Microfluidic Immunoarray for Point-of-Care Detection of Cytokines in COVID-19 Patients

The "cytokine storm" often induced in COVID-19 patients contributes to the onset of "acute respiratory distress syndrome" (ARDS) accompanied by lung infection and damage, multiorgan failure, and even death. This large increase in pro-inflammatory cytokines in blood may be related to severity. Rapid, on-demand cytokine analyses can thus be critical to inform treatment plans and improve survival rates. Here, we report a sensitive, low-cost, semiautomated 3D-printed microfluidic immunoarray to detect 2 cytokines and CRP simultaneously in a single 10 μL serum sample in 25 min. Accuracy was validated by analyzing 80 COVID-19 patient serum samples, with results well correlated to a commercial Meso Scale protein immunoassay. Capture antibodies immobilized in detection microwells in a flat well plate-type flow chamber facilitate the immunoassay, with a programmable syringe pump automatically delivering reagents. Chemiluminescence signals were captured in a dark box with a CCD camera integrated for 30 s. This system was optimized to detect inflammation biomarkers IL-6, IFN-γ, and CRP simultaneously in blood serum. Ultralow limits of detection (LODs) of 0.79 fg/mL for IL-6, 4.2 fg/mL for CRP, and 2.7 fg/mL for IFN-γ with dynamic ranges of up to 100 pg/mL were achieved. ROC statistical analyses showed a relatively good diagnostic value related to the samples assigned WHO COVID-19 scores for disease severity, with the best results for IL-6 and CRP. Monitoring these biomarkers for coronavirus severity may allow prediction of disease severity as a basis for critical treatment decisions and better survival rates.