Electrochemical immunosensing of Crohn´s disease biomarkers using diazonium salt grafted - crystalline nanocellulose / carbon nanotubes modified electrodes

This work reports the first dual immunosensor for the determination of IL-12 and IL-23, two relevant biomarkers of Crohn’s disease (CD). The strategy relies on the selective capture of the targets by the respective antibodies which were covalently immobilized onto SPCEs modified with crystalline nanocellulose (CNC) and multi-walled carbon nanotubes (MWCNTs) followed by conjugation with a detector antibody labelled with poly-HRP-Strept and amperometric transduction using the H ₂ O ₂ /HQ system. The developed bioplatform exhibits a high reproducibility and selectivity allowing the simultaneous determination of both biomarkers using a lower sample volume and lasting a much shorter assay time than those reported for each target with commercially available ELISA kits. It is worth highlighting the storage stability of the bioconjugates, which lasts at least 71 days. This excellent performance is probably due to the combination of the CNC properties, mainly its biocompatibility and hydrophilicity, the high surface area and open pore structure, together with the electrochemical properties of MWCNTs, which provide a nanocomposite excellent for biomolecules immobilization onto the transducer surface and electrochemical detection. The suitability and applicability of the dual immunosensor were demonstrated by analyzing raw serum and faeces spiked with IL-12 and IL-23 at the levels that can be found in samples from patients suffering severe CD.