ABSTRACT
Photodynamic therapy is an innovative treatment approach broadly directed towards oncological diseases. Its applicability and efficiency are closely related to the interaction of three main components, namely a photosensitizer, light and molecular triplet oxygen, which should drive cell death. Recently, several studies have demonstrated that squaraine cyanine dyes have a set of photophysical and photochemical properties that have made of these compounds' potential photosensitizers for this therapeutic modality. In the present research work, we describe the synthesis and characterization of four quinoline and benzoselenazolederived unsymmetrical squaraine cyanine dyes. Except for the precursor of aminosquaraine dyes, i.e., Omethylated derivative, all dyes were evaluated for their behavior and absorption capacity in different organic and aqueous solvents, their ability to form singlet oxygen, their lightstability, and in vitro phototherapeutic effects against two human breast cancer cell cultures (BT474 and MCF7). Regardless of the nature of the used solvents, the synthesized dyes showed intense absorption in the red and nearinfrared spectral regions, despite the formation of aggregates in aqueous media. Dyes showed high lightstability against light exposure. Despite the low ability to produce singlet oxygen, aminosquaraine dyes demonstrated worthy in vitro phototherapeutic activity.