Search

Stimuli‐responsive molecules with dynamic covalent bonds show physicochemical changes in response to external stimuli but also exhibit active molecular motions and poor luminescent properties. Hence, the manipulation and balance of dynamic and static behaviors are crucial for the development of multifunctional materials. In this work, a series of hydrazone‐based compounds with aggregation‐induced emission characteristics and hydrogen‐halogen interactions are designed and synthesized. Among them, TPAHPyCl showed the highest quantum yield of 54.0% and morphology‐dependent mechanochromic properties due to the strong chlorine‐hydrogen interactions and other multiple intermolecular interactions in the aggregate state. With the help of the turn‐on emission response to the non‐polar environment of lipid droplets, TPAHPyCl is also utilized for high‐resolution latent fingerprint detection and intracellular lipid‐droplet imaging, demonstrating multiple functions with dynamic and static properties. This work highlights the role of halogen‐hydrogen interactions and provides a new strategy to develop stimuli‐responsive materials with dynamic and static features. [ABSTRACT FROM AUTHOR]

Biological processes are of great significance for the normal physiological functions of living organisms and closely related to the health. Monitoring of biological processes and diagnosis of diseases based on fluorescent techniques would provide comprehensive insight into mechanism of life and pathogenesis of diseases, precisely guiding therapeutic effect in theranostics. It largely relied on fluorophores with the properties of excellent photostability, large Stokes shift, high signal-to-noise ratio and free of aggregation-caused quenching (ACQ) effect. Luminogens with aggregation-induced emission characteristic (AIEgens) could serve as superior agents for biological process monitoring and disease theranostics. Herein, we review the recent results in the aspects of monitoring biological processes such as autophagy, mitophagy, mitochondrion-related dynamics, cell mitotic, long-term cellular tracing and apoptosis as well as the diagnosis of related diseases based on AIEgens in real time. As part of AIEgens and AIEgen-based nanoparticles with the functionalities of drugs, photosensitizers and adjuvants accompanied with imaging, they exhibit huge potential in theranostic systems for image-guided chemotherapy, photodynamic therapy, radiotherapy and so on. Collectively, these examples show the potentials of AIEgens for understanding disease pathogenesis, for drug development and evaluation, and for clinical disease diagnosis and therapy. Future research efforts focused on developing long-wavelength excitable and phosphorescence-emissive AIEgens with improved depth-penetration and minimized background interference for fluorescence and photoacoustic imaging, will extend the potential applications of AIEgens in in vivo . [ABSTRACT FROM AUTHOR]

• Aggregation-induced emission dots with high brightness benefit precise imaging. • Second near-infrared fluorescence imaging moves into deciphering large animal in vivo. • Fluorescence imaging allows for visualizing rat brain vasculature in high resolution. • In vivo imaging enables monitoring of cerebral thrombosis and gastrointestinal tract. The emerging second near-infrared (NIR-II) fluorescence imaging has shown great promise for in vivo imaging of small animals such as mice, yet the onward movement to large-size animals such as rats is still undeveloped. In this work, for the first time, we report comprehensive NIR-II deciphering of brain blood vasculature and main organs of living rats based on aggregation-induced emission (AIE) dots. The AIE dots possess simultaneously high brightness, excellent stability with various treatments, and good biocompatibility. Thanks to the long emission range and high brightness, in vivo NIR-II fluorescence microscopic imaging with the AIE dots beyond 1200 nm allows for visualizing rat brain vasculature with high spatial resolution (∼4 μm) and deep penetration (700 μm), representing the highest penetration depth and best resolution of rat brain imaging yet achieved in the field. The NIR-II AIE dots also enable the detection of tiny vascular blockage in real time at the early stage of cerebral thrombosis. Furthermore, in vivo non-invasive monitoring of rat's gastrointestinal tract and bladder in a high-contrast manner helps to better understand the digestive system and excretory processes. This work will inspire new insights into the development of advanced NIR-II technique for large animal imaging, rendering great promise for real applications. [ABSTRACT FROM AUTHOR]

Owing to high sensitivity, selectivity, and non-invasiveness, fluorescence has been widely applied in the biomedical and sensing fields. Among the pool of fluorescent probes, luminogens with aggregation-induced emission (AIE) characteristic exhibit unique strengths in biological applications. However, most reported AIE luminogens (AIEgens) require complicated synthetic procedures, which raise the costs and biocompatibility concerns, especially in biomedical imaging and therapy. In contrast, bioproduct-inspired AIEgens (BioAIEgens) can compensate for the weakness of synthetic AIEgens in terms of their high biocompatibility, low costs, and easy preparation. This review highlights the latest development of BioAIEgens discovered from natural herbs, as well as their potential biomedical and sensing applications. As nature is full of potential resources, studying AIEgens from natural herbs can facilitate the strength of AIE properties in diverse applications and offer more inspiration to the future BioAIEgen structural design and development. [ABSTRACT FROM AUTHOR]

