A new electrochemical DNA biosensor for determination of menadione in human plasma

Menadione (vitamin K3, 2-methyl- 1,4- naphthoquinone) is a synthetic vitamin K analog which has been used chiefly as an antihemorrhagic agent [1 ]. In the present study, a fast, low cost and sensitive method for the electrochemical determination of menadione was proposed based on its intercalation into DNA double helix. The intercalation of menadione investigated using spectrofluorimetric technique. An electrochemical biosensor was fabricated using carbon paste electrode modified with Gr-Fe3O4 nanocomposite. A considerable increase was observed in the oxidation signal of menadione at carbon past electrode modified with Gr-Fe3O4 nanocomposite compared with unmodified electrode, After optimizing main experimental parameters such type of buffer, pH, accumulation time, etc. Its performance was evaluated from analytical point of view.A linear dependence of the anodic peak current of menadione on its concentration were observed in the range of 0.30–12 μM with detection limit of 0.09 μM . The relative standard deviations for 20 μM was 2.56% (n=5). The proposed sensor was successfully applied to the analysis of menadione in the human plasma