SB431542 <i>in vivo</i>. Moreover, MTT assay, alkaline phosphatase staining, RT-PCR, immunocytochemical analysis and western blot analysis were used to detect the influence on bone marrow stem cells (BMSC) after stimulating by varying concentration of fluoride with or without SB431542 <i>in vitro</i>. The <i>in vivo</i> study showed SB431542 treatment affected bone density and gene expression of rats, which indicated TGF-β1 and ALK5 might take part in fluoride-induced bone turnover and bone formation. The <i>in vitro</i> study showed low concentration of fluoride improved BMSC cells viability, alkaline phosphatase activity, and osteocalcin protein expression which were inhibited by high concentration of fluoride. The gene expression of Runx2 and ALK5 in cells increased after low concentration fluoride treatment which was also inhibited by high concentration of fluoride. Fluoride treatment inhibited gene and protein expression of Samd3 (except 1 mgF^-/L). Compared with fluoride treatment alone, cells differentiation was inhibited with SB431542 treatment. Moreover, the expression of Runx2, ALK5 and Smad3 were influenced by SB431542 treatment. In conclusion, this preliminary study indicated that fluoride regulated osteoblastic TGFβ1 signaling in bone turnover and cells differentiation via ALK5.</p></div

Design of Contact Electrodes for Semiconductor Nanowire Solar Energy Harvesting Devices

Transparent, low-resistive contacts are critical for efficient solar energy harvesting devices. It is important to reconsider the material choices and electrode design as devices move from 2D films to 1D nanostructures. In this paper, we study the effectiveness of indium tin oxide (ITO) and metals, such as Ag and Cu, as contacts in 2D and 1D systems. Although ITO has been studied extensively and developed into an effective transparent contact for 2D devices, our results show that effectiveness does not translate to 1D systems. Particularly with consideration of resistance requirement, nanowires with metal shells as contacts enable better absorption within the semiconductor as compared to ITO. Furthermore, there is a strong dependence of contact performance on the semiconductor band gap and diameter of nanowires. We found that metal contacts outperform ITO for nanowire devices, regardless of the sheet resistance constraint, in the regime of diameters less than 100 nm and band-gaps greater than 1 eV. These metal shells optimized for best absorption are significantly thinner than ITO, which enables for the design of devices with high nanowire number density and consequently higher device efficiencies

Bone Marrow-Derived Cells May Not Be the Original Cells for Carcinogen-Induced Mouse Gastrointestinal Carcinomas

<div><p>Aim</p><p>It has been reported that bone marrow-derived cells (BMDC) can be original cells of mouse gastric cancers induced by <i>Helicobacter felis</i> (<i>H. felis</i>) infection. However, it is unknown whether BMDCs are also the original cells of mouse gastrointestinal cancers induced by gastric carcinogens <i>N</i>-nitroso-<i>N</i>-methylurea (NMU) and <i>H. felis</i> infection.</p><p>Methods</p><p>C57BL/6 recipient mice were initially irradiated with 10Gy X-ray, reconstituted with bone marrow cells from the C57BL/6-Tg (CAG-EGFP) donor mice to label BMDCs with green fluorescence protein (GFP). After 4 weeks of recovery, the bone marrow-transplanted mice were given NMU in drinking water (240 ppm) and subsequently infected with <i>H. felis</i> by gavage. Eighty weeks later, all mice were euthanized for pathological examination. The BMDCs expressing GFP were detected in tissues using direct GFP fluorescence confocal microscopy analysis and immunohistochemistry staining (IHC) assays.</p><p>Results</p><p>Neoplastic lesions were induced by NMU treatment and/or <i>H. felis</i> infection at the antrum of the glandular stomach and small intestine. In the direct GFP fluorescence confocal assay, GFP(+) epithelial cell cluster or glands were not observed in these gastrointestinal tumors, however, most GFP(+) BMDCs sporadically located in the tumor stromal tissues. Some of these GFP(+) stromal BMDCs co-expressed the hematopoietic marker CD45 or myofibroblasts markers αSMA and SRF. In the indirect GFP IHC assay, similar results were observed among 11 gastric intraepithelial neoplasia lesions and 2 small intestine tumors.</p><p>Conclusion</p><p>These results demonstrated that BMDCs might not be the source of gastrointestinal tumor cells induced by NMU and/or <i>H. felis</i> infection.</p></div

Cellular Binding and Internalization of Functionalized Silicon Nanowires

Nanostructures with precise control of sizes and shapes, intrinsic read-out signals for tracking, and flexible surface chemistry for bioconjugation can offer an excellent system to study interaction between nanomaterials and cells. In this paper, a new nanobio system based on functionalized silicon nanowires (SiNWs) was developed. Using the intensive and intrinsic nonlinear optical signal of SiNWs, we visualized the interaction between the folate and amine group functionalized SiNWs and cells by monitoring the cellular binding and uptake of SiNWs in real time. We demonstrated that the strong specific ligand–receptor interaction between folate on NWs and folate receptors on CHO-β cell membranes expedited agglomeration of folate modified SiNWs on cells and internalization of NWs. Such specific targeting was further confirmed through control experiments done with normal CHO cell without folate receptors. Weaker nonspecific charge–charge attraction led to longer time required for amino group modified SiNWs to be bound on cell membrane. No effective accumulation was noticed for unmodified SiNW with native oxidized surface layer. In addition, we also observed the binding was independent of length for NWs ranging between 2.5 and 8.0 μm. Uptake of NWs highly depended on length and NWs longer than 5 μm were difficult to be internalized. Our results provided an insight of cellular interaction with 1-dimensional nanomaterials

Activity of Alkaline phosphatase of cells exposed to fluoride with and without SB431542.

