Noncovalent functionalization of carbon nanotubes with redox active lignin derivatives

Kraft lignin (KL) was adsorbed on multi-wall carbon nanotubes (MWCNTs). After dispersing in dimethylsulfoxide the biopolymer coated MWCNTs formed stable suspensions that could be used to form cast films on glassy carbon electrodes. The composite films after initial oxidation showed redox functions characteristic of quinone moieties. These could be further reacted with thionine (TH) to form a redox active composite with three distinct redox transitions. The eventually obtained nanocomposite showed high catalytic activity toward the electrooxidation of NADH. The obtained results demonstrate the high capability of lignin adsorption on MWCNTs and a possibility of its further modification in order to obtain multifunctional redox active nanocomposites for bioelectrochemical sensing purposes.