Modern Cyanine Dye-Based Photosensitizers for Medical Applications

The emergence of photochemical technology has revolutionized the fields of biology and medicine. Among them, photodynamic therapy represents a highly precise oncological treatment method. However, its therapeutic efficiency is severely hindered by inherent bottlenecks of traditional photosensitizers. While cyanine dyes have become the preferred molecular framework for overcoming these challenges. Over the past 8 years, our research team has made pioneering contributions in this field, which has catalyzed sustained interdisciplinary interest, spurring the rational design of a broad spectrum of photosensitizers. However, due to the fragmentation of internal communication within this field and the ambiguity of some key technologies, inconsistencies have emerged in some important application aspects. Given the significant contributions and professional expertise of our research team, we have conducted this review to provide a comprehensive introduction. We will examine the evolving biomedical applications of it through multiple perspectives, including photosensitization efficiency, hypoxic microenvironments, tissue penetration limitations, control of photosensitization activity, reactivation of the immune system, and transformation of molecular design paradigms. The aim is to provide both experts and non-experts with a clear and understandable resource, promoting a deeper understanding of modern cyanine dye-based photosensitizers and proposing actionable principles for the design and innovation of next-generation cyanine photosensitizers.