Rotating bioreactor based on an electron transfer mediated by osmium complexes incorporating a continuous-flow/stopped-flow system Application to the determination of glucose in serum samples

A recently introduced redox osmium complex of the type [Os(bpy)2Cl(pyX]+, where pyX corresponds to a pyridine derivative bearing an aldehyde group, and glucose oxidase [EC 1.1.3.4] were covalently immobilized on the glassy carbon electrode surface (upper cell body). This approach has been designed in a sealed cell to be used under continuousflow/stopped-flow/continuous-flow processing. The operating characteristic of the integrated bioreactor/detector unit has been utilized in the determination of glucose in serum samples using the electroactive polymer as mediator in the re-oxidation of GOx and amperometric monitoring. The determinations are based on the rate of response under stopped-flow conditions. The trend in values of the apparent Michaelis-Menten constant confirms the validity of the approach to sensitive determination utilizing very small amounts of biocatalysts. The determination of glucose was possible with a limit of detection of 0.020mM in the processing of as many as 30 samples per hour.