The Light-Addressable Potentiometric Sensor: Principles and Biological Applications

PRINCIPLES OF THE LIGHT-ADDRESSABLE POTENTIOMETRIC SENSOR 88 Measurement of pH 89 The Photoeffect 90 Light Addressability 93 Measurement of Other Chemical Species 93 THE LAPS AS A SENSOR IN AN ANALYTICAL SYSTEM 94 Electrical Measurement of Phospholipid Membranes 94 Discrete Sensor Arrays 94 LAPS as an Imaging Sensor 94 Microvolume Systems 95 The Sensor as a Structural Element of Analytical Systems 96 Data Analysis in LAPS Systems 96 APPLICATIONS FOR BIOCHEMICAL ASSAYS 98 Measurement of Enzyme Substrates and lnhibitors 98 Enzyme-Linked lmmunoassays 98 APPLICATIONS FOR CELL-BASED BIOASSAYS: THE MICROPHYSIOMETER 102 Biological Basis 102 Instrumental Characteristics 102 Applications of Microphysiometry 105 Prospects 108 CONCLUDING PERSPECTIVE 109