Latest ArticlesA simple and convenient method has been developed for the pre-concentration and separation of inorganic selenium species from environmental water samples using anion exchange chromatographic column combined with high resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) measurement. 75Se(Ⅳ) and 75Se(Ⅵ) were prepared and used as tracers during the experiments. The volatility of selenium during solution evaporation was investigated to establish a reliable water samples pretreatment procedure. The parameters which affect the uptake of Se(Ⅳ) and Se(Ⅵ) on Dowex1 × 8 resin was optimized and the procedure for Se(Ⅳ) and Se(Ⅵ) separation was proposed. Both Se(Ⅳ) and Se(Ⅵ) are retained on the column in natural or alkaline solution with high distribution coefficient. The successive gradient elution of pre-concentrated species of selenium with HNO3 solution allows to differentiate between them. Se(Ⅳ) and Se(Ⅵ) finally were eluted with 0.05 mol/L HNO3 and 5.0 mol/L HNO3, respectively. The proposed method has been successfully verified using the certified reference materials (CRMs) of real water samples, and spiked recoveries for real samples were 98%-104% with 5% relative standard deviations (RSDs). The developed procedure is proved to be reliable and can be used for the rapid determination of selenium species in environmental water samples.
The extraction complexes of uranyl(Ⅵ) in HNO3 to a hydroxyl-functionalized ionic liquid (IL) phase, HOEtmimNTf2 bearing CMPO, were investigated. Three possibly successive extraction complexes, UO2L2+ (L = CMPO), UO2L22+ and UO2L32+, were detected based on variable U/L ratios. Uranyl(Ⅵ) prefers to be extracted as complex UO2L32+, combining with the ions from HOEtmimNTf2 to construct a solid material through self-assembly. The thermodynamics of complexes, UO2L2+ (j = 1-3), were studied by spectrophotometry and microcalorimetry. All the formation reactions are principally driven by entropy, although a small part of the driving force of complexes UO2L22+ and UO2L32+ comes from enthalpy. Based on the thermodynamic properties for complex UO2L32+, we provide a possible coordination mode in HOEtmimNTf2: the first CMPO molecule coordinates with UO22+ in a bidentate fashion while the others do in a monodentate fashion. The results offer a thermodynamic insight into the formation behaviors of the uranyl(Ⅵ)/CMPO complexes involving the special IL HOEtmimNTf2, which is of significance to advance the novel IL extraction strategy.
The development of uranyl ion detection technology has exhibited its significance in public security and environmental fields for the radioactivity and chemical toxicity of uranyl ion. The WHO standard of uranyl ion makes it necessary to develop highly sensitive uranyl rapid warning system in drinking water monitoring. Herein, a visualized rapid warning system for trace uranyl ion is carried out based on electrochemiluminescence (ECL) imaging technology to give an ultra-low limit of detection (LOD) and high selectivity. Amidoxime, a bi-functional group with both uranyl ion capturing and co-reactive functions, is modified on a conjugated polymer backbone with strong ECL signal to be prepared into three-in-one polymer nanoparticles (PNPs) with self-enhanced ECL property. The captured uranyl ion can enhance the ECL signal of PNPs via resonance energy transfer process to give the LOD as 0.5 ng/L, which is much lower than the known luminescent uranyl sensors. Furthermore, ECL imaging technology is introduced into realizing visualized uranyl rapid warning, and can be successfully applied on natural water samples. This study provides a novel strategy for uranyl rapid warning, and shows its potential meaning in public security and environmental fields.
