Quantitative and Ultrasensitive Detection of Four Inflammatory Biomarkers by Gold Nanoparticle-Based Paper Sensor

Due to the complexity and diversity of infectious diseases, diagnosis based solely on symptoms and imaging manifestations is associated with a high rate of misdiagnosis, so it is particularly important to find reliable and accurate biomarkers. Four inflammatory biomarkers (CRP, IL-6, PCT and SAA) have different manifestations and roles in different infectious diseases and stages of infection, and the diagnosis and identification of infectious diseases can be realized through quantitative analysis of these four biomarkers simultaneously. In this study, we developed a colloidal gold nanoparticle (AuNP)-based multiplex LFA strip using eight highly-sensitive monoclonal antibodies that simultaneously detected CRP, IL-6, PCT and SAA in serum within 15 min. And quantitative analysis was achieved with a portable strip reader, the LODs were 2.5 μg/mL, 25.3 pg/mL 0.87 ng/mL and 8.8 μg/mL for CRP, IL-6, PCT and SAA, while detection ranges were 2.5–200 μg/mL, 25.3–8000 pg/mL 0.87–100 ng/mL and 8.8–200 μg/mL. Moreover, the quantitative colloidal gold assay correlated well with the results of a chemiluminescence immunoassay when testing clinical serum samples. Our developed method was reliable and accurate according to the recovery test results. Therefore, the strip can be used as an alternative method for the simultaneous monitoring of CRP, IL-6, PCT and SAA in serum samples.