Structural Morphology Changes the Fate of Semiconducting Polymers in Afterglow Luminescence Imaging
Liang Han, Jianhua Liu, Zixiang Wei, Ying Gu, Yulin Zhu, Lin Chen, Xindan Zhang, WU Weitao, Feng He, Leilei Tian
Abstract
Overcoming the highly hydrophobic and low polarity structural nature of π-conjugated polymers becomes the critical challenge for their biological applications in aqueous systems, especially for those applications that need dynamic interaction with the environment, for example, chemiluminescence, photodynamic therapy, fluorescent probe, and so on. Herein, we developed a self-assembly and morphology control strategy to enhance the afterglow luminescence of π-conjugated polymers in water. Specifically, a monodispersed afterglow π-conjugated polymer is synthesized and modified to be the macroinitiator for atom transfer radical polymerization, and consequently, a series of amphiphilic block copolymers PPV 8 - b -POEGMA n ( n = 30, 45, and 60) are prepared. Unique vesicular nanostructures with uniform sizes are self-assembled from PPV 8 - b -POEGMA n polymers, and we observe that such vesicle morphology will promote afterglow luminescence leading to long-persistent and bright signals. The special vesicle morphology enables the photosensitizers to be more accessible to light and O 2 and consequently improves the kinetics of the photochemical reactions for afterglow luminescence generation. Moreover, the vesicle morphology is also beneficial for the pharmacokinetics of in vivo applications, exhibiting a longer blood circulation time and higher tumor accumulation. In this work, the crucial role of structural morphology in determining the quality of optical bioimaging has been revealed, which deserves more attention for the design of imaging nanomaterials in the future.