A 3,2-Hydroxypyridinone-based Decorporation Agent that Removes Uranium from Bones In Vivo

Lacunary Selenotungstate Serves as a Therapeutic Agent for Uranium Intake

The internal contamination of uranium poses severe health risks to both professionals and the public in case of nuclear accidents due to its chemo- and radiotoxicity. Although chelation therapy has been considered the only practical treatment in emergencies, current clinical chelators show only limited efficacy for uranium. Herein, a recently designed lacunary selenotungstate polyoxometalate (Se6W45) was demonstrated as an effective therapeutic agent. In this construct, the open site in Se6W45 provides a suitable uranium binding environment, resulting in the selective removal of uranium from kidneys (85.87%) and femurs (39.81%) with an extremely low ligand/metal ratio of only 4:1. The redox active sites in Se6W45, primarily the incorporated selenium, were able to reduce the intracellular reactive oxygen species (ROS) to normal levels in NRK-52E cells exposed to uranium. This approach overcomes the disadvantages of the excessive use of current chelating ligands in the range from 100- to 1000-folds, avoiding the consequential depletion of heterogeneous cations, dysfunction of proteins, and/or acid-base imbalance. More importantly, it provides a synergistic antidotal therapy for uranium in reducing radiation damage and chemical toxicity.

COF-Derived Carbon Materials: Synthesis Strategies and Emerging Applications

Covalent organic framework (COF)-derived carbon materials seamlessly inherit the periodic porous architecture and high specific surface area of their precursors, while simultaneously enabling the confinement of nanoparticles in designated regions. This unique feature mitigates agglomeration, enhances intrinsic properties, and imparts novel functionalities to the resulting materials. Consequently, COF-derived carbon materials have garnered significant attention across diverse fields, including energy, environmental remediation, and biomedical applications. Despite this burgeoning interest, a comprehensive review encompassing the synthesis, classification, and multifaceted applications of these materials remains scarce. In this context, the state-of-the-art advancements in COF-derived carbon materials are reviewed systematically here. It categorizes the materials, delineates their primary synthesis strategies, and highlights their versatile applications in catalysis, electrochemical energy storage, water treatment, sensing, and cancer therapy. Lastly, fresh insights into the challenges and future prospects of COF-derived carbon materials, paving the way for their expanded exploration and utilization are offered here.

Efficient uranium(VI) recovery from fluorinated wastewater via deferiprone ligand complexation

Extracting uranium (U(VI)) from fluoride-rich radioactive wastewater is of great significance for the development of nuclear energy and environmental remediation. The presence of thermodynamically stable [UO2Fn]2-n (n = 0, 1, 2, 3, 4) aqueous complexes in fluoride-rich U(VI)-containing wastewater significantly hinders the efficiency of uranyl extraction and recovery using conventional methods. In this study, we report a direct precipitation method using deferiprone ligands for efficient uranyl extraction from fluoride-rich wastewater that offsets the preparation of solid materials. The deferiprone ligands exhibited exceptional chelating ability competing toward F-. In simulated 2.1 × 10-4 mol/L U(VI) wastewater with F- concentrations ranging from 1 to 10 g/L, adjusting the amount of deferiprone ligands enabled a high U(Ⅵ) precipitation rate of 97.60 % to 86.90 %, correspondingly. A remarkable 99.71 % recovery of U(Ⅵ) from real fluoride-rich alkaline wastewater was achieved within 2 h. Detailed investigations revealed that the competitive chelating by deferiprone ligands results in the formation of insoluble U(VI)-deferiprone complexes ([(UO2)(H2O)(C7NO2H8)2]·4H2O), driven by π-π stacking interactions, electrostatic attractions, and intermolecular hydrogen bonds. Given the cost-efficiency and excellent radiation resistance of deferiprone ligands, this efficient and straightforward precipitation approach holds great promise for practical applications in U(VI) remediation and resource recovery from fluoride-rich wastewater.

MSC-EXs inhibits uranium nephrotoxicity by competitively binding key proteins and inhibiting ROS production

Uranium poisoning, particularly from exposure to Depleted Uranium (DU), occurs when uranyl ions enter the bloodstream and bind primarily to transferrin, osteopontin, and albumin before entering cells via corresponding receptors on renal tubular membranes, leading to cellular damage. Uranium poisoning remains a significant clinical challenge, with no ideal treatment currently available. In this study, we investigate the therapeutic potential of human umbilical cord-derived mesenchymal stem cell exosomes (MSC-EXs) in mice exposed to DU. Our results showed that MSC-EXs could ameliorate renal damage and enhance kidney and bone marrow morphology but also effectively promote uranium excretion while reducing internal retention. Notably, the protective effects of MSC-EXs exceed those of MSCs and are comparable to those of sodium bicarbonate, as confirmed by various analytical techniques. Proteomic studies have shown that MSC-EXs reduce uranyl ion deposition in renal tubule cells through competitive binding with transferrin, osteopontin, and albumin. They also enhance oxidative stress resistance via modulation of glutathione metabolism, Cysteine and Methionine metabolism signaling pathways. This regulation leads to a reduction in mitochondrial ROS production, alleviates lipid peroxidation, and consequently decreases cellular apoptosis and ferroptosis. This study identifies MSC-EXs as a novel therapeutic strategy against depleted uranium poisoning, presenting potential advancements in treatment methodologies.

pH-dependent cadmium binding to hemoglobin: Implications for human excretion

Half-life of cadmium (Cd) in blood is around 3-4 months, which is much shorter than its half-life in human organs (30 years). Promoting the elimination of Cd from the blood is a crucial step in reducing the body's Cd burden. However, there is currently no effective method available to facilitate this process. In this study, we found that almost all (>98 %) of the Cd in blood samples from occupationally exposed workers was concentrated in blood cells. Hemoglobin (Hb) was identified as the primary Cd-binding protein within these cells. Further investigation revealed that pH, a key regulator of metabolic processes in the blood, played a crucial role in altering the binding capacity of Cd to Hb. We observed that as pH decreased, the binding capacity and the number of available binding sites for Cd on Hb significantly diminished. Cellular experiments confirmed that lower pH can promote the release of Cd from blood cells, facilitating its transfer into the serum. These findings suggested that manipulating blood pH could enhance the rate of Cd excretion from the body, offering a potential strategy for reducing Cd burden.

