Direct Electrochemistry of Cytochrome c Based on Poly(diallyldimethylammonium Chloride)- Graphene Nanosheets/Gold Nanoparticles Hybrid Nanocomposites and Its Biosensing

A novel biosensor was developed by entrapping cytochrome c (Cyt c ) in thin films of the room temperature ionic liquid (RTIL) containing nanocomposites of poly(diallyldimethylammonium chloride)-graphene nanosheets-gold nanoparticles (PDDA-Gp-AuNPs) at a 11-mercaptoundecanoic acid-6-mercapto-1-hexanol modified gold electrode. The synthesized PDDA-Gp-AuNPs hybrid nanocomposites were characterized by UV-vis spectroscopy, Raman spectroscopy, scanning electron microscopy and atomic force microscopy. The PDDA-Gp-AuNPs nanocomposites could increase the effective surface of the electrode, enhance the fixed amount of Cyt c on the electrode surface, promote the electron transfer and facilitate the catalytic activity of Cyt c . The RTIL could provide a biocompatible microenvironment to keep Cyt c biological activities, act as an effective mediator to immobilize a large number of Cyt c on the electrode and have good conductivity to improve electron transfer. Therefore, the resultant electrode exhibited good electrochemical performance and electrocatalytic activity. It could be used for electrochemical detection of H 2 O 2 with rapid response, high sensitivity, wide linear range and low detection limit, as well as good stability, repeatability and selectivity. The sensor might be promising for practical application.