Layer-by-layer assembled carbon nanotubes for selective determination of dopamine in the presence of ascorbic acid.

Multilayer films of shortened multi-walled carbon nanotubes (MWNTs) are homogeneously and stably assembled on glassy carbon (GC) electrodes using layer-by-layer (LBL) method based on electrostatic interaction of positively charged poly(diallyldimethylammonium chloride) (PDDA) and negatively charged shortened MWNTs. The assembled MWNT multilayer films were studied with respect to the electrocatalytic activity toward ascorbic acid (AA) and dopamine (DA) and were further applied for selective determination of DA in the presence of AA. Scanning electron microscopy (SEM) used for characterization of MWNT films indicates that the assembled MWNTs are almost in a form of small bundles or single nanotubes on the electrodes. Cyclic voltammetric results with assembled MWNT electrode indicate that the strategy based on the LBL method for assembling the MWNT multilayer films on substrate well retains the electrochemical catalytic activity of the MWNTs toward AA and DA, offering some advantages particularly attractive for analytical applications, such as the form of MWNTs assembled on the substrate, i.e., small bundles or single tubes, homogeneity and stability of the as-assembled MWNT films. These features make the assembled MWNTs relatively potential for selective and sensitive determination of DA in the presence of AA.