基于表面增强拉曼光谱的结肠癌组织免疫分析

Surface-Enhanced Raman Scattering Spectroscopic Assay of Immunohistochemically Stained Human Colon Cancer Tissue

通过表面增强拉曼散射(SERS)标记抗体检测结肠癌组织切片上癌胚抗原(CEA)的表达,探讨SERS标记免疫检测技术用于临床分析结肠癌组织切片中蛋白质表达的可行性。采用种子生长法合成Ag壳Au核复合纳米粒子,将4-巯基苯甲酸(4-MBA)作为标记分子吸附于纳米粒子表面,制备出SERS探针;再将这种探针与CEA单克隆抗体相结合形成SERS免疫探针;最后通过SERS标记的抗体与结肠癌组织切片上相应的抗原发生特异性结合,对滴加探针的组织切片进行SERS检测和成像。结肠癌腺上皮出现很强的SERS信号,而除了少数非特异性吸附产生的信号之外,间质及正常上皮中几乎不出现SERS信号。通过SERS成像可以清晰地看到结肠癌腺上皮显示红色,表明结肠癌腺上皮高表达CEA,而间质及正常上皮几乎显示黑色和深蓝色,只有极个别点为红色,表明间质及正常上皮基本不表达CEA。研究表明,SERS标记抗体检测分析技术具有高灵敏度和高特异性,有望应用于结肠癌组织切片中蛋白质表达的分析,成为结肠癌辅助诊断的一种重要方法。

To explore the feasibility of surface-enhanced Raman scattering （SERS） labeled immunoassay technology for clinical analysis protein expression in colon cancer tissue sections, we develop 4-mercaptobenzoic acid （4-MBA） labeled Au/Ag core-shell nanoparticles （NPs） as assay platform for the detection of carcinoembryonic antigen （CEA） in colon cancer tissue samples. Firstly, Raman active molecule 4-MBA is adsorbed on Ag shell Au core bimetallic NPs, and then the SERS-tagged nanoprobes are modified with CEA monoclonal antibody, forming CEA-SERS probes. Finally, according to the theory of specific binding of SERS-tagged antibody and the corresponding antigen, SERS spectra and imaging are performed in tissue sections after dropping the SERS-tagged immuno-nanoprobes. Data show that colon cancer epithelium appears strong SERS signals, while stroma and normal epithelium do not appear SERS signals, except a few non-specific adsorption signals. As can be clearly seen from the SERS images, the colon cancer epithelium highly expresses CEA, while stroma and normal epithelium do not. In conclusion, due to high sensitivity and high specificity of SERS-tagged immuno-nanoprobes, the SERS labeled immunoassay technology is promising for the analysis of the protein expression in colon cancer tissue sections and has the potential to be developed into a significant aiding tool for pathological diagnosis of colon cancer.