Chitosan Bio-Functionalization of Carbon Nanotube Arrayed Electrode

Nanostructured electrodes enable a new generation of electrochemical sensors by increasing their surface area that lead to
stronger signals generated by electrochemically-active molecules, such as diagnostic redox-active biomarkers. Yet, the
selectivity of these translational sensors is far from being sufficient for discriminating between individual molecules in
multicomponent samples, such as biofluids. Here, we propose an approach to improve the selectivity of nanostructured
electrodes using a simple modification with a functional bio-polymer. Specifically, we demonstrate the targeted modification
with a bio-polymer chitosan of carbon nanotubes organized in an array on a Au electrode. We describe the fabrication
process and we show the characterization of the structural morphology and the electrochemical activity of the fabricated
chitosan-modified carbon nanotube arrayed electrode. Electrochemical characterization yielded an increased effective surface
area for the optimized carbon nanotube arrayed electrode (0.46 ± 0.03 cm2
) that was similar to the area of the unmodified Au
electrode (0.48 ± 0.02 cm2
). Furthermore, despite decreased electrochemical current characteristics, we demonstrate the
feasibility to modify individual carbon nanotubes with chitosan. The modification of the carbon nanostructures with chitosan
will enable further functionalization with specific receptors, such as enzymes and antibodies that will provide the required
selectivity towards biomarkers in multicomponent biofluids.