Amperometric Biosensors Based on Biotinylated Single-Walled Carbon Nanotubes

One challenging goal for the development of biosensors is the conception of three dimensional biostructures on electrode surfaces. In this context, single-walled carbon nanotube coatings (SWCNTs), functionalized by biotin groups, were investigated to develop 3D conductive nanostructures allowing a post-functionalization by biological macromolecules. This specific anchoring of biomolecules was carried via the affinity interactions using the avidin-biotin system. For this purpose, a biotinylated pyrene was specially synthesized to develop a non-covalent functionalization based on -interactions between pyrene and the nanotube sidewall. SWCNT coatings were also biotinylated via electropolymerization of biotin-pyrrole derivatives at 0.95 V in CH₃CN electrolyte. The resulting biotinylated SWCNTs were modified by an avidin protein via affinity interactions and characterized with scanning electron microscopy. The biofunctionalization by a biotinylated glucose oxidase (GOX) was performed by successive incubation in avidin and GOX aqueous solutions via avidin bridges. The efficiency of the enzyme anchoring was examined through the electro-enzymatic activity of the modified electrodes towards the detection of glucose at 0.7 V versus SCE. The glucose sensitivity and maximum current density were 1.6 mAM⁻¹cm⁻² and 131 Acm⁻² respectively for pyrene biotin-SWCNTelectrode and 2.5 mAM⁻¹cm⁻² and 178 Acm⁻² respectively for the poly(pyrrole biotin)-SWCNT.