Stability adsorbed sensing layer

It is important to note that proteins tend to denature during such an adsorption process on noble metals or carbon electrodes. In addition, the stability of the adsorbed sensing layer is highly dependent on the pH value and ionic strength of the solution as well as the temperature, the electrode material, and other additional factors. For instance, as early as 1972 direct ET was observed on mercury electrodes employing cytochrome c as redox protein [108]. Reversible electrochemical behavior of cytochrome c was not observed because the protein denatured on the surface. 

Long Term Performance of Sensors. The sensors showed excellent long term stability stored in buffer at 4 °C. Table 1 shows the long term performance of four typical biosensors. The usual current response to 6 mM glucose for a new biosensor is about 2 fiA. The precision of the absolute current response to 6 mM glucose remains within 15 % for up to four months. This level of precision is unusual for amperometric biosensors. Normally, variations in current are compensated by calibration. The sensitivity of the biosensors, as indicated by the slope of the response, is also stable. This stability is due to the film which maintains the ferrocene within the sensing layer. Biosensors with adsorbed mediator and immobilized enzyme but without film are not stable for any period of... 

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