Optical Nanosensors for Biological Applications-Spectroscopic Techniques at the Cellular Level
This chapter describes the basic principles of optical-based biosensors as well as discusses the evolution of the relatively new class of biosensors with nanometer dimensions and their application to the monitoring of biological species on the cellular level. A biosensor can be generally defined as a device that consists of a biological recognition element, often called a bioreceptor, and a transducer. Despite the wide variety of bioreceptors and transducers employed, they are all based on the same principle. First, the sensor is placed in the environment of interest, where the target molecules bind to the bioreceptors in the biosensitive layer of the sensor. Bioreceptors can be biological molecules such as antibodies, enzymes, non-enzymatic proteins, nucleic acids or living biological systems such as cells, tissues, or whole organisms. The resulting interaction between the analyte and the bioreceptor then produces an effect that can be measured by the transducer, which converts this effect into some type of measurable signal (e.g., such as an electrical voltage).