<p>Cells were treated with 1 mg/L, 4 mg/L, and 16 mg/L of fluoride with or without 10μmol/L SB431542 for 7 days. The deposition of Cobalt sulfide particles was stained into light black granules in cytoplasm. The positive staining for deposition of Cobalt sulfide particles was shown in control group (a), 1 mg F⁻/L group (b), 4 mg F⁻/L (c), 16 mg F⁻/L group (d), SB431542 control group (e), SB431542 +1 mg F⁻/L group (f), SB431542 +4 mg F⁻/L (g), SB431542 + 16 mg F⁻/L group (h), TGF-β1control group (i), TGF-β1 + 1 mg F⁻/L group (j), TGF-β1 +4 mg F⁻/L (k), TGF-β1 + 16 mg F⁻/L group (l) under microscopy (red arrowheads; scale bar, 50 μm).</p

Average body weight of mice with different treatments.

<p>BMT, bone-marrow transplantation; Mock, normal mice without any treatment; <i>H.felis</i>, gavaged with <i>H. felis</i> suspension on three alternate days (one time/day); NMU, drinking water containing 240 ppm NMU in five alternate weeks.</p

Co-expression of αSMA and SRF in part of stromal cells originated from bone marrow-derived cells.

<p>(<b>A</b>) Images demonstrating that some GFP(+) BMDCs in the tumor stroma co-expressed αSMA (indicated by arrows) in a carcinogen-induced small intestinal tumor. (<b>B</b>) Images demonstrating that some GFP(+) BMDCs in the tumor stroma co-expressed SRF (indicated by arrows) in the small intestinal tumor. A SRF(+) cell without GFP expression is indicated by a filled arrow.</p

Photoisomerization of Silyl-Substituted Cyclobutadiene Induced by σ → π* Excitation: A Computational Study

Photoinduced chemical processes upon Franck–Condon (FC) excitation in tetrakis­(trimethylsilyl)-cyclobutadiene (TMS-CBD) have been investigated through the exploration of potential energy surface crossings among several low-lying excited states using the complete active space self-consistent field (CASSCF) method. Vertical excitation energies are also computed with the equation-of-motion coupled-cluster model with single and double excitations (EOM-CCSD) as well as the multireference Møller–Plesset (MRMP) methods. Upon finding an excellent coincidence between the computational results and experimental observations, it is suggested that the Franck–Condon excited state does not correspond to the first π–π* single excitation state (<i>S</i>₁, 1¹<i>B</i>₁ state in terms of <i>D</i>₂ symmetry), but to the second ¹<i>B</i>₁ state (<i>S</i>₃), which is characterized as a σ–π* single excitation state. Starting from the Franck–Condon region, a series of conical intersections (CIs) are located along one isomerization channel and one dissociation channel. Through the isomerization channel, TMS-CBD is transformed to tetrakis­(trimethylsilyl)-tetrahedrane (TMS-THD), and this isomerization process could take place by passing through a “tetra form” conical intersection. On the other hand, the dissociation channel yielding two bis­(trimethylsilyl)-acetylene (TMS-Ac) molecules through further stretching of the longer C–C bonds might be more competitive than the isomerization channel after excitation into <i>S</i>₃ state. This mechanistic picture is in good agreement with recently reported experimental observations

Protein level of osteocalcin in BMSC exposed to fluoride with and without SB431542.

<p>Cells were treated with 1 mg/L, 4 mg/L, and 16 mg/L of fluoride with or without 10μmol/L SB431542 for 28 days. Immunocytochemistry analysis was used to test osteocalcin expression in situ. Positive staining showed brown granules in cytoplasm as that in control group (a), 1 mg F⁻/L group (b), 4 mg F⁻/L (c),16 mg F⁻/L group (d), SB431542 control group (e), SB431542 + 1 mg F⁻/L group (f), SB431542 +4 mg F⁻/L (g), SB431542+ 16 mg F⁻/L group (h) under microscopy (red arrowheads; scale bar, 50 μm). Immunocytochemistry was analyzed by using Image-Pro Plus 6.0 software to measure integrated optical density. Results are expressed as mean±SD (n = 3). Results indicated the significant changes(*P < 0.05, **P < 0.01 compare with control group; a P< 0.05, compare with two groups).</p