Recent process of NIR-type AIE-active fluorescent materials for biomedical applications of fluorescent imaging and phototherapeutics

Near-infrared red (NIR) fluorescence imaging guided phototherapeutics hold a great promise for deep tissue imaging and tumor treatment. Organic photosensitizers (PSs) serve as one of the most important parts in the process of optical diagnosis and therapy, among which those having strong absorption and fluorescence at the region of NIR spectrum have always attracted tremendous research interests because of numerous merits of deep penetration, diminished tissue autofluorescence, reduced tissue absorption and scattering, minimal phototoxicity, better spatiotemporal controllability and almost no drug resistance. Recently, aggregation-induced emission active agents (AIEgens) with NIR optical property develop rapidly because of the advantages of aggregation enhance simultaneously the efficiency of fluorescence, reactive oxygen species (ROS) and photothermal conversion. Recent efforts in designing molecular structures of NIR-type AIEgens and developing advanced therapeutic applications have achieved a series of breakthroughs. In this review, the materials designing and biomedical applications of NIR-type AIEgens are summarized. Starting with the introduction of general design theory of AIEgens and NIR property, recent efforts in developing various NIR-type AIE-active PSs for different biomedical applications including vascular bioimaging and single phototherapeutic and their synergistic therapy are then discussed. Finally, perspectives and challenges in the field of NIR-type AIEgens are outlooked. This review is expected to promote the development of newly emerging NIR-type AIEgens in biomedical applications for future clinical translation.