Preparation and Evaluation of a Combination of Chelating Agents for the Removal of Inhaled Uranium

Inhalation of aerosolized uranium is recognized as a principal mode of exposure, posing significant risks of damage to the lungs, kidneys, and other vital organs. To enhance nuclide elimination from the body, chelating agents are employed; however, single-component chelators often exhibit limited spectral activity and low effectiveness, resulting in toxicologically relevant concentrations. We have developed a composite chelating agent composed of 3,4,3-Li(1,2-HOPO), DFP, and HEDP in optimized ratios, demonstrating marked improvements in eliminating inhaled uranium. The selection of these components was initially guided by an agarose gel dynamics method, focusing on uranium binding and removal efficacy. Optimization of the formula was conducted through response surface methodology in a cellular model. The compound's ability to enhance survival rates in mice subjected to acute uranium inhalation was confirmed, showing a dose-dependent improvement in survival in severely affected mice. Comparative assessments indicated that this multifaceted chelating agent substantially surpasses the uranium tissue clearance achieved by individual chelating agents.

Coordination-Induced Magnetism Strategy for Highly Selective and Efficient Uranium Separation

Highly efficient separation of dispersed uranium is important for the sustainable development of nuclear industry, and adsorption is the most recognized approach. However, there are many coexisting interfering metal ions that compete with uranyl ion for the chelating ligands in the adsorbents and lead to low separation selectivity and efficiency. Herein, a coordination-induced magnetism strategy is presented for the separation of uranium based on the conversion of diamagnetic cyanoferrocene (Fc-CN) nanocrystals to uranium-containing magnetic recoverable ferromagnetic aggregates. Different from previous adsorption strategies, this strategy combines the mechanisms of photocatalytic uranium enrichment and chemical uranium adsorption. Under light irradiation, electron of Fe(II) in Fc-CN is excited and transfers to uranyl ion via the cyano group to form tight coordination bond between N atom in cyano group and uranium. This phenomenon is unique for uranyl ion, and thus, a high uranium removal rate of 97.98% is achieved in simulated nuclear wastewater with the presence of tremendous interfering ions, proving its highly selective and efficient uranium separation performance. The ability to form highly stable magnetic aggregates via photoinduced interaction between Fc-CN and uranium enriches the understanding on the chemical properties of Fc-CN and uranium.

Enhanced thorium decorporation and mitigation of toxicity through combined use of Liv52® and diethylenetriamine pentaacetate

Thorium-232 (Th-232) is a promising fuel for advanced nuclear reactors. However, in case of internal human exposure to Th, there is currently no effective modality for its removal from liver and skeleton or for mitigating its effect. The FDA-approved agent, diethylenetriaminepentaacetate (DTPA), can remove Th and other actinides from blood circulation only. For the first time, a rationally-selected polyherbal hepatoprotective i.e. Liv52® (L52S), was evaluated in-combination with DTPA for its Th decorporation ability in Swiss mice. Inductively-coupled plasma mass spectroscopic analysis showed that oral administration of L52S in conjunction with DTPA significantly decreased Th burden from liver (20 %) and skeleton (33 %) as well as enhanced Th excretion (∼2.5 folds) through urine in comparison to DTPA or L52S alone. The combinatorial therapy was found to be complementary in-action, ameliorating Th-induced tissue damage in liver, spleen, and bone more effectively than monotherapy. Furthermore, markers of liver function (alanine transaminase) and liver inflammation and fibrosis (NF-κB & keratin) further validated the beneficial effect of L52S. The human consumption of L52S for various liver disorders further supports its clinical application for Th decorporation and mitigation of its health effects.

A Remarkable Strategy to Hijack U(VI) from Mixed Metal Ion Solutions Using 1-Hydroxy-2-pyridone

The present work envisages a chelation driven, facile, selective, and rapid method for uranium(VI) separation from a (U, Th) mixture using 1-hydroxy-2-pyridone (1,2-HOPO). Herein, U(VI) was selectively precipitated as the neutral [UO2(HOPO)2(H2O)]·nH2O (orange colored) complex while Th(IV) and other metal ions remained in the solution. The pH of the medium played a key role in facilitating the separation process.

A new in vitro uranium sequestration assay to analyze the effectiveness of 3,4,3-LI(1,2-HOPO) in reducing the harmful effects of this actinide on bone cells

Environmental or occupational exposure to natural uranium can have adverse health effects, with its chemical toxicity being mainly directed towards the kidneys and skeleton. This has led to the development of chelating agents to remove uranium from the human body, including the ligand 3,4,3-LI(1,2-HOPO). We have developed a new in vitro assay to assess the efficacy of 3,4,3-LI(1,2-HOPO) in attenuating uranium-induced bone cell damage. This approach uses osteoclasts whose formation and function are altered by exposure to uranium. This assay is an interesting and effective alternative to animal methods for assessing the efficacy and safety of new uranium decorporants.

Natural Products of Licorice for Uranium Decorporation with Low Toxicity and High Efficiency

The development and exploration of uranium decorporation agents with straightforward synthesis, high removal ability, and low toxicity are crucial guarantees for the safety of workers in the nuclear industry and the public. Herein, we report the use of traditional Chinese medicine licorice for uranium decorporation. Licorice has good adsorption performance and excellent selectivity for uranium in the simulated human environment. Glycyrrhizic acid (GL) has a high affinity for uranium (p(UO2) = 13.67) and will complex with uranium at the carbonyl site. Both licorice and GL exhibit lower cytotoxicity compared to the commercial clinical decorporation agent diethylenetriamine pentaacetate sodium salts (CaNa3-DTPA). Notably, at the cellular level, the uranium removal efficiency of GL is eight times higher than that of CaNa3-DTPA. Administration of GL by prophylactic intraperitoneal injection demonstrates that its uranium removal efficiency from kidneys and bones is 55.2 and 23.9%, while CaNa3-DTPA shows an insignificant effect. The density functional theory calculation of the bonding energy between GL and uranium demonstrates that GL exhibits a higher binding affinity (-2.01 vs -1.15 eV) to uranium compared to DTPA. These findings support the potential of licorice and its active ingredient, GL, as promising candidates for uranium decorporation agents.

