Diffusional Electrochemistry of Cytochrome c on Mixed Captopril/3-Mercapto-1-propanol Self-Assembled Monolayer Modified Gold Electrodes

Abstract

Well-defined, quasi-reversible, and diffusion controlled electrochemistry of cytochrome c (cyt c) has been observed at a gold electrode modified with a novel mixed captoptil/3-mercapto-1-propanol self-assembled monolayer (SAM) in ail aqueous solution. An exchange rate constant of 1.4 x 10(-3) cm/s, ail electron transfer coefficient of 0.52, a diffusion coefficient of 7.8 x 10(-7) cm(2)/s, an apparent number of electrons transferred of 0.98, and formal potential of 0.076 V vs AglAgCl (in saturated KCl) were obtained for the reaction from complete kinetic and thermodynamic analyses of the impedance data obtained using Fourier transform electrochemical impedance spectroscopic experiments. The differential Pulse voltammetric peak currents show ail excellent linearity with the cyt c concentration in a range of 5.0 x 10(-6) to 5.0 x 10(-4) M at the mixed SAM modified gold electrode.