Joining the Journey to Near Infrared (NIR) Imaging: The Emerging Role of Lanthanides in Designing of Molecular Probes
Near-infrared (NIR, 700-1700nm) bioimaging has gained considerable attention in the recent years owing to high imaging resolution and increasing penetration depths of tissue. NIR emissive lanthanide(III) complexes has emerged as alluring candidates for the design of NIR molecular probes in clinical imaging and diagnosis because of desirable temporal-spatial resolution, negligible photobleaching effect, long lifetime and low biotoxicity. In this minireview, we summarized our efforts in the molecular design of NIR luminescent lanthanide porphyrinoids and their biological applications in bioimaging and further clinical diagnosis and treatment. Remarkably, the -fluorinated porphyrin Yb3+ probes exhibit high luminescence (5-13% quantum yields in H2O), long decay lifetimes (>100 s) and enable in vivo fluorescence intensity imaging and time-resolved fluorescence lifetime imaging (FLIM). Finally, the main concerns and challenges for NIR emissive Ln biolabels such as the diversity of NIR Ln3+ optical toolbox, further biocompatibility and targeting capability in biological media are discussed so as to facilitate the long-term development of lanthanide chemical biology.