Synthesis, Photophysics, and Solvatochromic Studies of an Aggregated-Induced-Emission Luminogen Useful in Bioimaging

Rational Design of High-Performance Hemithioindigo-Based Photoswitchable AIE Photosensitizer and Enabling Reversible Control Singlet Oxygen Generation

A photosensitizer furnishing with reversible control singlet oxygen generation (¹O₂) is highly desirable for precise photodynamic therapy (PDT), lessening non-specific harm to healthy tissues. Here, a novel photoswitchable aggregation-induced emission (AIE) photosensitizer based on a triarylamine (TPA)-modified hemithioindigo (HTI), 6Br-HTI-TPA-OMe, was rationally designed. The triarylamine AIE photosensitizing moiety and HTI switch unit were covalently linked in one molecule, permitting reversible regulation of ¹O₂ production. The photophysical evaluations revealed that 6Br-HTI-TPA-OMe possessed excellent AIE properties and Z/E photoswitch performance in different solvents. Additionally, the amphiphilic phospholipid-fabricated nanoparticles (NPs) also exhibited photochromic behavior in water. The Z-NPs initiated the generation of ¹O₂ upon 520 nm light-emitting diode (LED) irradiation, but after switching to E-NPs, the generation of ¹O₂ was inhibited by the competitive energy transfer, suggesting that reversible Z/E isomerization could photocontrol ¹O₂ generation. The in vitro anti-tumor experiment verified that the 6Br-HTI-TPA-OMe can act as a photoswitchable AIE photosensitizer. This is the first report on the photoswitchable AIE photosensitizer of HTI-based molecules, to the best of our knowledge.

Aggregation-induced emission-active micelles: synthesis, characterization, and applications

Aggregation-induced emission (AIE)-active micelles are a type of fluorescent functional materials that exhibit enhanced emissions in the aggregated surfactant state. They have received significant interest due to their excellent fluorescence efficiency in the aggregated state, remarkable processability, and solubility. AIE-active micelles can be designed through the self-assembly of amphipathic AIE luminogens (AIEgens) and the encapsulation of non-emissive amphipathic molecules in AIEgens. Currently, a wide range of AIE-active micelles have been constructed, with a significant increase in research interest in this area. A series of advanced techniques has been used to characterize AIE-active micelles, such as cryogenic-electron microscopy (Cryo-EM) and confocal laser scanning microscopy (CLSM). This review provides an overview of the synthesis, characterization, and applications of AIE-active micelles, especially their applications in cell and in vivo imaging, biological and organic compound sensors, anticancer drugs, gene delivery, chemotherapy, photodynamic therapy, and photocatalytic reactions, with a focus on the most recent developments. Based on the synergistic effect of micelles and AIE, it is anticipated that this review will guide the development of innovative and fascinating AIE-active micelle materials with exciting architectures and functions in the future.

New bioisosteric sulphur-containing choline kinase inhibitors with a tracked mode of action

Since the identification of human choline kinase as a protein target against cancer progression, many compounds have been designed to inhibit its function and reduce the biosynthesis of phosphatidylcholine. Herein, we propose a series of bioisosteric inhibitors that are based on the introduction of sulphur and feature improved activity and lipophilic/hydrophilic balance. The evaluation of the inhibitory and of the antiproliferative properties of the PL (dithioethane) and FP (disulphide) libraries led to the identification of PL 48, PL 55 and PL 69 as the most active compounds of the series. Docking analysis using FLAP suggests that for hits to leads, binding mostly involves an interaction with the Mg²⁺ cofactor, or its destabilization. The most active compounds of the two series are capable of inducing apoptosis following the mitochondrial pathway and to significantly reduce the expression of anti-apoptotic proteins such as the Mcl-1. The fluorescence properties of the compounds of the PL library allowed the tracking of their mode of action, while PAINS (Pan Assays Interference Structures) filtration databases suggest the lack of any unspecific biological response.

A self-healing supramolecular hydrogel with temperature-responsive fluorescence based on an AIE luminogen

In this work, an AIE luminogen-based hydrogel with temperature-responsive fluorescence was designed and synthesized. The polymeric hydrogel consisted of a supramolecular network through coordination and ionic interactions. When the temperature was decreased, due to the motion restriction of the polyacrylic acid macromolecular segments and the enhancement in ionic interaction, the hydrogel exhibited a blue-shift in the fluorescence emission peak and increase in the fluorescence intensity, resulting in the visualization of fluorescence changes. The hydrogel network benefitted from non-covalent crosslinking and thus possessed self-healing properties at room temperature with good toughness and resiliency. Therefore, this fluorescent supramolecular hydrogel might be used as a temperature-responsive material.

A supramolecular hydrogel was synthesized by using tetra(4-(pyridin-4-yl)phenyl)ethylene (TPPE) as AIE luminogen. The gel not only featured self-healing performance, but also exhibited the temperature-responsive fluorescence with thermochromism.