Multiplex FET biosensor with vapor-deposited molecularly imprinted nanotubes for cancer biomarkers

Molecularly imprinted polymer (MIP) interfaces offer antibody-level selectivity without bioreceptor instability, yet their integration into transistor-based sensors remains limited. In this study, we present a novel multiplex field-effect transistor (FET) biosensor platform based on molecularly imprinted polypyrrole (PPy) nanotubes, synthesized through a template-assisted vapor deposition polymerization technique. The molecular imprinting process was employed to create specific recognition sites for the ovarian cancer biomarkers HE4 and CA125, enabling selective and sensitive detection of both biomarkers simultaneously. The molecularly imprinted PPy (MIP) nanotubes were fabricated with high uniformity, as confirmed by scanning electron microscopy (SEM), while Fourier-transform infrared spectroscopy (FTIR) verified the chemical composition. The dual-channel FET showed sensitivities of 0.06 (U ml^-1)^-1for CA125 and 0.22 pM^-1for HE4, limits of detection of 0.4 U ml^-1and 0.2 pM, and linear ranges of 0.1-25 U ml^-1(CA125) and 0.05-10 pM (HE4). Selectivity factors of 11.3 and 23.7 were obtained for the CA125 sensor and the HE4 sensor, respectively, indicating high specificity of the imprinted sensors for their respective target biomarkers. By combining vapor-deposited MIP nanotubes with a compact FET architecture, our work offers a promising route toward early, point-of-care diagnosis through the simultaneous quantification of multiple cancer biomarkers.