In situ cationic ring-opening polymerization and quaternization reactions to confine ferricyanide onto carbon nanotubes: a general approach to development of integrative nanostructured electrochemical biosensors.

This study demonstrates a new and relatively general route to the development of multiwalled carbon nanotube (MWNT)-based integrative electrochemical biosensors by confining ferricyanide redox mediator onto MWNTs. The ferricyanide-confined MWNTs are synthesized first through grafting of epoxy chloropropane onto MWNTs with in situ cationic ring-opening polymerization and then introducing the positively charged methylimidazolium moieties into the grafted polymer with a quaternization reaction. The grafted polymers with positively charged methylimidazolium moieties tethered onto MWNTs can essentially be used to confine redox-active ferricyanide onto MWNTs to form a redox mediator-confined nanocomposite with a good stability and excellent electrochemical property. The synthetic nanocomposite with surface-confined ferricyanide is demonstrated to be well-competent as the efficient electronic transducers for the general development of electrochemical biosensors upon combination with biorecognition units, which is illustrated by using glucose oxidase and laccase as two model biorecognition units. This study essentially paves a facile and general approach to the development of integrative nanostructured electrochemical biosensors.