Articulated Structures of D-A Type Dipolar Dye with AIEgen: Synthesis, Photophysical Properties, and Applications.
ABSTRACT: Articulated structures of naphthalene-based donor (D)-acceptor (A) type dipolar dye and aggregation-induced emission luminogen (AIEgen) based on tetraphenylethylene (TPE) were synthesized, and their photophysical properties were analyzed for the first time. There are many fluorophore backbones, which have dipolar structure and AIEgen. However, there has been neither property analysis nor research that closely articulates DA and AIE through non-conjugation linker. We have therefore prepared two representative fluorophores; DA-AIE series (DA-AIE-M and DA-AIE-D), and characterized their UV/vis absorption and emission properties with quantum chemical calculations. In addition, we utilized the unique photophysical properties of DA-AIE-D for monitoring a trace of dimethyl sulfoxide (DMSO) in aqueous media, including real water samples.
Project description:A ?-extended tetraphenylethylene derivative 1 was developed as a fluorescent "turn-on" and "naked-eye" color change probe for hydrazine detection. Probe 1 was composed of the representative AIE luminogen (AIEgen), tetraphenylethylene, and a dicyanovinyl group was adopted for hydrazine recognition. Upon exposure of hydrazine, probe 1 immediately gave a significant aggregation-induced emission around 575 nm and excellent photostability. A naked-eye color change was also observed from red to yellow. Moreover, probe 1 was simply coated with a glass-backed silica gel-coated thin-layer chromatography plate, showing rapid and on-site detection of hydrazine vapor.
Project description:The synthesis of water-soluble near-infrared (NIR)-emissive fluorescent molecules with aggregation-induced emission (AIE) characteristics and theranostic functions is highly desirable but remains challenging. In this work, we designed and readily prepared for the first time such a molecule with AIE features, good water-solubility and intense emission in the NIR region. This AIE luminogen (AIEgen) is able to specifically "light up" the cell membrane without the involvement of a washing procedure. Interestingly, the staining process can be performed by simply shaking the culture with cells at room temperature for only a few seconds after the addition of the AIEgen, indicating an ultrafast and easy-to-operate staining protocol. This is the first fluorescent "light-up" probe for cell-imaging that allows the combination of a short staining period (at the second-level) with a wash-free process. Additionally, the presented AIEgen has also been developed to serve as an excellent phototherapeutic agent for high efficiency generation of reactive oxygen species (ROS) upon visible light irradiation, which allows its effective application in the photodynamic ablation of cancer cells, demonstrating its dual role as an imaging and phototherapeutic agent.
Project description:Stimuli-responsive functional gels have shown significant potential for application in biosensing and drug release systems. In this study, aggregation-induced emission luminogen (AIEgen)-functionalized, diselenide-crosslinked polymer gels were synthesized via free radical copolymerization. A series of polymer gels with different crosslink densities or tetraphenylethylene (TPE) contents were synthesized. The diselenide crosslinker in the gels could be fragmented in the presence of H2O2 or dithiothreitol (DTT) due to its redox-responsive property. Thus, the TPE-containing polymer chains were released into the aqueous solution. As a result, the aqueous solution exhibited enhanced fluorescence emission due to the strong hydrophobicity of TPE. The degradation of polymer gels and fluorescence enhancement in an aqueous solution under different H2O2 or DTT concentrations were studied. Furthermore, the polymer gels could be used as drug carriers, suggesting a visual drug release process under the action of external redox agents. The AIEgen-functionalized, diselenide-crosslinked polymer gels hold great potential in the biomedical area for biosensing and controlled drug delivery.
