TERAHERTZ SPECTROSCOPY OF BIOLOGICAL SYSTEMS

Following recent developments in instrumentation, the terahertz part of the electromagnetic spectrum, lying between the microwave and infrared regions, now offers considerable potential for the study of the structure, dynamics and function of biological systems. The energies involved in many key biological processes lie in the terahertz frequency range, such as protein conformational changes and the collective motion of DNA base pairs along the hydrogen-bonded backbone. Terahertz spectroscopy is also a very sensitive probe of water in biological systems. This chapter will consider the terahertz spectroscopy of biological systems at three levels of increasing scale and complexity: the macromolecular, cellular and organism levels. Relevant instrumentation and spectroscopic techniques will be introduced, and biomedical applications, such as label-free detection of DNA mutations and non-invasive biopsy to distinguish between normal and cancerous tissue, will be described. The particular challenges involved in carrying out terahertz spectroscopy of biological systems will be considered, together with some possible future directions.