Development and Electrochemical Investigations of an EIS- (Electrolyte-Insulator-Semiconductor) based Biosensor for Cyanide Detection

• Main Authors: Michael J. Schöning, Michael Keusgen, Peter Krüger, Gereon Elbers, Heinz K. Berndt, Melanie Claßen, Lothar Ketterer, Monika Turek
• Format: Article
• Language: English
• Published: MDPI AG 2007-08-01
• Series: Sensors
• Subjects: cyanide biosensor; EIS structure; cyanidase; pH; differential measurement set- up.
• Online Access: http://www.mdpi.com/1424-8220/7/8/1415/

A cyanide biosensor based on a pH-sensitive p-doped electrolyte-insulator-semiconductor (EIS) structure with an immobilised enzyme (cyanidase) is realised at thelaboratory scale. The immobilisation of the cyanidase is performed in two distinct steps:first, the covalent coupling of cyanidase to an N-hydroxysuccinimide- (NHS) activatedSepharoseTM gel and then, the physical entrapment of NHS-activated SepharoseTM with theimmobilised cyanidase in a dialysis membrane onto the EIS structure. The immobilisationof the cyanidase to the NHS-activated SepharoseTM is studied by means of gelelectrophoresis measurements and investigations using an ammonia- (NH3) selectiveelectrode. For the electrochemical characterisation of the cyanide biosensor,capacitance/voltage and constant capacitance measurements, respectively, have beencarried out. A differential measurement procedure is presented to evaluate the cyanideconcentration-dependent biosensor signals.