Electrochemical detection of a breast cancer susceptible gene using cDNA immobilized chitosan-co-polyaniline electrode

An electrochemical breast cancer biosensor based on a chitosan-co-polyaniline (CHIT-co-PANI) copolymer coated onto indium–tin-oxide (ITO) was fabricated by immobilizing the complementary DNA (cDNA) probe (42 bases long) associated with the breast cancer susceptible gene BRCA1. Both the CHIT-co-PANI/ITO and the cDNA/CHIT-co-PANI/ITO electrodes were characterized with Fourier transform infrared (FTIR) spectroscopy, atomic force microscopy (AFM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). For the cDNA/CHIT-co-PANI/ITO electrode, the amperometric current decreased linearly with an increasing logarithm of molar concentration of the single-stranded target DNA (ssDNA) within the range of 0.05–25 fmol. The bioelectrode exhibited a sensitivity of 2.104 μA/fmol with a response time of 16 s. The cDNA/CHIT-co-PANI/ITO electrode had a shelf life of about six months, even when stored at room temperature.