An electrochemical biosensor for rapid detection of anti-dsDNA antibodies in absolute scale.
Autoimmune diseases are chronic inflammatory pathologies that are characterized by the presence of antibodies against own epitopes in serum (autoantibodies). Systemic lupus erythematosus (SLE) is a common autoimmune pathology, characterized by the presence of antinuclear antibodies (ANAs). These include anti-dsDNA (-dsDNA) antibodies, which are widely used for diagnosis and disease monitoring. Their determination is carried out by traditional techniques such as Indirect Immunofluorescence (IFI) or Enzyme Linked Immunosorbent Assay (ELISA), which are time consuming, require qualified technicians, and are not compatible with decentralized analysis outside a laboratory facility. Here, we show a sandwich-format electrochemical biosensor-based method for -dsDNA determination in a rapid and simple manner. Total assay time is only 30 minutes and the sensor is capable of detecting 16 ng (8 g / mL) of -dsDNA antibodies. Using the current derived from the detection limit of the method as a cut-off, we could discriminate positive from negative serum samples with 90% sensitivity and 100% specificity. By using monoclonal antibodies for calibration curves, our results are presented in absolute scale (i.e., concentration instead of serum title) what will help to perform comparisons between methods and further improvements of this protocol. In an effort to render the sensor compatible with automation, we minimized manipulation steps without compromise of the analytical performance, even in complex samples such as serum.