Study of metallothionein modified electrode surface behavior in the presence of heavy metal ions-biosensor

An increasing concentration of heavy metals in the environment is a serious problem for human and animal health protection and production of foodstuffs in many countries around the world. The aim of this paper was to suggest a new heavy metal biosensor based on interaction of metals (cadmium and zinc) with metallothionein, which belongs to group of intracellular, high molecular and cysteine-rich proteins binding heavy metals, using adsorptive transfer stripping (AdTS) differential pulse voltammetry (DPV). Primarily, we studied the electrochemical behavior of MT on the surface of hanging mercury drop electrode by AdTS DPV Perfect coverage of the electrode surface - forming of the surface assembled monolayer - was probably reached in about 240 s for 10 mu M protein concentration. The detection limits of the selected heavy metals (cadmium and zinc), which were analyzed in the presence of the basic electrolyte - 0.5 M NaCl (pH 6.4), were 250 fmol and 350 fmol in 5 mu L drop, respectively. In addition, we applied the biosensor to analyze heavy metals in human body liquids (human blood serum and human urine) and to compare with differential pulse anodic stripping voltammetry.