A superoxide dismutase mimic nanocomposite for amperometric sensing of superoxide anions

AuthorsFariba Dashtestani, Hedayatollah Ghourchian, Khadijeh Eskandari, Hossain Ali Rafiee Pour
JournalMicrochemica Acta
Page number1045–1053
Volume number182
Paper TypeFull Paper
Published At2014
Journal GradeISI
Journal TypeTypographic
Journal CountryAustria

Abstract

A nanocomposite consisting of gold nanoparticles and the copper(II) complex of cysteine (GNP/Cu-Cys) is shown to represent a useful mimic for the enzyme superoxide dismutase (SOD). The relative activities of plain GNPs, Cu metal, Cys, Cu-Cys and GNP/Cu-Cys were determined and compared to those of native SOD. The value for half-maximal inhibitory concentration of the nanocomposite is 0.3 μg mL‾1 which is 3 times higher than that of the native enzyme. The GNPs/Cu-Cys nanocomposite was immobilized on a carbon paste electrode and used as a biomimetic sensor for the detection of superoxide anions. The resulting sensor has a linear range over the concentration range from 3.1 to 326 μM, a detection limit of 2.8 μM (at an S/N of 3), and a sensitivity of 0.018 μA μM.cm−2. The selectivity for superoxide anions over potential interferents such as hydrogen peroxide, uric acid and citric acid is excellent.