“No calibration” type sensor in routine amperometric bio-sensing: An example of a disposable hydrogen peroxide biosensor

Abstract

Amperometric enzyme based biosensors using redox mediators capable of shuttling electrons from the redox centre of the enzyme to the surface of the electrode are by far the most popular and the most studied. In addition, this type of biosensor is the one that has had the greatest commercial success, following the launch into the market of glucose biosensors devices for the control of diabetics' glycemia. From the perspective of electrochemistry, these biosensors are based on the measurement of a kinetic current controlled by the enzymatic reaction that detects the substrate. This current depends on the activity of the enzyme and is therefore sensitive to several physicochemical factors that may influence the kinetics of the reaction. For this, a calibration step is necessary to obtain, in the operating conditions, reliable measurements. This calibration step, often considered tedious and time consuming, makes these biosensors unattractive for industries that want to use these analytical tools in remote locations utilising unskilled workers. The development of "no calibration" type biosensor concept could be considered as the important step to overcome this difficulty. We have validated this concept in producing reliable and reproducible disposable biosensors for H2O2 that operate with horse radish peroxidase and carboxymethyl ferrocene as redox mediator which are commercially available, cheap and stable. Such a "no calibration" type H2O2 biosensor will serve as a general platform for a very large number of biosensors that use enzymes such as oxidases or combination of dehydrogenases and NADH oxidase.