Electrochemical detection of nucleic acid sequences

A method of detecting a target molecule having at least one selected nucleic acid or protein segment, comprising:

• (a) interacting a bioreporter molecule attached to a working electrode surface with the target molecule to form a complex;
• (b) adding a reporter molecule that can be electrochemically reduced or oxidized upon interaction with said complex;
• (c) applying a first potential to the working electrode at or close to the open circuit potential;
• (d) measuring current close to the end of step (c);
• (e) applying a second potential or potential pulse to the working electrode that electrochemically oxidizes or reduces the reporter molecule at or near the electrode surface;
• (f) measuring a current close to the end of step (e);
• and
• (g) determining a signal by subtracting the current measured in step (d) from the current measured in step (f);
• wherein the signal indicates the presence of said target molecule.