Near-infrared II aggregation-induced electrochemiluminescence of organic dots.

For the first time, we report novel aggregation-induced electrochemiluminescence (AIECL) of organic dots in aqueous media, with near-infrared II (NIR-II) luminescence peaked at 906 nm. Furthermore, a hybrid mechanism of ECL generation is revealed by various experiments in conjunction with theoretical calculations. This work opens a window for exploring efficient organic dye-based NIR-II AIECL emitters.

Apoptotic extracellular vesicles are metabolized regulators nurturing the skin and hair.

Over 300 billion of cells die every day in the human body, producing a large number of endogenous apoptotic extracellular vesicles (apoEVs). Also, allogenic stem cell transplantation, a commonly used therapeutic approach in current clinical practice, generates exogenous apoEVs. It is well known that phagocytic cells engulf and digest apoEVs to maintain the body's homeostasis. In this study, we show that a fraction of exogenous apoEVs is metabolized in the integumentary skin and hair follicles. Mechanistically, apoEVs activate the Wnt/ß-catenin pathway to facilitate their metabolism in a wave-like pattern. The migration of apoEVs is enhanced by treadmill exercise and inhibited by tail suspension, which is associated with the mechanical force-regulated expression of DKK1 in circulation. Furthermore, we show that exogenous apoEVs promote wound healing and hair growth via activation of Wnt/ß-catenin pathway in skin and hair follicle mesenchymal stem cells. This study reveals a previously unrecognized metabolic pathway of apoEVs and opens a new avenue for exploring apoEV-based therapy for skin and hair disorders.

Ir(III) Complexes with AIE Characteristics for Biological Applications.

Both biological process detection and disease diagnosis on the basis of luminescence technology can provide comprehensive insights into the mechanisms of life and disease pathogenesis and also accurately guide therapeutics. As a family of prominent luminescent materials, Ir(III) complexes with aggregation-induced emission (AIE) tendency have been recently explored at a tremendous pace for biological applications, by virtue of their various distinct advantages, such as great stability in biological media, excellent fluorescence properties and distinctive photosensitizing features. Significant breakthroughs of AIE-active Ir(III) complexes have been achieved in the past few years and great progress has been witnessed in the construction of novel AIE-active Ir(III) complexes and their applications in organelle-specific targeting imaging, multiphoton imaging, biomarker-responsive bioimaging, as well as theranostics. This review systematically summarizes the basic concepts, seminal studies, recent trends and perspectives in this area.

Mechanical Force-Induced Blue-Shifted and Enhanced Emission for AIEgens.

Mechanochromic (MC) luminescence of organic molecules has been emerging as a promising smart material for optical recording and memory devices. At the same time, pressure-induced blue-shifted and enhanced luminescence are rarely reported now. Herein, a series of cyanostilbene-based AIEgens with different substituents were synthesized to evaluate the influence of morphology transformation and push-pull electronic effect on the MC luminescence. Among these luminophores, compound 1 with one cyano group and diethylamino group was more susceptible to mechanical stimuli and obtained blue-shifted and enhanced fluorescence in response to anisotropic grinding. Powder X-ray diffraction patterns indicated that the MC behaviors were ascribed to the solid-state morphology transition from crystal-to-crystal. Analysis of crystal structures revealed that loose molecular packing is a key factor for high high-contrast MC luminescence. The smart molecular design, together with the excellent performance, verified that luminophores with twisted structures are ideal candidates for MC luminogens.

Development of an HPV Genotype Detection Platform Based on Aggregation-Induced Emission (AIE) and Flow-Through Hybridization Technologies.

Genetic mutations can cause life-threatening diseases such as cancers and sickle cell anemia. Gene detection is thus of importance for disease-risk prediction or early diagnosis and treatment. Apart from genetic defects, gene detection techniques can also be applied to gene-related diseases with high risk to human health such as human papillomavirus (HPV) infection. HPV infection has been strongly linked to cervical cancer. To achieve a high-throughput HPV gene detection platform, the flow-through hybridization system appears to be one of the commercialized diagnostic techniques for this purpose. The flow-through hybridization technique is based on a vacuum-guided flow of DNA fragments which is continuously directed toward the oligoprobes that are immobilized on the testing membrane. However, the conventional colorimetric method and signal read-out approach suffers a problem of low sensitivity. On the contrary, fluorescence approaches allow more sensitive detection and broad sensing ranges. In this work, a fluorescent dye HCAP, which possesses aggregation-induced emission (AIE) properties and is responsive to alkaline phosphatase, was developed and applied to the flow-through hybridization platform to achieve HPV genome diagnosis of clinical samples. Also, an automatic membrane reader was constructed based on the AIE-based diagnosis platform which can identify the diagnostic result of patient DNA with a total concordance rate of 100% in the clinical trial.

