Flavoenzyme-based biosensors with redox polymer electron relays

A description is given of the design and testing of a class of amperometric bioanalytical sensor in which electrical communication between the flavin redox centers of an oxidase and a conventional electrode is achieved by means of a network of donor-acceptor relays chemically bound to a flexible siloxane polymer. Electrochemical results demonstrating this mediated electrical communication are discussed for several polymer/enzyme systems. The molecular weight range for these redox-containing polymeric materials is approximately 2000-10000. Purification of the polymers was achieved by reprecipitation from chloroform solution by dropwise addition to a large excess amount of acetonitrile at room temperature. This reprecipitation was repeated two to three times to ensure that no low-molecular-weight species (which could act as freely diffusing electron transfer mediators) were present. Redox-polymer/glucose-oxidase/carbon-paste electrodes were tested and found to be sensitive to small changes in glucose concentration over a clinically useful range of concentrations