Ultrafast Removal of Thorium and Uranium from Radioactive Waste and Groundwater Using Highly Efficient and Radiation-Resistant Functionalized Triptycene-Based Porous Organic Polymers

Thorium (Th) and uranium (U) are important strategic resources in nuclear energy-based heavy industries such as energy and defense sectors that also generate significant radioactive waste in the process. The management of nuclear waste is therefore of paramount importance. Contamination of groundwater/surface water by Th/U is increasing at an alarming rate in certain geographical locations. This necessitates the development of strategic adsorbent materials with improved performance for capturing Th/U species from radioactive waste and groundwater. This report describes the design of a unique, robust, and radiation-resistant porous organic polymer (POP: TP-POP-SO3NH4), which demonstrates ultrafast removal of Th(IV) (<30 s)/U(VI) (<60 s) species present in simulated radioactive wastewater/groundwater samples. Thermal, chemical, and radiation stabilities of these POPs were studied in detail. The synthesized ammoniated POP revealed exceptional capture efficiency for trace-level Th (<4 ppb) and U (<3 ppb) metal ions through the cation-exchange mechanism. TP-POP-SO3NH4 shows a significant sorption capacity [Th (787 mg/g) and U (854 mg/g)] with an exceptionally high distribution coefficient (Kd) of 107 mL/g for Th. This work also demonstrates a facile protocol to convert a nonperforming POP, by simple chemical modifications, into a superfast adsorbent for efficient uptake/removal of U/Th.

Cinnamic Acid: A Low-Toxicity Natural Bidentate Ligand for Uranium Decorporation

Uranium accumulation in the kidneys and bones following internal contamination results in severe damage, emphasizing the pressing need for the discovery of actinide decorporation agents with efficient removal of uranium and low toxicity. In this work, cinnamic acid (3-phenyl-2-propenoic acid, CD), a natural aromatic carboxylic acid, is investigated as a potential uranium decorporation ligand. CD demonstrates markedly lower cytotoxicity than that of diethylenetriaminepentaacetic acid (DTPA), an actinide decorporation agent approved by the FDA, and effectively removes approximately 44.5% of uranyl from NRK-52E cells. More importantly, the results of the prompt administration of the CD solution remove 48.2 and 27.3% of uranyl from the kidneys and femurs of mice, respectively. Assessments of serum renal function reveal the potential of CD to ameliorate uranyl-induced renal injury. Furthermore, the single crystal of CD and uranyl compound (C9H7O2)2·UO2 (denoted as UO2-CD) reveals the formation of uranyl dimers as secondary building units. Thermodynamic analysis of the solution shows that CD coordinates with uranyl to form a 2:1 molar ratio complex at a physiological pH of 7.4. Density functional theory (DFT) calculations further show that CD exhibits a significant 7-fold heightened affinity for uranyl binding in comparison to DTPA.

Enhancing radioprotection: A chitosan-based chelating polymer is a versatile radioprotective agent for prophylactic and therapeutic interventions against radionuclide contamination

To mitigate the risk of radioactive isotope dissemination, the development of preventative and curative measures is of particular interest. For mass treatment, the developed solution must be easily administered, preferably orally, with effective, nontoxic decorporating properties against a wide range of radioactive isotopes. Currently, most orally administered chelation therapy products are quickly absorbed into the blood circulation, where chelation of the radioactive isotope is a race against time due to the short circulation half-life of the therapeutic. This report presents an alternative therapeutic approach by using a functionalized chitosan (chitosan@DOTAGA) with chelating properties that remains within the gastrointestinal tract and is eliminated in feces, that can protect against ingested radioactive isotopes. The polymer shows important in vitro chelation properties towards different metallic cations of importance, including (Cs(I), Ir(III), Th(IV), Tl(I), Sr(II), U(VI) and Co(II)), at different pH (from 1 to 7) representing the different environments in the gastrointestinal tract. An in vivo proof of concept is presented on a rodent model of uranium contamination following an oral administration of Chitosan@DOTAGA. The polymer partially prevents the accumulation of uranium within the kidneys (providing a protective effect) and completely prevents its uptake by the spleen.

Synthesis and crystal structures of bis-[1-oxopyridin-2-olato(1-)]bis-(penta-fluoro-phen-yl)silicon(IV)-tetra-hydro-furan-pentane (2/1/1), bis-[1-oxopyridin-2-olato(1-)]bis-(p-tol-yl)silicon(IV), and dimesitylbis[1-oxopyridin-2-olato(1-)]silicon(IV)

The neutral organosilicon(IV) complex, (C6F5)2Si(OPO)2 (OPO = 1-oxopyridin-2-one, C5H4NO2), was synthesized from (C6F5)2Si(OCH3)2 and 2 equiv. of 1-hy-droxy-pyridin-2-one in tetra-hydro-furan (THF). Single crystals grown from the diffusion of n-pentane into a THF solution were identified as a THF hemisolvate and an n-pentane hemisolvate, (C6F5)2Si(OPO)2·0.5THF·0.5C5H12 (1). p-Tol-yl2Si(OPO)2 (2) and mesit-yl2Si(OPO)2 (3) crystallized directly from reaction mixtures of 2 equiv. of Me3Si(OPO) with p-tol-yl2SiCl2 and mesit-yl2SiCl2, respectively, in aceto-nitrile. The oxygen-bonded carbon and nitro-gen atoms of the OPO ligands in 1, 2, and 3 were modeled as disordered indicating co-crystallization of up to three possible diastereomers in each. Solution NMR studies support the presence of exclusively the all-cis isomer in 1 and multiple isomers in 2. Poor solubility of 3 limited its characterization in solution.