During the chemical weathering of the uranium mill tailings, released uranium could be immobilized by the newly formed secondary minerals such as oxyhydroxides. A deeper understanding of the interaction between uranium and common oxyhydroxides under environmental conditions is necessary. In this work, uranium sorption behaviors on Al-, Mn- and Fe-oxyhydroxide minerals (boehmite, manganite, goethite, and lepidocrocite) were investigated by batch experiments. Results showed that the uranium sorption on Al-oxyhydroxide behaved significantly differently from the other three minerals. The sorption edge of the Mn- and Fe-oxyhydroxides located around pH 5, while the sorption edge of boehmite shifted about 1.5 pH unit to near neutral. The sorption isotherms of uranium on manganite, goethite and lepidocrocite at pH 5.0 could be well fitted by the Langmuir model. Instead of surface complexation, sorption on boehmite happened mainly by uranium-bearing carbonates and hydroxides precipitation as illustrated by the characterization results. Both carbonate and phosphate strongly affected the uranium sorption behavior. The removal efficiency of uranium by boehmite exceeded 98% after three sorption-desorption cycles, indicating it may be a potential material for uranium removal and recovery.
Nitrogen enrichment and increased nitrogen content is an effective strategy for enhancing adsorption of uranium by carbon nitride polymers. Herein, we reported the uranium absorption by using a structurally well-defined and nitrogen-rich carbon nitride polymer with C3N5 stoichiometry for the first time. In comparison with the adsorption performance of g-C3N4 for U(VI), the conjugation system of the material was increased by connecting the heptazine unit through the azo bridge in the structure of C3N5, so that C3N5 exhibited several times higher adsorption performance than that of g-C3N4. The C3N5 has high kinetics for uranyl ions, which can adsorb 100 mg/g U(VI) in only 10 min and reach complete adsorption equilibrium in 60 min; the theoretical maximum adsorption capacity is 207 mg/g, meanwhile, the material exhibits high selectivity. The results of spectral analysis and theoretical calculations indicate that the process of uranyl ion capture by C3N5 is a combination of physical and chemical adsorption, and its higher density of electronic states makes the electrostatic binding ability enhanced, which is favorable to the adsorption of uranyl ions by C3N5. This work indicates that C3N5 has great promise and application in the separation and enrichment of uranyl ions, and also provides a reference for the systematic investigation of the adsorption ability of nitrogen-rich carbon nitrogen polymers on uranyl ions.
Targeted alpha-therapy (TAT) is increasingly attractive due to its extraordinary antitumor efficacy. However, the supply of α-emitters for TAT is insufficient and under control by a limited number of countries. 212Pb is a promising α-emitter with an optimal half-life (10.6 h) and favored decay chain. Of interest, 212Pb can be extracted directly from natural thorium, which may be abundant in the mining waste of rare-earth, uranium, etc. Indeed, radioactive thorium waste has been a longstanding environmental challenge that needs immediate action. Developing an on-demand and facile process to isolate 212Pb from natural thorium would be ideal to meet the above challenges, yet is difficult. In theory, the ratio of 212Pb to natTh is below 10−13 in commercially available thorium salts. As a pilot study, 2.2 MBq of 212Pb was successfully extracted from a 5 L solution of thorium nitrate by using a Pb-selective resin. The radiochemical purity of 212Pb is over 99.9% according to gamma-ray analysis. The purified 212Pb was applied to radiolabel a couple of peptides used in clinics (i.e. PSMA, TATE and FAPI-04), and the radiochemical yields are > 85%. Of note, 212Pb can be repeatedly separated from the thorium solution every 2 days. In summary, a practical and scalable method was developed to isolate 212Pb for potentially clinical use, which may be of great importance as it does not require either cyclotron or nuclear reactor.
