RAS proteins play critical roles in various cellular processes, including growth and transformation. RAS proteins are subjected to protein stability regulation via the Wnt/β‐catenin pathway, and ...glycogen synthase kinase 3 beta (GSK3β) is a key player for the phosphorylation‐dependent RAS degradation through proteasomes. GSK3β‐mediated RAS degradation does not occur in cells that express a nondegradable mutant (MT) β‐catenin. Here, we show that β‐catenin directly interacts with RAS at the α‐interface region that contains the GSK3β phosphorylation sites, threonine 144 and threonine 148 residues. Exposure of these sites by prior β‐catenin degradation is required for RAS degradation. The introduction of a peptide that blocks the β‐catenin‐RAS interaction by binding to β‐catenin rescues the GSK3β‐mediated RAS degradation in colorectal cancer (CRC) cells that express MT β‐catenin. The coregulation of β‐catenin and RAS stabilities by the modulation of their interaction provides a mechanism for Wnt/β‐catenin and RAS‐ERK pathway cross‐talk and the synergistic transformation of CRC by both APC and KRAS mutations.
Synopsis
GSK3β promotes phosphorylation‐ and polyubiquitination‐dependent proteasomal RAS degradation. β‐Catenin directly interacts with RAS, thereby preventing GSK3β‐dependent phosphorylation and degradation, defining the basis for the synergistic effect of β‐catenin and RAS on cancer growth.
β‐Catenin directly interacts with RAS at the α‐interface that contains GSK3β phosphorylation sites.
β‐Catenin degradation is required for subsequent GSK3β‐mediated RAS degradation.
Targeting both β‐catenin and RAS for degradation is a potential approach against colorectal cancer.
GSK3β promotes phosphorylation‐ and polyubiquitination‐dependent proteasomal RAS degradation. β‐Catenin directly interacts with RAS, thereby preventing GSK3β‐dependent phosphorylation and degradation, defining the basis for the synergistic effect of β‐catenin and RAS on cancer growth.
Single‐atom catalysts (SACs) have emerged as promising materials in heterogeneous catalysis. Previous studies reported controversial results about the relative level in activity for SACs and ...nanoparticles (NPs). These works have focused on the effect of metal atom arrangement, without considering the oxidation state of the SACs. Here, we immobilized Pt single atoms on defective ceria and controlled the oxidation state of Pt SACs, from highly oxidized (Pt0: 16.6 at %) to highly metallic states (Pt0: 83.8 at %). The Pt SACs with controlled oxidation states were then employed for oxidation of CO, CH4, or NO, and their activities compared with those of Pt NPs. The highly oxidized Pt SACs presented poorer activities than Pt NPs, whereas metallic Pt SACs showed higher activities. The Pt SAC reduced at 300 °C showed the highest activity for all the oxidations. The Pt SACs with controlled oxidation states revealed a crucial missing link between activity and SACs.
The oxidation state of Pt single‐atom catalysts (SACs) was controlled from highly oxidized to highly metallic states by reducing Pt single atoms deposited on defective ceria at various temperatures. The optimum oxidation state of the Pt SAC was found for maximizing the catalytic activity for the oxidation of CO, CH4, and NO.
A high power factor must be achieved to improve the thermoelectric (TE) output of organic TE materials though the tradeoff between electrical conductivity and the Seebeck coefficient is a serious ...obstacle to the further development of these materials. Here, systematic control of the electrostatic interaction between a conducting polymer and a dopant induces a positive deviation from this TE tradeoff relation so that the electrical conductivity and the Seebeck coefficient simultaneously increase. Upon reduction of the electrostatic interaction, substantial changes in the film morphology, chain conformation, and crystalline ordering are observed, all of which critically affect the TE charge transport. As a result, the electrostatic interaction control is found to be an effective strategy to enhance the power factor, overcoming the tradeoff between TE parameters. Adapting this strategy to poly(3,4‐ethylenedioxythiophene):polystyrene‐sulfonate results in a remarkable power factor (=700.2 µW m−1 K−2 ) and figure of merit ZT (=0.25).