In Situ Metal-Oxygen-Hydrogen Modified B-Tio2 @Co2 P-X S-Scheme Heterojunction Effectively Enhanced Charge Separation for Photo-assisted Uranium Reduction

Photo-assisted uranium reduction from uranium mine wastewater is expected to overcome the competition between impurity ions and U(VI) in the traditional process. Here, B-TiO2 @Co2 P-X S-scheme heterojunction with metal-oxygen-hydrogen (M-O-H) is developed insitu modification for photo-assisted U(VI) (hexavalent uranium) reduction. Relying on the DFT calculation and Hard-Soft-Acid-Base (HSAB) theory, the introduction of metal-oxygen-hydrogen (M-O-H, hard base) metallic bonds in the B-TiO2 @Co2 P-X is found to enhance the hydrophilicity and the capture capability for uranyl ion (hard acid). Accordingly, B-TiO2 @Co2 P-500 hybrid nanosheets exhibit excellent U(VI) reduction ability (>98%) in the presence of competing ions. By self-consistent energy band calculations and in-situ KPFM spectral analysis, the formation of the internal electric field between B-TiO2 and Co2 P at the heterojunction is proven, offering a strong driving force and atomic transportation highway for accelerating the S-scheme charge carriers directed migration and promoting the photocatalytic reduction of uranium. This work provides a valuable route to explore the functionally modified photocatalyst with high-efficiency photoelectron separation for U(VI) reduction.

Enhancing Uranium Removal with a Titanium-Incorporated Zirconium-Based Metal-Organic Framework

The urgent need to efficiently and rapidly decontaminate uranium contamination in aquatic environments underscores its significance for ecological preservation and environmental restoration. Herein, a series of titanium-doped zirconium-based metal-organic frameworks were meticulously synthesized through a stepwise process. The resultant hybrid bimetallic materials, denoted as NU-Zr-n%Ti, exhibited remarkable efficiency in eliminating uranium (U (VI)) from aqueous solution. Batch experiments were executed to comprehensively assess the adsorption capabilities of NU-Zr-n%Ti. Notably, the hybrid materials exhibited a substantial increase in adsorption capacity for U (VI) compared to the parent NU-1000 framework. Remarkably, the optimized NU-Zr-15%Ti displayed a noteworthy adsorption capacity (∼118 mg g-1) along with exceptionally rapid kinetics at pH 4.0, surpassing that of pristine NU-1000 by a factor of 10. This heightened selectivity for U (VI) persisted even when diverse ions exist. The dominant mechanisms driving this high adsorption capacity were identified as the robust electrostatic attraction between the negatively charged surface of NU-Zr-15%Ti and positively charged U (VI) species as well as surface complexation. Consequently, NU-Zr-15%Ti emerges as a promising contender for addressing uranium-laden wastewater treatment and disposal due to its favorable sequestration performance.

Self-Aggregated Nanoscale Metal-Organic Framework for Targeted Pulmonary Decorporation of Uranium

The limited availability of effective agents for removing actinides from the lungs significantly restricts the effectiveness of medical treatments for nuclear emergencies. Inhalation is the primary route of internal contamination in 44.3% of actinide-related accidents, leading to the accumulation of radionuclides in the lungs and resulting in infections and potential tumor formation (tumorigenesis). This study focuses on the synthesis of a nanometal-organic framework (nMOF) material called ZIF-71-COOH, which is achieved by post-synthetic carboxyl functionalization of ZIF-71. The material demonstrates high and selective adsorption of uranyl, while also exhibiting increased particle size (≈2100 nm) when it aggregates in the blood, enabling passive targeting of the lungs through mechanical filtration. This unique property facilitates the rapid enrichment and selective recognition of uranyl, making nano ZIF-71-COOH highly effective in removing uranyl from the lungs. The findings of this study highlight the potential of self-aggregated nMOFs as a promising drug delivery system for targeted uranium decorporation in the lungs.

Induction of lysosomal exocytosis and biogenesis via TRPML1 activation for the treatment of uranium-induced nephrotoxicity

Uranium (U) is a well-known nephrotoxicant which forms precipitates in the lysosomes of renal proximal tubular epithelial cells (PTECs) after U-exposure at a cytotoxic dose. However, the roles of lysosomes in U decorporation and detoxification remain to be elucidated. Mucolipin transient receptor potential channel 1 (TRPML1) is a major lysosomal Ca2+ channel regulating lysosomal exocytosis. We herein demonstrate that the delayed administration of the specific TRPML1 agonist ML-SA1 significantly decreases U accumulation in the kidney, mitigates renal proximal tubular injury, increases apical exocytosis of lysosomes and reduces lysosomal membrane permeabilization (LMP) in renal PTECs of male mice with single-dose U poisoning or multiple-dose U exposure. Mechanistic studies reveal that ML-SA1 stimulates intracellular U removal and reduces U-induced LMP and cell death through activating the positive TRPML1-TFEB feedback loop and consequent lysosomal exocytosis and biogenesis in U-loaded PTECs in vitro. Together, our studies demonstrate that TRPML1 activation is an attractive therapeutic strategy for the treatment of U-induced nephrotoxicity.

Toxicity of Heavy Metals and Recent Advances in Their Removal: A Review

Natural and anthropogenic sources of metals in the ecosystem are perpetually increasing; consequently, heavy metal (HM) accumulation has become a major environmental concern. Human exposure to HMs has increased dramatically due to the industrial activities of the 20th century. Mercury, arsenic lead, chrome, and cadmium have been the most prevalent HMs that have caused human toxicity. Poisonings can be acute or chronic following exposure via water, air, or food. The bioaccumulation of these HMs results in a variety of toxic effects on various tissues and organs. Comparing the mechanisms of action reveals that these metals induce toxicity via similar pathways, including the production of reactive oxygen species, the inactivation of enzymes, and oxidative stress. The conventional techniques employed for the elimination of HMs are deemed inadequate when the HM concentration is less than 100 mg/L. In addition, these methods exhibit certain limitations, including the production of secondary pollutants, a high demand for energy and chemicals, and reduced cost-effectiveness. As a result, the employment of microbial bioremediation for the purpose of HM detoxification has emerged as a viable solution, given that microorganisms, including fungi and bacteria, exhibit superior biosorption and bio-accumulation capabilities. This review deals with HM uptake and toxicity mechanisms associated with HMs, and will increase our knowledge on their toxic effects on the body organs, leading to better management of metal poisoning. This review aims to enhance comprehension and offer sources for the judicious selection of microbial remediation technology for the detoxification of HMs. Microbial-based solutions that are sustainable could potentially offer crucial and cost-effective methods for reducing the toxicity of HMs.

