Ak. Abass et Jp. Hart, Direct electrochemistry of cytochrome c at plain and membrane modified screen-printed carbon electrodes, ELECTR ACT, 46(6), 2001, pp. 829-836
Screen-printed carbon electrodes (SPCEs), both plain and modified with a po
lycarbonate membrane, have been investigated as base transducers to study t
he electrochemistry of cytochrome c in phosphate buffer; cyclic voltammetry
was used for all studies. It is proposed that the plain SPCE behaves as an
array of microelectrodes, therefore mass transport occurs by radial diffus
ion and a sigmoidal response is obtained. When a polycarbonate membrane is
attached to the SPCE the voltammogram is peak shaped indicating a change fr
om radial to linear diffusion. It is suggested that the membrane acts as a
'solid state promoter', which increases the density of active sites for ele
ctron transfer to the heme centre of the metalloprotein. In this case, the
distance between sites of electron transfer decreases with the result that
diffusion layers overlap and a linear diffusion model prevails. Possible me
chanisms of interaction of cytochrome c with surface active sites are postu
lated. (C) 2001 Elsevier Science Ltd. All rights reserved.