单克隆抗体ND-1-量子点荧光探针对大肠癌细胞的特异成像研究

目的制备抗人大肠癌单克隆抗体ND-1的量子点荧光探针,实现对大肠癌细胞的靶向成像。方法采用共价偶联方法,以1-乙基-(3-二甲基氨基丙基)碳酰二亚胺盐酸盐(EDC)和N-羟基硫代琥珀酰亚胺(NHS)为缩合剂,通过在反应体系中加入不同摩尔比例的单克隆抗体ND-1和游离量子点QD605进行条件优化,制备偶联产物ND-1-QD605荧光探针;利用荧光光谱扫描技术对ND-1-QD605进行光学特性表征,并检测其抗光漂白能力;利用免疫荧光方法检测ND-1-QD605对大肠癌细胞的靶向结合能力。结果在量子点QD605与单克隆抗体ND-1摩尔比1:40条件下,可实现二者的高效偶联;荧光光谱分析显示ND-1-QD605保留了游离量子点QD605优良的荧光特性;在激发光照射1h内,ND-1-QD605荧光强度未发生明显改变;荧光显微镜观察可见该探针能够与表达有相应抗原LEA的人大肠癌CCL187细胞特异性结合,呈现高灵敏度、特异性荧光成像。结论制备的单克隆抗体ND-1的量子点荧光探针具有大肠癌细胞靶向成像能力,有望为大肠癌的体内靶向成像研究和临床诊断提供新方法。

Specific Imaging of Colorectal Cancer Cells using Quantum Dots Probes Conjugated with ND-1 Monoclonal Antibodies

Objective To prepare the immuno-conjugate ot INI0-1 monoclonat antlt}octy ann quantum dots for targeted fluorescent imaging of colorectal cancer ceils. Methods ND-1, a monocional antibody a- gainst human colorectal cancer cells, was covalently coupled to QD605 at differnet ratios using EDC and NHS to optimize the conjugating condition. The obtained QD-linked conjugate was analyzed by fluorespec- trophotometry to characterise its optical properties and anti-photobleach ability. Immunofluorescence as- say was utilized to observe the targeted imaging of the probe. Results A high coupling efficiency was a- chieved at 1：40 molar ratio of QD605 to ND-1 rnonoclonal antibodies. The fluorescence spectrum showed lhat NI）1 QD605 had similar fluorescent property to free QD, and the fluorescence intensity-time curves showed no significant intensity change during lh of continuous illumination at 488nm. The fluorescence im- ages demonstrated that ND-1-QD605 was able to specifically bind and image colorectal cancer cells which expressed large external antigens （LEA）. Conclusion The results indicate that the QD-linked conjugate can be used to detect cancer cells owing to its ability of targeted binding and imaging, This is a novel approach for studying targeted imaging of colorectal cancer in vivo and clinical diagnosis.