Silver-111 is a promising β−-emitting radioisotope with ideal characteristics for targeted radionuclide therapy and associated single photon emission tomography imaging. Its decay properties closely resemble the clinically established lutetium-177, making it an attractive candidate for therapeutic applications. In addition, the clinical value of silver-111 is further enhanced by the existence of the positron-emitting counterpart silver-103, thus imparting a truly theranostic potential to this element. A so-fitting matching pair could potentially overcome the current limitations associated with the forced use of chemically different isotopes as imaging surrogates of lutetium-177, leading to more accurate and efficient diagnosis and treatment. However, the use of silver-111-based radiopharmaceuticals in vivo has faced obstacles due to the challenges related to its production and radiochemical separation from the target material. To address these issues, this study aims to implement a chromatographic separation methodology for the purification of reactor-produced silver-111. The ultimate goal is to achieve a ready-to-use formulation for the direct radiolabeling of tumour-seeking biomolecules. A two-step sequence chromatographic process was validated for cold Ag-Pd separation and then translated to the radioactive counterpart. Silver-111 was produced via the 110Pd(n,γ)111Pd nuclear reaction on a natural palladium target and the subsequent β−-decay of palladium-111. Silver-111 was chemically separated from the metallic target via the implemented chromatographic process by using commercially available LN and TK200 resins. The effectiveness of the separations was assessed by inductively coupled plasma optical emission spectroscopy and γ-spectrometry, respectively, and the Ag+ retrieval was afforded in pure water. Recovery of silver-111 was > 90% with a radionuclidic purity > 99% and a separation factor of around 4.21·10−4. The developed separation method was suitable to obtain silver-111 with high molar activity in a ready-to-use water-based formulation that can be directly employed for the labeling of radiotracers. By successfully establishing a robust and efficient production and purification method for silver-111, this research paves the way for its wider application in targeted radionuclide therapy and precision imaging.

中文翻译：

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中子辐照钯靶材中银 111 的色谱分离：直接标记放射性示踪剂

Silver-111 是一种很有前途的 β 发射放射性同位素，具有靶向放射性核素治疗和相关单光子发射断层扫描成像的理想特性。其衰变特性与临床上确定的镥 177 非常相似，使其成为治疗应用的有吸引力的候选者。此外，正电子发射对应物银103的存在进一步增强了银111的临床价值，从而赋予该元素真正的治疗潜力。如此合适的匹配对可能会克服目前强制使用化学上不同的同位素作为镥 177 成像替代物的局限性，从而实现更准确、更有效的诊断和治疗。然而，由于银111放射性药物的生产和与目标材料的放射化学分离相关的挑战，其在体内的使用面临着障碍。为了解决这些问题，本研究旨在实施色谱分离方法来纯化反应器生产的银 111。最终目标是实现用于直接放射性标记肿瘤寻找生物分子的即用型制剂。两步序列色谱法经过验证可用于冷银-钯分离，然后转化为放射性对应物。Silver-111 是通过天然钯靶上的 110Pd(n,γ)111Pd 核反应以及随后钯 111 的 β- 衰变产生的。使用市售的 LN 和 TK200 树脂，通过实施的色谱过程，将 Silver-111 从金属靶材中化学分离。分别通过电感耦合等离子体发射光谱法和 γ 能谱法评估分离的有效性，并在纯水中进行 Ag+ 回收。银 111 的回收率 > 90%，放射性核素纯度 > 99%，分离因子约为 4.21·10−4。所开发的分离方法适合在即用型水基配方中获得具有高摩尔活性的银111，可直接用于放射性示踪剂的标记。通过成功建立稳健高效的银111生产和纯化方法，该研究为其在靶向放射性核素治疗和精密成像中的更广泛应用铺平了道路。