Label-free electrochemiluminescence immunosensor for mucoprotein 1 using a graphene oxide-Ru(Bpy)₃²⁺-polyaniline nanocomposite

A graphene oxide-Ru(bpy)(3)(2+)-polyaniline-nanocomposite (GO-Ru(bpy)(3)(2+)-PANI) was prepared to develop a sensitive label-free electrochemiluminescence (ECL) immunosensor for mucoprotein 1 (MUC1). Ru(bpy)(3)(2+) and PANI were decorated together on graphene oxide for the first time. The GO-Ru(bpy)(3)(2+)-PANI material was characterized by scanning electron microscopy (SEM), absorption spectroscopy, Fourier transform infrared spectroscopy (FTIR), fluorescence, electrochemical impedance spectroscopy (EIS), and ECL. The GO-Ru(bpy)(3)(2+)-PANI exhibited excellent stability. The ECL immunosensor for MUC1 was fabricated by covalently immobilizing anti-MUC1 upon GO-Ru(bpy)(3)(2+)-PANI modified indium-doped tin oxide (ITO) electrode. In the presence of MUC1, a decrease of ECL was observed due to the formation of the anti-MUC1/MUC1 complex. The immunosensor showed a linear relationship from 1 x 10(-13) to 1 x 10(-7 )mg/mL with a detection limit of 8.2 x 10(-14 )mg/mL. The immunosensor was applied to the determination of MUC1 in human serum.