降钙素原(Procalcitonin, PCT)对于反映患者炎症甚至败血症患病程度具有重要意义。为实现低浓度PCT的免标记检测, 利用极大倾角光纤光栅(Excessively Tilted Fiber Grating, Ex-TFG)的低温度交叉敏感性和高折射率灵敏度的优点, 在光纤的表面修饰金黄色葡萄球菌(Staphylococcus Aureus Protein A, SPA), 再将PCT单克隆抗体固定在SPA分子层, 从而构成对PCT具有特异性检测功能的免疫传感器。实验结果表明: 降钙素原含量为0.5ng/mL时, 谐振波长红移约13pm; PCT的浓度为200ng/mL时, Ex-TFG的红移量基达约125pm; 浓度为1000ng/mL时, 红移量趋于饱和, 最大红移量约150pm。通过对实验数据拟合, 发现Ex-TFG谐振波长的红移量与PCT浓度之间的关系满足Langmuir模型, 相关性系数为0.98。该方法为低浓度PCT的检测提供了一种免标记、快速的检测方法。

Procalcitonin (PCT) plays an important role as the factor to reflect patients’ inflammation or sepsis degree. In order to reach a low concentration detection of PCT with label free method, proposed was a type of PCT immunosensor based on excessively tilted fiber grating (Ex-TFG) which is insensitive to temputere but sensitive to refractive index. Staphylococcus aureus Protein A (SPA) was used to modify the surface of Ex-TFG, then highly purified PCT monoclonal antibodies (MAbs) were immobilized on Ex-TFG’s surface through SPA molecules, so as to form the immunosensor which is specific to PCT. Experimental results show that the wavelength shift is about 13pm when PCT concentration is 0.5ng/mL, and it becomes to be 125pm with the concentration of PCT increasing to 200ng/mL. What’s more, the immunosensor becomes saturated at ~1000ng/mL, and the corresponding wavelength shift is about 150pm. Finally, by fitting the experimental data, it demonstrats that the fitting line meets the Langmuir model function with a corelated coefficient of 0.98.