Engineered PQQ glucose dehydrogenase based enzyme sensor for continuous glucose monitoring

Continuous glucose monitoring (CGM) is expected to become an ideal way to monitor the glycemic level of diabetic patients. A recent trend in the disposable self blood glucose sensing development has been the use of pyrroloquinoline quinone-harboring glucose dehydrogenase (PQQGDH). However, due to a number of limitations of PQQGDH, conventionally utilized glucose oxidase (GOD) remains widely utilized in CGM. Two major problems that arose in the application of PQQGDH for CGM are the poor stability and its requirement for artificial electron acceptors for electrochemical measurement. To solve these problems, we investigated the amenability of our engineered PQQGDH Ser415Cys, which has a far superior thermal stability over the wild-type enzyme, for the CGM system, and the applicability of cyt b(562) as the electron mediator to construct a CGM system free of synthetic mediator. As a result, the operational stability of CGM system employing Ser415Cys co-immobilized with cyt b562 was far superior to that of the wild-type enzyme-based electrode, with more than 60% of the initial response observed after 72 hr at 37degreesC. We achieved the successful application of PQQGDH in continuous operation without a significant decrease in the sensor signal.