Novel isoindigo compound with aggregation-induced emission: Br-Br bonding joint restriction of intramolecular motion and cell imaging properties

6,6'-Dibromided tert-butyloxycarbonyl isoindigo (Br-TBOCII) has intense fluorescence in the solid state via excitation with aggregation-induced emission (AIE), contrary to the classic heavy-atom effect. The unique AIE mechanism is attributed to the Br-Br bonding joint restricting intramolecular motion. Furthermore, the water-soluble nanoparticles Br-TBOCII/Pluronic® 127, possess robust photostability, low toxicity and good cell imaging performance.

Thermally responsive AIE-active polyurethanes based on a tetraaniline derivative

Polyurethanes with different soft–hard segment ratios were successfully synthesized, with an aggregation-induced-emission (AIE)-active tetraaniline derivative (NH₂–B₃–Ani₄–NH₂) as the hard segment. The resulting polyurethanes exhibited typical AIE features. The fluorescence intensities of polyurethane films changed with heat treatments. The fluorescence intensities of the polyurethane films decreased sharply after quenching treatment, yet their fluorescence intensities exceeded the original intensities of the films after thermal annealing at 80 °C for 24 h. Differential Scanning Calorimetry (DSC) results implied that the melting peaks in polyurethane films disappeared after quenching treatment, but the melting peaks appeared again after thermal annealing. These results proved that the arrangement of the structure had an important effect on the AIE properties of the polyurethane films. Meanwhile, the fluorescence intensities of these polyurethanes decreased with the increase of temperature, indicating that all three polyurethanes exhibited temperature-dependent fluorescent characteristics. Based on the above investigations, the AIE-active polyurethanes may provide a platform for the development of stimuli-responsive fluorescent materials.

Polyurethanes with an AIE fluorophore (tetraaniline derivative) are thermo-responsive, demonstrating that AIE-active polyurethane films have promising applications in stimuli-responsive materials.

Azoreductase-triggered fluorescent nanoprobe synthesized by RAFT-mediated polymerization-induced self-assembly for drug release

Herein, micelles loaded with doxorubicin (DOX) in situ were synthesized by polymerization-induced self-assembly. Furthermore, the DOX-loaded micelles showed release and fluorescence change, owing to azoreductase-triggered azo bond cleavage.

An acrylate AIE-active dye with a two-photon fluorescent switch for fluorescent nanoparticles by RAFT polymerization: synthesis, molecular structure and application in cell imaging

This work reported the synthesis of a novel acrylate AIE-active dye with a reversible two-photon fluorescent switch and its amphiphilic PEG-TM polymers via RAFT polymerization, which are attractive for applications in cell imaging.

A novel AIE-active dye for fluorescent nanoparticles by one-pot combination of Hantzsch reaction and RAFT polymerization: synthesis, molecular structure and application in cell imaging

In recent years, amphiphilic AIE-active fluorescent organic materials with aggregation-induced emission (AIE) properties have been extensively investigated due to their excellent properties. This study describes the synthesis of a novel AIE-active dye of tetraphenylethylene diphenylaldehyde (TPDA). As compared with the reported fluorescent dye TPB, the fluorescence intensity of TPDA is significantly enhanced with the distinct red shift of emission wavelength. Subsequently, the corresponding novel polymers PEG-TPD were obtained through the one-pot combination of Hantzsch reaction and RAFT polymerization. The structure of PEG-TPD1 by the two-step process was similar with that of PEG-TPD2 by the one-pot method at the same feeding ratio of TPDA and PEGMA. The molecular weights (M_n) of the polymers PEG-TPD1 and PEG-TPD2 were respectively 52 000 and 28 000 with narrow polydispersity index (PDI), and their molar fractions of TPDA were respectively about 9.5% and 14.3%, indicating that the degree of Hantzsch reaction in the one-pot process was more complete. Subsequently, the effect of feed ratio of TPDA and PEGMA on polymer structure was further studied. It can be seen that the M_n of the polymers gradually increases as the proportion of TPDA increases. In aqueous solution, these amphiphilic PEG-TPD polymers tended to self-assemble into corresponding fluorescent polymer nanoparticles (FPNs). The diameter of PEG-TPD2 FPNs ranged from 200 to 300 nm, and their fluorescence emission spectra have maximum emission peak at 509 nm. The PEG-TPD FPNs have significant advantages such as good fluorescence intensity, high water dispersibility, good biocompatibility and easy absorption by cells, which can be attractively used in the field of bioimaging.

This work reported the fabrication of a novel AIE-active dye and its amphiphilic PEG-TPD fluorescent polymers via one-pot combination of RAFT polymerization and Hantzsch reaction, which showed potential applications in bioimaging.