A novel drug-delivery system was developed by loading the anticancer drug, mitomycin C (MC) into an oil/water system with the aim of investigation by electrochemical sensing the interaction between the drug and DNA in microemulsion phase. The physical and physicochemical properties (droplet size, pH, viscosity, conductivity and refractive index) of this microemulsion were examined. The electrochemical detection of the interaction between MC and double-stranded DNA (dsDNA) in microemulsion phase was performed by using differential pulse voltammetry (DPV) in combination with a disposable sensor, pencil graphite electrode (PGE). The magnitude of guanine oxidation signal was monitored before and after interaction between MC and dsDNA. The effect of different experimental parameters, such as MC concentration, MC interaction time with dsDNA, and dsDNA concentration were also studied to find the optimum analytical performance based on electrochemical detection of this interaction in microemulsion phase. (c) 2007 Elsevier B.V. All rights reserved.