The Role of ATRA,Natural Ligand of Retinoic Acid Receptors,on EMT-Related Proteins in Breast Cancer: Minireview

The knowledge of the structure, function, and abundance of specific proteins related to the EMT process is essential for developing effective diagnostic approaches to cancer with the perspective of diagnosis and therapy of malignancies. The success of all-trans retinoic acid (ATRA) differentiation therapy in acute promyelocytic leukemia has stimulated studies in the treatment of other tumors with ATRA. This review will discuss the impact of ATRA use, emphasizing epithelial-mesenchymal transition (EMT) proteins in breast cancer, of which metastasis and recurrence are major causes of death.     

Design and stereoselective synthesis of retinoids with ferrocene or N-butylcarbazole pharmacophores that induce post-differentiation apoptosis in acute promyelocytic leukemia cells

New ferrocene and N‐alkylcarbazole retinoids were designed and synthesized stereoselectively in good yields. A number of these synthesized ligands, in particular 2 , 3 , and 11 , were found to exhibit a high RARα activation potential and to effectively induce post‐differentiation apoptosis in NB4 acute promyelocytic leukemia (APL) cells. Increasing the length of the side chain attached to the heterocycle of the carbazole arotinoids creates new opportunities for altered compound catabolism and for fine‐tuning of the apoptosis‐inducing potential of the ligand. In the carbazole series of new retinoids, maximal activity was established for N‐butylcarbazole analogue 11 in all assays (i.e., RARα activation, differentiation induction, and apoptosis induction). Study of the mechanism of apoptosis revealed an activation of initiator caspases‐8 and ‐9, followed by efficient cleavage of effector caspase‐3 on day 6 of treatment. Subsequent induction of a caspase cascade in NB4 cells triggered ultimate leukemic cell death. The selected ligands 2 , 3 , and 11 may provide alternate options for the treatment of APL in cases of life‐threatening ATRA syndrome, resistance, and high toxicity to conventionally used retinoids.     

Retinoids as Chemo-Preventive and Molecular-Targeted Anti-Cancer Therapies

Retinoic acid (RA) agents possess anti-tumor activity through their ability to induce cellular differentiation. However, retinoids have not yet been translated into effective systemic treatments for most solid tumors. RA signaling is mediated by the following two nuclear retinoic receptor subtypes: the retinoic acid receptor (RAR) and the retinoic X receptor (RXR), and their isoforms. The identification of mutations in retinoid receptors and other RA signaling pathway genes in human cancers offers opportunities for target discovery, drug design, and personalized medicine for distinct molecular retinoid subtypes. For example, chromosomal translocation involving RARA occurs in acute promyelocytic leukemia (APL), and all-trans retinoic acid (ATRA) is a highly effective and even curative therapeutic for APL patients. Thus, retinoid-based target discovery presents an important line of attack toward designing new, more effective strategies for treating other cancer types. Here, we review retinoid signaling, provide an update on retinoid agents and the current clinical research on retinoids in cancer, and discuss how the retinoid pathway genotype affects the ability of retinoid agents to inhibit the growth of colorectal cancer (CRC) cells. We also deliberate on why retinoid agents have not shown clinical efficacy against solid tumors and discuss alternative strategies that could overcome the lack of efficacy.     

Highly transparent low resistance ATO/AgNWs/ATO flexible transparent conductive thin films

