High‐Performance Quinoline‐Malononitrile Core as a Building Block for the Diversity‐Oriented Synthesis of AIEgens

Abstract

In vivo fluorescent monitoring of physiological processes with high‐fidelity is essential in disease diagnosis and biological research, but faces extreme challenges due to aggregation‐caused quenching (ACQ) and short‐wavelength fluorescence. The development of high‐performance and long‐wavelength aggregation‐induced emission (AIE) fluorophores is in high demand for precise optical bioimaging. The chromophore quinoline‐malononitrile (QM) has recently emerged as a new class of AIE building block that possesses several notable features, such as red to near‐infrared (NIR) emission, high brightness, marked photostability, and good biocompatibility. In this minireview, we summarize some recent advances of our established AIE building block of QM, focusing on the AIE mechanism, regulation of emission wavelength and morphology, the facile scale‐up and fast preparation for AIE nanoparticles, as well as potential biomedical imaging applications.

An Activatable and Switchable Nanoaggregate Probe for Detecting H2S and Its Application in Mice Brains

“…In addition, the quinolinium unit could contribute to the aggregationinduced-emission (AIE) feature of the nanoaggregates to some extent. [8] As for the fluorophore, 2-(2-hydroxy-phenyl) benzothiazole (HBT), a universal platform, served as the scaffold ascribed to its unique properties (Scheme 1c). It included advantages such as large Stokes shift, environmental sensitivity and potential for ratiometric sensing.…”

“…[5][6][7] Therefore, they are capable of responding specifically to the biomarkers of diseases and allow disease-specific diagnosis. [8] Accordingly, investigators have paid an increasing attention to the activatable probes in recent years. [9][10][11][12] On the other hand, as the third multifunctional gasotransmitter, H 2 S has been recognized as an important signaling molecule in the cardiovascular and nervous systems.…”

“…In comparison with the nonresponsive species (“always off”) and the “always on” tags, the activatable probes benefit from the signal changes, which further lead to the advantages including higher signal‐to‐noise ratio, lower detection of limit, permitting sensitive and so on [5–7] . Therefore, they are capable of responding specifically to the biomarkers of diseases and allow disease‐specific diagnosis [8] . Accordingly, investigators have paid an increasing attention to the activatable probes in recent years [9–12] …”

AIE-based nanoaggregate tracker: high-fidelity visualization of lysosomal movement and drug-escaping processes

“…[10][11][12][13][14][15][16][17] Moreover, AIE luminogens (AIEgens) have superiority in long-term imaging due to the good photostability by the high working concentration and aggregation state. [18][19][20][21] However, the recent lysosomal-mapping AIEgens always neglect the effect of nanoaggregates on targeting and long-term imaging of lysosomes. [22][23][24] Furthermore, the short emission wavelength of these AIEgens faces interference from biological background uorescence.…”

Fluorescent AIE-Active Materials for Two-Photon Bioimaging Applications

“…A new class of fluorescent materials ( Figure 1B) with aggregation-induced emission (AIE) discovered by Tang's group and others have received considerable attention due to their unique photophysical properties (Luo et al, 2001;An et al, 2002An et al, , 2012Shimizu et al, 2009;Shustova et al, 2013;Yan et al, 2015;Sasaki et al, 2016;Li and Li, 2017;Tsujimoto et al, 2017;Zhang et al, 2017;Ren et al, 2019;Guo et al, 2020;Hu et al, 2020;Kong et al, 2020;Mao et al, 2020;Qin et al, 2020). The widely accepted working mechanism of AIE-active fluorescent materials is restriction of intramolecular motions (Mei et al, 2015;Chen et al, 2019;Tu et al, 2020), thus the AIE materials generally show strong emission in aggregate and solid states and strong photobleaching resistance (Hong et al, 2011;Cao et al, 2019;Li et al, 2019;Chen et al, 2020;Feng H. et al, 2020;He et al, 2020b;Huang et al, 2020;Ni et al, 2020;Wei et al, 2020;Yin et al, 2020).…”