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Applied Optics

Applied Optics


  • Vol. 38, Iss. 9 — Mar. 20, 1999
  • pp: 1481–1487

Single-molecule analysis of ultradilute solutions with guided streams of 1-µm water droplets

Chung-yi Kung, Michael D. Barnes, Noah Lermer, William B. Whitten, and J. Michael Ramsey  »View Author Affiliations

Applied Optics, Vol. 38, Issue 9, pp. 1481-1487 (1999)

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We describe instrumentation for real-time detection of single-molecule fluorescence in guided streams of 1-µm (nominal) water droplets. In this technique, target molecules were confined to droplets whose volumes were comparable with illumination volumes in diffraction-limited fluorescence microscopy and guided to the waist of a cw probe laser with an electrostatic potential. Concentration detection limits for Rhodamine 6G in water were determined to be ∼1 fM, roughly 3 orders of magnitude lower than corresponding limits determined recently with diffraction-limited microscopy techniques for a chemical separation of similar dyes. In addition to its utility as a vehicle for probing single molecules, instrumentation for producing and focusing stable streams of 1–2-µm-diameter droplets may have other important analytical applications as well.

© 1999 Optical Society of America

OCIS Codes
(180.0180) Microscopy : Microscopy
(180.1790) Microscopy : Confocal microscopy
(260.2510) Physical optics : Fluorescence
(350.3950) Other areas of optics : Micro-optics

Original Manuscript: June 29, 1998
Revised Manuscript: September 28, 1998
Published: March 20, 1999

Chung-yi Kung, Michael D. Barnes, Noah Lermer, William B. Whitten, and J. Michael Ramsey, "Single-molecule analysis of ultradilute solutions with guided streams of 1-µm water droplets," Appl. Opt. 38, 1481-1487 (1999)

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