Project description:A facile and efficient approach for design and synthesis of organic fluorescent nanogels has been developed by using a pre-synthesized polymeric precursor. This strategy is achieved by two key steps: (i) precise synthesis of core?shell star-shaped block copolymers with crosslinkable AIEgen-precursor (AIEgen: aggregation induced emission luminogen) as pending groups on the inner blocks; (ii) gelation of the inner blocks by coupling the AIEgen-precursor moieties to generate AIE-active spacers, and thus, fluorescent nanogel. By using this strategy, a series of star-shaped block copolymers with benzophenone groups pending on the inner blocks were synthesized by grafting from a hexafunctional initiator through atom transfer radical copolymerization (ATRP) of 4-benzoylphenyl methacrylate (BPMA) or 2-(4-benzoylphenoxy)ethyl methacrylate (BPOEMA) with methyl methacrylate (MMA) and tert-butyldimethylsilyl-protected 2-hydroxyethyl methacrylate (ProHEMA) followed by a sequential ATRP to grow PMMA or PProHEMA. The pendent benzophenone groups were coupled by McMurry reaction to generate tetraphenylethylene (TPE) groups which served as AIE-active spacers, affording a fluorescent nanogel. The nanogel showed strong emission not only at aggregated state but also in dilute solution due to the strongly restricted inter- and intramolecular movement of TPE moiety in the crosslinked polymeric network. The nanogel has been used as a fluorescent macromolecular additive to fabricate fluorescent film.
Project description:Aggregation-induced emission (AIE) as a unique photophysical process has been intensively explored for their features in fields from optical sensing, bioimaging to optoelectronic devices. However, all AIE luminogens (AIEgens) hardly recover into the initial dispersed state after illuminating at the ultimate aggregated state, which limits AIEgens to achieve reversible sensing and reproducible devices. To real-time manipulate the emission of AIEgen, here we take the advantage of confined space in the quartz nanopore to achieve a nanopore-size-dependent restriction of AIEgens for reversible conversions of "on-to-off" and "off-to-on" emission. By electrochemically manipulating 26?fL AIEgen solution inside nanopore confinement, AIE illuminates while moves along nanopore from the constricted tip to inside cavity at a velocity of 1.4-2.2??m?s-1, and vice versa. We further apply this dynamic manipulation for a target delivery of AIEgen into single cells, which opens up new possibility to design powerful and practical AIE applications.
Project description:Effective cancer therapy largely depends on inducing apoptosis in cancer cells via chemotherapy and/or radiation. Monitoring apoptosis in real-time provides invaluable information for evaluating cancer therapy response and screening preclinical anticancer drugs. In this work, we describe the design, synthesis, characterization, and in vitro evaluation of caspase probe 1 (CP1), a bimodal fluorescence-magnetic resonance (FL-MR) probe that exhibits simultaneous FL-MR turn-on response to caspase-3/7. Both caspases exist as inactive zymogens in normal cells but are activated during apoptosis and are unique biomarkers for this process. CP1 has three distinct components: a DOTA-Gd(III) chelate that provides the MR signal enhancement, tetraphenylethylene as the aggregation induced emission luminogen (AIEgen), and DEVD peptide which is a substrate for caspase-3/7. In response to caspase-3/7, the water-soluble peptide DEVD is cleaved and the remaining Gd(III)-AIEgen (Gad-AIE) conjugate aggregates leading to increased FL-MR signals. CP1 exhibited sensitive and selective dual FL-MR turn-on response to caspase-3/7 in vitro and was successfully tested by fluorescence imaging of apoptotic cells. Remarkably, we were able to use the FL response of CP1 to quantify the exact concentrations of inactive and active agents and accurately predict the MR signal in vitro. We have demonstrated that the aggregation-driven FL-MR probe design is a unique method for MR signal quantification. This probe design platform can be adapted for a variety of different imaging targets, opening new and exciting avenues for multimodal molecular imaging.
