Nanostructured polyaniline–silicon substrate for protein biosensing

Polyaniline (PAni) has been electrochemically deposited on a silicon (Si) substrate to form thin nanostructured films of around 50 nm thickness. These films have been modified with avidin, followed by the immobilization of biotinylated anti-human IgG to form a sensing bioelectrode. The deposited PAni thin films on the Si substrate have been characterized by electron and atomic force microscopy. Successful immobilization of the biomolecules has been confirmed by Raman spectrometric studies. The current–voltage characteristics of the prepared sensor are exploited for the determination of human IgG antigen in the concentration range of 5–550 μg mL−1. The proposed biosensorʹs detection limit and sensitivity are 5 μg mL−1 and 0.15 μS ppm−1 human IgG, respectively.