The electrostatic interaction in poly(3,4‐ethylenedioxythiophene):polystyrene‐sulfonate (PEDOT:PSS) is systematically controlled by adding small‐molecule anions of different physical properties. This system facilitates effective charge transport and controls the oxidation level of PEDOT:PSS, which enhances the thermoelectric (TE) power factor to 700.2 µW m−1 K−2 by overcoming the TE tradeoff relation between the electrical conductivity and the Seebeck coefficient.
Porous architectures are important in determining the performance of lithium–sulfur batteries (LSBs). Among them, multiscale porous architecutures are highly desired to tackle the limitations of ...single‐sized porous architectures, and to combine the advantages of different pore scales. Although a few carbonaceous materials with multiscale porosity are employed in LSBs, their nonpolar surface properties cause the severe dissolution of lithium polysulfides (LiPSs). In this context, multiscale porous structure design of noncarbonaceous materials is highly required, but has not been exploited in LSBs yet because of the absence of a facile method to control the multiscale porous inorganic materials. Here, a hierarchically porous titanium nitride (h‐TiN) is reported as a multifunctional sulfur host, integrating the advantages of multiscale porous architectures with intrinsic surface properties of TiN to achieve high‐rate and long‐life LSBs. The macropores accommodate the high amount of sulfur, facilitate the electrolyte penetration and transportation of Li+ ions, while the mesopores effectively prevent the LiPS dissolution. TiN strongly adsorbs LiPS, mitigates the shuttle effect, and promotes the redox kinetics. Therefore, h‐TiN/S shows a reversible capacity of 557 mA h g−1 even after 1000 cycles at 5 C rate with only 0.016% of capacity decay per cycle.
A noncarbonaceous material (titanium nitride (TiN)) with a well‐defined multiscale porous architecture is easily developed by multiscale phase separation and applied as a sulfur host for lithium–sulfur batteries. The synergistic effect between the unique porous architecture and the surface chemical properties of TiN enables ultrastable, high‐rate lithium–sulfur batteries.
Nanomaterials-based biomimetic catalysts with multiple functions are necessary to address challenges in artificial enzymes mimicking physiological processes. Here we report a metal-free nanozyme of ...modified graphitic carbon nitride and demonstrate its bifunctional enzyme-mimicking roles. With oxidase mimicking, hydrogen peroxide is generated from the coupled photocatalysis of glucose oxidation and dioxygen reduction under visible-light irradiation with a near 100% apparent quantum efficiency. Then, the in situ generated hydrogen peroxide serves for the subsequent peroxidase-mimicking reaction that oxidises a chromogenic substrate on the same catalysts in dark to complete the bifunctional oxidase-peroxidase for biomimetic detection of glucose. The bifunctional cascade catalysis is successfully demonstrated in microfluidics for the real-time colorimetric detection of glucose with a low detection limit of 0.8 μM within 30 s. The artificial nanozymes with physiological functions provide the feasible strategies for mimicking the natural enzymes and realizing the biomedical diagnostics with a smart and miniature device.
Single‐atom catalysts (SACs) have attracted growing attention because they maximize the number of active sites, with unpredictable catalytic activity. Despite numerous studies on SACs, there is ...little research on the support, which is essential to understanding SAC. Herein, we systematically investigated the influence of the support on the performance of the SAC by comparing with single‐atom Pt supported on carbon (Pt SA/C) and Pt nanoparticles supported on WO3−x (Pt NP/WO3−x). The results revealed that the support effect was maximized for atomically dispersed Pt supported on WO3−x (Pt SA/WO3−x). The Pt SA/WO3−x exhibited a higher degree of hydrogen spillover from Pt atoms to WO3−x at the interface, compared with Pt NP/WO3−x, which drastically enhanced Pt mass activity for hydrogen evolution (up to 10 times). This strategy provides a new framework for enhancing catalytic activity for HER, by reducing noble metal usage in the field of SACs.
