Electrochemical Detection of a Breast Cancer Biomarker with an Amine-Functionalized Nanocomposite Pt-Fe₃O₄-MWCNTs-NH₂...

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.