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This review addresses the latest advancements in the integration of aggregation‐induced emission (AIE) materials with polymer electrospinning, to accomplish fine‐scale electrospun fibers with tunable photophysical and photochemical properties. Micro‐ and nanoscale fibers augmented with AIE dyes (termed AIEgens) are bespoke composite systems that can overcome the limitation posed by aggregation‐caused quenching, a critical deficiency of conventional luminescent materials. This review comprises three parts. First, the reader is exposed to the basic concepts of AIE and the fundamental mechanisms underpinning the restriction of intermolecular motions. This is followed by an introduction to electrospinning techniques pertinent to AIE‐based fibers, and the core parameters for controlling fiber architecture and resultant properties. Second, exemplars are drawn from latest research to demonstrate how electrospun nanofibers and porous films incorporating modified AIEgens (especially tetraphenylethylene and triphenylamine derivatives) can yield enhanced photostability, photothermal properties, photoefficiency (quantum yield), and improved device sensitivity. Advanced applications are drawn from several promising sectors, encompassing optoelectronics, drug delivery and biology, chemosensors and mechanochromic sensors, and innovative photothermal devices, among others. Finally, the outstanding challenges together with potential opportunities in the nascent field of electrospun AIE‐active fibers are presented, for stimulating frontier research and explorations in this exciting field. This review gives an overview of the advanced composite fibers engineered from electrospinning of AIE‐active (aggregation‐induced emission) materials, for potential use in photodynamic and photothermal devices, optoelectronics, sensors, biology, and biomedicines. Detailed structure–property relationships are addressed in terms of AIE chemical structures, fiber morphology, and composite microstructures.

In this review, we present a systematic and comprehensive summary of the recent development and applications of excited‐state intramolecular proton transfer‐based (ESIPT‐based) aggregation‐induced emission luminogens (AIEgens), a type of promising materials that inherit the advantages of ESIPT and AIE, such as large Stokes shift, excellent photostability, and low self‐quenching. We first summarize the backbones that have been used to construct the ESIPT‐based AIEgens and classify the constructed ones based on the relation between ESIPT and AIE unit. According to the sensing mechanisms and design strategies, we have reviewed the applications of ESIPT‐based AIEgens in bioimaging, drug delivery systems, organic light‐emitting diodes, photo‐patterning, liquid crystal, and the detection of metal cations, anions, small molecules, biothiols, biological enzymes, latent fingerprinting, and so on. We have also reviewed the recent advances in the development of new theoretical methods for investigating molecular photochemistry in crystals and their applications in ESIPT‐based AIEgens. We discussed the remaining challenges in this field and the issues that need to be addressed. We anticipate that this review can provide a comprehensive picture of the current condition of research in this field, and promote researchers to make more efforts to develop novel ESIPT‐based AIEgens with new applications. Combining the advantages of excited‐state intramolecular proton transfer (ESIPT) and aggregation‐induced emission (AIE) makes the ESIPT‐based AIE luminogens become promising materials in a wide range of areas. This review focuses on the design strategies, sensing mechanisms, the applications in fluorescent probes, bioimaging, and biodetection, as well as the recent theoretical advances in the excited‐state decays of the ESIPT‐based AIEgens.

Aggregation‐induced emission (AIE) is a photophysical phenomenon that a certain group of luminescent materials that become highly luminous when aggregated in a bad solvent or solid state. This year is the 20th anniversary since the AIE concept firstly proposed in 2001. Many advanced applications were gradually being explored, covering optics, electronics, energy, and bioscience and so on. At present, bibliometrics can enlighten the researchers with comprehensive sights of the achievements and trends of a specific field, which is critical for academic investigations. Herein, we presented a general bibliometric overview of AIE covering 20 years of evolution. With the assistance of Web of Science Core Collection database and several bibliometric software tools, the annual publication and citation, most influential countries/regions, most contributing authors, journals and institutions, second near‐infrared (NIR‐II) related hotspots, as well as the forecast of frontiers were demonstrated and systematically analyzed. This study summarizes the current research status in AIE research field and provides a reference for future research directions. A bibliometric analysis is conducted to overview the development of AIE in the past two decades and provides a unique perspective for this field. Researchers with high citations, keyword co‐occurrence networks, NIR‐II imaging related foamtree, and frontier perspectives on AIE are visualized via different software in this study. A multi‐interdisciplinary system has been formed with aggregate science as the core subject.

