صدیقه هاشم نیا

The present study was aimed at investigating the use of a mixture multiwall carbon nanotube (MWCNT) and thionine (Th) dye in designing of a thionine-based electrochemical biosensor containing catalase (Ct) enzyme (MWCNT-Nafion-Th/Ct) onto a glassy carbon electrode (GCE). The effects of pH, MWCNT concentration and thionine concentration on electrochemical response were explored for optimum analytical performance. The modified electrode exhibited a pair of well-defined, quasi-reversible peaks at formal potential (E?) = -0.218 ± 0.017 V vs. Ag/AgCl corresponding to the Thox/ Thred redox couples in the presence of MWCNT, Nafion, and Ct. The electrochemical parameters, including charge-transfer coefficient (0.36), and apparent heterogeneous electron transfer rate constant (4.28 ± 0.26 s-1) were determined. Using differential pulse voltammetry, the prepared enzyme electrode exhibited a linear response to hydrogen peroxide (H2O2) in the range of 10.0-100.0 ?M with a detection limit 8.7 ?M and a sensitivity of 6051.0 ?AmM-1 cm-2.