Indium-free flexible transparent conductive thin films (TCFs) composed of silver nanowire (AgNW) networks and Sb doped SnO₂ (ATO) layers were prepared on polyethylene terephthalate (PET) substrates. The ATO layers were deposited via radio frequency (RF) magnetron sputtering at room temperature. The AgNWs were achieved via a modified polyol reduction method and embedded between the ATO layers. The effects of AgNW networks and ATO layers on electrical and optical properties of the ATO/AgNWs/ATO flexible tri-layer thin films are investigated. The ATO layers can improve the optical transmittance and reduce the resistivity of tri-layers, and the corresponding mechanisms are proposed. Typically, an ATO/AgNWs/ATO flexible tri-layers show a high figure of merit value (30.06 × 10^-3 Ω^-1) with a low sheet resistance of 7.1 Ω/sq. and a high transmittance of 85.7%. Meanwhile, the tri-layers present excellent mechanical flexibility, and the ATO layers acted as the protecting layers improve the adhesive and environmental stability at high temperature and humidity for the ATO/AgNWs/ATO flexible tri-layers. These results indicate that ATO/AgNWs/ATO flexible tri-layer thin films can be useful for the fabrication of wearable electronic devices.     

Electrocatalytic activity of IrO2-RuO2 supported on Sb-doped SnO2 nanoparticles

Electrocatalytic IrO₂-RuO₂ supported on Sb-doped SnO₂ (ATO) nanoparticles is very active towards the oxygen evolution reaction. The IrO₂-RuO₂ material is XRD amorphous and exists as clusters on the surface of the ATO. Systematic changes to the surface chemical composition of the ATO as a function of the IrO₂:RuO₂ ratio suggests an interaction between the IrO₂-RuO₂ and ATO. Cyclic voltammetry indicates that the electrochemically active surface area of IrO₂-RuO₂ clusters is maximised when the composition is 75 mol% IrO₂-25 mol% RuO₂. Decreasing the loading of IrO₂-RuO₂ on ATO reduces the electrochemically active surface area, although there is evidence to support a decrease in the clusters size with decreased loading. Tafel slope analysis shows that if the clusters are too small, the kinetics of the oxygen evolution reaction are reduced. Overall, clusters of IrO₂-RuO₂ on ATO have similar or better performance for the oxygen evolution reaction than many previously reported materials, despite the low quantity of noble metals used in the electrocatalysts. This suggests that these oxides may be of economic advantage if used as PEM water electrolysis anodes.     

Mechanical properties of polymer‐ceramic nanocomposite coatings by depth‐sensing indentation

The mechanical properties of antimony‐doped tin oxide (ATO) nanoparticle/poly (vinyl acetate‐co‐acrylic) (PVAc‐co‐acrylic) coatings with various ATO contents were investigated using depth‐sensing indentation. These coatings were prepared from aqueous dispersions of ATO and PVAc‐co‐acrylic latex. Three types of methods, including a prolonged load holding time, analysis of the pull‐off portion of the unloading curve, and dynamic indentation, were used to characterize the mechanical properties of these composite coatings. As compared to dynamic indentation, quasistatic conventional indentation even with a prolonged load holding time and analysis of the pull‐off portion of unloading curves generate more scattered coating modulus data. This is due to the effect of creep deformation and inconsistency of the pull‐off portion dimension, respectively. The results obtained using dynamic indentation are more reliable because the technique minimizes the effect of creep deformation using a combination load including static and dynamic components. The dynamic indentation results indicate that the addition of the ATO nanoparticles made the composite coatings stiffer and more elastic solid–like. For example, the storage indentation modulus of the PVAc‐co‐acrylic coating is ～1 GPa and tan δ is ～1.6; the addition of 0.50 volume fraction of ATO increased the modulus to ～5 GPa and reduced the tan δ to ～0.01. POLYM. ENG. Sci. 45:207–216, 2005. © 2005 Society of Plastics Engineers.     