Bacterial keratitis (BK) is one of the most commonly leading causes of visual impairment and blindness worldwide, and suffers the risk of drug-resistant infections due to the abuse of antibiotics. Herein, we report a cationic diphenyl luminogen with aggregation-induced emission called IQ-Cm containing isoquinolinium and coumarin units for theranostic study of BK. IQ-Cm has no obvious cytotoxicity to mammalian cells below a certain concentration, and could preferentially bind to bacteria over mammalian cells. IQ-Cm can be used as a sensitive self-reporting probe to rapidly discriminate live and dead bacteria by the visual emission colors. The intrinsic dark toxicity to bacteria and generation of reactive oxygen species under light irradiation endow IQ-Cm with excellent antibacterial activity in vitro and in BK rabbit models infected with S. aureus. The present study provides a sensitive and efficient theranostic strategy for rapid discrimination of various bacterial states and the combined treatment of BK based on the intrinsic dark antibacterial activity and photodynamic therapy effect. [ABSTRACT FROM AUTHOR]

[Display omitted] Cancer is one of the most severe diseases and is challenging human health and longevity. Cancer diagnosis is extremely important to improve the survival rate of patients. Cancer tissues/cells have been characterized with four distinctive biological features that significantly differ from normal tissues/cells, including higher vascular permeability, specific microenvironments of acidic pH, high reducibility and hypoxia, higher mitochondrial membrane potential, and overexpressed proteins. Therefore, accurate cancer discrimination can be achieved by targeting these characteristics. Currently, various imaging modalities have been developed to discriminate cancerous tissues/cells. Amongst, fluorescent technology has dominated the central position because it can directly, in-situ and real-time visualize and distinguish cancer tissues/cells at nano-micrometer resolution. Since its first discovery in 2001, aggregation-induced emission (AIE) has developed as a promissing and powerful fluorescent technique. Fluorogens with AIE characteristics (AIEgens) are non-emissive in molecular state, but show enhanced emission in aggregated state due to its restriction of intramolecular motion. Besides, AIEgens can work at high concentrations without considering the aggregation-caused quenching effect encountered by conventional organic fluorescent dyes. Given their unique superiorities, AIE-based fluorescent imaging technologies have emerged as appealing alternatives to traditional ones and obtained wide-ranging uses in cancer discrimination. Thus, herein we provide a comprehensive review of the recent progress of AIEgen-based fluorescent probes for cancer discrimination. These fluorescent probes can be classified into four categories, corresponding to four characteristics of cancer. The design strategies and working mechanisms for these probes and their applications for cancer bioimaging were highlighted and the pros and cons of these probes were criticized. Ultimately, this review will end with the discussion of future development of AIEgen-based cancer discrimination. [ABSTRACT FROM AUTHOR]

• AIEgens exhibit incredible functionality and properties in many different fields. • AIE activity bestows additional detection mechanisms for new design strategies. • A modular approach allows the rational design of new AIE chemosensors. • This review examines recent AIE systems for the detection of metal ions. The past two decades have witnessed significant advances in the field of aggregation-induced emission (AIE). Luminescent materials with AIE characteristics (AIEgens) are of great importance because they can show enhanced and improved properties for different high-tech applications. Metal ions are vital for all living species. In the recent years, the AIE platform has been widely adopted in the design and synthesis of metal ion-responsive luminescent probes because of its excellent photophysical properties such as microenvironment sensitivity, high signal-to-noise ratio, high photostability, high emission efficiency in the aggregated state, and large Stokes' shift. In this review, we present an overview of the design principles of metal ion responsive AIEgens that can be generated using a modular approach. We have summarized the typical examples of metal ion responsive AIEgens, and their sensing mechanisms developed from 2005 to 2020. [ABSTRACT FROM AUTHOR]

Pathogenic microbes can cause infections or diseases in hosts and they pose ongoing threats to human health. Antibiotics have been taken an active role in treating a wide variety of infections or diseases since they were first introduced in the 1940s. However, the emergence of antibiotic-resistant microbes makes these previously effective drugs invalid regrettably. So it is urgently needed to accelerate research and development for new antimicrobial systems and strategies. Recently, luminogens with aggregation-induced emission characteristics (AIEgens) have emerged as powerful fluorescent tools for microbial detection and antimicrobial therapy. In this review, we highlighted the latest advancements of AIEgen-based biofunctional materials and systems in this research field. AIE fluorescent probes have the advantages of excellent sensitivity and rapid response, which make them useful for ultrafast bacterial imaging, bacteria classification, and pathogen discrimination. Early microbial detection and identification could help us study the mechanism of antibiotic resistance more scientifically. Moreover, the AIEgens-based photosensitizers (AIE-PSs) with strong photosensitization show good performance on the efficient elimination of multidrug-resistant bacteria and intracellular bacteria. At the end of the review, a short perspective on aggregate science is concluded. Image 1 [ABSTRACT FROM AUTHOR]

