A highly sensitive nitric oxide biosensor based on hemoglobin-chitosan/graphene-hexadecyltrimethylammonium bromide nanomatrix

Nitric oxide (NO) is a key signaling molecule in different physiological processes of plants. It is therefore very important to establish a simple, fast, sensitive and accurate detection method for NO detection. In this study, a novel amperometric biosensor based on immobilization of hemoglobin (Hb), chitosan (CS), graphene (GR) and the surfactant hexadecyltrimethylammonium bromide (CTAB) on a glassy carbon electrode was constructed to quantitatively measure NO. Atomic force microscopy, scanning electron microscopy and electrochemical methods were used to characterize the Hb-CS/GR-CTAB nanocomposite film. The biosensor fabricated from the nanocomposite film showed direct electrochemistry with a fast electron-transfer rate (60.3 s(-1)) and high electrocatalytic activity towards the reduction of NO. Under optimal conditions, the resulting biosensor exhibited a high sensitivity of 615 mu A mM(-1), a low detection limit of 6.75 x 10(-9) M (S/N = 3) and a small apparent Michaelis-Menten constant of 0.315 mu M. These results were superior to those for biosensors based on the graphite, GR/ionic liquid and carbon nanotubes. The biosensor was also used successfully for detection of additional NO in oilseed rape leaf homogenate samples. Furthermore, the biosensor had excellent long-term storage stability, as well as reproducibility and selectivity, and should have a potential application in monitoring NO in plant samples. (C) 2012 Elsevier B.V. All rights reserved.