Cyanine Dye-Based Compounds for Tumor Imaging With and Without Photodynamic Therapy

Among the near-infrared (NIR) dyes, cyanine dyes in general have shown enormous potential for optical imaging. Efforts are underway to increase their tumor-targeted specificity by conjugating these fluorophores with those targeting moieties known to bind certain receptors having high expression in tumor cells. Attempts are also underway to develop “multifunctional dyes” with nuclear, magnetic resonance (MR) and optical imaging properties. Recent studies have shown that certain tumor-avid photosensitizers conjugated with cyanine dyes can be used as “bifunctional agents” for tumor imaging and photodynamic therapy (PDT). Such compounds, which effectively function as imaging and therapeutic agents, would create an entirely new paradigm for tumor diagnosis and therapy. In this review article, the synthesis, imaging and therapeutic potential of selected cyanine dyes are briefly summarized.