Photobleaching statistics in single-molecule on-/off-time distributions

Area of Science:

• Photophysics
• Single-molecule spectroscopy
• Chemical kinetics

Background:

• Fluorescence single-molecule experiments analyze molecular behavior using on- and off-time distributions.
• Photobleaching, a transition to a nonemissive state, is an unavoidable complication in these experiments.
• Current analyses often overlook photobleaching's impact on off-time distributions.

Purpose of the Study:

• To develop a theoretical framework for incorporating photobleaching kinetics into single-molecule fluorescence data analysis.
• To derive analytical equations that account for photobleaching effects.
• To demonstrate that photobleaching can alter expected distribution shapes.

Main Methods:

• Development of a theoretical framework for analyzing single-molecule fluorescence data.
• Derivation of analytical equations incorporating photobleaching kinetics.
• Mathematical modeling to predict the influence of photobleaching on time distributions.

Main Results:

• A theoretical framework rigorously incorporating photobleaching kinetics was established.
• Analytical equations were derived to quantify the effects of photobleaching.
• Results show that off-time distributions can be nonexponential due to photobleaching, even with single exponential rate processes.

Conclusions:

• Photobleaching significantly impacts the interpretation of off-time distributions in single-molecule fluorescence experiments.
• The developed theoretical framework provides a method to accurately analyze kinetics in the presence of photobleaching.
• This approach enables routine inclusion of photobleaching in experimental analyses for more accurate kinetic parameter extraction.