Combined detection of C-reactive protein and PBMC quantification from whole blood in an integrated lab-on-a-disc microfluidic platform

There is an increasing need for portable and low-cost diagnostic devices for detecting inflammatory/infectious diseases in a rapid and user-friendly fashion. Here, we present a lab-on-a-disc solution, which performs automated sample pre-treatment and combinedly detects small molecules and counts cells in a whole blood sample with a volume of 8.75 μL with a sample to answer time of 14 min. It is used to detect two common inflammation/infection biomarkers, C-reactive protein (CRP) and peripheral blood mononuclear cell (PBMC) count. The whole blood sample was separated into plasma and PBMC fractions using density gradient centrifugation and centrifugo-pneumatic valving. On-disc CRP detection was performed in the extracted plasma using a CRP-antibody-functionalized magnetic nanobead (MNB)-based agglutination assay and a Blu-ray-based optomagnetic detection unit. On-disc PBMC scanning and quantification was performed using an optical imaging unit. Both detection units were integrated on the centrifugal platform and the entire study was automated in order to ensure reliability of the assay and user-friendliness of the method. We measured the CRP level of subjects with different CRP levels and obtained approximately 73% PBMC extraction efficiency compared to hospital results. The concurrent/combined detection of these two common biomarkers in an automated microfluidic platform with integrated detection units and with a low sample-to-answer time is a significant step forward towards a low-cost, out-of-lab, and portable tool to detect multiple biomarkers of significantly different nature (molecules and cells).