Wavelength-resolved measurements of fluorescence lifetime of indocyanine green

Abstract

We study fluorescence lifetime of indocyanine green (ICG) using femtosecond laser and sensitive detection based on time-correlated single-photon counting. A time-resolved multichannel spectral system is constructed and applied for determination of the fluorescence lifetime of the ICG in different solvents. Emission properties of ICG in water, milk, and 1% intralipid solution are investigated. Fluorescence of the fluorophore of different concentrations (in a range of 1.7-160 μM) dissolved in different solutions is excited by femtosecond pulses generated with the use of Ti:Sa laser tuned within the range of 740-790 nm. It is observed that fluorescence lifetime of ICG in water is 0.166 ± 0.02 ns and does not depend on excitation and emission wavelengths. We also show that for the diffusely scattering solvents (milk and intralipid), the lifetime may depend on the dye concentration (especially for large concentrations of ICG). This effect should be taken into account when analyzing changes in the mean time of arrival of fluorescence photons excited in ICG dissolved in such optically turbid media.

Time-resolved multi-channel optical system for assessment of brain oxygenation and perfusion by monitoring of diffuse reflectance and fluorescence

“…It was also shown that changes in statistical moments of DTOFs and DTAs can be obtained during in−vivo experi− ments during injections of optical contrast agent, e.g. ICG [82]. Quality of the signals measured suggest that the instru− ment can be used in estimation of brain perfusion using techniques proposed in several previous studies [37,39,40,44,83,84].…”

Multifunctionality of indocyanine green-loaded biodegradable nanoparticles for enhanced optical imaging and hyperthermia intervention of cancer

“…Moreover, the obtained actual lifetime of ICG (0.19 AE 0.01 ns) became very close to the published lifetime value of 0.17 ns. 20,21 This part of observations reports (1) the lengthening effect of PLGA on the lifetime of ICG in PIN; (2) the consistency between our results and published lifetime of ICG; (3) the necessity to de-convolve the instrument response function for more accurate lifetime quantification.…”

“…However, our measured lifetime of ICG was a little longer than the lifetime value of ICG in published data. 20 Hence the influence of the system response on lifetime of ICG and PIN was studied. The response function obtained from white sample measurements gave a Gaussian curve with a narrow width of 80 ps.…”

Long-distance fluorescence lifetime imaging using stimulated emission

“…It is known that this solution is chemically not stable and changes its fluorescence properties over time, depending upon the storage conditions, especially with respect to the intensity of the fluorescence. 30,31 However, changes in fluorescence lifetimes over storage time have, to our knowledge, not yet been reported in literature. We recorded fluorescence lifetimes for freshly prepared ICG samples and for samples stored at room temperature in a light-tight case for 48 h. The fluorescence lifetime of ICG diluted in water reported in the literature is 0.51 ns.…”

“…This change in ICG lifetime is, to our knowledge, reported for the first time, even though changes in the fluorescence response of ICG as a dependence of storage time have been published earlier. 30,31 Fig. 4 LDFLI images of a two-dimensional distribution of Indocyanine Green dissolved in deionized water after 48 h of storage at room temperature.…”