气相色谱法在核化学与放射化学中的应用

在核化学与放射化学研究中,气相色谱法是一种非常重要的快速分离工具。它可以用于核反应产物的分离、核谱学研究,以及测定吸附焓,吸附熵,扩散系数等物化数据,研究超锕系元素的性质,探索其中的相对论性效应。本文主要介绍了在此领域中,气相色谱法的实验技术及应用,对其发展前景亦有所展望。     

Copper‐64‐Alloyed Gold Nanoparticles for Cancer Imaging: Improved Radiolabel Stability and Diagnostic Accuracy

Gold nanoparticles, especially positron‐emitter‐ labeled gold nanostructures, have gained steadily increasing attention in biomedical applications. Of the radionuclides used for nanoparticle positron emission tomography imaging, radiometals such as ⁶⁴Cu have been widely employed. Currently, radiolabeling through macrocyclic chelators is the most commonly used strategy. However, the radiolabel stability may be a limiting factor for further translational research. We report the integration of ⁶⁴Cu into the structures of gold nanoparticles. With this approach, the specific radioactivity of the alloyed gold nanoparticles could be freely and precisely controlled by the addition of the precursor ⁶⁴CuCl₂ to afford sensitive detection. The direct incorporation of ⁶⁴Cu into the lattice of the gold nanoparticle structure ensured the radiolabel stability for accurate localization in vivo. The superior pharmacokinetic and positron emission tomography imaging capabilities demonstrate high passive tumor targeting and contrast ratios in a mouse breast cancer model, as well as the great potential of this unique alloyed nanostructure for preclinical and translational imaging.     

99mTc Radiolabeling and Biological Evaluation of Nanoparticles Functionalized with a Versatile Coating Ligand

Radiolabeling allows noninvasive imaging by single photon emission computed tomography (SPECT) or positron emission tomography (PET) for assessing the biodistribution of nanostructures. Herein, the synthesis of a new coating ligand for gold nanoparticles (AuNPs) and quantum dots (QDs) is reported. This ligand is multifunctional; it combines the metal chelate with conjugating functions to biological vectors. The concept allows the coupling of any targeting function to the chelator; an example for the prostate specific membrane antigen is given. Derivatized NPs can directly be labeled in one step with [^99mTc(OH₂)₃(CO)₃]⁺. AuNPs in particular are highly stable, a prerequisite for in vivo studies excluding misinterpretation of the biodistribution data. AuNPs with differing sizes (7 and 14 nm core diameter) were administered intravenously into nude NMRI mice bearing LNCaP xenografts. MicroSPECT images show for both probes rapid clearance from the blood pool through the hepatobiliary pathway. The 7 nm AuNPs revealed a significantly higher bone uptake than the 14 nm AuNPs. The high affinity towards bone mineral is further confirmed in vitro with hydroxyapatite.     

超铀区缺中子新同位素~（235）Am的合成与鉴别

用３５ＭｅＶ质子轰击同位素靶２３８Ｐｕ，通过２３８Ｐｕ（Ｐ，４ｎ）２３５Ａｍ反应，合成了新的缺中子同位素２３５Ａｍ．利用Ｈｅ－ｊｅｔ及毛细管传输技术收集反应产物，然后用放射化学法除去产物中的裂变碎片并分离出Ａｍ活性．根据观测到的２３５Ｐｕ的衰变Ｙ及ＮＰ的特征Ｘ射线的生长－衰变行为和Ｘ－Ｙ符合测量，肯定了２３５Ａｍ的首次合成，测得２３５Ａｍ的半衰期为１５±５ｍｉｎ．     

Synthesis of 11C, 18F, 15O, and 13N radiolabels for positron emission tomography

Positron emission tomography (PET) is a powerful and rapidly developing area of molecular imaging that is used to study and visualize human physiology by the detection of positron-emitting radiopharmaceuticals. Information about metabolism, receptor/enzyme function, and biochemical mechanisms in living tissue can be obtained directly from PET experiments. Unlike magnetic resonance imaging (MRI) or computerized tomography (CT), which mainly provide detailed anatomical images, PET can measure chemical changes that occur before macroscopic anatomical signs of a disease are observed. PET is emerging as a revolutionary method for measuring body function and tailoring disease treatment in living subjects. The development of synthetic strategies for the synthesis of new positron-emitting molecules is, however, not trivial. This Review highlights key aspects of the synthesis of PET radiotracers with the short-lived positron-emitting radionuclides (11)C, (18)F, (15)O, and (13)N, with emphasis on the most recent strategies.     

Bifunctional Cyclam‐Based Ligands with Phosphorus Acid Pendant Moieties for Radiocopper Separation: Thermodynamic and Kinetic Studies

Two macrocyclic ligands based on cyclam with trans‐disposed N‐methyl and N‐(4‐aminobenzyl) substituents as well as two methylphosphinic (H₂ L1 ) or methylphosphonic (H₄ L2 ) acid pendant arms were synthesised and investigated in solution. The ligands form stable complexes with transition metal ions. Both ligands show high thermodynamic selectivity for divalent copper over nickel(II) and zinc(II)—K(CuL) is larger than K(Ni/ZnL) by about seven orders of magnitude. Complexation is significantly faster for the phosphonate ligand H₄ L2 , probably due to the stronger coordination ability of the more basic phosphonate groups, which efficiently bind the metal ion in an “out‐of‐cage” complex and thus accelerate its “in‐cage” binding. The rate of Cu^II complexation by the phosphinate ligand H₂ L1 is comparable to that of cyclam itself and its derivatives with non‐coordinating substituents. Acid‐assisted decomplexation of the copper(II) complexes is relatively fast (τ_1/2=44 and 42 s in 1 M aq. HClO₄ at 25 °C for H₂ L1 and H₄ L2 , respectively). This combination of properties is convenient for selective copper removal/purification. Thus, the title ligands were employed in the preparation of ion‐selective resins for radiocopper(II) separation. Glycidyl methacrylate copolymer beads were modified with the ligands through a diazotisation reaction. The separation ability of the modified polymers was tested with cold copper(II) and non‐carrier‐added ⁶⁴Cu in the presence of a large excess of both nickel(II) and zinc(II). The experiments exhibited high overall separation efficiency leading to 60–70 % recovery of radiocopper with high selectivity over the other metal ions, which were originally present in 900‐fold molar excess. The results showed that chelating resins with properly tuned selectivity of their complexing moieties can be employed for radiocopper separation.