Fluorescence resonance energy transfer: Concepts, applications and advances

Bio-analytical techniques that utitize fluorescence resonance energy transfer (FRET) are particularly attractive to scientists due to the intrinsic sensitivity of this photo-physical process for detecting small variations in molecular distance and orientation. This means, when appropriately configured, any change in proximity between 2 appropriately Labeled molecules can be detected both qualitatively and quantitatively. FRET is finding an ever increasing role in bio-analytical techniques, especially in the monitoring of binding events both intra-cellularly and as a reporter for in vitro assays. Furthermore, use of FRET can dramatically improve optical resolution in multi-analyte or'multiplex'roles. In the present review, we describe many aspects of FRET as an analytical technique with a special emphasis on items of interest to the biologist in general. Among the areas covered are a brief history of FRET, an introduction to relevant concepts and Föster formalism, the mechanism of FRET, FRET as a tool to elucidate biological structures, FRET as a sensing technique in vitro and in vivo, FRET usage with analytical and diagnostic DNA testing, as well as the use of novel proteins and nanocrystalline quantum dot materials in FRET. As more researchers learn about this versatile technique, FRET will continue to gain an ever increasing role in bio-applications.