Application and New Developments in Fluorescence Spectroscopic Techniques in Studying Individual Molecules

Abstract

Techniques based on fluorescence have played a variety of roles in chemistry, physics, spectroscopy, medicine, nanotechnology, and biotechnology due to their high selectivity, sensitivity, simplicity, and fastness in spectroscopic and imaging measurements. While detecting fluorescence from individual molecules by fluorescence‐based techniques, poor signal, limited lifespan of fluorophores, trade‐off between time resolution, and the level of detail of information were few major concerns. Ultrasensitive detectors permit the combination of the high time resolution of single photon counting devices with the large field of view and spectral resolution allowed by two‐dimensional detectors. Photobleaching and on‐off blinking of fluorophores can be improved dramatically by chemical modifications or changing the reagents. New ways of controlling local fields such as optic, electric, magnetic, chemical, or biochemical environments take advantage of the noninvasiveness and high temporal and spatial resolution of single‐molecule fluorescence (SMF) to get a direct feedback of events at the nanometer scale in various domains of research. Some of the applications and new developments in fluorescence spectroscopic techniques in detecting, investigating, and/or manipulating individual molecules have been discussed.

Keywords:

• SMF
• SMD
• SMS
• spFRET
• defocused imaging
• FIONA
• FCS

Acknowledgment

The author is grateful to Professor Joerg Enderlein, Department of Physical and Theoretical Chemistry, Eberhard Karls University Tübingen, Germany, for his lab facilities, support, and constant encouragement. Financial support provided to the author by the American University of Beirut, Lebanon, through the URB Seed research grant to carry out this work is greatly appreciated.