Aggregation‐Induced Emission for Highly Selective and Sensitive Fluorescent Biosensing and Cell Imaging

Abstract

Fluorescent bioprobes are powerful analytical tools for studying biological activities in living systems. Fluorogens with aggregation-induced emission (AIE) characteristics have recently emerged as a new class of fluorescent bioprobes for biosensing and cell imaging. As discovered by Tang, AIE fluorogens are nearly nonemissive in molecular states with their intermolecular rotations being not restricted whereas their fluorescence is turned on by binding with certain biomolecules, leading to highly selective turn-on fluorescent probes for specific biomolecules and fluorescent cell imaging with a high signal-to-background noise ratio. By introducing the AIE characteristics into polymeric materials, AIE polymers could possess a good solubility and biocompatibility, excellent structural diversity, and ease for functionalization useful for efficient biosensing and cell imaging. Herein, we highlight a few recently published articles on small and macromolecular AIE molecules to provide a fundamental understanding of the AIE mechanism and illustrate the working principle for AIE based biosensing and cell imaging.

Squaraine Dyes: Interaction with Bovine Serum Albumin to Investigate Supramolecular Adducts with Aggregation‐Induced Emission (AIE) Properties

“…AIE is a unique photophysical phenomenon associated with chromophore aggregation. Fluorogens with aggregation‐induced emission characteristics have recently emerged as a new class of fluorescent bioprobes for biosensing and cell imaging . Instead of fluorescence quenching, the emission of luminogens with AIE characteristics is turned on when they are aggregated.…”

“…[9,10] AIE is a unique photophysical phenomenon associated with chromophore aggregation.F luorogens with aggregation-induced emission characteristics have recently emerged as an ew class of fluorescent bioprobes for biosensing [11,12] and cell imaging. [13,14] Instead of fluorescenceq uenching, the emission of luminogens with AIE characteristics is turned on when they are aggregated. Suzuki and Yokoyama noticedacolour change of as quaraine dye upon complexation with BSA [15] while the group of Ramaiah showed ah uge enhancementi nf luorescence quantum yields for as quaraine binding to BSA.…”

Progress and Trends in AIE-Based Bioprobes: A Brief Overview

“…Under appropriate conditions, AIE-based bioprobe luminesces dimly with a low background noise. Once interacted with biospecies or influenced by the surrounding bioenvironment, the AIEgen’s intramolecular motions are restricted, the lighted-up luminescence can thereby detect the bioanalytes and reveal certain biological status in a sensitive manner. − Furthermore, the high brightness of nanoaggregates or NPs formed by AIEgens can visualize the organelles, cells, bacteria, or tissues, etc., with high contrast and superb spatial resolution and without the need for washing. − In addition, these AIE NPs are fairly photostable under laser excitation, enabling reliable long-term tracking of dynamic biological processes. ,,− …”

Unity Makes Strength: How Aggregation‐Induced Emission Luminogens Advance the Biomedical Field

“…On the other hand, hydrophobic AIEgens are excellent candidates to synthesize fluorescent NPs with high loading doses to achieve desired brightness and excellent photobleaching resistance . Along with the rapid development of AIEgens in the past decades, several exciting reviews have been published . Nevertheless, most of them focused on the discovery, mechanism, property, and molecular library of AIEgens, as well as their applications in different research areas.…”