Biosensors : An outline of general principles and application

Biosensors are a class of devices that provide a specific detection of analytes using biological receptors (antigens, enzymes, liposomes, whole cells, molecular receptors). A review of the major types of biological components and interactions on which biosensors can be designed is presented; the applications of these systems in clinical (glucose, cholesterol monitoring) and environmental (BOD-sensor, detection of pesticides with inhibited enzyme electrodes) fields are reported, too. Moreover, the importance of innovative systems, like liposomes and Langmuir-Blodgett films, is highlighted. Enzyme-entrapping liposomes, lipid vesicles with different membrane permeabilities, could be exploited in biosensing devices, acting on the substrate permeability and hence on its availabilty, preserving the enzyme from the adverse environmental conditions. The Langmuir-Blodgett technique is a new mild technique of functionalisation, that permits to obtain organized, ultrathin monolayers, inducing short response times.