The fabrication of a label-free electrochemical immunosensor using Nafion/carbon nanotubes/charged pyridinecarboxaldehyde composite film

A label-free electrochemical immunosensor based on Nafion/carbon nanotubes (CNTs)/charged pyridinecarboxaldehyde composite film was developed for the detection of hepatitis B surface antigen. Nafion/CNTs/charged pyridinecarboxaldehyde nanocomposites were prepared by dispersing charged pyridinecarboxaldehyde and CNTs in Nafion solution. The nanocomposites were cast on the electrode surface to form aldehyde-terminated composite film that can covalently bind antibody on the film without using other reagent. The immunosensor response was linearly changed with hepatitis B surface antigen concentration in the range from 0.1 to 25 ng ml−1 with a detection limit (signal/noise ratio = 3) of 0.04 ng ml−1. Some important advantages such as simple preparation, good stability, reproducibility, and selectivity of the immunosensor were achieved.