FAP和αβ3双靶向分子探针18FAlF-NOTA-FAPI-RGD的制备与标记条件优化

Preparation and Optimization of Radiolabeling Conditions of Targeted Fibroblast Activating Protein and Integrin Receptor Probe 18FAlF-NOTA-FAPI-RGD

  • 摘要: 基于肿瘤细胞及新生血管表面特定受体的高表达,非侵袭性的分子影像可以用短半衰期同位素氟18F标记示踪剂的特异性配体与之结合,通过分子影像的方法活体、无创地监测病变情况,提供特定的肿瘤成像,具有临床应用前景。本研究基于氟铝标记工艺,设计合成了一种新型靶向成纤维细胞激活蛋白(FAP)和整合素受体αβ3的双靶点放射性探针18FAlF-NOTA-FAPI-RGD,通过将无载体的氟18FF加入到含有标记前体NOTA-FAPI-RGD、AlCl3、有机溶剂(乙醇、乙腈、DMSO)和醋酸-醋酸钠缓冲溶液的反应瓶中,振荡摇匀后于80 ℃加热20 min,经Waters Oasis HLB柱纯化和0.22 µm微孔无菌滤膜过滤,制得18FAlF-NOTA-FAPI-RGD。为进一步探索该前体氟铝标记的最佳工艺条件,通过调节溶剂类型、NOTA-FAPI-RGD用量、pH及AlCl3用量等进行条件优化,最终制得的18FAlF-NOTA-FAPI-RGD的未经衰变校正产率为35.0%±5.0%,放化纯度大于90%,且具有良好的稳定性,制剂形式的药品在2~8 ℃放置4 h后放化纯度仍可保持91.71%。以上结果表明该放射性探针有望成为一种新型的高稳定性肿瘤靶向显像剂。

     

    Abstract: Based on the high expression of specific receptors on the surface of tumor cells and neovascularization, non-invasive molecular imaging can be combined with specific ligands labeled with short half-life isotopes 18FF to monitor the lesion, which has the clinical application prospects. Due to the heterogeneity of various tumor biomarkers and complex tumor-matrix interactions, current imaging tracers still need to be improved, to develop a highly sensitive and specific molecular probe which targeting biological markers that are overexpressed in tumors. Small molecule-based heterodimeric radiotracer is a promising direction for future development. In this paper a dual targeting radioactive probe, 18FAlF-NOTA-FAPI-RGD, was designed and synthesized based on fluoaluminum labeling technology, leveraging the high expression of tumor-specific receptors on cancer cell surfaces and neovasculature, which targeted fibroblast activation protein (FAP) and integrin αβ3. To further investigate the procedural conditions for fluorine aluminum labeling, non-carrier-added 18FF was introduced into reaction vials containing the labeled precursor NOTA-FAPI-RGD, AlCl3, organic solvents (ethanol, acetonitrile, DMSO), and an acetic acid-sodium acetate buffer solution. The mixture was homogenized by vigorous shaking and heated at 80 ℃ for 20 min. Subsequently, 18FAlF-NOTA-FAPI-RGD was obtained through purification using a Waters Oasis HLB column and sterile filtration through a 0.22 µm microporous membrane. During labeling process optimization, key reaction parameters were systematically investigated. Solvent screening reveals that acetonitrile is the optimal condition in facilitating Al-F bond formation, with its high polarity and low coordination capacity. pH optimization via orthogonal experiments identified an optimal range of 4.0-4.5 using an acetic acid-sodium acetate buffer, balancing aluminum ion stability and ligand structural integrity. In addition, precursor quantity and AlCl3 quantity were explored through dose titration, that demonstrated 50 μg of NOTA-FAPI-RGD precursor and 20 nmol/L AlCl3 promote the peak labeling efficiency. After radiolabeling, the non-decay-corrected yield of 18FAlF-NOTA-FAPI-RGD is determined to be 35.0%±5.0%, with a radiochemical purity exceeding 90% and exhibiting excellent stability. The radiochemical purity of pharmaceutic preparation is still retained 91.71% after place in 2-8 ℃ for 4 h. The above results indicate that the radioactive probe has the potential to be a novel and high stability tumor targeted imaging agent. This dual-targeting design could enhance tumor localization accuracy and diagnostic sensitivity, it holds significant promise for early diagnosis and treatment monitoring of tumors, offering a powerful tool for precision oncology and advancing molecular imaging capabilities.

     

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