Radiolytic Water Splitting Sensitized by Nanoscale Metal-Organic Frameworks

Hafnium Metal-Organic Framework-Based Glutamine Metabolism Disruptor For Potentiating Radio-Immunotherapy in MYC-Amplified Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) with MYC oncogene amplification remains a serious challenge in clinical practice. Recent advances in comprehensive treatment strategies, particularly the combination of radiotherapy and immunotherapy, offer new hope. To further improve efficacy while lowering radiation doses, nanopharmaceuticals based on high-Z elements have been extensively studied in radio-immunotherapy. In this work, a hafnium-based metal-organic framework (Hf-MOF), UiO-66-Hf(2OH)-CB-839/BSO@HA (UiO-66-Hf(2OH)-C/B@HA), was designed to codeliver telaglenastat (CB-839) and buthionine sulfoximine (BSO), which synergistically inhibited glutamine metabolism and alleviated tumor hypoxia. Further modification with hyaluronic acid (HA) enhanced tumor targeting, ultimately strengthening the efficacy of radiotherapy in MYC-amplified HCC. Beyond increasing reactive oxygen species (ROS) generation, promoting DNA damage, and inducing tumor apoptosis, more importantly, UiO66-Hf(2OH)-C/B@HA triggered immunogenic cell death (ICD), driving the antitumor immune response. Combination with immune checkpoint blockade (ICB) further enhanced the efficacy, accompanied by increased infiltration of T cells with high granzyme B expression (GZMB+ T cells) within the tumor microenvironment (TME). In the orthotopic HCC model, established with MYC-amplified tumor cells, intravenous administration of UiO66-Hf(2OH)-C/B@HA significantly potentiated the efficacy of radio-immunotherapy, resulting in superior tumor regression. In summary, our study provides insights into the design of Hf-MOF for radio-immunotherapy and proposes a promising therapeutic approach for MYC-amplified HCC.

Symmetry Breaking in Rationally Designed Copper Oxide Electrocatalyst Boosts the Oxygen Reduction Reaction

Oxygen reduction reaction (ORR) kinetics is critically dependent on the precise modulation of the interactions between the key oxygen intermediates and catalytic active sites. Herein, a novel electrocatalyst is reported, featuring nitrogen-doped carbon-supported ultra-small copper oxide nanoparticles with the broken-symmetry C4v coordination filed sites, achieved by a mild γ-ray radiation-induced method. The as-synthesized catalyst exhibits an excellent ORR activity with a half-wave potential of 0.873 V and shows no obvious decay over 50 h durability in alkaline solution. This superior catalytic activity is further corroborated by the high-performance in both primary and rechargeable Zn-air batteries with an ultrahigh-peak-power density (255.4 mW cm-2) and robust cycling stability. The experimental characterizations and density functional theory calculations show that the surface Cu atoms are configured in a compressed octahedron coordination. This geometric arrangement interacts with the key intermediate OH*, facilitating localized charge transfer and thereby weakening the Cu─O bond, which promotes the efficient transformation of OH* to OH- and the subsequent desorption, and markedly accelerates kinetics of the rate-determining step in the reaction. This study provides new insights for developing the utilization of γ-ray radiation chemistry to construct high-performance metal oxide-based catalysts with broken symmetry toward ORR.

Radiation-induced aerobic oxidation via solvent-derived peroxyl radicals

Oxidation is a fundamental transformation in synthesis. Developing facile and effective aerobic oxidation processes under ambient conditions is always in high demand. Benefiting from its high energy and good penetrability, ionizing radiation can readily produce various reactive species to trigger chemical reactions, offering another option for synthesis. Here, we report an ionizing radiation-induced aerobic oxidation strategy to synthesize oxygen-containing compounds. We discovered that molecular oxygen (O2) could be activated by reactive particles generated from solvent radiolysis to produce solvent-derived peroxyl radicals (RsolOO·), which facilitated the selective oxidation of sulfides and phosphorus(iii) compounds at room temperature without catalysts. Density functional theory (DFT) calculations further revealed that multiple RsolOO· enable the oxidation reaction through an oxygen atom transfer process. This aerobic oxidation strategy broadens the research scope of radiation-induced chemical transformations while offering an opportunity to convert nuclear energy into chemical energy.