Sulfonic-Pendent Vinylene-Linked Covalent Organic Frameworks Enabling Benchmark Potential in Advanced Energy

Both proton exchange membrane fuel cells and uranium-based nuclear techniques represent two green and advanced energies. However, both of them still face some intractable scientific and industrial problems. For the former, established proton-conduction materials always suffer one or another defect such as low proton conductivity, high activation energy, bad durability, or just small-scale product; while for the later, there still lacks available adsorbent to selectively recover of UO₂ ²⁺ from concentrated nitric acid (>1 M) during the spent fuel reprocessing due to the deactivation of the adsorption site or the decomposition of adsorbent under such rigorous conditions. It is found that the above two issues can be well solved by the construction of sulfonic-pendent vinylene-linked covalent organic frameworks (COFs), since these COFs contain abundant sulfonic units for both intrinsic proton conduction and UO₂ ²⁺ capture through strong coordination fixation and vinylene linkage that enhances the stability up to 12 M nitric acid (one of the best materials surviving in 12 M HNO₃ ).

Direct Separation of UO2 2+ by Coordination Sieve Effect via Spherical Coordination Traps

Molecule sieve effect (MSE) can enable direct separation of target, thus overcoming two major scientific and industrial separation problems in traditional separation, coadsorption, and desorption. Inspired by this, herein, the concept of coordination sieve effect (CSE) for direct separation of UO₂ ²⁺ , different from the previously established two-step separation method, adsorption plus desorption is reported. The used adsorbent, polyhedron-based hydrogen-bond framework (P-HOF-1), made from a metal-organic framework (MOF) precursor through a two-step postmodification approach, afforded high uptake capacity (close to theoretical value) towards monovalent Cs⁺ , divalent Sr²⁺ , trivalent Eu³⁺ , and tetravalent Th⁴⁺ ions, but completely excluded UO₂ ²⁺ ion, suggesting excellent CSE. Direct separation of UO₂ ²⁺ can be achieved from a mixed solution containing Cs⁺ , Sr²⁺ , Eu³⁺ , Th⁴⁺ , and UO₂ ²⁺ ions, giving >99.9% removal efficiency for Cs⁺ , Sr²⁺ , Eu³⁺ , and Th⁴⁺ ions, but <1.2% removal efficiency for UO₂ ²⁺ , affording benchmark reverse selectivity (S_M/U ) of >83 and direct generation of high purity UO₂ ²⁺ (>99.9%). The mechanism for such direct separation via CSE, as unveiled by both single crystal X-ray diffraction and density-functional theory (DFT) calculation, is due to the spherical coordination trap in P-HOF-1 that can exactly accommodate the spherical coordination ions of Cs⁺ , Sr²⁺ , Eu³⁺ , and Th⁴⁺ , but excludes the planar coordination UO₂ ²⁺ ion.

Selective Complexation and Separation of Uranium(VI) from Thorium(IV) with New Tetradentate N,O-Hybrid Diamide Ligands: Synthesis, Extraction, Spectroscopy, and Crystallographic Studies

An unmet challenge in the thorium-uranium fuel cycle is the efficient separation of uranium from thorium. Herein, two new tetradentate N,O-hybrid ligands, N,N'-diethyl-N,N'-di-p-tolyl-2,2'-bipyridine-6,6'-dicarboxamide (Et-Tol-BPDA) and N,N'-diethyl-N,N'-di-p-tolyl-2,2'-bipyrimidine-4,4'-dicarboxamide (Et-Tol-BPymDA), comprising a bipyridine or bipyrimidine core and amide moieties were designed and synthesized for selectively complexing and separating U(VI) from Th(IV). The high U(VI)/Th(IV) extraction selectivity was achieved by Et-Tol-BPDA (SF_U/Th = 33 at 3 M HNO₃) and Et-Tol-BPymDA (SF_U/Th = 73 at 3 M HNO₃) in nitric acid solutions. The extraction process for U(VI) or Th(IV) with these two ligands primarily proceeded through the solvation mechanism, as evidenced by slope analyses. Thermodynamic studies for the extraction of U(VI) and Th(IV) revealed a spontaneous process. Results from UV-vis spectroscopic titration and slope analyses demonstrated that U(VI) and Th(IV) each form a 1:1 complex with the two ligands both in the monophasic organic solution and the biphasic extraction system. The stability constants of the 1:1 complexes of Et-Tol-BPDA or Et-Tol-BPymDA with U(VI) were found to be larger than those with Th(IV), which coincide well with the high U(VI)/Th(IV) extraction selectivity. The solid-state structures of Et-Tol-BPDA, Et-Tol-BPymDA, and 1:1 complexes of the two ligands with U(VI) or Th(IV) were analyzed by X-ray diffraction technique. The results from this work implicate the potential of bipyridine- and bipyrimidine-derived diamide ligands for uranium/thorium separation.

