A fully automated immunoassay from whole blood on a disc.

A portable, disc-based, and fully automated enzyme-linked immuno-sorbent assay (ELISA) system is developed to test infectious diseases from whole blood. The innovative laser irradiated ferrowax microvalves and centrifugal microfluidics were utilized for the full integration of microbead-based suspension ELISA assays on a disc starting from whole blood. The concentrations of the antigen and the antibody of Hepatitis B virus (HBV), HBsAg and Anti-HBs respectively, were measured using the lab-on-a-disc (LOD). All the necessary reagents are preloaded on the disc and the total process of the plasma separation, incubation with target specific antigen or antibody coated microbeads, multiple steps of washing, enzyme reaction with substrates, and the absorbance detection could be finished within 30 minutes. Compared to the conventional ELISA, the operation time was dramatically reduced from over 2 hours to less than 30 minutes while the limit of detection was kept similar; e.g. the limit of detection of Anti-HBs tests were 8.6 mIU mL(-1) and 10 mIU mL(-1) for the disc-based and the conventional ELISA respectively.