Metal‐Based Aggregation‐Induced Emission Theranostic Systems

Abstract

Efficient theranostic systems can realize better outcomes in disease treatment because of precise diagnosis and the concomitant effective therapy. Aggregation‐induced emission luminogens (AIEgens) are a unique type of organic emitters with intriguing photophysical properties in the aggregate state. Among the AIEgens studied for biomedical applications, so far, metal‐based AIE systems have shown great potential in theranostics due to the enhanced multimodal bioimaging ability and therapeutic effect. This research field has been growing rapidly, and many rationally designed systems with promising activities to cancer and other diseases have been reported recently. In this review, we summarized the recent progress of metal‐based AIE materials in bioimaging and biological theranostics, and deciphered the pertinent design strategies. We hope that this review can offer new insights into the development of this growing field.

Origin of luminescence properties and synthetic methods for gold- and bimetallic gold-based nanomaterials

“…The review by Khan et al highlighted the evolution of AuNCs and highlighted the importance of modifying synthetic methods for various biological applications in detail. 84 Surface functionalization is crucial for catalysis given that it protects nanoclusters from aggregation, improves their stability and alters their electronic structure. Recent progress in the surface-modified gold nanoclusters such as thiolate-protected AuNCs, phosphine-protected AuNCs, alkynyl-protected AuNCs and their role in the catalysis and selectivity for oxidation, reduction, cycloisomerization, hydrolysis, heterocoupling and electrocatalysis reactions has been summarized in the review article by Li et al The steric hindrance of ligands, Au active sites, and lattice oxygen atoms are a few factors affecting their catalytic activity.…”

“…79,80 The atomic-level synthetic approach for the preparation of noble metal NPs and the complexity in their synthetic process have been discussed in recent reviews (Table 2). 34,[81][82][83][84][85][86][87][88][89][90][91][92][93] Simultaneously, the correlation of the atomic-level modification of the surface of nanomaterials with their corresponding catalytic activity is important for understanding the role of metal doping in these NPs. The sensing applications of these metal-incorporated nanomaterials depend on their inherent luminescent property.…”

Interplay of Anion‐π+ and π+‐π+ Interactions in Novel Pyrido[2,1‐a]isoquinolinium‐Based AIEgens ‐ Substituent‐ and Counterion‐Dependent Fluorescence Modulation and Applications in Live Cell Mitochondrial Imaging**

“…This is in striking contrast to conventional organic fluorophores which are emissive in solutions, but become non‐fluorescent upon aggregation (Scheme 1a). Among other miscellaneous emitters, metal‐organic complexes have emerged as a new member in the AIEgen family showing several interesting features such as emission in deep red or near‐infrared region, high solution processability, and impressive external quantum efficiency in OLED devices [21–23] …”

“…Among other miscellaneous emitters, metal-organic complexes have emerged as a new member in the AIEgen family showing several interesting features such as emission in deep red or near-infrared region, high solution processability, and impressive external quantum efficiency in OLED devices. [21][22][23] Interestingly, various non-covalent interactions have been found to play an important role in inhibiting the undesired ACQ effect in aggregate state. [24] For instance, non-covalent interactions like CÀ H•••O, CÀ H•••F and CÀ H•••π interactions play a significant role in modulating the emission properties of AIEgens by restricting conformational motion and activating AIE effects in the solid state.…”

Rational Design of NIR-II AIEgens with Ultrahigh Quantum Yields for Photo- and Chemiluminescence Imaging

“…[18][19][20][21][22][23] Various AIE luminogens (AIEgens) have been developed and have shown great potential for biomedical applications. [24][25][26] In NIR-II bioimaging, the AIE strategy is also promising. Many NIR-II AIEgens with acceptable QYs can act as superior imaging materials (the highest QY approaches 15% using IR26 as the reference fluorophore with a QY of 0.5% in 1,2-dichloroethane).…”