%A Li,Yahui
%A Natakorn,Sapermsap
%A Chen,Yu
%A Safar,Mohammed
%A Cunningham,Margaret
%A Tian,Jinshou
%A Li,David Day-Uei
%D 2020
%J Frontiers in Physics
%C
%F
%G English
%K fluorescence lifetime imaging,Lifetime determination algorithm,Average lifetimes,Multi-exponential decays,Lifetime image visualization,FRET – fluorescence resonance energy transfer
%Q
%R 10.3389/fphy.2020.576862
%W
%L
%N 447
%M
%P
%7
%8 2020-October-16
%9 Original Research
%#
%! Average lifetimes for multi-exponential decays
%*
%<
%T Investigations on Average Fluorescence Lifetimes for Visualizing Multi-Exponential Decays
%U https://www.frontiersin.org/article/10.3389/fphy.2020.576862
%V 8
%0 JOURNAL ARTICLE
%@ 2296-424X
%X Intensity- and amplitude-weighted average lifetimes, denoted as τ_{I} and τ_{A} hereafter, are useful indicators for revealing Förster resonance energy transfer (FRET) or fluorescence quenching behaviors. In this work, we discussed the differences between τ_{I} and τ_{A} and presented several model-free lifetime determination algorithms (LDA), including the center-of-mass, phasor, and integral equation methods for fast τ_{I} and τ_{A} estimations. For model-based LDAs, we discussed the model-mismatch problems, and the results suggest that a bi-exponential model can well approximate a signal following a multi-exponential model. Depending on the application requirements, suggestions about the LDAs to be used are given. The instrument responses of the imaging systems were included in the analysis. We explained why only using the τ_{I} model for FRET analysis can be misleading; both τ_{I} and τ_{A} models should be considered. We also proposed using τ_{A}/τ_{I} as a new indicator on two-photon fluorescence lifetime images, and the results show that τ_{A}/τ_{I} is an intuitive tool for visualizing multi-exponential decays.