Electrospun Carbon Nanofiber Supports for Bioelectrodes

A high surface-area electrospun carbon nanofiber (CNF) support for bioelectrodes is introduced to enhance enzyme utilization.¹ This study employed Glucose Oxidase (GOx) in redox hydrogel system, which mediated electron transfer via Osmium (Os²⁺/Os⁺) centers, to create a glucose bioelectrode. The strategy was to enhance the transport of electrons via the redox mediator by reducing the average hydrogel thickness at fixed hydrogel volume. The tunable electrospun carbon fiber enables of hydrogel film thickness of hydrogel film by uniform distribution on small fibers. Glucose oxidizing current density made from electrospun carbon nanofiber and several commercial counterparts suggest a possibility for a cheap fibers, in a diameter range below100 nm, that enable high current density (~8.5 mA cm^-2) comparable to carbon nanotubes (CNTs).

To adjust electrospun CNF size, varied concentrations of Polyacrylonitrile (PAN)/ Dimethylformamide (DMF) precursor solution (7 wt% to 14 wt%) was spun in a high voltage field prior to oxidation stabilization and carbonization in Argon environment at two temperatures, 850°C and 1100°C.² Graphiticity of CNFs was improved with the increasing heat treatment temperature (shown by Raman spectroscopy), leading to higher conductivity of bioelectrode. CNFs based on 7 wt% PAN/DMF carbonized at 1100°C had a diameter of 150 nm (Figure 1b), a decrease from the 250 nm PAN fiber (Figure 1a), and showed good performance in electrochemical characterization compared to MWCNTs electrode (Figure 2).

Acknowledgement

We thank Buckeye Composites Inc. and Pyrograf Products Inc. for providing material samples.

Reference

(1)       Wen, H.; Nallathambi, V.; Chakraborty, D.; Calabrese Barton, S. Carbon Fiber Microelectrodes Modified with Carbon Nanotubes as a New Support for Immobilization of Glucose Oxidase. Microchim. Acta 2011, 175, 283–289.

(2)       Bhardwaj, N.; Kundu, S. C. Electrospinning: A Fascinating Fiber Fabrication Technique. Biotechnol. Adv. 2010, 28, 325–347.