Sensitive determination of breast cancer biomarker, CA 15-3, using a label free electrochemical aptasensor based on palladium nanoparticles decorated carbon nanofibers.

This study introduces an electrochemical aptasensor for the sensitive determination of the breast cancer biomarker, carbohydrate antigen 15-3 (CA 15-3). The aptasensor was fabricated by modifying a glassy carbon electrode (GCE) with carbon nanofibers (CNFs) and electrodepositing palladium nanoparticles (PdNPs) on it. CNFs provide a large surface area and active sites for the subsequent electrodeposition of PdNPs. Moreover, PdNPs provide binding sites for attachment of aptamers through coordinate bonds between Pd and amino groups. The fabrication process was monitored using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The assay is based on the difference in charge transfer resistance (Rct) before and after CA 15-3 binding. Using the EIS technique, a linear concentration range of 1.0 × 10-2 - 200.0 U mL⁻1 and a detection limit of 7.8 × 10-3 U mL⁻1 were obtained for CA 15-3. Furthermore, its clinical utility was confirmed through successful analysis of human serum samples, with results correlating well with the standard ELISA method.