Effect of SnO2 and Sb‐doped SnO2 on the structure and electrical conductivity of epichlorohydrin rubber

Nanosized Sb‐doped SnO₂ (ATO) particles were successfully synthesized. Electrically conducting rubbery composites based on epichlorohydrin rubber (ECO) and two kinds of conductive fillers (SnO₂ and ATO) were prepared by a conventional blending method. The morphology, structure and electrical conductivity of ECO/SnO₂ and ECO/ATO composites were investigated. Results showed that SnO₂ and ATO had great influence on the structure of ECO composite. Besides, the addition of oxide particles enhanced its electrical conductivity significantly. The electrical conductivity of ECO/ATO composite appeared an obvious threshold value with the variation of the loading amount of ATO fillers, whereas the resistivity of ECO filled with SnO₂ decreased monotonically with the increasing SnO₂. The temperature dependence of resistivity indicated that the ECO/SnO₂ and ECO/ATO composites exhibited a negative temperature coefficient (NTC) effect. Scanning electron microscopy (SEM) was used to investigate the morphological states of oxide fillers in ECO matrix, and specifically continuous networks were observed. POLYM. COMPOS., 37:2411–2416, 2016. © 2015 Society of Plastics Engineers     

Study on the wet processable antimony tin oxide (ATO) transparent electrode for PLEDs

A polymer light emitting diodes (PLEDs) was fabricated using the wet processable antimony tin oxide (ATO) as the transparent electrode by spin coating method. PLED were fabricated with ATO (or ITO)/PEDOT:PSS/polymer/BaF₂/Ba/Al configurations. Electrical and optical properties of ATO transparent electrode were measured. Transmittance of ATO thin film was more than 90% in the visible region, sheet resistance was 30 Ω/□ and had a strong solvent resistance. The maximum brightness and maximum efficiency of PLED device using an ATO transparent electrode was 3637 cd/m² and 1.03 cd/A, respectively.     

Olfactory Receptor OR7A17 Expression Correlates with All-Trans Retinoic Acid (ATRA)-Induced Suppression of Proliferation in Human Keratinocyte Cells

Olfactory receptors (ORs), which belong to the G-protein-coupled receptor family, have been widely studied as ectopically expressed receptors in various human tissues, including the skin. However, the physiological functions of only a few OR types have been elucidated in skin cells. All-trans retinoic acid (ATRA) is a well-known medication for various skin diseases. However, many studies have shown that ATRA can have adverse effects, resulting from the suppression of cell proliferation. Here, we investigated the involvement of OR7A17 in the ATRA-induced suppression of human keratinocyte (HaCaT) proliferation. We demonstrated that OR7A17 is expressed in HaCaT keratinocytes, and its expression was downregulated by ATRA. The ATRA-induced downregulation of OR7A17 was attenuated via RAR α or RAR γ antagonist treatment, indicating that the effects of ATRA on OR7A17 expression were mediated through nuclear retinoic acid receptor signaling. Moreover, we found that the overexpression of OR7A17 induced the proliferation of HaCaT cells while counteracting the antiproliferative effect of ATRA. Mechanistically, OR7A17 overexpression reversed the ATRA-induced attenuation of Ca²⁺ entry. Our findings indicated that ATRA suppresses cell proliferation through the downregulation of OR7A17 via RAR α- and γ-mediated retinoid signaling. Taken together, OR7A17 is a potential therapeutic target for ameliorating the anti-proliferative effects of ATRA.     

Mechanically stable flat anodic titania membranes for gas transport applications

Anodic titanium oxide (ATO) membranes were produced by two-step anodic oxidation of titanium foil in ethylene glycol electrolyte containing NH₄F at the anodization voltage of 60?V. To provide the mechanical strength necessary for applying tubular anodic films as gas membranes, we utilized the formation of protective continuous TiO₂ layer at the top film surface prior to second anodization. As compared to conventional two-step anodic oxidation this technique decreases dissolution rates of titanium oxide phases with oxidation states lower than +4 (Ti₂O₃, Ti₃O₅), which are forming between titania nanotubes during anodization. The structural parameters of anodic titania films were determined by small-angle X-ray scattering and scanning electron microscopy techniques. According to SEM the proposed method resulted in growth of ATO films with a flat surface without nanotube endings, which enabled to use the films as gas separation membranes. The permeance of individual gases through ATO membranes were found to depend on gas molecular weight (M^?0.5), with absolute values twice exceeding theoretical permeabilities as it was predicted by Knudsen diffusion (up to 63?m³/(m²?×?bar?×?h) for nitrogen at 298?K). Here we ascribe this phenomenon to diffusion according to Knudsen-Smoluchoski mechanism (diffusion with slip, involving specular reflections of molecules), which is appropriate for membranes with straight pores and smooth internal pore surfaces.     

