Tetraphenylethylene-based AIE nanoprobes for labeling lysosome by two-photon imaging in living cells

Lysosomes are essential cellular organelles, serving vital functions in cellular metabolism and degradation. The design of specifically targeting lysosomes probes with aggregation-induced emission (AIE) characteristics using two-photon excitation techniques is significance and challenging work. Here we designed and synthesized two tetraphenylethylene (TPE)-based AIE fluorescence probes, naming TPE-Ma and TPE-Py, with TPE as the matrix and morpholine (Ma) or pyrrolidone (Py) as the targeting group. These probes exhibit a significant Stokes shift, low cytotoxicity, two-photo fluorescence imaging and lysosome-specific targeting capability ensuring their suitability for fluorescence imaging applications. To enhance the water solubility and cellular accumulation of TPE-Ma and TPE-Py in tumor cells, we employed a biocompatible polymer 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-mPEG2000) as a nanocarrier. By encapsulating TPE-Ma and TPE-Py within DSPE-mPEG2000, we successfully developed two AIE fluorescent nanoprobes known as DSPE@ TPE-Ma and DSPE@ TPE-Py. The results demonstrated that fluorescent nanoprobes DSPE@ TPE-Ma and DSPE@ TPE-Py possess excellent cell permeability, biocompatibility, superior photostability and specific targeting towards lysosomes in MCF-7 cells. Our findings highlight the potential of these fluorescent nanoprobes as effective tools for two-photon fluorescence imaging and targeted detection of lysosomes in cancer cells.

Aggregation-Induced Emission Luminogens for Cell Death Research

Cell death is closely related to various diseases, and monitoring and controlling cell death is a promising strategy to develop efficient therapy. Aggregation-induced emission luminogens (AIEgens) are ideal candidates for developing novel theranostic agents because of their intriguing properties in the aggregate state. The rational application of AIE materials in cell death-related research is still in its infancy but has shown great clinical potential. This review discussed the research frontier and our understanding of AIE materials in various subroutines of cell death, including apoptosis, necrosis, immunogenic cell death, pyroptosis, autophagy, lysosome-dependent cell death, and ferroptosis. We hope that the new insights can be offered to this growing field and attract more researchers to provide valuable contributions.

Cationic Conjugated Polyelectrolytes with Aggregation-Induced Ratiometric Fluorescence

The molecular diversity of aggregation-induced emission remains to be challenging due to the limitation of conventional synthesis methods. Here, a series of novel neutral and cationic conjugated polymers composed with various ratios of tetraarylethylene (TAE) containing a bridged oxygen (O) and fluorene (F) units are designed and synthesized via the geminal cross-coupling (GCC) of 1,1-dibromoolefins. The incorporation of TAE segments into the conjugated backbone of polyfluorene produces pronounced aggregation-induced ratiometric fluorescence (AIRF), i.e., aggregation-induced emission (AIE) at 520-600 nm grows synergistically with aggregations-caused quenching (ACQ) at 400-450 nm. The content of fluorene unit in the polymer backbones determines the intensity of the initial fluorescence at blue light region. The huge distinction (about 150 nm) in dual emission wavelengths caused by the environment change makes these conjugated polyelectrolytes particularly suitable for ratiometric fluorescence sensing. Based on electrostatic interaction mechanism, the gradual addition of heparin into the cationic conjugated polymers aqueous solutions could induce dual-color fluorescence changes with a detection limit of 9 nM. This work exhibits the great facility of using GCC reaction to synthesis the conjugated TAE polymers with superior AIE properties and special functions. This article is protected by copyright. All rights reserved.

Photooxidation-Driven Purely Organic Room-Temperature Phosphorescent Lysosome-Targeted Imaging

The construction of host-guest-binding-induced phosphorescent supramolecular assemblies has become one of increasingly significant topics in biomaterial research. Herein, we demonstrate that the cucurbit[8]uril host can induce the anthracene-conjugated bromophenylpyridinium guest to form a linear supramolecular assembly, thus facilitating the enhancement of red fluorescence emission by the host-stabilized charge-transfer interactions. When the anthryl group is photo-oxidized to anthraquinone, the obtained linear nanoconstructs can be readily converted into the homoternary inclusion complex, accompanied by the emergence of strong green phosphorescence in aqueous solution. More intriguingly, dual organelle-targeted imaging abilities have been also distinctively achieved in nuclei and lysosomes after undergoing photochemical reaction upon UV irradiation. This photooxidation-driven purely organic room-temperature phosphorescence provides a convenient and feasible strategy for supramolecular organelle identification to track specific biospecies and physiological events in the living cells.

Chemical sensors for selective and quantitative heparin sensing

In this review article, chemical sensors for selective and quantitative heparin sensing are discussed with detailed examples.