Electrocatalytic Response of Dopamine at a Metallothioneins Self-Assembled Gold Electrode

Abstract

The metallothioneins (MT) self-assembled monolayer modified gold electrode (MT/Au) is demonstrated to catalyze the electrochemical response of dopamine (DA) by cyclic voltammetry. A pair of well-defined redox waves was obtained and the calculated standard rate constant (k_s) is 6.97 × 10^-3 cm s^-1 (20°C) at the self-assembled electrode. The electrode reaction is a quasi-reversible process. The oxidation peak of DA can be used to determine the concentration of DA. The peak current and the concentration of DA follow a linear relationship in the range of 2.0 × 10^-5 M to 8.0 × 10^-4 M. The detection limit is 6.0 × 10^-6 M. By ac impedance spectroscopy, the apparent electron transfer rate constant (k_app) of Fe(CN)₆^3-/Fe(CN)₆^4- at the MT/Au electrode was obtained as 2.0 × 10^-5 cm s^-1. The MT/Au was characterized with grazing angle FT-IR spectroscopy and contact angle goniometry.