A functionalized heterobimetallic<sup>99m</sup>Tc/Re complex as a potential dual-modality imaging probe: synthesis, photophysical properties, cytotoxicity and cellular imaging investigations
作者:Alison François、Céline Auzanneau、Valérie Le Morvan、Chantal Galaup、Hannah S. Godfrey、Louise Marty、Alexandre Boulay、Marine Artigau、Béatrice Mestre-Voegtlé、Nadine Leygue、Claude Picard、Yvon Coulais、Jacques Robert、Eric Benoist
DOI:10.1039/c3dt51968f
日期:——
A novel bimodal fluorescent/radiolabelled probe based on a pyridyltriazole scaffold (known as pyta) is reported here. The final dual imaging agent combines carboxylate functionalization, for biomolecule conjugation, with two distinct metal chelating sites: a pyta-based tricarbonylrhenium moiety as a fluorescent probe and a 99mTc(CO3)+ core through the tridentate chelating iminodiacetic acid (IDA) clamp as a SPECT reporter. The heterodinuclear 99mTc/Re complex 8, as well as its non-radioactive dirhenium analog 7, was prepared in six steps. The 99mTc/Re agent is water-soluble and stable against histidine challenge. Its structural characterization was achieved by HPLC comparison with the non-radioactive complex 7. Upon excitation in the MLCT band at 321 nm, the compound 7 exhibits a bright green luminescence centered at 496 nm, with a quantum yield of 0.86% in Tris buffer, pH 7.4. Additionally, the influence of this compound on cell viability was tested on malignant cell lines (A549, HT29 and MCF-7 human lung, colon and breast carcinomas, respectively). Cell viability after 72 h incubation at 37 °C with 300 μmol of complex 7 was >60% for all cell lines. Finally, cellular uptake studies of compound 7 were performed by fluorescent microscopy, showing that the complex was clearly detected at the cellular level in A549 cells and to a lesser extent in HT29 cells. Taking into consideration the luminescent properties, the good radiochemical purity and the promising biological data (in vitro stability, non-toxicity, and cell tracking in two cell lines), the functionalized 99mTc/Re dinuclear compound 8 can be considered a potential pre- and intraoperative diagnostic probe.
本文报道了一种基于吡啶基三唑骨架(称为pyta)的新型双模态荧光/放射性标记探针。最终的双重成像试剂结合了羧酸盐功能化(用于生物分子缀合)和两种不同的金属螯合位点:基于pyta的三羰基铼部分作为荧光探针,以及通过三齿螯合的亚氨基二乙酸(IDA)夹钳的99mTc(CO3)+核心作为SPECT报告器。异双核99mTc/Re配合物8及其非放射性双铼类似物7在六步反应中制备。99mTc/Re试剂水溶性良好且对组氨酸具有稳定性。其结构表征通过高效液相色谱与非放射性配合物7进行比较实现。在321 nm的MLCT带激发下,化合物7在496 nm处显示出明亮的绿色发光,在Tris缓冲液(pH 7.4)中的量子产率为0.86%。此外,在恶性细胞系(分别是人肺A549、结肠HT29和乳腺癌MCF-7)上测试了该化合物对细胞活力的影响。在37°C下与300 μmol的配合物7共同孵育72小时后,所有细胞系的细胞活力均>60%。最后,通过荧光显微镜进行了化合物7的细胞摄取研究,显示该配合物在A549细胞中清晰可见,在HT29细胞中程度较小。考虑到其发光特性、良好的放射化学纯度和有前景的生物数据(体外稳定性、无毒性以及在两种细胞系中的细胞追踪),功能化的99mTc/Re双核化合物8可被视为潜在的术前和术中诊断探针。