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Understanding the properties of the precursor can provide deeper insight into the crystallization and nucleation mechanisms of perovskites, which is vital for the solution-process device performance. Herein, we conducted a detailed investigation into the photophysics properties of CsPbBr3 precursors in a broad concentration and various solvents. The precursor transformed from the solution state into the colloidal state and exhibited aggregation-induced emission character as the concentration increased. The aggregative luminescence from the precursors originates from the polybromide plumbous that is formed through the coordination of solvent molecules to the lead metal center. Two adducts with monodentate (PbBr2 ⋅ solvent) and bidentate (PbBr2 ⋅ 2solvent) ligands can be obtained, accompanied by emission with photoluminescence at 610 and 565 nm, respectively. Furthermore, the aggregative luminescence intensity and color could be regulated by changing the solvent and precursor ratio. Besides, we discussed the difference between the molecular aggregate in the organic system and the ionic aggregate in the inorganic system: the ionic aggregate is composed of solvated ions rather than individual molecules as in organic systems, which could possess properties that ions do not have. The fluorescence that is sensitive to Pb2+ coordination reported here could be applied to screen perovskite additives and judge the precursor aging. © 2024 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.

The engineering of aggregation-induced emission luminogens (AIEgen) based covalent organic frameworks (COFs), TDTA-COF, BTDTA-COF, and BTDBETA-COF are reported, as hyperthermia agents for inhibiting the occurrence of malignant ventricular arrhythmias (VAs). These AIE COFs exhibit dual functionality, as they not only directly modulate the function and neural activity of stellate ganglion (SG) through local hyperthermia therapy (LHT) but also induce the browning of white fat and improve the neuroinflammation peri-SG microenvironment, which is favorable for inhibiting ischemia-induced VAs. In vivo studies have confirmed that BTDBETA-COF-mediated LHT enhances thermogenesis and browning-related gene expression, thereby serving a synergistic role in combating VAs. Transcriptome analysis of peri-SG adipose tissue reveals a substantial downregulation of inflammatory cytokines, highlighting the potency of BTDBETA-COF-mediated LHT in ameliorating the neuroinflammation peri-SG microenvironment and offering myocardial and arrhythmia protection. The work on AIE COF-based hyperthermia agent for VAs inhibition provides a new avenue for mitigating cardiac sympathetic nerve hyperactivity. A series of AIEgen-based covalent organic frameworks are constructed with a unique "one stone, two birds" functionality, which is not only efficient in directly modulating the function and neural activity of stellate ganglion (SG) through local hyperthermia therapy, but also further inducing browning of white fat and ameliorating the neuroinflammation of peri-SG, favorable for inhibiting malignant ventricular arrhythmias.image

Organic photosensitizers (PSs) with aggregation-induced emission (AIE) characteristics have shown several advantages in photodynamic therapy (PDT). However, how to design PSs with the required optical and biological properties is a formidable challenge. In this work, a series of AIE active pyridine- and pyridinium-functionalized carbazole with different substituents are designed and synthesized. Compared to other analogs, BK-Pys-BP containing benzophenone moiety on the pyridinium unit produces reactive oxygen species (ROS) efficiently in the presence of light due to its large spin-orbit coupling constant to promote efficient intersystem crossing. Based on its structure, three molecules with enhanced donor-acceptor strength and conjugation are further investigated to realize emission covering the whole visible region. The cationic nature and excellent ROS generation ability of benzophenone-containing AIE photosensitizers allows for specific imaging of mitochondria, killing cancer cells, and as a singlet oxygen donor to catalyze the formation of endoperoxides. Thus, the present work presents an effective strategy for creating AIE photosensitizers with efficient ROS generation for wide biological applications. A molecular design concept to enhance reactive oxygen species (ROS) generation is presented, and full-wavelength visible light materials are synthesized and applied to photodynamic therapy and catalysis of endoperoxide formation. This work provides insight into improving the ROS efficiency of photosensitizers and controlling the release of 1O2 to achieve afterglow therapy.image

