Fabrication of an electrochemical immunosensor for α-fetoprotein based on a poly-L-lysine-single-walled carbon nanotubes/Prussian blue composite film interface

Abstract

Single-walled carbon nanotubes functionalized with poly-L-lysine (PLL-SWCNTs) were successfully prepared and were used as a biocompatible platform to immobilize α-fetoprotein antibody (anti-AFP) which was labeled with horseradish peroxidase (HRP). Then, anti-AFP-HRP/PLL-SWCNT nanocomposites were coated onto a Prussian blue (PB) film-modified glassy carbon electrode surface. Glutaraldehyde was used to further stabilize the biosensing interface through a cross-linking step. All unspecific sites were blocked by bovine serum albumin to fabricate a novel electrochemical immunosensor for α-fetoprotein determination. The immunosensor was characterized by voltammetry and electrochemical impedance spectroscopy. Based on the catalytic current response of H2O2, the experimental conditions for α-fetoprotein determination were optimized. Under optimal conditions, the current response was linearly related to α-fetoprotein concentration in the range of 0.05∼10.0 and 10.0∼50.0 ng/mL with a detection limit of 0.011 ng/mL. The immunosensor was successfully used for the determination of α-fetoprotein in human blood plasma. The results were satisfied with that obtained with ELISA, demonstrating a good accuracy of the immunosensor.