Hexacyanoferrates as Mediators for Microelectrode Biosensors

Hexacyanoferrates such as Prussian blue or Ruthenium Purple have great potential for use in microelectrode biosensors. They act as surface-bound mediators that greatly facilitate the detection of H₂ O₂ at modest potentials, thereby increasing the selectivity of the biosensors versus electroactive interferences. We review the structure of this class of mediator, their electrochemical properties, and their actions as “artificial peroxidases.” We give a brief outline of how hexacyanoferrate layers can be deposited onto microelectrodes and activated and the means by which they can be integrated into enzymatic biosensors. We discuss the performance of such biosensors and their potential limitations with regard to stability, ionic sensitivity, and speed of response.