The development of water-soluble aggregation-induced emission luminogens (AIEgens) emitting in the near-infrared (NIR) window holds promise for efficient biomedical applications. Nevertheless, synthesizing water-soluble counterparts of NIR AIEgens presents difficulties due to their intrinsic hydrophobic properties. To address this issue, researchers have developed various molecular design strategies to improve the water solubility of NIR AIEgens. The integration of hydrophilic groups and targeting moieties is a crucial aspect of achieving precise phototheranostics. Here, diverse approaches to attain water-soluble NIR AIEgens for biomedical applications are presented, and three commonly used strategies that involve decorating NIR AIEgens with positively or negatively charged groups, hydrophilic chains, and bioactive moieties are elaborated. These rational design strategies are believed to provide solutions for enhancing the water solubility and biological performance of NIR AIEgens in a single action. The remaining challenges and opportunities in this field are also discussed. The aim is to provide new insights into the design of water-soluble NIR AIEgens and inspire more researchers to make significant contributions to this promising research area. © 2023 The Authors. Small Science published by Wiley-VCH GmbH.

Immunogenic programmed cell death, such as pyroptosis and ferroptosis, efficiently induces an acute inflammatory response and boosts antitumor immunity. However, the exploration of dual-inducers, particularly nonmetallic inducers, capable of triggering both pyroptosis and ferroptosis remains limited. Here we show the construction of a covalent organic framework (COF-919) from planar and twisted AIEgen-based motifs as a dual-inducer of pyroptosis and ferroptosis for efficient antitumor immunity. Mechanistic studies reveal that COF-919 displays stronger near-infrared light absorption, lower band energy, and longer lifetime to favor the generation of reactive oxygen species (ROS) and photothermal conversion, triggering pyroptosis. Because of its good ROS production capability, it upregulates intracellular lipid peroxidation, leading to glutathione depletion, low expression of glutathione peroxidase 4, and induction of ferroptosis. Additionally, the induction of pyroptosis and ferroptosis by COF-919 effectively inhibits tumor metastasis and recurrence, resulting in over 90% tumor growth inhibition and cure rates exceeding 80%.

The aggregation-induced emission photosensitizer (AIEPS) has stoodout as an alternative and competent candidate in bacterial theranostics,particularly with the use of cationic AIE PS in bacterial discriminationand elimination. Most reported work emphasizes the role of electrostaticinteraction between cationic AIE PS and negatively charged bacterialsurfaces, enabling broad applications from bacterial discriminationto bacterial killing. However, the underlying targeting mechanismand the design rationale of the cationic AIE PS for effective bacteriallabeling remain poorly investigated. In this Article, we designedand synthesized a series of cationic amphiphilic AIE PSs with differentcalculated log P values. Then, we systemically studiedthe relationship between the hydrophobicity variation of AIE PS andbacterial targeting outcomes, the dose of AIE PS needed to label variousspecies of bacteria, and their photodynamic antibacterial efficiency.The findings in this work provide a better understanding of the unclearAIE PS-bacterial interaction mechanism and some insights intothe structural design strategies of cationic amphiphilic AIE PS forbetter development in bacterial theranostics.

