ABSTRACT
Photodynamic therapy is a noninvasive approach for the treatment of oncological and nononcological diseases which has attempted to address the shortcomings and disadvantages of conventional cancer therapies. Given the scarcity of photosensitizers that exhibit desirable characteristics for its potential application in this therapeutic strategy, the main aims of this work were the study of the photophysical and photochemical properties, and the in vitro photobiological activity of several squaraine cyanine dyes. Thus, herein, the synthesis of indolenine-based N-methyl and N-ethyl mono- and dithiosquaraine dyes, the study of their spectroscopical properties, aggregation behavior, photodegradation and singlet oxygen production ability, and the further application of the previously synthesized dyes in colorectal adenocarninoma and hepatocellular carcinoma cell lines to evaluate their phototherapeutic effects, are described. Thionation significantly favored the ability to singlet oxygen production, and moderate photostability was observed for squaraine and monothionated dyes. Squaraine and monothiosquaraine cyanine dyes showed high promise within the tested concentration range regarding their potential application as cancer photodynamic therapy photosensitizers. Squaraine dyes' monothionation resulted in the preparation of compounds with poor photocytotoxicity, which was an undesirable effect on their phototherapeutic application.