New effective process to fabricate fast switching and high contrast electrochromic device based on viologen and Prussian blue/antimony tin oxide nano-composites with dark colored state

We developed a new electrochromic device by using compact Prussian blue (PB)/antimony tin oxide (ATO) nano-composites as anodic electrode and viologen anchoring on titanium dioxide (TiO₂) nano-particles as cathodic electrode. The anodic electrode was based on a transparent nanostructured ATO nano-particle film and was electro-deposited by Prussian blue to form compact Prussian blue/ATO nano-composites by means of galvanostatic electrodeposition process. Nanocrystalline TiO₂ thin films on conducting glass were modified with a mono-layer of viologen with two anchoring groups, which were much strongly adsorbed onto the surface of TiO₂ nano-particles. A polymer gel electrolyte sandwiched between the anodic and cathodic layers is used as the ionic transport layer. The 2.5 cm × 2.5 cm electrochromic device shows high contrast (64.8%, at 600 nm) very low transmittance at colored stage (0.1%, at 600 nm), fast switching time (600 and 720 ms for coloration and bleaching, respectively), high coloration efficiency of 912 cm² C⁻¹ at 600 nm and good stability. The enhanced performance of the electrochromic device can be attributed to the ATO nano-particles as inter-conductive materials.     

Low-temperature conducting performance of transparent indium tin oxide/antimony tin oxide electrodes

We fabricated transparent indium tin oxide (ITO)/antimony tin oxide (ATO) electrodes using a combined process of spin-coating of hybrid ITO nanoinks, electrospraying of ATO, and hydrogen (H₂) activation carried out at a low annealing temperature of 200 °C. The produced ITO electrode exhibited an enhanced surface densification and phase conversion of In(OH)₃ to ITO. As a result, the H₂-activated ITO/ATO electrodes exhibited excellent transparent conducting performances with a superior sheet resistance of ~47.5 Ω/□ and a good transmittance of ~85.3% as compared to the ITO and ITO/ATO electrodes. Despite the use of the low annealing temperature, the achieved improvement in the conducting performance could be attributed to the synergistic effect of the enhanced carrier concentration and the Hall mobility related to the improved surface densification achieved with the electrosprayed ATO thin film and reduction of the residual In(OH)₃ phase by H₂ activation. Therefore, our method can be used as a novel strategy for obtaining high-performance solution-processed transparent conducting oxides at a low annealing temperature of 200 °C for use in various optoelectronic applications.     

Electrochemically hydrogenated TiO2 nanotubes with improved photoelectrochemical water splitting performance

One-dimensional anodic titanium oxide (ATO) nanotube arrays hold great potential as photoanode for photoelectrochemical (PEC) water splitting. In this work, we report a facile and eco-friendly electrochemical hydrogenation method to modify the electronic and PEC properties of ATO nanotube films. The hydrogenated ATO (ATO-H) electrodes present a significantly improved photocurrent of 0.65 mA/cm² in comparison with that of pristine ATO nanotubes (0.29 mA/cm²) recorded under air mass 1.5 global illumination. The incident photon-to-current efficiency measurement suggests that the enhanced photocurrent of ATO-H nanotubes is mainly ascribed to the improved photoactivity in the UV region. We propose that the electrochemical hydrogenation induced surface oxygen vacancies contribute to the substantially enhanced electrical conductivity and photoactivity.     