Cytokine monitoring has attracted great attention due to its significance in the diagnosis and treatment of many diseases, such as tumors, microbial infections, and immunological diseases. Enzyme-linked immunosorbent assay (ELISA) is one of the most popular methods in cytokine detection, ascribing to the lavish signal amplification methods in the ELISA platform. In addition to classical enzymes, other signal amplifiers such as fluorescent probes, artificial nano-enzymes, and photothermal reagents have been applied to reduce the detection limit and produce more sensitive ELISA kits. Due to the accumulative effect of heat, photothermal reagents are promising materials in the signal amplification of ELISA. However, the lack of efficient photothermal generation material at an aggregate scale may delay the further development of this area. In this contribution, based on an efficient organic photothermal aggregate material, an enzyme-free photothermally amplified fluorescent immunosorbent assay system consisting of an assay microfluidic chip and detecting platform was developed. The photothermal nanoparticles with highly efficient photothermal conversion by harvesting energy via excited-state intramolecular motions and enlarging molar absorptivity were successfully prepared. The detection concentration at 50 pg/mL of interleukin-2 was achieved, realizing a signal improvement of detection limits by 20-fold compared to that of previously reported photothermal ELISA. The microscopic imaging integrated with plane sweeping technology provided high spatial resolution and precision, indicating the potential of achieving high throughput profiling at the microscale. Moreover, as an alternative excitation source, light-emitting diode not only provided a more affordable and miniaturized detection system but also revealed the great feasibility of intramolecular motion-induced photothermy nanoparticles for biological analyses. © 2023 The Authors. Aggregate published by SCUT, AIEI, and

Although organic materials with near infrared (NIR)-II fluorescence and a photothermal effect have been widely investigated for the accurate diagnosis and treatment of tumors, optimizing the output signals of both remain challenging. Here, a strategy by “enlarging absorption reservoir” to address this issue, since an increase in photon absorption can naturally enhance output signals, is proposed. As a proof-of-concept, a large π-conjugated diketopyrrolopyrrole (DPP) unit is selected to fabricate strong light-absorbing systems. To enhance solid-state fluorescence, highly twisted alkylthiophene–benzobisthiadiazole–alkylthiophene and triphenylamine rotor are introduced to restrict the strong intermolecular π–π interactions. Moreover, the number of DPP units in molecules is engineered to optimize photophysical properties. Results show that TDADT with two DPP units possesses an exceptionally high molar absorptivity of 2.1 × 105 L mol−1 cm−1 at 808 nm, an acceptable NIR-II quantum yield of 0.1% (emission peak at 1270 nm), and a sizeable photothermal conversion efficiency of 60.4%. The excellent photophysical properties of the TDADT nanoparticles are particularly suitable for in vivo NIR-II imaging-guided cancer surgery and NIR-I photothermal therapy. The presented strategy provides a new approach of designing highly efficient NIR-II phototheranostic agents. © 2021 Wiley-VCH GmbH

Aggregation-induced emission (AIE) luminogens (AIEgens) with red/near-infrared (NIR) emissions are appealing for applications in optoelectronics and biomedical engineering owing to their intrinsic advantages of efficient solid-state emission, low background, and deep tissue penetration. In this context, an AIEgen with long-wavelength emission is synthesized by introducing tetraphenylethene (TPE) to the periphery of electron-deficient spiro-benzo[d]imidazole-2,1-cyclohexane (BI). The resulting AIEgen, abbreviated as 2TPE-BI, adopts a donor-acceptor structure and shows bathochromic absorption and emission with a larger Stokes shift of 157 nm in acetonitrile than that based on benzo[c][1,2,5]thiadiazole. It also exhibits a high solid-state fluorescence quantum yield of 56.6%. By further insertion of thiophene to its molecular structure generates 2TPE-2T-BI with higher conjugation and NIR emission. 2TPE-2T-BI can be fabricated into AIE dots for in vivo metabolic labeling through bio-orthogonal click chemistry. These results open a new approach for facile construction of long-wavelength emissive AIEgens based on the BI core.

Aggregation-induced emission (AIE) luminogens (AIEgens) with red/near-infrared (NIR) emissions are appealing for applications in optoelectronics and biomedical engineering owing to their intrinsic advantages of efficient solid-state emission, low background, and deep tissue penetration. In this context, an AIEgen with long-wavelength emission is synthesized by introducing tetraphenylethene (TPE) to the periphery of electron-deficient spiro-benzo[d]imidazole-2,1-cyclohexane (BI). The resulting AIEgen, abbreviated as 2TPE-BI, adopts a donor-acceptor structure and shows bathochromic absorption and emission with a larger Stokes shift of 157 nm in acetonitrile than that based on benzo[c][1,2,5]thiadiazole. It also exhibits a high solid-state fluorescence quantum yield of 56.6%. By further insertion of thiophene to its molecular structure generates 2TPE-2T-BI with higher conjugation and NIR emission. 2TPE-2T-BI can be fabricated into AIE dots for in vivo metabolic labeling through bio-orthogonal click chemistry. These results open a new approach for facile construction of long-wavelength emissive AIEgens based on the BI core.

