INFLUENCE OF POLYMER PREADSORPTION ON THE PERFORMANCE OF AN ELECTROCHEMICAL SERUM BIOSENSOR

We compare the performance of platinum and glassy carbon electrodes wi th and without polymer pretreatment, in detecting the presence of H2O2 after passage of blood serum through an enzymatic minireactor. The si mple pretreatment is performed by physisorption from a dilute aqueous solution of the polymer, leading to a diffuse layer of polymer segment s which protects the electrode from large entities such as proteins, w hile allowing the small electroactive species to reach the electrode s urface. Three polymers, all with a high polyoxyethylene content, were tested and the results were evaluated. The signal on starting sequence s of serum injections is less high in the pretreated electrode than in the untreated electrode. However, the loss of signal on increasing th e number of injections is lower and leads to a more stable response an d finally, after 20 injections, to a higher signal than at untreated e lectrodes.