Layer-by-layer assembly of poly(p-xylyleneviologen)–DNA multilayers and their electrochemical properties

Multilayers of poly(p-xylyleneviologen) (PXV) and calf thymus DNA were constructed on the gold surface by layer-by-layer (LBL) method. The assembly process was examined by quartz crystal microbalance (QCM) measurements. According to the frequency change, the average mass increase was estimated to be about 97 and 110 ng/cm2 for each assembly of PXV and DNA layer, respectively. Cyclic voltammograms of the multilayer modified gold electrodes showed a couple of redox peaks, the potentials of which were closely dependent on the layer numbers and nature of the outmost layer. The alternatively assembled DNA layers could hinder formation of π-complex dimer of viologen groups due to the strong interlayer electrostatic interaction. The charge transfer process was discussed by the chronocoulometry method. The assembled PXV–DNA multilayers showed high long-term stability at ambient conditions and in electrolyte solution.