Fluorescence imaging in the spectral region beyond the conventional near-infrared biological window (700-900 nm) can theoretically afford high resolution and deep tissue penetration. Although some efforts have been devoted to developing a short-wave infrared (SWIR; 900-1700 nm) imaging modality in the past decade, long-wavelength biomedical imaging is still suboptimal owing to the unsatisfactory materials properties of SWIR fluorophores. Taking advantage of organic dots based on an aggregation-induced emission luminogen (AIEgen), herein microscopic vasculature imaging of brain and tumor is reported in living mice in the SWIR spectral region. The long-wavelength emission of AIE dots with certain brightness facilitates resolving brain capillaries with high spatial resolution (approximate to 3 mu m) and deep penetration (800 mu m). Owning to the deep penetration depth and real-time imaging capability, in vivo SWIR microscopic angiography exhibits superior resolution in monitoring blood-brain barrier damage in mouse brain, and visualizing enhanced permeability and retention effect in tumor sites. Furthermore, the AIE dots show good biocompatibility, and no noticeable abnormalities, inflammations or lesions are observed in the main organs of the mice. This work will inspire new insights on development of advanced SWIR techniques for biomedical imaging.

Aggregation-induced emission (AIE) luminogens (AIEgens) with red/near-infrared (NIR) emissions are appealing for applications in optoelectronics and biomedical engineering owing to their intrinsic advantages of efficient solid-state emission, low background, and deep tissue penetration. In this context, an AIEgen with long-wavelength emission is synthesized by introducing tetraphenylethene (TPE) to the periphery of electron-deficient spiro-benzo[d]imidazole-2,1-cyclohexane (BI). The resulting AIEgen, abbreviated as 2TPE-BI, adopts a donor-acceptor structure and shows bathochromic absorption and emission with a larger Stokes shift of 157 nm in acetonitrile than that based on benzo[c][1,2,5]thiadiazole. It also exhibits a high solid-state fluorescence quantum yield of 56.6%. By further insertion of thiophene to its molecular structure generates 2TPE-2T-BI with higher conjugation and NIR emission. 2TPE-2T-BI can be fabricated into AIE dots for in vivo metabolic labeling through bio-orthogonal click chemistry. These results open a new approach for facile construction of long-wavelength emissive AIEgens based on the BI core.

Fluorescence imaging in the spectral region beyond the conventional near-infrared biological window (700-900 nm) can theoretically afford high resolution and deep tissue penetration. Although some efforts have been devoted to developing a short-wave infrared (SWIR; 900-1700 nm) imaging modality in the past decade, long-wavelength biomedical imaging is still suboptimal owing to the unsatisfactory materials properties of SWIR fluorophores. Taking advantage of organic dots based on an aggregation-induced emission luminogen (AIEgen), herein microscopic vasculature imaging of brain and tumor is reported in living mice in the SWIR spectral region. The long-wavelength emission of AIE dots with certain brightness facilitates resolving brain capillaries with high spatial resolution (approximate to 3 mu m) and deep penetration (800 mu m). Owning to the deep penetration depth and real-time imaging capability, in vivo SWIR microscopic angiography exhibits superior resolution in monitoring blood-brain barrier damage in mouse brain, and visualizing enhanced permeability and retention effect in tumor sites. Furthermore, the AIE dots show good biocompatibility, and no noticeable abnormalities, inflammations or lesions are observed in the main organs of the mice. This work will inspire new insights on development of advanced SWIR techniques for biomedical imaging.

