氧化石墨烯集成极大倾角光纤光栅LSPR的癌症标记物传感器

Cancer biomarker sensor based on graphene oxide-integrated excessively tilted fiber grating LSPR

提出了一种基于氧化石墨烯(GO)集成极大倾角光纤光栅(ExTFG)的局域表面等离子体共振(Local Surface Plasmon Resonance,LSPR)免疫传感器,用于对癌症标志物——细胞程序性死亡-配体1(PD-L1)的无标记和特异性检测。利用大尺寸(粒径约为165 nm)金纳米壳(AuNs)作为LSPR载体固定在光纤表面,然后再将GO涂敷于光纤表面来改善ExTFG-LSPR传感器的疏水特性,以增强传感器对生物分子蛋白的吸附能力,最后将PD-L1单克隆抗体(anti-PD-L1MAbs)通过共价键结合在光纤表面GO的羧基端用于PD-L1的特异性检测。实验结果表明:该免疫传感器对磷酸盐缓冲液中PD-L1抗原的检测范围为0.038~38.46 pmol/L,在0~2 pmol/L的低浓度区保持着良好的线性度,灵敏度约达0.114 nm/(pmol·L^(-1)),对PD-L1抗原的检测极限低至约0.076 pmol/L,解离系数约为2.801×10^(-12)mol/L;当用于不同的健康血清样本和肝细胞癌(HCC)血清样本的临床免疫检测,对前者的响应极其微弱,而对后者具有明显的响应。因此,该免疫传感器在复杂血清环境下对PD-L1标记物具有良好的临床特异性,具有较大的应用潜力。

This study proposed a graphene oxide(GO)-integrated excessively tilted fiber grating(ExT⁃FG)local surface plasmon resonance(LSPR)immunosensor for the label-free and specific detection of the cancer biomarker programmed cell death-ligand 1(PD-L1).First,large-sized(165 nm)gold nanoshells were used as LSPR carriers to be immobilized on the fiber surface;then,GO was coated on the fiber surface to improve the hydrophobic properties of the ExTFG-LSPR sensor to enhance the sensor's ability to adsorb biomolecular proteins.Finally,anti-PD-L1 monoclonal antibodies were covalently bound to the carboxyl terminal of the GO on the fiber surface for the specific detection of PD-L1.Experimental results showed that the detection range of the immunosensor for PD-L1 antigens in phosphate buffer is 0.038–38.46 pmol/L,exhibiting suitable linearity in the low concentration region of 0–2 pmol/L with a sensitivity of approximately 0.114 nm/(pmol·L^(-1)).The detection limit of the immunosensor for the PDL1 antigen dissolved in phosphate buffer is as low as approximately 0.076 pmol/L,and the dissociation co⁃efficient is approximately 2.801×10^(-12) mol/L.When the immunosensor was used in clinical immunoas⁃says with different healthy serum samples and hepatocellular carcinoma serum samples,its responses to the former were extremely weak but were noticeable toward the latter,indicating that it had suitable clini⁃cal specificity for PD-L1 in complex serum environments and thus showed potential for clinical application.