Design and Biomedical Applications of AIE-Active Nanoaggregates

Nanomedicine is an emerging and fast-growing field in which the application of nanotechnology to healthcare offers numerous improvements to medical diagnosis, therapy, etc. The design and development of novel fluorescent nanomaterials for biomedical applications have become one of the most important aspects of nanomedicine and have attracted increasing research interest. Previous studies have mainly focused on fluorescent inorganic nanoparticles, such as fluorescent carbon dots, metallic nanoclusters, etc. The major issues for their practical biomedical applications, especially <i>in vivo</i> applications, are still challenging, mainly due to their notorious toxicity to living organisms. As alternative nanomaterials for various biomedical applications, fluorescent organic nanoparticles have emerged and gained significant interest because of their various interesting optical properties, facile fabrication, and excellent biocompatibility. However, the fluorescence of most conventional organic dyes is quenched in the aggregate state or at high concentration, which is named aggregation-caused quenching (ACQ). This ACQ effect seriously hampers their potential applications in nanomedicine, such as bioimaging, diagnosis, and therapy. By contrast, aggregation-induced emission luminogens (AIEgens) are weakly emissive when molecules are uniformly dispersed in solution but “light up” when forming (nano)aggregates. With the significant advantages of high emission efficiency in the aggregate state, low background noise in dilute solution, excellent photostability, and large Stokes’ shift, AIEgens and AIE nanoparticles are especially suitable for bioimaging, diagnosis and therapy. AIEgens with various skeletons are designed as superior agents for biological process monitoring and disease theranostics. Moreover, AIEgens and AIE nanoparticles can be conveniently incorporated into the present theranostic platforms by combining them with various imaging and therapeutics modalities, such as multiphoton imaging, photoacoustic imaging, photothermal imaging, chemotherapy, photodynamic therapy, photothermal therapy, gene therapy, etc.<br/>[1] Mei, J.; Leung, N. L. C.; Kwok, R. T. K.; Lam, J. W. Y.; Tang, B. Z. <i>Chem. Rev.</i> <b>2015</b>, <i>115</i>, 11718-11940.<br/>[2] Gu, X.; Kwok, R. T. K.; Lam, J. W. Y.; Tang, B. Z. <i>Biomaterials </i><b>2017,</b> <i>146</i>, 115.<br/>[3] Qian, J.; Tang, B. Z. <i>Chem </i><b>2017,</b> <i>3</i>, 56-91.<br/>[4] Qi, J.; Chen, C.; Ding, D.; Tang, B. Z. <i>Adv. Healthcare Mater.</i> <b>2018</b>, 1800477.<br/>[5] Shen, H.; Xu, C.; Sun, F.;Zhao, M.; Wu, Q.; Zhang, J.; Li, S.; Zhang, J; Lam, J. W. Y.; Tang, B. Z., <i>ChemMedChem </i><b>2022</b>, <i>17</i>, e202100578.<br/>[6] Zuo, Y.; Shen, H.; Sun, F.; Li, P.; Sun, J.; Kwok, R. T. K.; Lam, J. W. Y.; Tang, B. Z., <i>ACS Bio & Med Chem Au</i> <b>2022</b>, <i>2</i>, 236-257.