Dresden 2009 – scientific programme

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O: Fachverband Oberflächenphysik

O 51: Surface chemical reactions I

O 51.12: Talk

Thursday, March 26, 2009, 19:00–19:15, SCH A01

Ferrocene Affinity Label for the Electrochemical Detection of Enzymes down to a Single Molecule Level — •Claudia Baier, Alice Schlichtiger, Jörg Eppinger, and Ulrich Stimming — TU München, Garching, Deutschland

The research field of biosensors and bioelectronics offers a large potential for the development of functional devices. In this presentation, we show that we are able to electrochemically detect enzymes which are originally not redox-active such as papain and trypsin by using ferrocene affinity labels. These ferrocene-based affinity labels are ideally suited since they combine the electrochemically active ferrocene moiety which is stable under physiological conditions with the selectivity and activity sensing properties of the affinity label concept. The redox-labeled enzymes are immobilized on highly oriented pyrolytic graphite (HOPG) and are electrochemically investigated using cyclic voltammetry and impedance measurements. Furthermore, we established a nano-scale readout i.e. the detection of direct electron transfer processes on a single molecule level by in-situ SPM visualization. Therefore, potential dependent in-situ electrochemical scanning tunneling microscopy (EC-STM) studies and first results of scanning electrochemical potential microscopy (SECPM) will be presented. SECPM, which is the latest invention of the electrochemical SPM techniques, uses the electrochemical potential at the solid/liquid interface as feedback signal by measuring the potential difference between a potentiometric tip and the potential controlled working electrode.