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Photochemistry and Cytotoxicity Evaluation of Heptamethinecyanine Near Infrared (NIR) Dyes
Molecular Physical Chemistry Center, and IN-Institute of Nanoscience and Nanotechnology, Instituto Superior Técnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisboa, Portugal
* Author to whom correspondence should be addressed.
Received: 31 July 2013; in revised form: 19 August 2013 / Accepted: 2 September 2013 / Published: 9 September 2013
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.
Keywords: heptamethine cyanine dyes; fluorescence quantum yields and lifetimes; transient absorption; PDT; HeLa cells; photo and dark cytotoxicity; confocal microscopy
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Conceição, D.S.; Ferreira, D.P.; Ferreira, L.F.V. Photochemistry and Cytotoxicity Evaluation of Heptamethinecyanine Near Infrared (NIR) Dyes. Int. J. Mol. Sci. 2013, 14, 18557-18571.
Conceição DS, Ferreira DP, Ferreira LFV. Photochemistry and Cytotoxicity Evaluation of Heptamethinecyanine Near Infrared (NIR) Dyes. International Journal of Molecular Sciences. 2013; 14(9):18557-18571.
Conceição, David S.; Ferreira, Diana P.; Ferreira, Luís F.V. 2013. "Photochemistry and Cytotoxicity Evaluation of Heptamethinecyanine Near Infrared (NIR) Dyes." Int. J. Mol. Sci. 14, no. 9: 18557-18571.