Biosensor for total antinuclear antibody determination at the point-of-care

Antinuclear antibodies (ANA) are important in diagnosis and follow-up of patients with autoimmune conditions. The current increase in ANA requests is driven by broadening the use of ANA from a test for lupus to a test for diverse autoimmune diseases, but the standard method is protracted, cumbersome and prone to error. We describe an electrochemical method for quantifying total ANA for use as a point-of-care diagnostic aid. In this technology the target autoantigens are derived from a protein nucleoprotein mixture prepared from an inexpensive source and adsorbed to a porous membrane with high protein binding capacity. Serum is slowly drawn through the membrane comprising the high density auto antigen mixture to induce rapid binding of patient autoantibodies. After rinsing, peroxidase-conjugated anti-IgG is drawn through the membrane followed by rinsing, insertion of an electrode assembly, and addition of the enzyme substrate. Substrate peroxidation is measured by microamperage-level current accompanying electrochemical reduction of the intermediate product. Values are comparable to a standard ANA test but require a total processing time of similar to 20 min. This method has the promise to greatly expand ANA testing in clinical settings for initial patient assessment of autoimmune disease. (C) 2016 Elsevier B.V. All rights reserved.