Synthesis, characterization and protein-association of dicyanomethylene squaraine dyes

Red and Near-Infrared Absorbing Dicyanomethylene Squaraine Cyanine Dyes: Photophysicochemical Properties and Anti-Tumor Photosensitizing Effects

“…Squaraine cyanine dyes, usually called squaraine dyes, are a family of compounds discovered in 1965 by Treibs and Jacob [13], whose suitable photochemical and photophysical properties give them the potential to be ideal for use in many biotechnological and biomedical applications, such as sensitizers for solar energy conversion [14,15], probes for metal ions and biomolecules detection [16][17][18][19][20], photodynamic therapy photosensitizers [7][8][9]21], among many others. The aforementioned dyes are known by their high molar extinction coefficient and also by their intense and narrow absorption bands in the visible and near-infrared regions due to the charge transfer system within the molecule.…”

“…Although the synthesis of dicyanomethylene-substituted dyes is already known [25], reports on the preparation of novel dyes from this core of compounds are still ongoing, and the results of the studies of their potential application in technological [26] and biomedical areas [16,24,27] are very encouraging. Regarding its possible use as photosensitizers, Wei et al [24] reported an in vitro and in vivo study in which this dye's scaffold presents an intense phototherapeutic activity.…”

“…Regarding the dicyanomethylene squaraine cyanine dyes shown in Figure 1, their experimental details and spectroscopic characterization were recently published by us, as fluorescent probes for protein detection [16]. However, and as far as we know, the in vitro phototherapeutic effects presented by these dyes have never been tested, nevertheless, this study is assumed to be quite pertinent, given the encouraging results of some in vitro and in vivo works already reported [24] and the scantiness of photodynamic therapy studies related to this scaffold of compounds.…”

“…However, and as far as we know, the in vitro phototherapeutic effects presented by these dyes have never been tested, nevertheless, this study is assumed to be quite pertinent, given the encouraging results of some in vitro and in vivo works already reported [24] and the scantiness of photodynamic therapy studies related to this scaffold of compounds. The fact that these dyes have shown good interaction with serum albumin [16], according to some studies [28][29][30], also makes these compounds potential photodynamic therapy photosensitizers with increased phototherapeutic efficiency. Additionally, the choice to evaluate the in vitro photodynamic activity of indolenine-based squaraine dyes is due to the fact that this heterocycle, according to recent studies [7,31], provides desirable photophysical properties, such as excellent stability, as well as the high yield of photocytotoxicity.…”

Photophysicochemical Properties and In Vitro Phototherapeutic Effects of Iodoquinoline- and Benzothiazole-Derived Unsymmetrical Squaraine Cyanine Dyes

“…Among the squaric acid derivatives, it is essential to emphasize the squaraine cyanine dyes, a core of functional dyes, first reported by Treibs and Jacob [10], known for its good photochemical stability, conductivity, sharp and intense Vis/NIR absorption and high absorption coefficients [8,11,12]. These photochemical and photophysical properties encourage the study of the suitability of these core of dyes to their application as photoconductive and nonlinear optical materials [13,14], sensitizers for organic solar cells [15,16], fluorescent probes for detection of functional groups [17], toxic substances [18][19][20] or biomolecules [21][22][23], and as photodynamic therapy (PDT) photosensitizers [9,24,25].…”