Detection of cancer biomarker CA15-3 in serums by label-free immunosensor based on multiwall-carbon nanotube/doped-poly (2-chloroaniline)

Breast cancer is a prevalent and leading cause of death among women worldwide. In this study, we developed an electrochemical immunosensor using a composite of HClO4-doped poly(2-chloroaniline) (dP2ClAn) and multiwalled carbon nanotubes (MWCNT). The composite was coated layer-by-layer onto a screen-printed electrode (SPE) to monitor CA15-3 levels. Anti-CA15-3 antibodies were successfully immobilized on the dP2ClAn-MWCNT composite through physical adsorption without a crosslinking agent, where bovine serum albumin (BSA) was used to prevent nonspecific binding. The immunosensor performance was evaluated using differential pulse voltammetry (DPV), where the concentration of CA15-3 was related to the current response with a power law from to the antigen-antibody immunocomplex acting as an insulator; as the CA15-3 concentration increased, the current decreased. The immunosensor demonstrated excellent performances within the range of 5-100 U center dot mL- 1, with a limit of detection (LOD) of 0.66 U center dot mL- 1, and a sensitivity of 254.67 mu A center dot mL center dot U-1 center dot cm- 2. Additionally, testing with real serum samples (n = 10) produced results comparable to those obtained using the conventional ELISA method. The immunosensor exhibited excellent electrode stability (4 weeks), reproducibility, and selectivity relative to interferences, making it a reliable single-use device. It is a potential alternative route to replace the expensive and complex laboratory-based traditional CA15-3 diagnostic.