Red/near-infrared (NIR) fluorescent molecules with aggregation-induced emission (AIE) characteristics are of great interest in bioimaging and therapeutic applications. However, their complicated synthetic approaches remain the major barrier to implementing these applications. Herein, a one-pot synthetic strategy to prepare a series of red/NIR-emissive AIE luminogens (AIEgens) by fine-tuning their molecular structures and substituents is reported. The obtained AIEgens possess simple structures, good solubilities, large Stokes shifts, and bright emissions, which enable their applications toward in vitro and in vivo imaging without any pre-encapsulation or -modification steps. Excellent targeting specificities to lipid droplets (LDs), remarkable photostabilities, high brightness, and low working concentrations in cell imaging application make them remarkably impressive and superior to commercially available LD-specific dyes. Interestingly, these AIEgens can efficiently generate reactive oxygen species upon visible light irradiation, endowing their effective application for photodynamic ablation of cancer cells. This study, thus, not only demonstrates a facile synthesis of red/NIR AIEgens for dual applications in simultaneous imaging and therapy, but also offers an ideal architecture for the construction of AIEgens with long emission wavelengths.

The detection of food spoilage is a major concern in food safety as large amounts of food are transported globally. Direct analysis of food samples is often time-consuming and requires expensive analytical instrumentation. A much simpler and more cost-effective method for monitoring food fermentation is to detect biogenic amines generated as a by-product during food decomposition. In this work, a series of 1,2-dihydroquinoxaline derivatives (DQs) with aggregation-induced emission (AIE) characteristics were synthesised and their protonated forms, that is, H+DQs, can be utilised for the sensitive detection of biogenic amines. For example, upon exposure to amine vapours, deprotonation occurs that converts the red-coloured, non-emissive H+DQ2 back to its yellow-coloured, fluorescent parent form. The bimodal absorption and emission changes endow the system with high sensitivity, capable of detecting ammonia vapour at a concentration of as low as 690 ppb. Taking advantage of this, H+DQ2 was successfully applied for the detection of food spoilage and was established as a robust and cost effective technique to monitor food safety.

The detection of food spoilage is a major concern in food safety as large amounts of food are transported globally. Direct analysis of food samples is often time-consuming and requires expensive analytical instrumentation. A much simpler and more cost-effective method for monitoring food fermentation is to detect biogenic amines generated as a by-product during food decomposition. In this work, a series of 1,2-dihydroquinoxaline derivatives (DQs) with aggregation-induced emission (AIE) characteristics were synthesised and their protonated forms, that is, H+DQs, can be utilised for the sensitive detection of biogenic amines. For example, upon exposure to amine vapours, deprotonation occurs that converts the red-coloured, non-emissive H+DQ2 back to its yellow-coloured, fluorescent parent form. The bimodal absorption and emission changes endow the system with high sensitivity, capable of detecting ammonia vapour at a concentration of as low as 690 ppb. Taking advantage of this, H+DQ2 was successfully applied for the detection of food spoilage and was established as a robust and cost effective technique to monitor food safety.

The detection of food spoilage is a major concern in food safety as large amounts of food are transported globally. Direct analysis of food samples is often time-consuming and requires expensive analytical instrumentation. A much simpler and more cost-effective method for monitoring food fermentation is to detect biogenic amines generated as a by-product during food decomposition. In this work, a series of 1,2-dihydroquinoxaline derivatives (DQs) with aggregation-induced emission (AIE) characteristics were synthesised and their protonated forms, that is, H+DQs, can be utilised for the sensitive detection of biogenic amines. For example, upon exposure to amine vapours, deprotonation occurs that converts the red-coloured, non-emissive H+DQ2 back to its yellow-coloured, fluorescent parent form. The bimodal absorption and emission changes endow the system with high sensitivity, capable of detecting ammonia vapour at a concentration of as low as 690 ppb. Taking advantage of this, H+DQ2 was successfully applied for the detection of food spoilage and was established as a robust and cost effective technique to monitor food safety.