Myoglobin-clay electrode for nitric oxide (NO) detection in solution

Sodium montmorillonite was prepared via a colloidal chemical approach and deposited onto glassy carbon electrodes (GCE). Myoglobin was immobilized on the clay membrane modified electrode by spontaneous adsorption. Characterization of the myoglobin/clay/glassy carbon electrode (Mb/clay/GCE) showed a quasi-reversible, electrochemical redox behavior of the adsorbed protein with a formal potential of -0.380 +/- 0.010 V (vs. Ag/AgCl). The heterogeneous electron transfer rate constant was found to be strongly influenced by the buffer concentration. The Mb/clay/GCE was stable for several days in solution. The interaction of the immobilized Mb with nitric oxide (NO) is characterized by coordination chemistry. The reaction was found to be reversible and could be applied for NO detection in the nanomolar concentration range by a voltammetric analysis. In addition a mixed protein electrode with co-immmobilized myoglobin (Mb) and cytochrome c (Cyt.c) was developed. By choice of the electrode potential both proteins can be addressed independently.