Release of Iron Ions From the Stainless Steel Anode Occurring During High-Voltage Pulses and Its Consequences for Cell Electroporation Technology

One of the plausible reactions occurring during high-voltage pulses, which are used to electroporate the cells, is the oxidation of the metal ions of the anode resulting in the dissolution of the anode. In the case of the anode made from stainless steel, which is one of the most popular electrode materials, iron ions ( Fe²⁺ and Fe³⁺) are released from the anode. Here, this process and its consequences have been studied. A single square-wave electric pulse with the duration of 2 ms and the amplitude of 1.2 kV/cm increased the concentration of iron ions in solution by over 0.5 mM. Iron ions released from the anode behave as a Lewis acid and hydrolyze the water molecules in the solution, reducing the pH of a solution and might play a role in the changes of the medium conductivity. In addition, the roughness of the stainless steel anode increased progressively, in proportion with the total amount of the electric charge that had passed through the unit area of the electrode. The reduction of the viability of cells by iron ions has been demonstrated. The iron ions quench the fluorescence of anticancer drugs, which are used when photodynamic tumor therapy is combined with electroporation, such as porphyrin sulfonate and Adriamycin.