Fluorescence Imaging with One Nanometer Accuracy: In Vitro and In Vivo Studies of Molecular Motors

Melinda Tonks Hoffman, Janet Sheung, Paul R. Selvin

Research output: Chapter in Book/Report/Conference proceedingChapter


Traditional microscopy techniques are limited by the wave-like characteristics of light, which dictate that about 250 nm (or roughly half the wavelength of the light) is the smallest distance by which two identical objects can be separated while still being able to distinguish between them. Since most biological molecules are much smaller than this limit, traditional light microscopes are generally not sufficient for single-molecule biological studies. Fluorescence Imaging with One Nanometer Accuracy (FIONA) is a technique that makes possible localization of an object to approximately one nanometer. The FIONA technique is simple in concept; it is built upon the idea that, if enough photons are collected, one can find the exact center of a fluorophore’s emission to within a single nanometer and track its motion with a very high level of precision. The center can be localized to approximately (λ/2)/Ö—N, where λ is the wavelength of the light and N is the number of photons collected. When N = 10,000, FIONA achieves an accuracy of 1–2 nm, assuming the background is sufficiently low. FIONA, thus, works best with the use of high-quality dyes and fluorescence stabilization buffers, sensitive detection methods, and special microscopy techniques to reduce background fluorescence. FIONA is particularly well suited to the study of molecular motors, which are enzymes that couple ATP hydrolysis to conformational change and motion. In this chapter, we discuss the practical application of FIONA to molecular motors or other enzymes in biological systems.

Original languageEnglish (US)
Title of host publicationSingle Molecule Enzymology
Subtitle of host publicationMethods and Protocols
PublisherHumana Press Inc.
Number of pages24
ISBN (Print)9781617792601
StatePublished - 2011

Publication series

NameMethods in Molecular Biology
ISSN (Print)1064-3745
ISSN (Electronic)1940-6029


  • Molecular motors
  • Single-molecule tracking
  • TIRF microscopy

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics


Dive into the research topics of 'Fluorescence Imaging with One Nanometer Accuracy: In Vitro and In Vivo Studies of Molecular Motors'. Together they form a unique fingerprint.

Cite this