Highly sensitive amperometric biosensor based on electrochemically-reduced graphene oxide-chitosan/hemoglobin nanocomposite for nitromethane determination

Nitromethane (CH 3 NO 2 ) is an important organic chemical raw material with a wide variety of applications as well as one of the most common pollutants. Therefore it is pretty important to establish a simple and sensitive detection method for CH 3 NO 2 . In our study, a novel amperometric biosensor for nitromethane (CH 3 NO 2 ) based on immobilization of electrochemically-reduced graphene oxide (rGO), chitosan (CS) and hemoglobin (Hb) on a glassy carbon electrode (GCE) was constructed. Scanning electron microscopy, infrared spectroscopy and electrochemical methods were used to characterize the Hb-CS/rGO-CS composite film. The effects of scan rate and pH of phosphate buffer on the biosensor have been studied in detail and optimized. Due to the graphene and chitosan nanocomposite, the developed biosensor demonstrating direct electrochemistry with faster electron-transfer rate (6.48 s −1 ) and excellent catalytic activity towards CH 3 NO 2 . Under optimal conditions, the proposed biosensor exhibited fast amperometric response ( 3 NO 2 with a wide linear range of 5 μM~1.46 mM ( R =0.999) and a low detection limit of 1.5 μM ( S / N =3). In addition, the biosensor had high selectivity, reproducibility and stability, providing the possibility for monitoring CH 3 NO 2 in complex real samples.