探讨¹³¹Ⅰ标记肝癌核酸适配子JHIT2（¹³¹Ⅰ-JHIT2）作为肝癌靶向显像新型分子探针的可行性。

采用Ⅰodogen法制备¹³¹Ⅰ-JHIT2，纸层析法测标记率及放射化学纯度（放化纯度），检测其在不同溶液中不同时间的放化纯度。采用γ计数器分别测定¹³¹I-JHIT2与人肝癌细胞HepG2、正常肝细胞L02结合后细胞的放射性计数。HepG2荷瘤裸鼠尾静脉注射约0.74 MBq¹³¹Ⅰ-JHIT2后不同时间处死，测定并计算各脏器每克组织放射性摄取值、肿瘤/肌肉（T/M）放射性比值。荷瘤裸鼠尾静脉注射约9.25 MBq ¹³¹Ⅰ-JHIT2后单光子发射计算机断层成像术（SPECT）-CT显像，观察并计算不同时间肿瘤/非肿瘤（T/NT）比值。两种细胞放射性计数比较采用t检验。

¹³¹Ⅰ-JHIT2标记率为（67.8±0.5）%，纯化后放化纯度为（91.4±1.1）%。室温下¹³¹Ⅰ-JHIT2在PBS、生理盐水24 h的放化纯度均>80%。¹³¹Ⅰ-JHIT2分别与两种细胞结合后，HepG2细胞的放射性计数为（415±9）CPM，明显高于L02细胞的（288±7）CPM（t=15.3，P<0.05）。尾静脉注射¹³¹Ⅰ-JHIT2后，荷瘤鼠体内30 min、2 h肿瘤部位每克组织放射性摄取值分别为（4.17±2.83）、（2.22±0.64）%ID/g，T/M比值相应为2.01±1.15、2.07±0.82。SPECT-CT显像示，荷瘤裸鼠注射¹³¹Ⅰ-JHIT2后30 min，肿瘤部位可见放射性摄取，T/NT比值为2.63；2 h放射性减低，T/NT比值为1.82。

¹³¹Ⅰ-JHIT2探针在体外稳定性较好，对体外HepG2细胞及HepG2细胞荷瘤裸鼠模型具有一定靶向作用，为肝癌靶向核素诊疗奠定一定的基础。

To investigate the feasibility of ¹³¹I-labeled hepatoma aptamer JHIT2 (¹³¹I-JHIT2) as a novel molecular probe for hepatoma-targeted imaging.

The ¹³¹I-JHIT2 was prepared by Iodogen method. The labeling rate and radiochemical purity were measured by paper chromatography. The radiochemical purity of ¹³¹I-JHIT2 was detected in different solutions at different time points. The radioactivity count of ¹³¹I-JHIT2 after combining with human hepatoma HepG2 and normal liver cell L02 was measured by gamma counter. The HepG2 tumor-bearing nude mice were sacrificed at different time points after caudal venous injection of approximately 0.74 MBq ¹³¹I-JHIT2. The percentage of radioactivity uptake value and tumor/muscle (T/M) radioactivity ratio per 1 g tissues of each organ were measured and calculated. Single-photon emission computed tomography (SPECT)-CT imaging was performed after caudal venous injection of approximately 9.25 MBq ¹³¹I-JHIT2 in tumor-bearing nude mice. The tumor/non-tumor (T/NT) ratio was observed and measured at different time points. The radioactive count was statistically compared between two types of cells by t test.

The labeling rate of ¹³¹I-JHIT2 was (67.8±0.5)%, and the radiochemical purity after purification was (91.4±1.1)%. The radiochemical purity of ¹³¹I-JHIT2 in PBS or normal saline at room temperature for 24 h was both above 80%. After ¹³¹I-JHIT2 combining with two types of cells, the radioactive count of HepG2 cells was (415±9) CPM, significantly higher than (288±7) CPM of L02 cells (t=15.3, P<0.05). At 30 min and 2 h after caudal venous injection of ¹³¹I-JHIT2, the percentage of radioactivity uptake value per 1 g tumor tissue in tumor-bearing mice was (4.17±2.83) and (2.22±0.64) %ID/g, and the T/M ratio was 2.01±1.15 and 2.07±0.82. SPECT-CT imaging demonstrated that radioactive uptake was observed at the tumor site in tumor-bearing nude mice and the T/NT ratio was 2.63 at 30 min after ¹³¹I-JHIT2 injection. The radioactivity decreased at 2 h, and the T/NT ratio was 1.82.

¹³¹I-JHIT2 probe possesses relatively high stability in vitro, and has certain targeting capacity towards HepG2 cells in vitro and HepG2 tumor-bearing nude mouse model, which lays certain foundation for the targeted radionuclide diagnosis and treatment of liver cancer.