Nanocellulose-modified electrodes for simultaneous biosensing of microbiome-related oral diseases biomarkers

The preparation of a dual immunosensor for the simultaneous determination of two important microbiome-related oral disease biomarker matrix metalloproteinases MMP-9 and MMP-13 is reported. Screen-printed dual carbon electrodes (SPdCEs) modified with reduced graphene oxide and crystalline nanocellulose (rGO/CNC) were used for the immobilization of specific capture antibodies and the implementation of sandwich-type immunoassays using biotinylated secondary antibodies. Amperometric detection through the hydroquinone HQ/H₂O₂ system was employed. The limits of detection (LOD) achieved were 0.25 and 0.30 ng mL^-1 for MMP-9 and MMP-13, respectively. The developed immunosensor proved to be useful for the determination of both MMPs in saliva from healthy individuals and patients of periodontitis as well as in serum from patients diagnosed with rheumatoid arthritis (RA) and chronic obstructive pulmonary disease (COPD). The obtained results agreed with those provided by commercial ELISA kits, and the developed dual immunosensor proved to be competitive versus this methodology, requiring less than 2 h for the simultaneous determination of both biomarkers.