Radiocatalytic ammonia synthesis from nitrogen and water

The development of alternative methods to the Haber-Bosch process for ammonia (NH3) synthesis is a pressing and formidable challenge. Nuclear energy represents a low-carbon, efficient and stable source of power. The harnessing of nuclear energy to drive nitrogen (N2) reduction not only allows 'green' NH3 synthesis, but also offers the potential for the storage of nuclear energy as a readily transportable zero-carbon fuel. Herein, we explore radiocatalytic N2 fixation to NH3 induced by γ-ray radiation. Hydrated electrons (e- aq) that are generated from water radiolysis enable N2 reduction to produce NH3. Ru-based catalysts synthesized by using γ-ray radiation with excellent radiation stability substantially improve NH3 production in which the B5 sites of Ru particles may play an important role in the activation of N2. By benefitting from the remarkable penetrating power of γ-ray radiation, radiocatalytic NH3 synthesis can proceed in an autoclave under appropriate pressure conditions, resulting in an NH3 concentration of ≤5.1 mM. The energy conversion efficiency of the reaction is as high as 563.7 mgNH3·MJ-1. This radiocatalytic chemistry broadens the research scope of catalytic N2 fixation while offering promising opportunities for converting nuclear energy into chemical energy.

Radiocatalytic Synthesis of Acetic Acid from CH4 and CO2

The C-C coupling of methane (CH4) and carbon dioxide (CO2) to generate acetic acid (CH3COOH) represents a highly atom-efficient chemical conversion, fostering the comprehensive utilization of greenhouse gases. However, the inherent thermodynamic stability and kinetic inertness of CH4 and CO2 present obstacles to achieving efficient and selective conversion at room temperature. Our study reveals that hydroxyl radicals (⋅OH) and hydrated electrons (eaq -) produced by water radiolysis can effectively activate CH4 and CO2, yielding methyl radicals (⋅CH3) and carbon dioxide radical anions(⋅CO2 -) that facilitate the production of CH3COOH at ambient temperature. The introduction of radiation-synthesized CuO-anchored TiO2 bifunctional catalyst could further enhance reaction efficiency and selectivity remarkably by boosting radiation absorption and radical stability, resulting in a concentration of 7.1 mmol ⋅ L-1 of CH3COOH with near-unity selectivity (>95 %). These findings offer valuable insights for catalyst design and implementation in radiation-induced chemical conversion.

Water Radiocatalysis for Selective Aqueous-Phase Methane Carboxylation with Carbon Dioxide into Acetic Acid at Room Temperature

Methane (CH4) carboxylation with carbon dioxide (CO2) into acetic acid (CH3COOH) is an ideal chemical reaction to utilize both greenhouse gases with 100% atom efficiency but remains a great challenge under mild conditions. Herein, we introduce a concept of water (H2O) radiocatalysis for efficient and selective aqueous-phase CH4 carboxylation with CO2 into CH3COOH at room temperature. H2O radiolysis occurs under γ-ray radiation to produce ·OH radicals and hydrated electrons that efficiently react with CH4 and CO2, respectively, to produce ·CH3 radicals and ·CO2- species facilely coupling to produce CH3COOH. CH3COOH selectivity as high as 96.9 and 96.6% calculated respectively from CH4 and CO2 and a CH3COOH production rate of as high as 121.9 μmol·h-1 are acquired. The water radiocatalysis driven by γ-rays is also applicable to selectively produce organic acids from other hydrocarbons and CO2.