Application of hot-melt coating for controlled release of propranolol hydrochloride pellets

Waxes are available in various lyophilicity, and they can be used to regulate the release from multiunit-controlled release pellets. In this study, the application of saturated polyglycolysed glyceride (Gelucire® 50/02) and glycerol palmitostearate (Precirol® ATO5) as drug release regulators for propranolol pellets and the kinetics of release were investigated. Propranolol pellets containing 60% microcrystalline cellulose (Avicel® PH101) were prepared by using direct pelletization technique in a fluidized-bed rotary granulator (Glatt GPCG1). The pellets of 16:18 mesh size were collected and coated with the molten wax(es) at various ratios and thicknesses in a fluidized-bed top spray coater (Glatt GPCG1). The dissolution was determined using test method for Propranolol Extended Release Capsules USP 24 and was found to be very rapid with the uncoated pellets. The dissolution of coated pellet was decreased with the increases in Precirol ATO5 proportion and coating thickness. Plot of log % drug release vs. reciprocal of time showed a good linear relationship. The k value derived from the slope of the plot and designated as a “diffusive resistance constant” linearly increased with the coating level. The findings indicated that drug release could be adjusted by varying the ratio of Precirol® ATO5 to Gelucire® 50/02 as well as the thickness of the coat.     

Effects of Sb-doped SnO2–WO3 nanocomposite on electrochromic performance

With the increase in global challenges related to energy depletion, there is significant emphasis on studies involving next-generation optoelectronic applications such as smart windows and electronic displays. In particular, electrochromic devices (ECDs) have been identified as strategic innovations for energy-saving “smart windows” to address these challenges. Despite this increased level of attentions, ECDs have not yet attained broad commercial acceptance because of their limited electrochromic (EC) properties including coloration efficiency (CE,< 30.0 cm²/C) and switching speeds (> 10.0 s). To address these limitations, critical effort is required to enhance the EC properties by tuning the film structure and electronic structure of ECDs. In this study, we demonstrated the effect of nanocomposite structure of conductive metal oxides and WO₃ EC films. Antimony-doped tin oxide nanoparticles (ATO NPs) were utilized because of their superior electrical conductivity and large band gap. To achieve the optimum addition amount of ATO NPs in EC films, we adjusted the amount as 0, 0.6, 1.2, 2.4 wt%. WO₃ EC films with the optimum addition amount (1.2 wt%) of ATO NPs exhibited improved EC performance including both the switching speeds (5.4 s for the coloration speed and 2.4 s for the bleaching speed) and CE value (48.2 cm²/C). The enhancement of EC performance was attributed to the well-dispersed ATO NPs in the WO₃ films that can effectively improve electrical conductivity via the formation of by forming preferred electron pathway. In addition, the large band gap of ATO NPs broadens the transmittance modulation of the EC layer which contributed to the increment of the CE value. Therefore, our results suggest a strategy to obtain the enhanced WO₃ films with superior EC performances using conductive metal oxides nanocomposite structure.     

Synthesis and characterization of Sb-doped SnO2 with high near-infrared shielding property for energy-efficient windows by a facile dual-titration co-precipitation method

Sb-doped SnO₂ (ATO) powders were favorably synthesized using a dual-titration co-precipitation method for the application of energy-efficient windows. A dual-titration co-precipitation method can effectively inhibit the aggregation of primary nanoparticles, which is conducive to prepare stable dispersion applied to glazing materials for blocking part of solar radiation. Various annealing temperatures, doping molar ratios and ethanol content of precursor solution were used to investigate the influence on the morphology and phase composition of the as-synthesized ATO powders. The results illustrated that the reasonable reaction conditions to prepare ATO powders with near-infrared shielding property should be: the doping molar ratio of 10%, the content of ethanol in precursor solution of 100% and the annealing temperature of 1000 °C. Besides, ATO primary nanoparticles were gained ranging from 45 to 55 nm with a low aggregated degree. The ATO coating prepared by the ATO dispersion with 20 wt% demonstrated the optimal selective transmitted spectra, which simultaneously achieved the average visible transmittance of 80.15% but average near-infrared transmittance of 23.31%. In addition, a simulated experiment demonstrated that ATO coated glass exhibited a better near-infrared shielding property than ITO (Sn-doped In₂O₃) coated glass.     

