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

• Total autoantibodies in human sera were measured electrochemically in only 20 min
• The sensor showed good quantitative correspondence to the standard immunofluorescence assay on sera from patients.
• Biosensor assessment regarding assay reproducibility, storage stability, and exclusion of contaminants was highly favorable.
• This device has the promise to shift current practice from centralized laboratories to patient-centered environments.

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 autoantigen 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 ~20 min. This method has the promise to greatly expand ANA testing in clinical settings for initial patient assessment of autoimmune disease.