Phototheranostics have attracted tremendous attention in cancer diagnosis and treatment because of the noninvasiveness and promising effectiveness. Developing advanced phototheranostic agents with long emission wavelength, excellent biocompatibility, great tumor-targeting capability, and efficient therapeutic effect is highly desirable. However, the mutual constraint between imaging and therapeutic functions usually hinders their wide applications in biomedical field. To balance this contradiction, we herein rationally designed and synthesized three novel tumor-targeted NIR-II probes (QR-2PEG321, QR-2PEG1000, and QR-2PEG5000) by conjugating three different chain lengths of PEG onto an integrin αvβ3-targeted NIR-II heptamethine cyanine fluorophore, respectively. In virtue of the essential amphiphilic characteristics of PEG polymers, these probes display various degree of aggregation in aqueous buffer accompanying with differential NIR-II imaging and photothermal (PTT) therapeutic performance. Both in vitro and in vivo results have demonstrated that probe QR-2PEG5000 has the best NIR-II imaging performance with prominent renal clearance, whereas QR-2PEG321 possesses excellent photoacoustic signal as well as PTT effect, which undoubtedly provides a promising toolbox for tumor diagnosis and therapy. We thus envision that these synthesized probes have great potential to be explored as a toolkit for precise diagnosis and treatment of malignant tumors.
The in vivo degradation behavior of metallic nanoparticles (NPs) is very important for their biomedical applications and safety evaluation. Here, a method of laser ablation-single particle inductively coupled plasma mass spectrometry (LA-sp-ICP-MS) is shown to have high spatial resolution, sensitivity and accuracy for simultaneous imaging the in situ distribution of particulate Ag (P-Ag) and released ionic Ag (Ion-Ag) in the sub-organs of spleen, liver and kidney after intravenous injection of Ag nanoparticles (50 nm, AgNPs) to mice. Under the optimized parameters of 0.4 J/cm2 laser fluence on a 30 µm spot with dwell time at 100 µs, the signals of P-Ag and Ion-Ag in the organic tissues can be easily distinguished from the mass spectra. The method of iterative threshold algorithm has been used to distract the signals of P-Ag and Ion-Ag and separate each other. The resulting images for the first time provide visualized evidence that a considerable amount of P-Ag accumulated in the splenic marginal zone, but widely distributed in the liver parenchyma at 24 h after injection of AgNPs, and in the meantime, obvious amounts of ionic Ag released and distributed in the organs. In addition, the imaging results indicate that the AgNP excretion in the kidney is mainly in ionic forms. The investigation here demonstrates that the developed LA-sp-ICP-MS method with high spatial resolution, sensitivity and visualization capability can become a powerful tool in the clinical context of metallic NPs.
Thioredoxin reductase 1 (TrxR1) is over activity in tumor cell to maintain their redox balance. Although gold clusters have great potential in antitumor drug as they could well inhibit TrxR1, the molecular mechanism has not been disclosed yet. In this work, we revealed gold clusters can well inhibit the activity of TrxR1 in lung tumor cells and further disclosed the inhibition mechanism by using computational simulation methods. We firstly inferred the binding sites of gold in the hydrophobic cavities on TrxR1. The simulation results show that the gold ion (released from Au cluster) interact with –SH of Cys189 in TrxR1, this greatly increase the distance between the C-terminal redox center of TrxR1 and the Trx redox center, thereby destroy the electron transfer pathway between them. Our electron transfer destroying mechanism is different from the previous hypothesis that gold binds to the Sec498 of TrxR1 which has never been proved by experimental and theory studies. This work provides a new understanding of the gold clusters to inhibit TrxR1 activity.
As one of the most common cancers in the world, hepatocellular carcinoma (HCC) has become a major threat to human health. Radioembolization is a first-line option for the treatment of HCC, especially when other conventional treatments fail or there exist some relative contraindications. Herein, we developed a facile and efficient method for preparing 177Lu-microspheres potentially useful for precise radioembolization therapy of HCC. The radiolabeling efficiency of 177Lu-microspheres was as high as 96.8% ± 0.5%, and the radiolabeling process did not alter the morphology of the mother microspheres. The SPECT/CT studies enabled by the unique emissions of 177Lu suggested that almost no 177Lu ion loaded by the microspheres was released over more than 32 d in vivo, which led to remarkable inhibition effect on the growth of HepG2 tumors subcutaneously transplanted in mice. The current approach may thus offer promising 177Lu-microspheres for clinical radioembolization of HCC.
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