Highly specific and selective fluorescent chemosensor for sensing of Hg(II) by NH-pyrazolate-functionalized AIEgens.

Luminescent organic molecules are of important realistic significance to the human health and ecological environment due to their fascinating applications. Here we report the design and synthesis of luminescent organic-molecules by introducing two or four NH-pyrazolate groups as mercury-binding moieties to aromatic cores. Interestingly, the new aromatic tetraphenylene-bridged multi-NH-pyrazoles exhibit strong fluorescence in both aggregate and solid state and constitutes highly selective proof-of-concept luminescent sensor for Hg(II) ion among various competitive transition-metal ions in both organic and mixed solutions via metal-nitrogen binding. Especially, the present sensor including two NH-pyrazolyl groups showed an extremely high sensitivity with low limit of detection of 7.26 and 3.67 nM. The proposed design strategy provides a wide scope for the construction of unique turn-on sensors with substantial potential in the sense of heavy metal pollution in enviromental water samples.

A smartphone-based electroporation system with highly robust and low-voltage silicon nanopillar chips.

In this work, a novel smartphone-based electroporation (EP) system integrated with 3D scalable and robust gold-coated silicon-nanopillar Electroporation (Au-Si NP-EP) chip using projection photolithography is developed, for the first time, for both EP and electric cell lysing (ECL) at low voltages. Au-SiNP-EP chip consists of silicon nanopillars fabricated by using ASML stepper, Deep Reactive Ion Etching (DRIE) process and coated with a gold microelectrode. The silicon nanopillars were optimized based on theoretical analysis and numerical simulations to enhance the electrical field intensity and mechanical strength. The fabricated Au-SiNP-EP chips are tested with both permeable (Acridine Orange (AO) and impermeable (Propidium Iodide (PI)) molecules for HeLa cells at different volts (1-8 V) and pulse duration (1-9 µs). The fabricated chip achieved an optimized EP efficiency of 84.3% and cell viability of 81.4% at a much smaller voltage (4.5V) than reported planar electroporation (PEP) devices (8-100V). Compared with nanostructures-based devices (2-20 V), our devices show both higher mechanical strength and fabrication yield. Besides, a smartphone app integrated with a low-cost open-source portable Arduino-based system is developed to provide optimized electrical protocols for both EP and ECL. The electric cell lysing with ECL efficiency of 97.0% at 7 V and pulse duration of 9 ms has been successfully demonstrated. The experimental results show that the proposed smartphone-based EP system with Au-SiNP EP chips is promising for various applications, including intracellular delivery of various biomolecules, drugs, and release of DNA/RNA molecules from biological cells.

Visible-near infrared-II skull optical clearing window for in vivo cortical vasculature imaging and targeted manipulation.

Skull optical clearing window permits us to perform in vivo cortical imaging without craniotomy, but mainly limits to visible (vis)-near infrared (NIR)-I light imaging. If the skull optical clearing window is available for NIR-II, the imaging depth will be further enhanced. Herein, we developed a vis-NIR-II skull optical clearing agents with deuterium oxide instead of water, which could make the skull transparent in the range of visible to NIR-II. Using a NIR-II excited third harmonic generation microscope, the cortical vasculature of mice could be clearly distinguished even at the depth of 650 µm through the vis-NIR-II skull clearing window. The imaging depth after clearing is close to that without skull, and increases by three times through turbid skull. Furthermore, the new skull optical clearing window promises to realize NIR-II laser-induced targeted injury of cortical single vessel. This work enhances the ability of NIR-II excited nonlinear imaging techniques for accessing to cortical neurovasculature in deep tissue.

Nonenzyme Cascaded Amplification Biosensor Based on Effective Aggregation Luminescence Caused by Disintegration of Silver Nanoparticles.

