A new approach to developing diagnostics and therapeutics: Aggregation‐induced emission‐based fluorescence turn‐on

Abstract

Fluorescence imaging is a promising visualization tool and possesses the advantages of in situ response and facile operation; thus, it is widely exploited for bioassays. However, traditional fluorophores suffer from concentration limits because they are always quenched when they aggregate, which impedes applications, especially for trace analysis and real‐time monitoring. Recently, novel molecules with aggregation‐induced emission (AIE) characteristics were developed to solve the problems encountered when using traditional organic dyes, because these new molecules exhibit weak or even no fluorescence when they are in free movement states but emit intensely upon the restriction of intramolecular motions. Inspired by the excellent performances of AIE molecules, a substantial number of AIE‐based probes have been designed, synthesized, and applied to various fields to fulfill diverse detection tasks. According to numerous experiments, AIE probes are more practical than traditional fluorescent probes, especially when used in bioassays. To bridge bioimaging and materials engineering, this review provides a comprehensive understanding of the development of AIE bioprobes. It begins with a summary of mechanisms of the AIE phenomenon. Then, the strategies to realize accurate detection using AIE probes are discussed. In addition, typical examples of AIE‐active materials applied in diagnosis, treatment, and nanocarrier tracking are presented. In addition, some challenges are put forward to inspire more ideas in the promising field of AIE‐active materials.

Visible-to-NIR-Light Activated Release: From Small Molecules to Nanomaterials

“…Nanoparticles (NPs) and nanocarriers are frequently used for diagnostics, biosensing, photodynamic therapy, photothermal therapy, and targeted and controlled drug delivery/release. Developments in this field have been reviewed extensively in the past decade. ,,,,,,,,− Various materials can be used in the design of nanocarriers including metal NPs, semiconductor NPs, nanocarbons, virus- and bacteriophage-based NPs, microcapsules, and hydrogel-based systems. ,, NPs can be both carriers (transporters) or active participants in drug (species) delivery. Photoactivatable NP systems may feature direct covalent bonds to drug molecules, or drugs may be encapsulated via non-covalent interactions.…”

Recent Advances in Aggregation-Induced Emission Active Materials for Sensing of Biologically Important Molecules and Drug Delivery System

“…However, many traditional nanocarriers are invisible making it impossible to undertake intracellular trafficking which is the limitation on the drug delivery system. Therefore, a nano-drug delivery system with fluorescence imaging was developed and needed to be promoted [ 126 , 127 ]. Many fluorophores suffer from ACQ which hampers fluorescence; therefore, the novel AIE active fluorophore made it possible to overcome the ACQ and was found to be a very promising application in biomedical application.…”

Polypseudorotaxanes Derived from Tetraphenylethylene: Preparation and Tandem-Activated Aggregation-Induced Emission

“…10,11 To date, some methods have been developed to switch the fluorescence, 12 such as changing the solubility of AIE molecules, triggering spatial restriction, and combining with other photophysical processes. 6 For example, Hu et al designed an AIE molecule with an arylboronic ester group, and the emission was sharply enhanced after incubating with hydrogen peroxide. 13 Liu's group reported a bioprobe that the fluorescence was successively light up after the cleavage of the probe between TPECM-GFLG and D3-cRGD.…”

“…For example, the AIE molecules, especially the most studied tetraphenylethylene (TPE) derivatives, , exhibit strong fluorescence in the poor solvent, where the TPE derivatives are in the aggregated state, and just the opposite, the disaggregation state quenches the emission . The AIE character endows efforts to bring the molecules to a wide array of multidisciplinary applications, such as in diagnosis, treatment, and nanocarrier tracking. − Among all these applications, how to realize the reversible adjustment of fluorescence is essential and a requisite. Conceptually, the molecular rotation of AIE molecules can be enhanced by disaggregation or hindered by aggregation of molecules, indicating that the methods of tuning disaggregation and aggregation of molecules can be used to adjust the fluorescence of AIE molecules. , To date, some methods have been developed to switch the fluorescence, such as changing the solubility of AIE molecules, triggering spatial restriction, and combining with other photophysical processes .…”