3.1.3. CNT amount
Since its discovery in 1991, CNTs have been used in various applications. Combination with electrode materials for fabricating chemical sensors or biosensors is a growing area. CNTs have an outstanding ability to mediate fast electron-transfer kinetics for a
wide range of electroactive species, such as hydrogen peroxide, NADH or mediators [39,40]. In this work, the influence of the CNT amount on the amperometric biosensor response was tested between 0.2 and 0.7 mg/ml of CNT solutions in 1.0% of CHIT. The response of the bienzymatic biosensor was almost constant with 0.5 mg/ml of CNT
modification. When the concentration of CNT was increased, a sharp drop in the response was observed. This might be due to the restricted diffusion of oxygen towards the electrode as well as restricted diffusion of substrate from the electrode (data not shown).