The Combination of Molecularly Imprinted Polymer and Aptamer for Electrochemical Detection of Cancer Antigen 15-3

Cancer antigen 15-3 (CA 15-3) is a crucial biomarker for breast cancer monitoring. Tracking of CA 15-3
levels can aid in assessing treatment effectiveness and detecting disease recurrence. Herein, Molecularly Imprinted Polymer (MIP) and aptamer as recognition elements were developed to perform a sandwich assay for the selective electrochemical detection of CA 15-3. The sensitivity of Screen-Printed Carbon
Electrode (SPCE) was improved by incorporating Multi-Walled Carbon Nanotubes (MWCNTs). Subsequently, MIP was fabricated layer on MWCNTs/SPCE for the initial selective capture of CA 15-3. The signal probe, a CA 15-3-specific aptamer functionalized with a polydopamine-cadmium complex (PDA-Cd-Apt), was then proposed for secondary selective binding to the captured CA 15-3. Additionally, PDA-Cd-Apt
enabled signal generation for electrochemical measurement. Square Wave Voltammetry (SWV) was used to measure electrochemical response of cadmium ions, which was proportional to CA 15-3 concentration. The developed sandwich assay offered a detection range from 5 to 30 U/mL, with a detection limit of 4.44 U/mL. This sensor was suitable for CA 15- 3 detection, offering cost-effectiveness, high sensitivity, simple fabrication, and ease of use.