Rjm Roeland Nolte

Poly(3,4-ethylenedioxythiophene)-based glucose biosensors

Amperometric biosensors for the recognition of glucose oxidase (GOx) based on poly(3,4-ethylenedioxythiophene) (PEDOT) were fabricated for the first time. The resulting biosensor has potential applications for long-term glucose measurements.

Influence of inflammatory cells and serum on the performance of implantable glucose sensors

The objective of this investigation was to evaluate the influence of polymorphonuclear granulocytes on the performance of uncoated and cellulose acetate/Nafion coated amperometric glucose sensors in vitro. The response of these sensors was also investigated in serum. Uncoated and coated sensors showed lower sensitivities to glucose, with a significant drift in sensor output upon exposure to serum or leukocytes. Although the use of a coating resulted in higher sensitivity, the progressive loss of output was not completely prevented. Stimulated granulocytes were shown to excrete components, probably catalase and myeloperoxidase, which consumed the hydrogen peroxide formed by the oxidation of glucose. In addition, adsorbed serum proteins formed a diffusional barrier for glucose. Furthermore, serum was found to contain low-molecular weight components that alone inhibited glucose oxidase activity. Based on preliminary electrochemical results, we postulate that rabbit serum contains oxidizing substrates that compete with molecular oxygen for the acceptance of electrons from the oxidized enzyme. Consequently, future efforts should be aimed at elucidating the mechanisms involved in the interference of unknown serum components with electron transfer. In addition, further investigations have to be performed to develop an outer membrane that minimizes protein adsorption as well as the actions of inflammatory cells.

EXPRESSION OF SUPRAMOLECULAR CHIRALITY IN AGGREGATES OF CHIRAL AMIDE-CONTAINING SURFACTANTS

We can induce or altersupramolecular expressionof chirality in the aggregates of a series of chiral amide-containing surfactants (1, R = C(O)C3H7, C6H5; R′ = C11H23, C17H35; X = phosphate, imidazole) by changing the pH or by addition of metal ions. Chirality at a higher level, such as in the formation of helical structures, is found to depend strongly on the head-group organisation of the surfactant molecules.