The influence of the support on the performance of a single‐atom catalyst was investigated by comparing single‐atom Pt supported on carbon and Pt nanoparticles supported on WO3−x (Pt NP/WO3−x). The support effect is maximized for single‐atom Pt on WO3−x, which drastically enhances the Pt mass activity for the hydrogen evolution reaction compared with Pt NP/WO3−x and Pt/C.
Utilizing electricity and heat from renewable energy to convert small molecules into value‐added chemicals through electro/thermal catalytic processes has enormous socioeconomic and environmental ...benefits. However, the lack of catalysts with high activity, good long‐term stability, and low cost strongly inhibits the practical implementation of these processes. Oxides with exsolved metal nanoparticles have recently been emerging as promising catalysts with outstanding activity and stability for the conversion of small molecules, which provides new possibilities for application of the processes. In this review, it starts with an introduction on the mechanism of exsolution, discussing representative exsolution materials, the impacts of intrinsic material properties and external environmental conditions on the exsolution behavior, and the driving forces for exsolution. The performances of exsolution materials in various reactions, such as alkane reforming reaction, carbon monoxide oxidation, carbon dioxide utilization, high temperature steam electrolysis, and low temperature electrocatalysis, are then summarized. Finally, the challenges and future perspectives for the development of exsolution materials as high‐performance catalysts are discussed.
Oxides with exsolved metal nanoparticles have recently been emerging as promising catalysts with outstanding activity and stability for the conversion of small molecules. This review introduces the mechanism of exsolution and summarizes the performances of exsolution materials in reactions including alkane reforming reaction, carbon monoxide oxidation, carbon dioxide utilization, high temperature steam electrolysis, and low temperature electrocatalysis.
A new type of cellular material named Shellular, in which cells are composed of a continuous, smooth‐curved shell according to the minimal surface theory, is proposed. Shellular specimens are ...fabricated using 3D lithography with negative templates and hard coating, and exhibit superb strength and stiffness at densities lower than 10−2 Mg m−3, incorporating benefits from hierarchical structures and constituent materials with nanosized grains.
Surface cation segregation and phase separation, of strontium in particular, have been suggested to be the key reason behind the chemical instability of perovskite oxide surfaces and the ...corresponding performance degradation of solid oxide electrochemical cell electrodes. However, there is no well-established solution for effectively suppressing Sr-related surface instabilities. Here, we control the degree of Sr-excess at the surface of SrTi 0.5 Fe 0.5 O 3−δ thin films, a model mixed conducting perovskite O 2 -electrode, through lattice strain, which significantly improves the electrode surface reactivity. Combined theoretical and experimental analyses reveal that Sr cations are intrinsically under a compressive state in the SrTi 0.5 Fe 0.5 O 3−δ lattice and that the Sr–O bonds are weakened by the local pressure around the Sr cation, which is the key origin of surface Sr enrichment. Based on these findings, we successfully demonstrate that when a large-sized isovalent dopant is added, Sr-excess can be remarkably alleviated, improving the chemical stability of the resulting perovskite O 2 -electrodes.
Exsolution has been intensively studied in the fields of energy conversion and storage as a method for the preparation of catalytically active and durable metal nanoparticles. Under typical ...conditions, however, only a limited number of nanoparticles can be exsolved from the host oxides. Herein, we report the preparation of catalytic nanoparticles by selective exsolution through topotactic ion exchange, where deposited Fe guest cations can be exchanged with Co host cations in PrBaMn
Co
O
. Interestingly, this phenomenon spontaneously yields the host PrBaMn
Fe
O
, liberating all the Co cations from the host owing to the favorable incorporation energy of Fe into the lattice of the parent host (ΔE
= -0.41 eV) and the cation exchange energy (ΔE
= -0.34 eV). Remarkably, the increase in the number of exsolved nanoparticles leads to their improved catalytic activity as a solid oxide fuel cell electrode and in the dry reforming of methane.
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