Sensitive and portable quantification of biomarkers has particular significance in the monitoring and treatment of clinical diseases. Conventional immunoassays were accustomed to introducing or incorporating enzymes for signal amplification, which commonly suffered from poor stability and inferior tolerance. Herein, we constructed a novel nonenzyme amplification methodology based on fluorogenic Ag+-tetrazolate aggregation coupled with silver corrosion sensitization for biomarker determination. A significant cascade enhancement strategy was achieved by the valid aggregation luminescence caused by the potent disintegration of silver nanoparticles. Furthermore, efficient magnetic separation was also combined and performed for the rapidity and simplicity of operation. As the target, the detection limit of prostate-specific antigen was 15.66 pg/mL in our designed biosensor. Besides, a good linear relationship was obtained. The designed biosensor demonstrated good specificity and was successfully applied to clinical serum sample detection.

Structure design and performance of photomultiplication-type organic photodetectors based on an aggregation-induced emission material.

Aggregation-induced emission (AIE) materials have shown attractive prospects in the fields of biological probes, chemical sensing, optoelectronic systems and stimuli responses. Here, we have successfully fabricated photomultiplication-type organic photodetectors based on an AIE material by designing a device structure. The high photoconductive gain was attributed to the interfacial trap-assisted hole-tunneling injection caused by MoO3 as the trap for electrons. The fabricated AIE-based photomultiplication-type organic photodetectors exhibited the figures of merits of high external quantum efficiency in excess of 60 000%, responsivity of 172 A W-1, detectivity of 3.08 × 1012 Jones, and photoresponse with a rise time of 1.69 ms. Moreover, the devices also showed good stability with a half-life of 700 hours at continuous testing under ambient conditions, which makes them one of the most stable OPDs reported so far. The results demonstrate that AIE molecules are an excellent kind of photodetective material.

Reaction-based chiroptical sensing of ClO- using circularly polarized luminescence via self-assembly organogel.

By covalent combination of a chiral amino acid, lipid, and achiral phenothiazine derivative, a reaction-based chiroptical probe, PTZ-D, was obtained. PTZ-D could self-assemble into a chiral organogel realizing the chirality transformation from a chiral amino acid to a self-assembled system and displaying unprecedented chiroptical monitoring of ClO- with switchable CPL signals.

Amorphous Ag2S Micro-rods-Enhanced Fluorescence on Liquid Crystals: Cation-π Interaction-Triggered Aggregation-Induced Emission Effect.

Aggregation-induced emission (AIE) system has long been regarded as a promising substitute to overcome the aggregation-caused quenching in traditional luminescent liquid crystals, which could further enhance its efficiency and application. However, due to the intrinsic weak interaction between hybrid components, heterogeneous inorganic materials-induced AIE process was rarely reported. In this study, trace amounts of amorphous Ag2S microrods and an AIE-active liquid crystalline compound tetraphenylethylene-propylbenzene (TPE-PPE) were proposed to construct additional intense interaction to trigger AIE effect. The enhanced concentration of unsaturated Ag ions and excess positive charge on Ag2S surface promote a cation-π interaction with TPE-PPE, leading to a 36-fold increase in fluorescence, which is predominately high in luminescent liquid crystal system. To the best of our knowledge, this is the first report of the AIE process activated by cation-π interaction. This novel approach would provide guidance to fabricate high-luminescence meso phases for future luminescent display device.

Converting Thioether Waste into Organic Semiconductors by Carbon-Sulfur Bond Activation.

A goal for human society is to convert organic waste into valuable materials. Herein, 2-(methylthio)-bezothiazole (MTBT), an important organic waste in urban runoff, was catalytically converted into a series of organic semiconductors through carbon-sulfur bond activation. The efficient conversion of various substrates with different aromatic moieties and reacting functional groups (tin and boron) proved the generality of this novel diarylation Liebeskind-Srogl methodology. Moreover, the resulting organic semiconductors showed excellent performance in field effect transistors and cell imaging. This contribution presents an excellent example of converting organic waste into valuable materials and may open a new avenue to utilizing widely available aromatic thioethers.

Prediction and understanding of AIE effect by quantum mechanics-aided machine-learning algorithm.

