Peroxidase-modified cup-stacked carbon nanofiber networks for electrochemical biosensing with adjustable dynamic range

Cup-stacked carbon nanofibers (CSCNFs) were treated with ozone to introduce oxygen-containing groups to the edges of the graphene cups. The O/C atomic ratio at the surface was estimated to be 5.3 x 10(-2). The hydrophilic CSCNFs were used for constructing a three-dimensional network that works both as an electrical nanowire and an enzyme support. Horseradish peroxidase (HRP) molecules were immobilized onto the network for amperometric sensing of H2O2 and inhibition-based sensing of cyanide. Both the upper sensing limit of H2O2 and the upper and lower sensing limits of cyanide were controlled by about two orders of magnitude by changing the HRP coverage.