^(99)Tc^m-RC-160的制备及其生物活性分析

Preparation and Analysis on Biological Activity of ^(99)Tc^m-RC-160

分别以抗坏血酸钠和酒石酸亚锡为还原剂,用直接标记法制备^(99)Tc^m-RC-160。采用抗坏血酸钠为还原剂时,标记率为45％;酒石酸亚锡为还原剂时,标记率为68％。其最佳标记条件为:酒石酸亚锡用量为500μg,反应温度为90℃,反应时间为30min。标记物经HLB小柱纯化后,放化纯度>95％;放置4h后,其放化纯度仍>95％。用Cystein将^(99)Tc^m从标记肽中置换出50％所需浓度为50mmol/L。这表明其体内外稳定性较好。标记物与受体有较高的亲和力(K_d=0.83±0.09 nmol/L,B_(max)=45±3nmol/g)。

RC-160 (Vapreotide) is labeled with 99Tcm by a direct method and the biological activity of 99Tcm-RC-160 is identified by combined with somatostatin receptor. The labeling yield is about 45% using sodium ascorbate as reductant; the labeling yield is 68% using stannous tartrate as reductant. The radiochemical purity of 99Tcm-RC-160 is more than 95% after purification through HLB cartridge; it is still more than 95% after 4 hours. The concentration of cysteine used to replace 50% 99Tcm from 99Tcm-RC-160 is 5 mmol/L, so that the internal and external stability of 99Tcm-RC-160 is good. 99Tcm-RC-160 have high affinity with somatostatin receptor (Kd = 0. 83 + 0. 09 nmol/L,Bmax = 45 + 3 nmol/g).