Significant effort has been devoted to the research of aggregation-induced emission (AIE); however, the discovery of new AIE materials is driven mainly by laborious trial-and-error. In this study, taking triphenylamine (TPA)-based luminophores as an example, we propose an efficient machine-learning scheme for predicting AIE-activity based on quantum mechanics.

Novel Dimethylmethylene-Bridged Triphenylamine-PDI Acceptor for Bulk-Heterojunction Organic Solar Cells.

A novel, star-shaped electron acceptor, DMTPA-PDI3, derived from a planar dimethylmethylene-bridged triphenylamine core with three acetylene-linked perylene diimide (PDI) units is developed as a nonfullerene acceptor for organic solar cells (OSCs). DMTPA-PDI3 manifests significantly reduced intramolecular twisting, enabling sufficient system-wide π-electron delocalization leading to broadened spectral absorption and raised lowest unoccupied molecular orbital level. As a result, higher and more balanced hole and electron transport properties are observed. Active layers for OSCs comprising DMTPA-PDI3 acceptor and PBT7-Th donor exhibit suppressed intermolecular aggregation, giving rise to uniform nanophase network formation. These OSC devices have afforded respectably high power-conversion efficiency of about 5%.

Reduced Intramolecular Twisting Improves the Performance of 3D Molecular Acceptors in Non-Fullerene Organic Solar Cells.

A small-molecular acceptor, tetraphenylpyrazine-perylenediimide tetramer (TPPz-PDI4 ), which has a reduced extent of intramolecular twisting compared to two other small-molecular acceptors is designed. Benefiting from the lowest extent of intramolecular twisting, TPPz-PDI4 exhibits the highest aggregation tendency and electron mobility, and therefore achieves a highest power conversion efficiency of 7.1%.

Low photobleaching and high emission depletion efficiency: the potential of AIE luminogen as fluorescent probe for STED microscopy.

We present a preliminary study which explores the potential of aggregation-induced emission (AIE) luminogen as a new fluorescent probe for STED microscopy. Compared with Coumarin 102, which is a commonly used organic fluorophore in STED microscopy, HPS, a typical AIE luminogen, is more resistant to photobleaching. In addition, HPS-doped nanoparticles have higher emission depletion efficiency than Coumarin 102 in organic solution. These two advantages of AIE luminogen can facilitate the improvement of spatial resolution, as well as long-term imaging, in STED microscopy. AIE luminogen will be a promising candidate for STED microscopy in the future.

Highly aligned graphene/polymer nanocomposites with excellent dielectric properties for high-performance electromagnetic interference shielding.

Nanocomposites that contain reinforcements with preferred orientation have attracted significant attention because of their promising applications in a wide range of multifunctional fields. Many efforts have recently been focused on developing facile methods for preparing aligned graphene sheets in solvents and polymers because of their fascinating properties including liquid crystallinity and highly anisotropic characteristics. Self-aligned in situ reduced graphene oxide (rGO)/polymer nanocomposites are prepared using an all aqueous casting method. A remarkably low percolation threshold of 0.12 vol% is achieved in the rGO/epoxy system owing to the uniformly dispersed, monolayer graphene sheets with extremely high aspect ratios (>30000). The self-alignment into a layered structure at above a critical filler content induces a unique anisotropy in electrical and mechanical properties due to the preferential formation of conductive and reinforcing networks along the alignment direction. Accompanied by the anisotropic electrical conductivities are exceptionally high dielectric constants of over 14000 with 3 wt% of rGO at 1 kHz due to the charge accumulation at the highly-aligned conductive filler/insulating polymer interface according to the Maxwell-Wagner-Sillars polarization principle. The highly dielectric rGO/epoxy nanocomposites with the engineered structure and properties present high performance electromagnetic interference shielding with a remarkable shilding efficiency of 38 dB.

Morphology controllable self-assembly of hierarchical hexaphenylsilole structures and their properties.

Morphology controllable hexaphenylsilole hierarchical homo-aggregations have been prepared by the self-assembly method in this paper. Tuning the solvent parameters can significantly affect the morphologies of the resulting HPS aggregations. The solvent properties play an important role in the shape-controlled synthesis of nanostructures. The possible self-assembly mechanism was also discussed. All of the different hierarchical structures aggregated from different solvents show different florescence and different absorption spectra properties, which could be of importance and have potential applications in the fields of optoelectronic functional materials.