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Biomed Opt Express. 2010 Oct 5;1(4):1075-1083.

Two-photon fluorescence correlation spectroscopy with high count rates and low background using dielectric microspheres.

Abstract

Two-photon excitation fluorescence is a powerful technique commonly used for biological imaging. However, the low absorption cross section of this non-linear process is a critical issue for performing biomolecular spectroscopy at the single molecule level. Enhancing the two-photon fluorescence signal would greatly improve the effectiveness of this technique, yet current methods struggle with medium enhancement factors and/or high background noise. Here, we show that the two-photon fluorescence signal from single Alexa Fluor 488 molecules can be enhanced up to 10 times by using a 3 µm diameter latex sphere while adding almost no photoluminescence background. We report a full characterization of the two-photon fluorescence enhancement by a single microsphere using fluorescence correlation spectroscopy. This opens new routes to enhance non-linear optical signals and extend biophotonic applications.

PMID:
21258531
[PubMed - as supplied by publisher]
PMCID:
PMC3018086
Free PMC Article
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