Ambient γ-Rays-Mediated Noble-Metal Deposition on Defect-Rich Manganese Oxide for Glycerol-Assisted H2 Evolution at Industrial-Level Current Density

Developing novel synthesis technologies is crucial to expanding bifunctional electrocatalysts for energy-saving hydrogen production. Herein, we report an ambient and controllable γ-ray radiation reduction to synthesize a series of noble metal nanoparticles anchored on defect-rich manganese oxides (M@MnO2-x , M=Ru, Pt, Pd, Ir) for glycerol-assisted H2 evolution. Benefiting from the strong penetrability of γ-rays, nanoparticles and defect supports are formed simultaneously and bridged by metal-oxygen bonds, guaranteeing structural stability and active site exposure. The special Ru-O-Mn bonds activate the Ru and Mn sites in Ru@MnO2-x through strong interfacial coordination, driving glycerol electrolysis at low overpotential. Furthermore, only a low cell voltage of 1.68 V is required to achieve 0.5 A cm-2 in a continuous-flow electrolyzer system along with excellent stability. In situ spectroscopic analysis reveals that the strong interfacial coordination in Ru@MnO2-x balances the competitive adsorption of glycerol and OH* on the catalyst surface. Theoretical calculations further demonstrate that the defect-rich MnO2 support promotes the dissociation of H2 O, while the defect-regulated Ru sites promote deprotonation and hydrogen desorption, synergistically enhancing glycerol-assisted hydrogen production.

Direct time-resolved observation of surface-bound carbon dioxide radical anions on metallic nanocatalysts

Time-resolved identification of surface-bound intermediates on metallic nanocatalysts is imperative to develop an accurate understanding of the elementary steps of CO2 reduction. Direct observation on initial electron transfer to CO2 to form surface-bound CO2•- radicals is lacking due to the technical challenges. Here, we use picosecond pulse radiolysis to generate CO2•- via aqueous electron attachment and observe the stabilization processes toward well-defined nanoscale metallic sites. The time-resolved method combined with molecular simulations identifies surface-bound intermediates with characteristic transient absorption bands and distinct kinetics from nanosecond to the second timescale for three typical metallic nanocatalysts: Cu, Au, and Ni. The interfacial interactions are further investigated by varying the important factors, such as catalyst size and the presence of cation in the electrolyte. This work highlights fundamental ultrafast spectroscopy to clarify the critical initial step in the CO2 catalytic reduction mechanism.

A Multifunctional Covalent Organic Framework Nanozyme for Promoting Ferroptotic Radiotherapy against Esophageal Cancer

Radiotherapy is inevitably accompanied by some degree of radiation resistance, which leads to local recurrence and even therapeutic failure. To overcome this limitation, herein, we report the room-temperature synthesis of an iodine- and ferrocene-loaded covalent organic framework (COF) nanozyme, termed TADI-COF-Fc, for the enhancement of radiotherapeutic efficacy in the treatment of radioresistant esophageal cancer. The iodine atoms on the COF framework not only exerted a direct effect on radiotherapy, increasing its efficacy by increasing X-ray absorption, but also promoted the radiolysis of water, which increased the production of reactive oxygen species (ROS). In addition, the ferrocene surface decoration disrupted redox homeostasis by increasing the levels of hydroxyl and lipid peroxide radicals and depleting intracellular antioxidants. Both in vitro and in vivo experiments substantiated the excellent radiotherapeutic response of TADI-COF-Fc. This study demonstrates the potential of COF-based multinanozymes as radiosensitizers and suggests a possible treatment integration strategy for combination oncotherapy.

Selective CO2 reduction to CH3OH over atomic dual-metal sites embedded in a metal-organic framework with high-energy radiation

The efficient use of renewable X/γ-rays or accelerated electrons for chemical transformation of CO2 and water to fuels holds promise for a carbon-neutral economy; however, such processes are challenging to implement and require the assistance of catalysts capable of sensitizing secondary electron scattering and providing active metal sites to bind intermediates. Here we show atomic Cu-Ni dual-metal sites embedded in a metal-organic framework enable efficient and selective CH3OH production (~98%) over multiple irradiated cycles. The usage of practical electron-beam irradiation (200 keV; 40 kGy min-1) with a cost-effective hydroxyl radical scavenger promotes CH3OH production rate to 0.27 mmol g-1 min-1. Moreover, time-resolved experiments with calculations reveal the direct generation of CO2•‒ radical anions via aqueous electrons attachment occurred on nanosecond timescale, and cascade hydrogenation steps. Our study highlights a radiolytic route to produce CH3OH with CO2 feedstock and introduces a desirable atomic structure to improve performance.