Simultaneous determination of CXCL7 chemokine and MMP3 metalloproteinase as biomarkers for rheumatoid arthritis

This paper reports the preparation of the first dual electrochemical immunosensor for the simultaneous determination of the CXCL7 chemokine and the MMP3 metalloproteinase as relevant biomarkers for the better diagnosis and monitoring of rheumatoid arthritis derived from the multiple biomarkers measurement. The developed immunosensor involves the use of carboxylated magnetic beads (MBs) and dual screen-printed carbon electrodes (SPdCEs). Sandwich-type configurations implied the covalent immobilization of specific anti-CXCL7 (cAb1) or anti-MMP3 (cAb2) capture antibodies onto MBs and the use of biotinylated detection antibodies with further labelling with HRP-Strept conjugates. The resulting MBS bioconjugates were magnetically captured on the respective working electrode of the SPdCE and the determination of the antigens was accomplished by measuring the amperometric responses of H2O2 mediated by hydroquinone (HQ) at a potential value of −0.20 V. The dual immunosensor provided calibration plots with linear ranges between 1 and 75 ng mL−1 (CXCL7) (R2 = 0.997) and from 2.0 to 2000 pg mL−1 (MMP3) (R2 = 0.998) with detection limits of 0.8 ng mL−1 and 1.2 pg mL−1, respectively. The assay took 2 h 20 min for the simultaneous determination of both biomarkers. The dual immunosensor was successfully applied to the analysis of human serum from positive and negative RA patients.