Although phagocytosis serves as the front line to attack invading pathogens, its low bacterial encounter and killing rates leads to an ineffective bactericidal output. In view of this, developing multifunctional theranostic probe to effectively discriminate and ablate intracellular bacteria is highly desirable. However, the shielding effect of the host macrophages put the detection and elimination of macrophage-engulfed bacteria into a challenging task. Herein, we utilize a luminogen with aggregation-induced emission (AIE) characteristics, namely TTVP, as a simple and effective probe for simultaneous tracing and photodynamic killing of intracellular Gram-positive bacteria. With the help of the AIE property, excellent water solubility, near-infrared (NIR) emission and strong reactive oxygen species (ROS) generating ability, TTVP performed ideally to be a targeting agent to intracellular Gram-positive bacteria with high signal contrast, as well as to be a photosensitizer to effectively ablate intracellular bacteria without attacking host macrophages. This work thus provides insights for the next generation antibiosis theranostic application for potential clinical trials. [ABSTRACT FROM AUTHOR]

Organic near-infrared (NIR) emitters with simultaneously high absorption coefficient and photoluminescence quantum yield (PLQY) are highly desirable for biomedical imaging yet seldom reported because these two aspects are usually contradictory. The conjugated planar structures exhibit strong absorption but the emission is seriously quenched in aggregate state, whereas the twisted unplanar molecules display opposite phenomena. Herein, we report a kind of dragonfly-shaped NIR aggregation-induced emission luminogen (AIEgen) with both high absorption coefficient (6.24 × 104 M−1 cm−1) and superior PLQY (51.2%) for precise image-guided cancer surgery. The compound possessing a conjugated structure with vibrational substitutes has been synthesized, in which the good conjugation enables strong absorption, and the molecular vibration affords AIE signature. Moreover, the nonfluorescent processes are significantly suppressed, making every effort to boost fluorescence. The highly bright and stable AIE nanoparticles warrant efficient in vitro cellular imaging and in vivo tumor imaging. Moreover, the fluorescence imaging-guided cancer surgery helps to precisely delineate tiny tumor nodules, significantly improving the cancer surgery outcome. This work will inspire more insights into the development of organic NIR emitters with high brightness for biomedical applications. Image 1 [ABSTRACT FROM AUTHOR]

Organic fluorescent bioprobes provide robust and powerful analytical techniques for direct detection and monitoring of important biological species and their related biological processes in live samples. In contrast to conventional fluorophores with aggregation-caused quenching effect, aggregation-induced emission (AIE) luminogens (AIEgens) exhibit remarkable photophysical properties such as bright fluorescence in aggregate or solid state, large Stokes shift, excellent photostability, and long retention time in live samples. Benefiting from these advantages, AIEgen-based bioprobes have been widely applied in diverse biomedical applications. In this review, we first introduce the AIE concept and working principles of AIE bioprobes. Then we briefly summarize their applications in biosensing and bioimaging with some representative examples recently reported mainly in our group. The challenge and future development of AIE bioprobes are also discussed and highlighted. Hopefully, this review can inspire more researchers to participate in this fascinating area and expand the versatile biomedical applications. Image 1 • The AIE concept and working principles of AIE bioprobes are first introduced. • The applicaions of AIE bioprobes in biosensing and bioimaging are briefly summarized. • Our recent works about AIE bioprobes with some representative example are presented. • Future perspectives of AIE bioprobes are discussed to further expand their versatile applications. [ABSTRACT FROM AUTHOR]

With the increase of bacterial infections in clinical practice, it becomes a public health problem which has aroused worldwide attention. Fluorescence imaging-guided photodynamic antibiosis has recently emerged as a promising protocol to solve this problem. However, developing a super powerful fluorescent material allowing facile preparation, long emission wavelength, rapid bacterial discrimination, washing-free staining, and high photodynamic antibacterial efficiency in a single entity, is highly desirable but remains challenging. In this study, we utilize for the first time a water-soluble near-infrared (NIR) emissive luminogen with aggregation-induced emission (AIE) characteristics, namely TTVP, for simultaneous dual applications of Gram-positive bacteria discrimination and photodynamic antibiosis. TTVP is able to selectively target Gram-positive bacteria over Gram-negative bacteria through a washing-free procedure after only 3 s incubation period, which is at least 100-fold shorter than those of previously reported protocols, implying ultrafast bacterial discrimination features. Meanwhile, TTVP exhibits extremely high reactive oxygen species generation efficiency, which is far superior to that of most popularly used photosensitizers, representing one of the best candidates for photodynamic antibiosis. In vitro and in vivo results demonstrate that TTVP provides extraordinary performance on photodynamic antibacterial therapy. This study thus offers a blueprint for the next generation of antibacterial materials. [ABSTRACT FROM AUTHOR]

Detection and discrimination viable cells with high selectivity are critically important in monitoring cell activity to provide key information on therapeutic efficacy. In this work, a tetraphenylethene-based conjugated polymer featuring aggregation-induced emission (AIE) characteristic was designed and synthesized, which could be used to selectively discriminate viable cells from apoptotical cells, dead cells and pathogens. Thanks to its synergistic effect and high molecular weight, the polymer shows unique advantages over low-mass organic probes, such as better biocompatibility, higher selectivity and stronger tracing ability. Moreover, we figured out that the negatively charged side-chain of the conjugated polymer and the endocytosis process both play crucial roles in this selective discrimination behavior, making this probe a powerful tool for guiding precise cancer therapy. [ABSTRACT FROM AUTHOR]