Electrochemical enzymatic biosensors detect their targets based on enzymatic catalysis of a reaction that produces or consumes electrons. Electron communication between the enzymes and the electrode is a major barrier in the development of electrochemical enzymatic sensors. One of the reasons is that the active redox centers of enzymes are deeply embedded in an electrically insulate protein shell. In order to solve this problem, Dr Nick Wu’s research group at West Virginia University has utilized metal oxide nanotubes as the shuttles to transport electrons between the electrode and the redox centers of enzymes.

In their approach, titanate nanotubes are used to immobilize lactate oxidase (LOx) enzymes to make an electrochemical biosensor for lactate detection. The nanotubes offer the pathway for direct electron transfer between the electrode surface and the active redox centers of LOx, which enables the biosensor to operate at a low working potential and to avoid the influence of the O2 presence on the amperometric current response. This work offers a general platform for development of enzymatic electrochemical biosensors. The direct electron transfer between the electrode and the redox center of enzymes obviates the need for redox mediators for electrochemical enzymatic sensors, which is attractive for the development of reagentless biosensors.