Nanophotonics and Metrology Laboratory (NAM), Swiss Federal Institute of Technology Lausanne (EPFL), 1015 Lausanne, Switzerland.
Biosensors (Basel). 2018 Mar 30;8(2):34. doi: 10.3390/bios8020034.
C-reactive protein (CRP) is one of the most expressed proteins in blood during acute phase inflammation, and its minute level increase has also been recognized for the clinical diagnosis of cardio vascular diseases. Unfortunately, the available commercial immunoassays are labour intensive, require large sample volumes, and have practical limitations, such as low stability and high production costs. Hence, we have developed a simple, cost effective, and label-free electrochemical immunoassay for the measurement of CRP in a drop of serum sample using an immunosensor strip made up of a screen printed carbon electrode (SPE) modified with anti-CRP functionalized gold nanoparticles (AuNPs). The measurement relies on the decrease of the oxidation current of the redox indicator Fe/Fe, resulting from the immunoreaction between CRP and anti-CRP. Under optimal conditions, the present immunoassay measures CRP in a linear range from 0.4-200 nM (0.047-23.6 µg mL), with a detection limit of 0.15 nM (17 ng mL, S/N = 3) and sensitivity of 90.7 nA nM, in addition to a good reproducibility and storage stability. The analytical applicability of the presented immunoassay is verified by CRP measurements in human blood serum samples. This work provides the basis for a low-priced, safe, and easy-to-use point-of-care immunosensor assay to measure CRP at clinically relevant concentrations.
C-反应蛋白（CRP）是急性炎症期间血液中表达量最高的蛋白质之一，其微量水平的增加也已被用于心血管疾病的临床诊断。然而，现有的商业免疫分析方法劳动强度大，需要大量的样本体积，并且存在实际限制，如稳定性低和生产成本高。因此，我们开发了一种简单、经济高效且无需标记的电化学免疫分析方法，用于使用由抗 CRP 功能化金纳米粒子（AuNPs）修饰的丝网印刷碳电极（SPE）制成的免疫传感器条在一滴血清样本中测量 CRP。该测量依赖于 CRP 和抗 CRP 之间的免疫反应导致氧化还原指示剂 Fe/Fe 的氧化电流降低。在最佳条件下，本免疫分析方法在 0.4-200 nM（0.047-23.6 µg mL）的线性范围内测量 CRP，检测限为 0.15 nM（17 ng mL，S/N = 3），灵敏度为 90.7 nA nM，此外还具有良好的重现性和储存稳定性。通过对人血清样本中的 CRP 进行测量，验证了所提出的免疫分析的分析适用性。这项工作为在临床相关浓度下测量 CRP 的低成本、安全且易于使用的即时检测免疫传感器分析提供了基础。