Nonaqueous and template-free synthesis of Sb doped SnO2 microspheres and their application to lithium-ion battery anode

Antimony doped SnO₂ (ATO) microspheres composed of ATO nanoparticles were prepared by using a hydrothermal process in a nonaqueous and template-free solution from the inorganic precursors (SnCl₄ and Sb(OC₂H₅)₃). The physical properties of the as-synthesized samples were investigated by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption-desorption isotherms, and X-ray photoelectron spectrum (XPS). The resulting particles were highly crystalline ATO microspheres in the diameter range of 3-10 μm and with many pores. The as-prepared samples were used as negative materials for lithium-ion battery, whose charge-discharge properties, cyclic voltammetry, and cycle performance were examined. The results showed that a high initial discharge capacity of 1981 mAh g⁻¹ and a charge capacity of 957 mAh g⁻¹ in a potential range of 0.005-3.0 V was achieved, which suggests that tin oxide-based materials work as high capacity anodes for lithium-ion rechargeable batteries. The cycle performance is improved because the conducting ATO nanoparticles can also perform as a better matrix for lithium-ion battery anode.     

Anodic titanium oxide: A new template for the synthesis of larger diameter multi-walled carbon nanotubes

Carbon nanotubes (CNTs) with larger diameter were synthesized over anodic titanium oxide (ATO) template by CVD method using acetylene as carbon source. The porous titanium oxide was obtained by anodization of titanium metal in a mixture of 1 M H₂SO₄ + 0.5% HF electrolyte at a constant applied potential of 40 V. The XRD analysis of anodized titanium revealed that rutile and anatase forms of TiO₂ are formed due to anodization. Further, SEM analysis was used to follow the development of pores on titanium surface. The TEM analysis revealed that the formed CNTs are straight and hollow with uniform wall thickness as well as larger diameter (70–80 nm). HRTEM study showed that the formed CNTs are multi-walled and their wall thickness is around 2–3 nm. Further, the structural features of the formed CNTs were studied by XRD. Raman spectroscopy was used to study the degree of graphitization of CNTs. The Lewis acid sites of TiO₂ present in the internal surface of the pores play an important role in the catalytic decomposition of acetylene and hence the formation of CNTs. When increasing the carbon deposition time, the wall thickness of CNTs is not increased significantly, indicating that the decomposition of acetylene is due to Lewis acid sites of TiO₂ and not due to thermal decomposition. Further, the morphology of CNTs formed over ATO template was compared with that of CNTs formed on Co electrodeposited ATO. There is no significant difference in morphology as well as wall thickness was observed between the CNTs grown over ATO with and without Co catalyst. But, still further investigations are necessary to study the structural differences between the CNTs grown over ATO with and without Co catalyst.     

Effect of Crystal Size on Acetone Conversion over SAPO-34 Crystals

Abstract  

Catalytic properties of the 75 nm and 0.8 μm-sized SAPO-34 crystals on acetone-to-olefins (ATO) reaction were compared. The 75 nm-sized crystals (nanocrystals) showed longer catalyst lifetime than 0.8 μm-sized crystals, and products selectivity was similar for the two SAPO-34 catalysts, as is the case in methanol-to-olefins (MTO) and dimethyleter-to-olefins (DTO) reactions. The reaction site of ATO reaction over SAPO-34 was studied using coke-deposited SAPO-34 as catalysts whose pores are deactivated through the DTO reaction. The reason for longer catalyst lifetime of the nanocrystals in the ATO reaction must be a large surface area of the SAPO-34 nanocrystals, unlike in the case of the MTO and DTO reactions.