Electrochemical Detection of a Breast Cancer Biomarker with an Amine-Functionalized Nanocomposite Pt–Fe3O4–MWCNTs–NH2 as a Signal-Amplifying Label

We report an ultrasensitive sandwich-type electrochemical immunosensor to detect the breast cancer biomarker CA 15-3. Amine-functionalized composite of reduced graphene oxide and Fe3O4 nanoparticles (MRGO-NH2) was used as an electrochemical sensing platform material to modify the electrodes. The nanocomposite comprising Pt and Fe3O4 nanoparticles (NPs) anchored on multiwalled carbon nanotubes (Pt–Fe3O4–MWCNTs–NH2) was utilized as a pseudoenzymatic signal-amplifying label. Compared to reduced graphene oxide, the composite MRGO-NH2 platform material demonstrated a higher electrochemical signal. In the Pt–Fe3O4–MWCNTs–NH2 label, multiwalled carbon nanotubes provided the substratum to anchor abundant catalytic Pt and Fe3O4 NPs. The nanocomposites were thoroughly characterized using transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. An electroanalytical study and prevalidation of the immunosensor was carried out. The immunosensor exhibited exceptional capabilities in detecting CA 15-3, offering a wider linear range of 0.0005–100 U mL–1 and a lower detection limit of 0.00008 U mL–1. Moreover, the designed immunosensor showed good specificity, reproducibility, and acceptable stability. The sensor was successfully applied to analyze samples from breast cancer patients, yielding reliable results.