As a natural response to a stressful situation, the human body produces cortisol. For this reason, cortisol is also called “the stress hormone” and is considered to be the principal stress biomarker. Although cortisol response to stress is essential for survival, abnormal levels in biological fluids may represent serious health risks. In this work, we present a cortisol biosensor which relies on a highly sensitive technique (surface-enhanced Raman spectroscopy, SERS) and a specific recognition (immunoassay). Gold nanostars were used as SERS nanotags, since they provide a better response than nanorods or nanospheres. Using the same concept, two different immunoassay modalities were evaluated, using either magnetic beads or gold-coated glass slides decorated with cortisol antibodies, as the capture substrates. The magnetically-assisted SERS immunoassay presented a better performance and was therefore selected to quantify cortisol content in biological fluids (urine and serum). Significant advantages of this assay were found over standard methods such as Ultra Performance Liquid Chromatography-Mass Spectrometry (UPLC-MS) and Enzyme-Linked Immunosorbent Assay (ELISA), including higher sensitivity and repeatability, minimum sample preparation, simplicity, and portability. Therefore, the proposed SERS immunoassay might be implemented as a highly efficient tool for in situ monitoring of human stress levels and cortisol-related disorders (e.g. Cushing's syndrome and Addison's disease).

作为对压力状况的自然反应，人体会产生皮质醇。因此，皮质醇也被称为“压力激素”，被认为是主要的压力生物标志物。尽管皮质醇对压力的反应对于生存至关重要，但生物体液中异常含量可能代表严重的健康风险。在这项工作中，我们提出了一种皮质醇生物传感器，它依赖于高度敏感的技术（表面增强拉曼光谱，SERS）和特异性识别（免疫测定）。金纳米星被用作SERS纳米标签，因为它们提供的响应比纳米棒或纳米球更好。使用相同的概念，使用磁珠或装饰有皮质醇抗体的镀金玻片作为捕获底物，评估了两种不同的免疫测定方法。磁辅助SERS免疫测定具有更好的性能，因此被选择用于定量生物液（尿液和血清）中的皮质醇含量。与标准方法（如超高效液相色谱-质谱法（UPLC-MS）和酶联免疫吸附测定（ELISA））相比，该测定法具有显着优势，包括更高的灵敏度和可重复性，最少的样品制备，简便性和便携性。因此，建议的SERS免疫测定法可作为一种高效工具用于就地监测人类压力水平和皮质醇相关疾病（例如库欣综合征和艾迪生病）。与标准方法（如超高效液相色谱-质谱法（UPLC-MS）和酶联免疫吸附测定（ELISA））相比，该测定法具有显着优势，包括更高的灵敏度和可重复性，最少的样品制备，简便性和便携性。因此，建议的SERS免疫测定法可作为一种高效工具用于就地监测人类压力水平和皮质醇相关疾病（例如库欣综合征和艾迪生病）。与标准方法（如超高效液相色谱-质谱法（UPLC-MS）和酶联免疫吸附测定（ELISA））相比，该测定法具有显着优势，包括更高的灵敏度和可重复性，最少的样品制备，简便性和便携性。因此，建议的SERS免疫测定法可作为一种高效工具用于就地监测人类压力水平和皮质醇相关疾病（例如库欣综合征和艾迪生病）。