Fluorescent imaging is one of the most rapidly expanding research area in biological science. As the high demand of new technologies in fluorescence, the fluorescent materials have been taken to the central stage due to their unique optical properties, low background noise, and good processibility.

The development of fluorescent bioprobes with excellent sensitivity, specificity, and biocompatibility is highly desirable because it allows on-site detection of biological macromolecules and real-time monitoring of biological events in living systems. Nevertheless, most of the conventional organic fluorophores suffer from a severe problem of aggregation-caused quenching (ACQ) at high concentration or in the aggregated state, resulting in great limitations in the biological applicati...[ Read more ]

Fluorescent imaging is one of the most rapidly expanding research area in biological science. As the high demand of new technologies in fluorescence, the fluorescent materials have been taken to the central stage due to their unique optical properties, low background noise, and good processibility.

The development of fluorescent bioprobes with excellent sensitivity, specificity, and biocompatibility is highly desirable because it allows on-site detection of biological macromolecules and real-time monitoring of biological events in living systems. Nevertheless, most of the conventional organic fluorophores suffer from a severe problem of aggregation-caused quenching (ACQ) at high concentration or in the aggregated state, resulting in great limitations in the biological applications.

Recently, our group discovered such a novel system, in which fluorogen aggregation plays a constructive, instead of destructive, role in the light-emitting process. We coined this abnormal phenomenon as “aggregation-induced emission” (AIE), and identified the restriction of intramolecular rotation (RIR) as the main cause of the AIE effect. Thanks to the enthusiastic effort of scientists working in AIE research, many AIE materials with different structures and emission colors have been developed. The high brightness of AIE materials in the aggregated state makes them promising candidate materials as fluorescent bioprobes for sensing and imaging applications.

In this work, a series of new AIE fluorogens have been designed and synthesized. They are weakly emissive in water but emit intensely when their intramolecular rotations have been restricted upon binding to the specific sites in cells. Such a light-up feature of fluorescent probe enables the quantitation and visualization of research of interest in cells.

Moreover, these AIE probes do not only serve as fluorescent visualizers for fast intracellular imaging, they also serve as therapeutic agents for cancer treatment. The AIE bioprobes can be utilized as a long-term tracer for monitoring the drug distribution and responses.