Snail maintains metastatic potential, cancer stem-like properties, and chemoresistance in mesenchymal mouse breast cancer TUBO­P2J cells.

Snail, a zinc-finger transcriptional repressor of E-cadherin expression, is one of the key inducers of epithelial-mesenchymal transition (EMT) in epithelial cancer. In breast cancer, EMT has been associated with malignancies, including metastasis, cancer stem-like properties, and resistance to chemotherapy and radiotherapy. In this study, we analysed the role of Snail in the highly metastatic mesenchymal TUBO­P2J mouse breast cancer cells, by loss of function using short hairpin RNA. Though silencing Snail did not restore the E-cadherin expression or induce morphological changes, Snail silencing significantly ablated in vitro and in vivo metastatic potentials. In addition, Snail silencing also reduced resistance to chemotherapy drugs and cancer stem-like properties, such as CD44 expression, aldehyde dehydrogenase (ALDH) activity, colony formation, and in vivo tumour formation and growth. However, radioresistance was not decreased by silencing Snail. Collectively, this study suggested that Snail is a main regulator of the maintenance of malignancy potentials and is a good target to prevent cancer metastasis and to increase chemotherapy susceptibility.

SnO2 nanoslab as NO2 sensor: identification of the NO2 sensing mechanism on a SnO2 surface.

Among the various metal oxides, SnO2 has been most widely exploited as a semiconductor gas sensor for its excellent functionalities. Models illustrating the sensing mechanism of SnO2 have been proposed and tested to explain experimentally derived "power laws". The models, however, are often based on somewhat simplistic assumptions; for instance, the net charge transfer from an adsorbate to a sensor surface site is assumed to occur only by integer values independent of the crystallographic planes. In this work, we use layer-shaped SnO2 crystallites with one nanodimension (1ND-crystallites) as NO2 gas sensing elements under flat band conditions, and derive appropriate "power laws" by combining the dynamics of gas molecules on the sensor surface with a depletion theory of semiconductor. Our experimentally measured sensor response as a function of NO2 concentration when compared with the theoretically derived power law indicates that sensing occurs primarily through the chemisorption of single NO2 molecules at oxygen vacancy sites on the sensor surface.

Sensitivity-tuned CO gas sensors with tailored Ga-doping in ZnO nanowires.

Sensitivity-customization of zinc oxide (ZnO) nanowire (NW) gas sensors has been demonstrated by controlling Ga-doping, thereby tuning the resistance of the NWs. Both un-doped and 5 weight% Ga-doped ZnO (GZO) NWs are synthesized for the highly sensitive sensing within a narrow detection window and a less sensitive one within an expanded window, respectively. We have employed hot-walled pulsed laser deposition (HW-PLD) for the NW synthesis. With CO gas injection, the resistance reduction of NWs is detected and analyzed in a self-designed gas chamber that guarantees the precise control of gas flow and, gas concentration, as well as temperature. NW sensitivity is proportional to the sensing temperature and inversely proportional to the doping concentration resulting in widening the sensing window up to 230 times by the 5 wt.% Ga-doping.

Effect of Ag/Al co-doping method on optically p-type ZnO nanowires synthesized by hot-walled pulsed laser deposition.

Silver and aluminum-co-doped zinc oxide (SAZO) nanowires (NWs) of 1, 3, and 5 at.% were grown on sapphire substrates. Low-temperature photoluminescence (PL) was studied experimentally to investigate the p-type behavior observed by the exciton bound to a neutral acceptor (A0X). The A0X was not observed in the 1 at.% SAZO NWs by low-temperature PL because 1 at.% SAZO NWs do not have a Ag-O chemical bonding as confirmed by XPS measurement. The activation energies (Ea) of the A0X were calculated to be about 18.14 and 19.77 meV for 3 and 5 at.% SAZO NWs, respectively, which are lower than the activation energy of single Ag-doped NW which is about 25 meV. These results indicate that Ag/Al co-doping method is a good candidate to make optically p-type ZnO NWs.

Effects of silver impurity on the structural, electrical, and optical properties of ZnO nanowires.

1, 3, and 5 wt.% silver-doped ZnO (SZO) nanowires (NWs) are grown by hot-walled pulsed laser deposition. After silver-doping process, SZO NWs show some change behaviors, including structural, electrical, and optical properties. In case of structural property, the primary growth plane of SZO NWs is switched from (002) to (103) plane, and the electrical properties of SZO NWs are variously measured to be about 4.26 × 106, 1.34 × 106, and 3.04 × 105 Ω for 1, 3, and 5 SZO NWs, respectively. In other words, the electrical properties of SZO NWs depend on different Ag ratios resulting in controlling the carrier concentration. Finally, the optical properties of SZO NWs are investigated to confirm p-type semiconductor by observing the exciton bound to a neutral acceptor (A0X). Also, Ag presence in ZnO NWs is directly detected by both X-ray photoelectron spectroscopy and energy dispersive spectroscopy. These results imply that Ag doping facilitates the possibility of changing the properties in ZnO NWs by the atomic substitution of Ag with Zn in the lattice.