Simultaneous electrochemical immunosensing of relevant cytokines to diagnose and track cancer and autoimmune diseases.

[Display omitted] • First dual immunoplatform for simultaneous determination of BAFF and APRIL cytokines. • Improved sensitivity and much shorter assay time compared with ELISA kits. • Patients with systemic lupus erythematosus or colorectal cancer can be discriminated. This work reports the first dual magnetic beads (MBs) assisted immunoplatform for the simultaneous determination of BAFF (B cell activation factor) and APRIL (a proliferation-induced ligand), two cytokines related to immunity and tumour invasion, growth and metastasis. The electrochemical immunoplatform involves sandwich-type immunoassays implemented on magnetic microparticles functionalized with neutravidin (NA-MBs) or carboxylic groups (HOOC-MBs), and amperometric detection (E app = − 0.20 V vs. Ag pseudo-reference electrode) at screen-printed dual carbon electrodes (SPdCE) using the H 2 O 2 /hydroquinone (HQ) system. The developed immunosensors provide improved sensitivity, with LOD values of 0.33 and 16.4 pg mL−1 for BAFF and APRIL, respectively, and much shorter assay time that those claimed for ELISA kits and allow their simultaneous determination. The dual immunosensor permits discrimination between healthy individuals and patients diagnosed with Systemic Lupus Erythematosus (SLE) or colorectal cancer (CRC) through the determination of both cytokines in 100-times diluted human sera with results in agreement with those provided by the individual ELISA methodologies. [ABSTRACT FROM AUTHOR]