1 7. Prussian Blue and analogues: Biosensing applications in health care Salazar P 1,2 , Martín M 1,3 , O’Neill RD 4 , Lorenzo-Luis P 5 , Roche R 1,2 , and González- Mora JL 1 1 Neurochemistry and Neuroimaging group, Faculty of Medicine, University of La Laguna, Tenerife, Spain. 2 Informática y Equipamiento Médico de Canarias S.A., Tenerife, Spain 3 Atlántica Biomédica S.L., Tenerife, Spain. 4 UCD School of Chemistry and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland. 5 Department of Inorganic Chemistry, Faculty of Chemistry, University of La Laguna, Tenerife, Spain. Abstract: Prussian Blue (PB), Fe 4 [Fe(CN) 6 ] 3 , belongs to a transition metal hexacyanometallate family. Its electrochemical properties were revealed in 1978 when Neff reported the successful deposition of a thin layer on platinum foil. After that, numerous publications have appeared exploring its electrocatalytic properties and its applications in biomedical science. During the last decade, a great number of studies involving PB have appeared, using different biosensor substrates and different oxidase enzymes. Together with the facile modification of the electrode substrate and the low cost of production, this has led to an on-going replacement of the more common enzymatic detection method involving horseradish peroxidase. Its high electrocatalytic activity and low operating overpotential have contributed to the diversification of its use in enzyme-based biosensors and immunosensors. Based on these results, it is clear that PB and its analogues will have important roles in the future development of biomedical devices for next generation health-care strategies. Keywords: Prussian Blue, biosensors, immunosensors, health care. Table of Contents: 7.1. Introduction 7.2. General aspects of Prussian Blue and other hexacyanoferrates 7.2.1. Overview 7.2.2. Chemical and structure of Prussian Blue and its analogues 7.2.3. pH stability and deposition method 7.3. Prussian Blue: hydrogen peroxide electrocatalysis 7.4. Prussian Blue: Biosensor applications 7.4.1. Prussian Blue and analogues enzyme system 7.4.1.1. Glucose oxidase 7.4.1.2. Lactate oxidase 7.4.1.3. Cholesterol oxidase 7.4.1.4. Alcohol oxidase 7.4.1.5. NADH oxidase 7.4.1.6. Diamine oxidase 7.4.1.7. Choline oxidase 7.4.1.8. Acetilcholinesterase and butyrylcholinesterase 7.5. Prussian Blue: Immunosensor applications