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

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) activatedSepharose^TM gel and then, the physical entrapment of NHS-activated Sepharose^TM with theimmobilised cyanidase in a dialysis membrane onto the EIS structure. The immobilisationof the cyanidase to the NHS-activated Sepharose^TM 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. View Full-Text