The CNT fibre (figure 1a; click on the image to enlarge) is spun directly from a chemical vapour deposition (CVD) reaction and consists of double-walled CNTs self-assembled into nanobundles that are organized into multiple concentric nanolayers. It resembles a scaled-down multistranded electric wire and has a nanoscale surface topography and porosity (figure 1b). The CNT bundles at the end of the fibre are unwound to form a brush-like structure that can be used as an electrode for glucose biosensing (figure 1c).

The individual CNT bundles within the brush-like end act as multi-nanoelectrodes that facilitate the efficient capture and promotion of electron transfer reactions, as well as increase the electro-active surface area for enzyme immobilization. The Brunel team designed and fabricated the amperometric glucose biosensor by immobilizing glucose oxidase at the brush-like end of the CNT fibre.

Implantable future

Owing to its small size, high electrochemical activity, excellent physical properties, low density and biocompatibility, the CNT fibre has huge potential for implantable applications for continuous monitoring of clinically relevant analytes, including glucose (to aid the control of diabetes), lactate, antibodies and antigens. Other areas of interest include the analysis of analytes in bioreactors, veterinary and clinical chemistry, the food industry and environmental science.

Currently the Brunel team is addressing the long-term ex vivo and in vivo stability of the CNT-fibre-based glucose biosensors, and exploring other biosensor applications for CNT fibres.

More details can be found in the journal Nanotechnology.