Design and synthesis of folate receptor-targeted squaraine dye complex for photodynamic therapy

In recent years, new treatment methods have been developed in addition to traditional treatments to eliminate cancer, one of the deadliest diseases. Given the shortcomings of conventional therapies, including the emergence of drug resistance and selectivity to the target cell, a considerable number of researchers have directed their attention toward the investigation of alternative, less invasive strategies for the treatment of cancer. Photodynamic therapy (PDT) has received great attention in the scientific community as it is seen as a promising method of cancer treatment. Various approaches have been adopted to identify new and more effective photosensitizers (PSs) that reduce adverse effects. In this context, it is suggested that squaraine dyes could potentially overcome the disadvantages associated with conventional PSs. Moreover, conjugating targeting agents such as folic acid (FA) to these PSs is suggested as a promising approach that can provide rational solutions for their applications in PDT. In this study, the SQ-FA compound, obtained by conjugation of squaraine dye and folic acid (SQ-FA), was synthesized, its structure was characterized by various methods, and cytotoxicity studies were presented. SQ-FA is designed as a diagnostic and therapeutic tool for use in cancer treatment for human lung carcinoma epithelial cells (A549). In addition, biocompatibility studies of dermal fibroblast cell lines (L929) were carried out. SQ-FA can function as a PS and be used as a targeting agent. Spectroscopic analysis and optical properties of SQ-FA, a new dye belonging to the squaraine family, were investigated.