An electrochemical immunosensor for intraepithelial neoplasia in cervicovaginal lavage using a fullerene-TCNQ...

An electrochemical immunosensor for p16 peptide (p16) was successfully developed for diagnosis of precancerous lesions from samples of cervicovaginal lavage. An increase in p16 expression in these cells is correlated with malignant lesions. Herein, an electrochemical immunosensor is described based on an electrocatalytic buckminsterfullerene (C₆₀) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) complex forming a charge transfer complex associated with polyethylenimine (PEI). The π-π stacking between the quinoid and aromatic rings of TCNQ and C₆₀ provides greater stability and faster electron transfer to the electrode surface, due to the formation of superlattices by intermolecular self-assembly. Anti-p16 antibodies were immobilized on the electrode surface via the amine groups of PEI to specifically detect p16 by square-wave voltammetry. This immunosensor showed a wide linear range from 1 to 10 ng mL^-1 (r = 0.997, p < 0.01) and a real limit of detection of 1.26 ng mL^-1 p16. Ex vivo assays were performed, showing a relationship between p16 levels and the cervical intraepithelial neoplasia grade, making this sensor a promising tool for early diagnosis of cervical cancer. To the best of our knowledge, this is the first electrochemical biosensor for diagnosis of cervical intraepithelial neoplasia by p16 measurements using cervicovaginal lavage samples.