Project description:Lysosomes are involved in a multitude of cellular processes and their dysfunction is associated with various diseases. They are the most acidic organelles (pH 3.8-6.6, size 0.1-1.2 ?m) with the highest viscosity (47-190 cP at 25 °C) in the cell. Because of their acidity, pH dependent non-AIE active fluorescent lysosomal probes have been developed that rely on protonation inhibited photoinduced electron transfer (PET). In this work, an acidic pH independent lysosome targetable piperazine-TPE (PIP-TPE) AIEgen has been designed with unique photophysical properties making it a suitable probe for quantifying viscosity. In a non-aggregated state PIP-TPE shows deep-blue emission as opposed to its yellowish-green emission in the bulk. It possesses high specificity for lysosomes with negligible cytotoxicity and good tracing ability due to its better photostability compared to LysoTracker Red. In contrast to most known lysosome probes that rely solely on PET, restriction of intramolecular motion (RIM) due to the larger viscosity inside the lysosomes is the mechanism responsible for PIP-TPE's fluorescence. PIP-TPE's high selectivity is attributed to its unique molecular design that features piperazine fragments providing a perfect balance between lipophilicity and polarity.
Project description:Multiphoton microscopy is an exciting tool for biomedical research because it can be used to image single cells <i>in vivo</i> due to its greater penetration depth, lower phototoxicity and higher resolution when compared to confocal laser scanning microscopy. This helps researchers understand how certain cells change over time and evaluate the efficacy of different therapies. Herein, we report a new AIE luminogen (AIEgen), abbreviated as TPE-TETRAD, with a favorable absorption and efficient deep-red emission in the solid state. TPE-TETRAD possesses a high two-photon absorption cross-section (313 MG at 830 nm) and a rich array of non-linear optical properties including aggregation-induced three-photon luminescence. Biotinylated TPE-TETRAD nanoparticles are also fabricated and applied to stain mitochondria in live cancer cells with high specificity. The purpose of this study is to characterize a novel deep-red AIEgen and fabricate biotinylated nanoparticles for applications as (1) biocompatible and photostable AIE probes for specific mitochondria imaging and (2) multiphoton imaging probes suitable for two/three-photon fluorescence microscopy.
Project description:The rational design of robust fluorescent organic materials for long-term cell tracing is still challenging, and aggregation-caused quenching of emission is a big limitation of this strategy. Organic dyes with aggregation-induced emission (AIE) can effectively address this problem. Herein, AIEgen-containing nanoparticles, with different morphologies and emission, were prepared by assembling amphiphilic copolymers with an AIEgen. We compared the physical and chemical properties of rod-like and spherical nanoparticles, particularly investigating the effects of the shape on internalization and the imaging effect. The formulated nanoparticles exhibit advantageous features, such as a large Stokes shift, robust stability in physiological conditions, strong fluorescent emission, and photobleaching resistance. Interestingly, the rod-like nanoparticles were internalized more efficiently than their spherical counterparts, and their strong green fluorescence can still be clearly observed even after 15 days in vitro and in vivo. This work demonstrates the great potential of regulating the morphology of nanoparticles to obtain an ideal biological function.
Project description:Luminogens with aggregation-induced emission (AIE) characteristics are nowadays undergoing explosive development in the fields of imaging, process visualization, diagnosis and therapy. However, exploration of an AIE luminogen (AIEgen) system allowing for extremely wide color tunability remains challenging. In this contribution, the facile synthesis of triphenylamine (TPA)-thiophene building block-based AIEgens having tunable maximum emission wavelengths covering violet, blue, green, yellow, orange, red, deep red and NIR regions is reported. The obtained AIEgens can be utilized as extraordinary fluorescent probes for lipid droplet (LD)-specific cell imaging and cell fusion assessment, showing excellent image contrast to the cell background and high photostability, as well as satisfactory visualization outcomes. Interestingly, quantitative evaluation of the phototherapy effect demonstrates that one of these presented AIEgens, namely TTNIR, performs well as a photosensitizer for photodynamic ablation of cancer cells upon white light irradiation. This study thus provides useful insights into rational design of fluorescence systems for widely tuning emission colors with high brightness, and remarkably extends the applications of AIEgens.