Photochemistry and Cytotoxicity Evaluation of Heptamethinecyanine Near Infrared (NIR) Dyes

Abstract

The present study investigates the photochemical properties of potential photosensitizers for photodynamic therapy, namely four commercial heptamethinecyanine dyes (IR125, IR780, IR813, IR820). Spectroscopic studies were made by means of laser induced fluorescence and laser flash photolysis in order to obtain fluorescence quantum yields and transient absorption spectra. Fluorescence lifetimes were also determined. The differences encountered were essentially related with the interaction of the sulfonate groups with the solvent, and also regarding the rigidification of the central bridge connecting the two nitrogen-containing heterocyclic groups. Transient absorption studies were performed both in aerated and oxygen free samples, to conclude about the formation of photoisomers and triplet state. For the four dyes under study, a cytotoxic evaluation in the dark and after irradiation was performed using HeLa cells as the model cell line, which revealed significant changes after irradiation mainly in IR125 and IR813 dyes. Confocal microscopy analysis showed that these dyes tend to enter to the intracellular space.

A Near-IR Uncaging Strategy Based on Cyanine Photochemistry

“…This result is consistent with previous observations suggesting that heptamethine cyanine fluorophores are generally only weakly cytotoxic, even upon protracted irradiation. 24 The findings presented here, as well as these previous observations, appear to suggest the products of the cyanine photodecomposition process, 19 – 24 , are relatively well-tolerated, despite the presence of potentially reactive carbonyl groups. As expected with this low energy light, no phototoxicity was observed with irradiation alone.…”

“…The indoline nitrogen of the cyanine was substituted with either n- propyl or 4-butanesulfonate substituents, the latter being more well tolerated by biological systems. 24 Compounds 6 – 10 were accessed through a protocol comprising initial conjugation of N , N ′-dimethylethylenediamine to commercially available IR-780 ( 4 ) and IR-783 ( 5 ), followed by addition of a chloroformate to the unpurified diamine cyanine intermediate. The 4-hydroxycyclofen conjugate 11 was prepared by adding the corresponding mixed nitrophenyl carbonate to the same cyanine intermediate formed from N , N ′-dimethylethylenediamine and 5 .…”

Stimuli‐responsive liposomes for drug delivery

“…To use light as a trigger, activating photons must safely pass through the biological tissues to initiate the release process. Light in the 600–900 nm wavelength range is transmissible deep into biological tissues due to low scattering and small absorption coefficients . Photodynamic therapy (PDT), a therapeutic modality for cancer treatment, involves the use of photosensitizing agents that can be activated using different wavelengths, intensities, or pulse durations to achieve direct cell killing or selective drug release from a carrier system .…”

Photothermal and photodynamic activity of polymeric nanoparticles based on α-tocopheryl succinate-RAFT block copolymers conjugated to IR-780

“…Au, Ag, Pt), metal oxides or carbon[15]. The most important drawbacks for the clinical use of IR-780 iodide are its poor solubility in physiological medium[16] and the low tolerance observed in in vivo models[17]. To overcome these limitations, IR-780 dye has been encapsulated into polymeric multifunctional micelles labeled with rhenium-188[18], silica NPs[19] or liposomes[20].…”