Ferrocene-modified multiwalled carbon nanotubes as building block for construction of reagentless enzyme-based biosensors

A novel amperometric sensor for glucose was constructed by entrapping glucose oxidase (GOD) in a new chitosan composite doped with ferrocene monocarboxylic acid-modified 3-(aminopropyl) triethoxysilane enwrapping multiwalled carbon nanotubes (FMC-AMWNTs). The approach was very simple, timesaving and effectively prevented the leakage of the ferrocene monocarboxylic acid mediator during measurements. The entrapped FMC-AMWNTs composite performed excellent redox electrochemistry and acted as an electron transfer mediator. This matrix showed a biocompatible microenvironment for retaining the native activity of the entrapped GOD and a very low mass transport barrier to the substrate. Under optimal conditions, this biosensor was able to detect glucose in the linear range of 0.01–4.2 mM with a detection limit of 3.4 μM (S/N = 3), the value of KMapp was 6.3 mM. This immobilization approach effectively improved the stability of the electron transfer mediator and is promising for construction of biosensor and bioelectronic devices.