Pulsed-Interleaved-Excitation Two-Dimensional Fluorescence Lifetime Correlation Spectroscopy.

Area of Science:

• Biophysics
• Biochemistry
• Analytical Chemistry

Background:

• Single-molecule fluorescence spectroscopy offers high sensitivity for studying biomolecular dynamics.
• Two-dimensional fluorescence lifetime correlation spectroscopy (2D FLCS) analyzes molecular interactions and dynamics.
• Existing 2D FLCS methods struggle to differentiate low-FRET species from donor-only species due to single-color excitation.

Purpose of the Study:

• To introduce and validate pulsed-interleaved-excitation two-dimensional fluorescence lifetime correlation spectroscopy (PIE 2D FLCS) for enhanced biomolecular studies.
• To overcome limitations of traditional 2D FLCS in distinguishing low-FRET species.
• To improve the sensitivity and time resolution of single-molecule FRET studies.

Main Methods:

• Implementation of the pulsed-interleaved-excitation (PIE) scheme for two-color excitation and detection in 2D FLCS.
• Utilizing fluorescence lifetime information to resolve interconversion dynamics of different species.
• Application of PIE 2D FLCS to a DNA-hairpin sample after Monte Carlo simulation validation.

Main Results:

• PIE 2D FLCS successfully distinguishes four fluorescent species: high-FRET, low-FRET, and two single-dye-labeled species.
• The method demonstrates high sensitivity and submicrosecond time resolution for analyzing biomolecular structural dynamics.
• Quantitative evaluation of donor-acceptor spectral crosstalk artifacts is achieved, improving data accuracy.

Conclusions:

• PIE 2D FLCS is a powerful advancement for single-molecule FRET studies, enabling precise analysis of complex biomolecular systems.
• This technique significantly enhances the ability to resolve distinct molecular species and their dynamics.
• PIE 2D FLCS offers a robust solution for overcoming spectral crosstalk challenges in FRET measurements.