Non-targeted metabolomics and 16s rDNA reveal the impact of uranium stress on rhizosphere and non-rhizosphere soil of ryegrass

As a radioactive heavy metal element with a long half-life, uranium causes environmental pollution when it enters the surrounding soil. This study analyzed the changes about soil enzyme activity, non-targeted metabolomics, microbial community structure and function microbial community structure and function to assess the differences in the effects of uranium stress on rhizosphere and non-rhizosphere soil. Results showed that uranium stress significantly inhibited the activities of urease and sucrase in rhizosphere and non-rhizosphere, which had less effect on rhizosphere. Compare to the non-rhizosphere soil, the uranium stress induced the production of gibberellin A1, to promoted several metabolic pathways, such as nitrogen and PTS (Phosphotransferase system) metabolic in rhizosphere soil. The species and abundance of Aspergillus, Acidobacter, and Synechococcus in both rhizosphere and non-rhizosphere soil were decreased by uranium stress. However, the microorganisms in rhizosphere soil were less inhibited according to the soil metabolism and microbial network map analysis. Furthermore, the Chujaibacter in rhizosphere soil under uranium stress was found significantly positively correlated with lipid and organic oxygen compounds. Overall, the results indicated that ryegrass roots significantly alleviated the effects of uranium stress on soil microbial activity and population abundances, thus playing a protective role. The study also provided a theoretical basis for in-depth understanding of the biological effects, prevention and control mechanisms of uranium-contaminated soil.

Novel biocompatible and sensitive visual sensor based on aggregation-induced emission for on-site detection of radioactive uranium in water and live cell imaging

In consideration of the severe hazards of radioactive uranium pollution, the rapid assessment of uranium in field and in vivo are urgently needed. In this work a novel biocompatible and sensitive visual fluorescent sensor based on aggregation-induced emission (AIE) was designed for onsite detection of UO₂²⁺ in complex environmental samples, including wastewater from Uranium Plant, river water and living cell. The AIE-active sensor (named as TPA-SP) was prepared with a "bottom-up" strategy by introducing a trianiline group (TPA) with a single-bond rotatable helix structure into the salicylaldehyde Schiff-base molecule. The photophysical properties, cytotoxicity test, recognition mechanism and the analytical performance for the detection of UO₂²⁺ in actual water samples and cell imaging were systematically investigated. TPA-SP exhibited high sensitivity and selectivity toward UO₂²⁺ as well as outstanding anti-interference ability against large equivalent of different ions in a wide effective pH range. A good linear relationship in the UO₂²⁺ concentration range of 0.05-1 μM was obtained with a low limit of detection (LOD) of 39.4 nM (9.38 ppb) for uranium detection. The prepared visual sensor showed great potential for fast risk assessment of uranium pollution in environmental systems. In addition, our results also indicated that the TPA-SP exhibited very low cytotoxicity in cells and demonstrated great potential for uranium detection in vivo.

Uranium extraction from seawater: material design, emerging technologies and marine engineering

Uranium extraction from seawater (UES), a potential approach to securing the long-term uranium supply and sustainability of nuclear energy, has experienced significant progress in the past decade. Promising adsorbents with record-high capacities have been developed by diverse innovative synthetic strategies, and scale-up marine field tests have been put forward by several countries. However, significant challenges remain in terms of the adsorbents' properties in complex marine environments, deployment methods, and the economic viability of current UES systems. This review presents an up-to-date overview of the latest advancements in the UES field, highlighting new insights into the mechanistic basis of UES and the methodologies towards the function-oriented development of uranium adsorbents with high adsorption capacity, selectivity, biofouling resistance, and durability. A distinctive emphasis is placed on emerging electrochemical and photochemical strategies that have been employed to develop efficient UES systems. The most recent achievements in marine tests by the major countries are summarized. Challenges and perspectives related to the fundamental, technical, and engineering aspects of UES are discussed. This review is envisaged to inspire innovative ideas and bring technical solutions towards the development of technically and economically viable UES systems.

Chelating decorporation agents for internal contamination by actinides: Designs, mechanisms, and advances

During the wide utilization of the actinides in medicine, energy, military, and other fields, internal contaminations can profoundly endanger human health and public security. Chelating decorporation agents are the most effective therapies to reduce internal contamination that includes radiological and chemical toxicities. This review introduces the structures of chelating decorporation agents including inorganic salts, polyaminocarboxylic acids, peptides, polyphosphonates, siderophores, calixarenes, polyethylenimines, and fullerenes, and highlights ongoing advances in their designs and mechanisms. However, there are still numerous challenges that block their applications including coordination properties, pharmacokinetic properties, oral bioavailability, limited timing of administration, and toxicity. Therefore, additional efforts are needed to push novel decorporation agents with high efficiency and low toxicity for the treatment of internal contamination by actinides.

A study on the catalytic activity of polypeptides toward the hydrolysis of glucoside compounds gastrodin, polydatin and esculin

The self-assembly of a series of catalytically active polypeptides toward hydrolysis of glucoside compounds, namely, gastrodin, polydatin and esculin was investigated. These active peptides are composed of two functional fragments: one is the hydrophobic sequence LHLHLRL, which forms assembling segments in the presence of Zn ions (Zn²⁺); another functional sequence of active peptides are catalytic sites such as Glu (E), Asp (D) and His (H), where carboxylic acids (-COOH) or imidazole groups act like scissors to cleave glucoside bonds of the compounds (according to the acid-base coupling mechanism). The effects of the amino acid sequence of the peptide, Zn²⁺ concentration, pH and the size or steric hindrance of glucoside compounds on the hydrolytic activity were studied. It was found that the crystalline structure of assembled peptides was crucial to provide the peptide with catalytic hydrolytic activity. Noncovalent interaction index was used to analyse the noncovalent interaction of PEs with glucoside compounds, including hydrogen bonds, van der Waals, and steric effect in the complexes. The binding energy of complexes, the direction and site of nucleophilic attack during deglycosylation processes were also investigated by molecular docking and the electron density Laplace function. This revealed that the differences in the hydrolytic activity of peptides toward glucoside compounds with different sizes originated from different hydrogen bond interactions between the peptides and substrates. These active peptides may find application in the preparation of drugs by de-glycosylation of natural compounds.

