Multiwalled carbon nanotubes noncovalently functionalized by electro-active amphiphilic copolymer micelles for selective dopamine detection

We have synthesized an electro-active amphiphilic copolymer with carbazole side chains via free radical polymerization using 7-(4-vinylbenzyloxy)-4-methyl coumarin and 9-(4-vinylbenzyl)-9H-carbazole as the monomers. The copolymer can self-assemble to form micelles (termed EACMs) in aqueous solution and can adsorb onto the surfaces of MWCNTs via pi-pi interactions and thereby cause the efficient dispersion of the MWCNTs in aqueous solution. The coumarin groups in the copolymer undergo UV-induced photo-crosslinking, which further improves the stability of the suspension. Moreover, the electro-active carbazole moieties in the EACMs can undergo electropolymerization to form a conducting network on the MWCNTs that significantly accelerates electron transfer. The EACM/MWCNTs hybrid was applied to the amperometric sensing of dopamine (DA) as a model analyte. After electropolymerization, the electrode exhibited good sensitivity and selectivity toward the determination of dopamine with a 0.2 mu M detection limit and a wide linear range. The method described here provides a viable route to water-dispersible and stable carbon nanotubes while preserving their outstanding electrical properties. We presume that the composite described here represents a valuable tool for the construction of electrochemical sensors and electronics.