Intravenous pharmacological dose of ascorbate has been proposed as a potential antitumor therapy; however, its therapeutic efficacy is limited due to the slow autoxidation. Here, we report that palladium (Pd) nanocrystals, which possess intrinsic oxidase-like activity, accelerate the autoxidation of ascorbate, leading to the enhancement of its antitumor efficacy. The oxidase-like activity of Pd nanocrystals was facet-dependent, with the concave nanostructure enclosed by high-index facets catalyzing ascorbate autoxidation more efficiently than the planar nanostructure enclosed by low-index facets. Our first-principles calculations provide the underlying molecular mechanisms for the facet-dependent activation of O2 molecule and subsequent ascorbate oxidation. Further in vitro and in vivo assays demonstrate the enhancement of the antitumor efficacy of ascorbate with these Pd concave nanocubes. Our animal experiments also indicate the combined approach with both ascorbate and Pd concave nanocubes displays an even better efficacy than currently available clinical medicines, with no obvious cytotoxicity to normal cells.
Radio‐photoluminescence (RPL) materials display a distinct radiation‐induced permanent luminescence center, and therefore find application in the detection of ionizing radiation. The current inventory of RPL materials, which were discovered by serendipity, has been limited to a small number of metal‐ion‐doped inorganic materials. Here we document the RPL of a metal–organic framework (MOF) for the first time: X‐ray induced free radicals are accumulated on the organic linker and are subsequently stabilized in the conjugated fragment in the structure, while the metal center acts as the X‐ray attenuator. These radicals afford new emission features in both UV‐excited and X‐ray excited luminescence spectra, making it possible to establish linear relationships between the radiation dose and the normalized intensity of the new emission feature. The MOF‐based RPL materials exhibit advantages in terms of the dose detection range, reusability, emission stability, and energy threshold. Based on a comprehensive electronic structure and energy diagram study, the rational design and a substantial expansion of candidate RPL materials can be anticipated.
Heteroatom nitrogen doping is considered an effective strategy to enhance the electromagnetic wave (EMW) absorption capacity of reduced graphene oxide (RGO). Herein, nitrogen‐doped RGO aerogels (NGAs) are synthesized via hydrothermal self‐assembly followed by lyophilization processes. Results of micromorphology analysis show that the as‐prepared NGAs display unique 3D porous and netlike structure. Moreover, the effects of nitrogen doping and filler contents on EMW absorption properties of NGAs are studied. The as‐synthesized NGA with nitrogen content of 9.41 at% and a bulk density of 8.7 mg cm–3 presents the integrated optimal EMW absorption performance. Specifically, the minimum reflection loss of –56.4 dB is achieved and maximum absorption bandwidth of 6.8 GHz is reached, covering the whole Ku band. In addition, the possible EMW absorption mechanisms of obtained NGAs are proposed. Therefore, the as‐synthesized NGAs can be exploited as promising high‐efficiency and lightweight EMW absorbers.
One‐dimensional (1D) porous materials have shown great potential for gas storage and separation, sensing, energy storage, and conversion. However, the controlled approach for preparation of 1D porous materials, especially porous organic materials, still remains a great challenge due to the poor dispersibility and solution processability of the porous materials. Here, carbon nanotube (CNT) templated 1D conjugated microporous polymers (CMPs) are prepared using a layer‐by‐layer method. As‐prepared CMPs possess high specific surface areas of up to 623 m2 g−1 and exhibit strong electronic interactions between p‐type CMPs and n‐type CNTs. The CMPs are used as precursors to produce heteroatom‐doped 1D porous carbons through direct pyrolysis. As‐produced ternary heteroatom‐doped (B/N/S) 1D porous carbons possess high specific surface areas of up to 750 m2 g−1, hierarchical porous structures, and excellent electrochemical‐catalytic performance for oxygen reduction reaction. Both of the diffusion‐limited current density (4.4 mA cm−2) and electron transfer number (n = 3.8) for three‐layered 1D porous carbons are superior to those for random 1D porous carbon. These results demonstrate that layered and core–shell type 1D CMPs and related heteroatom‐doped 1D porous carbons can be rationally designed and controlled prepared for high performance energy‐related applications.
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