Multiphoton processes in photoreactions of indocyanine green in ethanol

Investigating the role of human serum albumin protein pocket on the excited state dynamics of indocyanine green using shaped femtosecond laser pulses

“…Several single and multi-photon photoisomerization pathways have been proposed to address the nonradiative behavior of ICG. [34][35][36] They can be summarized as excited state trans-cis isomerization, triplet state formation through intersystem crossing and formation of photo degradation products. ICG cis photo-isomer and triplet state have a lifetime of B1 ms, 34 and thus can accumulate and be observed when the pulse repetition rate is 1 kHz, because consecutive pulses arrive at the sample every 1 ms. We confirmed the presence of triplet state by removing O 2 , which acts as a triplet state quencher, from the sample by bubbling argon (Ar) in the solution and recording the chirp scans in the oxygen depleted samples.…”

“…[24][25][26][27][28][29] The spectroscopic properties of ICG have already been well investigated [30][31][32][33] and several photoisomerization mechanisms were sought for ICG that address multiphoton processes to produce triplet state, photodegraded species and cis isomers. [34][35][36] Being a tricarbocyanine dye, ICG aggregation and photophysical behavior is highly dependent on the environment 31 and the molecule tends to exist in an all-trans form while in the ground state. 34,35 Moreover, the low fluorescence quantum yield for ICG in water (f F = 0.027) 31 can be attributed to the excited state trans-cis isomerization, 37,38 large triplet state formation cross section 32 and several other photoreactions.…”

“…[34][35][36] Being a tricarbocyanine dye, ICG aggregation and photophysical behavior is highly dependent on the environment 31 and the molecule tends to exist in an all-trans form while in the ground state. 34,35 Moreover, the low fluorescence quantum yield for ICG in water (f F = 0.027) 31 can be attributed to the excited state trans-cis isomerization, 37,38 large triplet state formation cross section 32 and several other photoreactions. [34][35][36] The main medical use of ICG arises from its ability to bind with albumin 39,40 and is therefore extensively used in the labeling of HSA.…”

“…34,35 Moreover, the low fluorescence quantum yield for ICG in water (f F = 0.027) 31 can be attributed to the excited state trans-cis isomerization, 37,38 large triplet state formation cross section 32 and several other photoreactions. [34][35][36] The main medical use of ICG arises from its ability to bind with albumin 39,40 and is therefore extensively used in the labeling of HSA. 41,42 ICG has a binding constant of 5.7 Â 10 5 M À1 to HSA 43 and results in a bathochromic shift (red shift) of the ICG absorbance (ESI †, Fig.…”

Vibronic relaxation dynamics at intermediate state of two-pump excitation: Photoisomerization of indocyanine green in ethanol

“…11 Recently, we found that the quantum yield of the trans-to-cis photoisomerization of indocyanine green (ICG), a widely used and investigated dye, [12][13][14][15][16][17][18][19] in ethanol was drastically increased by exciting ICG molecules by the four-photon process induced by a femtosecond near infrared (NIR) pulse resonant to the S 1 r S 0 transition. 20 The absorbance change of the photoproduced cis isomers was proportional to the fourth power of the NIR fluence. This is the first clear evidence for the superiority of the multiphoton process to the one-photon process for the isomerization of cyanine dye, and thus ICG molecules can serve as new model compounds for multiphoton photoisomerization.…”