AIEgens: Next Generation Signaling Source for Immunoassays?

Abstract

Luminogens with aggregation-induced emission (AIEgens) properties have numerous broad applications in fields of chemical and biological analyses due to their exceptional photostability, excellent signal reliability, high quantum yield, and large Stokes’ shift. In particular, AIEgens also bring new blood for immunoassay. Since publication of the first 2004 paper, AIEgens-based immunoassays have received significant attention because of their high sensitivity, specificity, accuracy, and reliability. However, until now, there have been no comprehensive literature reviews focused on the evolving field of AIEgens-based immunoassays. Thus, we have extensively reviewed AIEgens-based immunoassays from their basic working principles to specific applications. We focus on several fundamental elements of AIEgens-based immunoassays, including the typical structures of AIEgens, emission mechanism of AIEgens probes, function of AIEgens in immunoassays, and platform of AIEgens-based immunoassays. Then, the representative applications of AIEgens-based immunoassays in food safety, medical diagnostics, and environmental monitoring are explored. Thus, proposals on how to further improve the AIEgens-based immunoassay performance are also discussed, as well as future challenges and perspectives, aiming to provide brief and valid guidelines for choosing suitable AIEgens-based immunoassays according to specific application requirements.

Overview on the Development of Alkaline-Phosphatase-Linked Optical Immunoassays

“…The aggregation of fluorophores with AIE characteristics (AIEgens) results in a significantly enhanced and stable emission. Notably, the AIEgens-based signal output strategy has paved a new way for fluorescent immunoassays [ 119 ]. In particular, the ALP/AIEgens-based immunoassays integrate the advantages of the immune reaction, ALP catalysis, and AIE phenomenon, in which ALP catalysis can finely regulate the aggregation or disaggregation of AIEgens.…”

Dynamic Imaging of Lipid Droplets in Cells and Tissues by Using Dioxaborine Barbiturate-Based Fluorogenic Probes

“…31 AIE-based fluorophores are particularly useful for bioimaging because they exhibit a turnon signal without requiring additional washing steps and are highly photostable. 32,33 The AIE property is also advantageous for monitoring cellular organelles and specific analytes because once these fluorophores are accumulated at the site of interest, their signals are even further enhanced, unlike many commonly used fluorophores that exhibit self-quenching effects. Thus, fluorophores with AIE properties have been actively developed for organelle imaging applications such as mitochondria, 34 lysosomes, 35,36 nuclei, 37,38 and LDs.…”

“…Although the push–pull system can enhance selectivity and sensitivity, the AIE property can boost signal intensity, especially when probes are concentrated and aggregated . AIE-based fluorophores are particularly useful for bioimaging because they exhibit a turn-on signal without requiring additional washing steps and are highly photostable. , …”

High-Performance Fluorescent Microspheres Based on Fluorescence Resonance Energy Transfer Mode for Lateral Flow Immunoassays

“…Excitingly, aggregation-induced emission luminogens (AIEgens), exhibiting a low fluorescence signal in the solvent state but strong emission in the aggregated state, were developed for overcoming the ACQ effect. 15 Currently, the restriction of intramolecular motion as the mechanism of AIE has been extensively used for designing AIEgens by molecular engineering to achieve high quantum yields (QYs) and large Stokes shifts, which is still a substantial challenge owing to multistep reactions. 16 Fluorescence resonance energy transfer (FRET), 17 occurring by the interaction of two types of luminogens, could be used for solving the aforementioned issues.…”

“…However, these fluorescent materials suffered from the aggregation-induced quenching (ACQ) effect, resulting in low fluorescence signals in the aggregated state owing to intermolecular π–π interactions or other nonradiative channels to form radical conjugates. Excitingly, aggregation-induced emission luminogens (AIEgens), exhibiting a low fluorescence signal in the solvent state but strong emission in the aggregated state, were developed for overcoming the ACQ effect …”