Membranes for Amperometric Biosensors
AbstraktBiosensors consist of a biological entity that recognizes the target analyte and the transducer that translates the biorecognition event into an electrical signal. The use of biological materials as recognizing elements imparts to biosensors the ability to specifically respond to the analyte of interest, distinguishing it from structurally similar compounds. Amperometric biosensors are based on measurements of the electric current resulting from the oxidation or reduction of an electroactive species, by keeping a constant potential at the working electrode. Enzymes can be immobilized in a thin layer on the transducer surface. Besides the reactive layer or membrane many biosensors contain one or several inner or outer membranes with different functions. The protective inner membrane may decrease the influence of interfering species. The outer membrane serves as a diffusion-limiting barrier to the enzyme substrate. Biosensors are considered biocompatible if their implantation does not affect normal functioning of the host medium and, vice versa, the host medium does not materially affect their normal operation. The present review focuses on the immobilisation techniques and preparation and utilization of protective inner and outer diffusion-limiting membranes of amperometric biosensors.