Impedimetric Detection of Breast Cancer‐Related <scp>BRCA1</scp> Gene Using Molecular Imprinted Polymer Modified <scp>ITO</scp> Electrode

ABSTRACT Early detection of breast cancer, the leading cause of death among women, is crucial for diagnosis and monitoring during treatment. This study presents a highly sensitive and selective aptasensor designed to detect the BRCA1 gene biomarker in phosphate buffer solution and human serum samples. The sensor was developed by electropolymerizing o ‐phenylenediamine with the BRCA1 gene as the monomer and template, respectively, to create a molecularly imprinted polymer (MIP) receptor film on an ITO electrode surface. Microscopic techniques were employed to thoroughly characterize both the non‐imprinted polymer (NIP) and the MIP films, before and after the removal of the template. Electrochemical impedance spectroscopy (EIS) was used to measure changes in charge transfer resistance (Δ R ct ), which enabled the construction of calibration curves. As the concentration of BRCA1 ssDNA increased from 100 aM to 10 pM, a significant decrease in R ct was observed with a detection limit of 30.0 aM for the MIP‐modified electrode. In contrast, the NIP‐modified electrode exhibited negligible Δ R ct within this concentration range. The aptasensor demonstrated excellent selectivity, distinguishing between complementary, three‐base mismatch, and non‐complementary sequences. Moreover, it could sensitively detect BRCA1 ssDNA in spiked human serum samples across a wide concentration range (100 aM to 10 pM) with a low detection limit of 10.0 aM. Analysis of adsorption isotherm diagrams revealed that the imprinted polymer network's cavities and binding sites were uniformly distributed, selectively interacting with high association constants ( K A ) to detect BRCA1 ssDNA over mismatched and non‐complementary ssDNAs. The MIP/ITO aptasensor demonstrated exceptional recovery rates (ranging from 101.5% to 105.2%) along with relatively low standard deviation values (less than 5%). These findings suggest that the developed platform, combining the proposed principle, offers a reliable method for detecting trace amounts of BRCA1 ssDNA in clinical breast cancer samples.