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HL: Halbleiterphysik

HL 43: GaN: Devices I

HL 43.1: Vortrag

Donnerstag, 30. März 2006, 11:00–11:15, BEY 118

Biocatalytic Activity of Enzymes Immobilized on Group III-Nitride Surfaces — •Barbara Baur, Georg Steinhoff, Hans-Georg von Ribbeck, Yvonne Gawlina, Florian Furtmayr, Martin Stutzmann, and Martin Eickhoff — Walter Schottky Institut, Technische Universität München, 85748 Garching, Germany

AlGaN/GaN electrolyte gate field effect transistors (EGFETs) have a great potential as sensor devices for electronic detection of biochemical processes, as they combine excellent electronic characteristics with biocompatibility and long term stability in liquid electrolytes. In addition, they show a high pH sensitivity, which enables the quantitative electrical detection of enzymatic biocatalytical reactions accompanied by local pH changes. In this context, we describe the covalent immobilization of different enzymes on GaN surfaces. The influence of the pH-value in the chemical medium during the immobilization processes has been investigated. Adjustment of the pH-value results in selective covalent immobilization at crosslinker molecules on a self assembled monolayer of aminopropyltriethoxysilane (APTES) deposited on the surface. At the same time, the non-specific physisorption due to electrostatic interaction can be suppressed, as proven by fluorescence microscopy. The influence of the immobilization process on the enzyme activity and long-term stability is analyzed by photometric measurements. The biocatalytic activity of immobilized penicillinase and urease is detected electronically, employing the ion sensitivity of the underlying AlGaN/GaN EGFETs.