Integration of quantum dots with Zn2GeO4 nanoellipsoids to expand the dynamic detection range of uranyl ions in fluorescent test strips

Fluorescent colorimetric test strips normally have a narrow dynamic detection-range due to the limited responsive range from single responsive materials, which cannot meet the wide detection requirement in practical applications. Herein, we developed an approach to detect uranyl ions (UO₂²⁺) with a broad detection range using the synthesized ZnS:Mn quantum dots (QDs) modified Zn₂GeO₄ nanoellipsoids (Zn₂GeO₄ @ZnS:Mn NEs), containing two responsive materials with the opposite signal responses at different UO₂²⁺ concentrations. Specifically, a red to chocolate color change was observed at low analyte concentrations (0.01-100 μM) resulting from the photoinduced electron transfer effect from ZnS:Mn QDs to UO₂²⁺. A sequentially olive drab to green color change has been observed when further increasing the UO₂²⁺ concentration (100-1000 μM) as a result of the antenna effect between Zn₂GeO₄ nanoellipsoids and UO₂²⁺. In addition, a low-cost and portable fluorescent test strip has been further fabricated through embedding Zn₂GeO₄ @ZnS:Mn NEs on a microporous structure membrane, demonstrating a facile yet effective colorimetric response to UO₂²⁺ in lab water, lake water, and seawater with a wide dynamic range. Therefore, it is potentially attractive for real-time and on-site detection of UO₂²⁺ in sudden-onset situations.

Actinide Decorporation: A Review on Chelation Chemistry and Nanocarriers for Pulmonary Administration

Chelation is considered the best method for detoxification by promoting excretion of actinides (Am, Np, Pu, Th, U) from the human body after internal contamination. Chemical agents that possess carboxylic acid or hydroxypyridinonate groups play a vital role in actinide decorporation. In this review article, we provide considerable background details on the chelation chemistry of actinides with an aim to formulate better decorporation agents. Nanocarriers for pulmonary delivery represent an exciting prospect in the development of novel therapies for actinide decorporation that both reduce toxic side effects of the agent and improve its retention in the body. Recent studies have demonstrated the benefits of using a nebulizer or an inhaler to administer chelating agents for the decorporation of actinides. Effective chelation therapy with large groups of internally contaminated people can be a challenge unless both the agent and the nanocarrier are readily available from strategic national stockpiles for radiological or nuclear emergencies. Sunflower lecithin is particularly adept at alleviating the burden of administration when used to form liposomes as a nanocarrier for pulmonary delivery of diethylenetriamine-pentaacetic acid (DTPA) or hydroxypyridinone (HOPO). Better physiologically-based pharmacokinetic models must be developed for each agent in order to minimize the frequency of multiple doses that can overload the emergency response operations.

Amidoxime functionalized chitosan for uranium sequestration in vivo

Amidoxime functionalized chitosan (AC) was recommended as a chelator for uranium sequestration in vivo in this study, and the structure-activity relationship was also explored. Compared with ZnNa₃-DTPA, which was a commercial uranium mobilization drug, AC exhibited excellent biocompatibility and uranium removal efficiency, whether by injection or orally, which could reduce the amounts of uranium deposited in kidneys and femurs by up to 43.6% and 32.3%. In particular, ACs still possessed the ability to mobilize uranium in vivo even if administration was delayed for 72 h.

In Vivo Uranium Decorporation by a Tailor-Made Hexadentate Ligand

The sequestration of uranium, particularly from the deposited bones, has been an incomplete task in chelation therapy for actinide decorporation. Part of the reason is that all previous decorporation ligands are not delicately designed to meet the coordination requirement of uranyl cations. Herein, guided by DFT calculation, we elaborately design a hexadentate ligand (TAM-2LI-MAM₂), whose preorganized planar oxo-donor configuration perfectly matches the typical coordination geometry of the uranyl cation. This leads to an ultrahigh binding affinity to uranyl supported by an in vitro desorption experiment of uranyl phosphate. Administration of this ligand by prompt intraperitoneal injection demonstrates its uranyl removal efficiencies from the kidneys and bones are up to 95.4% and 81.2%, respectively, which notably exceeds all the tested chelating agents as well as the clinical drug ZnNa₃-DTPA, setting a new record in uranyl decorporation efficacy.

Uranium chelating ability of decorporation agents in serum evaluated by X-ray absorption spectroscopy

Internal exposure to actinides such as uranium and plutonium has been reduced using chelating agents for decorporation because of their potential to induce both radiological and chemical toxicities. This study measures uranium chemical forms in serum in the presence and absence of chelating agents based on X-ray absorption spectroscopy (XAS). The chelating agents used were 1-hydroxyethane 1,1-bisphosphonate (EHBP), inositol hexaphosphate (IP6), deferoxamine B (DFO), and diethylenetriaminepentaacetate (DTPA). Percentages of uranium-chelating agents and uranium-bioligands (bioligands: inorganic and organic ligands coordinating with uranium) dissolving in the serum were successfully evaluated based on principal component analysis of XAS spectra. The main ligands forming complexes with uranium in the serum were estimated as follows: IP6 > EHBP > bioligands > DFO ≫ DTPA when the concentration ratio of the chelating agent to uranium was 10. Measurements of uranium chemical forms and their concentrations in the serum would be useful for the appropriate treatment using chelating agents for the decorporation of uranium.

Two different coordination modes of the Schiff base derived from ortho-vanillin and 2-(2-aminomethyl)pyridine in a mononuclear uranyl complex

This work describes the reaction of the potentially tetradentate Schiff-base ligand N-(2-pyridylmethy)-3-methoxysalicylaldimine (HL) with UO2(O2CMe)2·2H2O and UO2(NO3)2· 6H2O in MeOH in the absence or presence of an external base, respectively. The product from these reactions is the mononuclear complex [UO2(L)2] (1). Its structure has been determined by single-crystal, X-ray crystallography. The anionic ligand adopts two different coordination modes (1.1011, 1.1010; Harris notation) in the complex. The new compound was fully characterized by solid-state (IR, Raman and Photoluminescence spectroscopies) and solution (UV-Vis and 1H NMR spectra, conductivity measurements) techniques.

