Method for Low Nanomolar Concentration Analyte Sensing Using Electrochemical Enzymatic Biosensors.

We introduce a new electrochemical measurement method compatible with an enzymatic biosensor that is capable of analyte sensing down to the low nanomolar concentration regime. This method is termed accumulation mode sensing and utilizes an immobilized redox polymer mediator wired to an oxidoreductase enzyme to store charge during a premeasurement charge concentration step, followed by a measurement step in which this accumulated charge is quantified. We demonstrate this new method using a model glucose sensor and show how the sensitivity of a sensor can be modified simply by adjusting the time duration of the charge concentration step. We achieve a limit of detection of 4.7 ± 1.4 nM using accumulation mode sensing, which represents a 25-fold improvement over traditional amperometry.