UV-POLYMERIZABLE SCREEN-PRINTED ENZYME PASTES

A new technique for immobilization of enzymes on amperometric thick-film electrodes was developed with the aim to generate stable enzyme layers suitable for use as the analyte-specific part of biosensors with sufficient mechanical stability to withstand the continuous use in wall-jet cells of now injection analysis (FIA) systems. To demonstrate the successful production of defined enzyme layers, the oxidoreductase glucose oxidase (GOx) was used as a model protein for immobilization. The enzyme was mixed with a UV-polymerizable screen-printable paste, and the influence of various additives on viscosity and sensor sensitivity was tested. The enzyme layer was formed try screen printing of this mixture and UV polymerization for 3-5 s. Scanning electron microscopy visualized the surface properties of different enzyme layers. Amperometric measurements were performed in a FIA device with respect to operational stability, sensitivity, linear range, influence of pH, and influence of ascorbic acid used as a model for an interfering compound. These parameters were compared to those obtained with sensors based on glutardialdehyde cross-linked GOx. The sensors showed an improved stability but a reduced sensitivity compared to those with glutardialdehyde immobilization. Within a series of 10 measurements, the standard deviation was <1%, and between sensors produced in one batch it was <10%.