Chelating Polymers for Targeted Decontamination of Actinides: Application of PEI-MP to Hydroxyapatite-Th(IV)

In case of an incident in the nuclear industry or an act of war or terrorism, the dissemination of plutonium could contaminate the environment and, hence, humans. Human contamination mainly occurs via inhalation and/or wounding (and, less likely, ingestion). In such cases, plutonium, if soluble, reaches circulation, whereas the poorly soluble fraction (such as small colloids) is trapped in alveolar macrophages or remains at the site of wounding. Once in the blood, the plutonium is delivered to the liver and/or to the bone, particularly into its mineral part, mostly composed of hydroxyapatite. Countermeasures against plutonium exist and consist of intravenous injections or inhalation of diethylenetetraminepentaacetate salts. Their effectiveness is, however, mainly confined to the circulating soluble forms of plutonium. Furthermore, the short bioavailability of diethylenetetraminepentaacetate results in its rapid elimination. To overcome these limitations and to provide a complementary approach to this common therapy, we developed polymeric analogs to indirectly target the problematic retention sites. We present herein a first study regarding the decontamination abilities of polyethyleneimine methylcarboxylate (structural diethylenetetraminepentaacetate polymer analog) and polyethyleneimine methylphosphonate (phosphonate polymeric analog) directed against Th(IV), used here as a Pu(IV) surrogate, which was incorporated into hydroxyapatite used as a bone model. Our results suggest that polyethylenimine methylphosphonate could be a good candidate for powerful bone decontamination action.

China’s radiopharmaceuticals on expressway: 2014–2021

This review provides an essential overview on the progress of rapidly-developing China’s radiopharmaceuticals in recent years (2014–2021). Our discussion reflects on efforts to develop potential, preclinical, and in-clinical radiopharmaceuticals including the following areas: (1) brain imaging agents, (2) cardiovascular imaging agents, (3) infection and inflammation imaging agents, (4) tumor radiopharmaceuticals, and (5) boron delivery agents (a class of radiopharmaceutical prodrug) for neutron capture therapy. Especially, the progress in basic research, including new radiolabeling methodology, is highlighted from a standpoint of radiopharmaceutical chemistry. Meanwhile, we briefly reflect on the recent major events related to radiopharmaceuticals along with the distribution of major R&D forces (universities, institutions, facilities, and companies), clinical study status, and national regulatory supports. We conclude with a brief commentary on remaining limitations and emerging opportunities for China’s radiopharmaceuticals.

Protective effects of Polygonatum kingianum polysaccharides and aqueous extract on uranium-induced toxicity in human kidney (HK-2) cells

The current detoxification options of uranium, a toxic radioactive heavy metal, have obvious side effects. Polygonatum kingianum (PK), a natural product with the function of antioxidant, may be effective in detoxification and prevention of uranium-induced nephrotoxicity. Here, we studied the protective effects of PK polysaccharides (PKP) and aqueous extract (PKAE) on uranium-induced toxicity in human kidney (HK-2) cells. First, the physicochemical properties of PKP and PKAE were characterized. Assays on cultured cells demonstrated that pretreatment with PKP and PKAE significantly increased metabolic activity, relieved morphological impairments, and alleviated apoptosis. The impairments caused by uranium exposure were ameliorated (mitochondrial membrane potential and ATP level increased while reactive oxygen species decreased). Molecular mechanistic studies revealed that PKP and PKAE alleviated uranium-induced cytotoxicity by regulating mitochondria-mediated apoptosis and the GSK-3β/Fyn/Nrf2 pathway. Collectively, our data support the preventive and therapeutic applications of PKP and PKAE for uranium poisoning.

Enhanced uranium photoreduction on Ti3C2Tx MXene by modulation of surface functional groups and deposition of plasmonic metal nanoparticles

Photocatalytic reduction of soluble hexavalent uranium (U(VI)) is a novel and efficient avenue to enriching U(VI), where the free U(VI) is firstly bound on the surface of photocatalysts and then reduced to insoluble tetravalent uranium (U(IV)) by photoelectrons. Therefore, constructing the efficient U(VI) binding sites on photocatalysts is an efficient strategy to boost catalytic activity toward U(VI) photoreduction. Herein, we successfully constructed an efficient catalyst for U(VI) photoreduction by depositing Ag nanoparticles on Ti₃C₂T_x MXene with abundant U(VI) binding sites (Ag/Ti₃C₂T_x-O). Impressively, the U(VI) extracting mass over Ag/Ti₃C₂T_x-O under light reached up to 1257.6 mg/g in 120 min, which was almost 11 times as high as that without light. Further mechanistic studies indicated that the U(VI) binding sites on Ti₃C₂T_x MXene in Ag/Ti₃C₂T_x-O were beneficial to the reduction of U(VI) by significantly decreasing its reduction potential. More importantly, hot electrons generated by Ag nanoparticles were transferred into the binding sites to easily reduce the bound U(VI), resulting in the remarkable performance of Ag/Ti₃C₂T_x-O during U(VI) enrichment.

Light Promotes the Immobilization of U(VI) by Ferrihydrite

The environmental behaviors of uranium closely depend on its interaction with natural minerals. Ferrihydrite widely distributed in nature is considered as one main natural media that is able to change the geochemical behaviors of various elements. However, the semiconductor properties of ferrihydrite and its impacts on the environmental fate of elements are sometimes ignored. The present study systematically clarified the photocatalysis of U(VI) on ferrihydrite under anaerobic and aerobic conditions, respectively. Ferrihydrite showed excellent photoelectric response. Under anaerobic conditions, U(VI) was converted to U(IV) by light-irradiated ferrihydrite, in the form of UO2+x (x < 0.25), where •O2− was the dominant reactive reductive species. At pH 5.0, ~50% of U(VI) was removed after light irradiation for 2 h, while 100% U(VI) was eliminated at pH 6.0. The presence of methanol accelerated the reduction of U(VI). Under aerobic conditions, the light illumination on ferrihydrite also led to an obvious but slower removal of U(VI). The removal of U(VI) increased from ~25% to 70% as the pH increased from 5.0 to 6.0. The generation of H2O2 under aerobic conditions led to the formation of UO4•xH2O precipitates on ferrihydrite. Therefore, it is proved that light irradiation on ferrihydrite significantly changed the species of U(VI) and promoted the removal of uranium both under anaerobic and aerobic conditions.