基于核酸适配体和量子点的胃癌靶向成像研究

Targeted imaging of gastric cancer based on aptamer and quantum dots

目的构建一种基于适配体W3和量子点(QD)的探针W3-QD,实现胃癌细胞系和临床胃癌组织的靶向成像。方法通过流式细胞术检测核酸适配体W3与SGC-7901细胞的结合情况;采用生物素-链霉亲和素的交联方法,将核酸适配体W3与QD偶联形成W3-QD,利用荧光染色观察W3-QD探针对胃癌细胞SGC-7901以及混合细胞中SGC-7901的成像情况;分别采用FAM-W3和QD-W3对SGC-7901细胞进行成像,结果显示QD探针具有更高的灵敏度和光稳定性;构建荷瘤裸鼠模型探究W3-QD探针对体内肿瘤细胞的靶向成像情况;收集临床胃癌组织样本,通过组织石蜡切片及荧光染色证明W3-QD探针对胃癌组织具有特异性识别能力。结果W3-QD探针能够对胃癌细胞SGC-7901进行特异性成像,且在人类正常胃黏膜上皮细胞GES-1存在的情况下,仍然能够在混合细胞中特异性识别胃癌细胞SGC-7901。与FAM-W3探针相比,W3-QD探针表现出良好的抗漂白性、稳定性和灵敏性。W3-QD对胃癌细胞和组织有良好的特异性。结论将核酸适配体W3与QD结合能够实现胃癌的靶向成像,可作为一种胃癌早期诊断的工具。

Objective To construct a molecular probe for targeted imaging of gastric cancer based on aptamer W3 and quantum dots.Methods The binding of aptamer W3 to SGC-7901 cells was detected by flow cytometry.A quantum dot probe(W3-QD)was formed by coupling the aptamer W3 with a quantum dot by the biotin-streptavidin cross-linking method.The imaging of the W3-QD probe on gastric cancer cells SGC-7901 and SGC-7901 in mixed cells was observed by fluorescence staining.FAM-W3 and QD-W3,respectively,were used to image SGC-7901 cells which proved that the quantum dot probe had higher sensitivity and photostability.A tumor-bearing nude mouse model was constructed to investigate the targeting imaging of tumor cells by W3-QD probe.Clinical gastric cancer tissue samples were collected.Paraffin sections and fluorescent staining proved that the W3-QD probe had specific recognition ability for gastric cancer tissue.Results W3-QD probe can perform specific imaging on gastric cancer cell SGC-7901 while specifically recognizing gastric cancer cell SGC-7901 in the mixed cells mucosal epithelial cells GES-1.Compared with FAM-W3 probe,W3-QD probe showed good bleaching resistance,stability,and sensitivity.W3-QD showed good specificity to gastric cancer cells/tissues.Conclusion The combination of aptamer W3 and quantum dots can achieve targeted imaging of gastric cancer,and can be used as a tool for early diagnosis of gastric cancer.