Integration of amine-functionalized magnetic reduced graphene oxide and Fe3O4-MWCNTs-NH2 nanocomposites for highly sensitive CA 15-3 breast cancer biomarker detection in a sandwich-type electrochemical immunosensor

This study reports the electrochemical detection of breast cancer marker CA 15-3 using a sandwich-type immunosensor. Amine-functionalized composite of reduced graphene oxide and Fe3O4 nanoparticles (MRGO-NH2) was used as a platform material to modify the electrodes. Amine functionalized nanocomposite of Fe3O4 NPs and multiwalled carbon nanotubes (Fe3O4-MWCNTs-NH2) was used as a signal amplifying label. Both these nanocomposites were prepared by using a linker-free approach. The amine groups on the nanocomposites were employed as a binding site for the antibodies. The MRGO-NH2 platform offered an improved electrochemical performance owing to the synergistic effect of the high conductivity of the RGO and redox activity of the Fe3O4 nanoparticles (NPs). In the Fe3O4-MWCNTs-NH2 label, MWCNTs provided a high surface area to load Fe3O4 NPs and secondary antibodies. Whereas, Fe3O4 NPs offered high electrocatalytic activity in the context of H2O2 reduction, thereby amplifying the signal. The reported electrochemical immunosensor showed good analytical performance in the range 0.0005 to 100 U mL−1 of CA 15-3 with a detection limit of 0.0001 U mL−1. Furthermore, the immunosensor demonstrated acceptable selectivity, reproducibility, and stability. The developed immunosensor was validated using serum samples of breast cancer patients.