Synthesis and characterization of ferracarborane–chitosan and ferracarborane–multiwalled carbon nanotube redox mediator conjugates for bioanode applications

Abstract

We present the synthesis and characterization of various ferracarborane derivatives for use as electron transfer mediators in polymer-modified bioanodes. The preliminary objective is to retain the ferracarborane electron transfer mediator at the electrode interface in the polymer film, exploiting the reversible FeIII/II redox chemistry of ferracarborane sandwich complexes. Different methods of anchoring the ferracarborane in the polymer matrix have been established. The first involves covalently tethering the mediator to the polymer backbone while other methods entail the tethering of the mediator to activated multi-walled carbon nanotubes (MWCNTs). The mediator modified carbon nanotubes are then suspended in the polymer matrix. In all cases fabricated thin film electrodes were examined using cyclic voltammetry (CV). Scanning electron microscopy (SEM) images of the ferracarborane–MWCNT/chitosan films were also taken to evaluate their porosity. A comparison is made between the modes of ferracarborane mediator tethering.