The ongoing outbreak of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS‐CoV‐2) pandemic has posed significant challenges in early viral diagnosis. Hence, it is urgently desirable to develop a rapid, inexpensive, and sensitive method to aid point‐of‐care SARS‐CoV‐2 detection. In this work, we report a highly sequence‐specific biosensor based on nanocomposites with aggregation‐induced emission luminogens (AIEgen)‐labeled oligonucleotide probes on graphene oxide nanosheets (AIEgen@GO) for one step‐detection of SARS‐CoV‐2‐specific nucleic acid sequences (Orf1ab or N genes). A dual “turn‐on” mechanism based on AIEgen@GO was established for viral nucleic acids detection. Here, the first‐stage fluorescence recovery was due to dissociation of the AIEgen from GO surface in the presence of target viral nucleic acid, and the second‐stage enhancement of AIE‐based fluorescent signal was due to the formation of a nucleic acid duplex to restrict the intramolecular rotation of the AIEgen. Furthermore, the feasibility of our platform for diagnostic application was demonstrated by detecting SARS‐CoV‐2 virus plasmids containing both Orf1ab and N genes with rapid detection around 1 h and good sensitivity at pM level without amplification. Our platform shows great promise in assisting the initial rapid detection of the SARS‐CoV‐2 nucleic acid sequence before utilizing quantitative reverse transcription‐polymerase chain reaction for second confirmation. An AIEgen‐graphene oxide (GO) nanocomposite‐based assay is designed for rapid detection of SARS‐CoV‐2 nucleic acids. The sensing mechanism is based on two‐stage fluorescence signal recovery due to fluorescence resonance energy transfer (FRET) effect by detaching AIEgen from GO surface and restricted intramolecular rotation (RIR) effect by formation of nucleic acid duplexes.

Specific bioconjugation for native primary amines is highly valuable for both chemistry and biomedical research. Despite all the efforts, scientists lack a proper strategy to achieve high selectivity for primary amines, not to mention the requirement of fast response in real applications. Herein, we report a chromone‐based aggregation‐induced emission (AIE) fluorogen called CMVMN as a self‐reporting bioconjugation reagent for selective primary amine identification, and its applications for monitoring bioprocesses of amination and protein labeling. CMVMN is AIE‐active and capable of solid‐state sensing. Thus, its electrospun films are manufactured for visualization of amine diffusion and leakage process. CMVMN also shows good biocompatibility and potential mitochondria‐staining ability, which provides new insight for organelle‐staining probe design. Combined with its facile synthesis and good reversibility, CMVMN would not only show wide potential applications in biology, but also offer new possibilities for molecular engineering. A chromone‐based aggregation‐induced emission (AIE) fluorogen called CMVMN as a self‐reporting bioconjugation reagent for selective primary amine identification in situ was reported, along with its applications of monitoring bioprocesses of amination, protein labeling, and mitochondria staining. It is capable of solid‐state sensing and its electrospun films are manufactured for visualization of amine diffusion and leakage process.

Aggregation induced emission (AIE)-active bright two-photon fluorescent probes with second near-infrared (NIR-II) light excitability can be used for efficient brain bioimaging studies, wherein the fabrication of water-dispersible nanoparticles by encapsulating the hydrophobic probes with amphiphilic polymer holds the key to ensuring biocompatibility and adaptability. However, barely any study has evaluated the structural requirements that can substantially affect the water-dispersible nanoparticle formation ability of an organic AIE-active dye with amphiphilic polymers. The present study systematically assessed the structural dependency of a well-known acrylonitrile based AIE system/fluorogenic core upon the formation of water-dispersible nanoparticles and elucidated how the structural modifications can impact the two-photon imaging. A total of four acrylonitrile-based aggregation induced emission (AIE)-active two-photon (TP) fluorescent probes (AIETP, AIETP C1, AIETP C2 and AIETP C3) have been judiciously designed and synthesized with structural variations to realize how the structural alterations could substantially influence the water-dispersible nanoparticle formation ability (with amphiphilic polymers) and photo-stability to impact the imaging. It has been found that the incorporation of the phenyl-thiazole unit in AIETP, AIETP C2 and AIETP C3 facilitated the formation of water-dispersible nanoparticles (NPs) with amphiphilic polymers (Pluronic F127) whereas the presence of only phenyl moiety instead in AIETP C1 could not meet the suitable condition to form the NPs with good aqueous dispersibility. Rationally designed AIETP NPs that exhibited higher brightness, improved photostability and good two-photon absorption cross section was successfully employed for brain vasculature imaging. Robust noninvasive 2D and 3D two-photon (NIR-II light, 1040 nm) brain vasculature imaging with beneficial attributes such as outstanding penetration depth (800 µm) and exceptional spatial resolution (1.92 µm), were achieved by utilizing AIETP NPs in this study.

Here, in the present work, a new hydroxybenzothiazole derivative (HBT 2) with AIE+ESIPT features was synthesized by Suzuki–Miyora coupling of HBT 1 with 4-formylphenylboronic acid. The AIE and ESIPT features were confirmed by optical, microscopic (AFM) and dynamic light scattering (DLS) techniques. The yellow fluorescent aggregates of HBT 2 can specifically detect Cu[sup.2+] /Cu[sup.+] ions with limits of detection as low as 250 nM and 69 nM. The Job’s plot revealed the formation of a 1:1 complex. The Cu[sup.2+] complexation was further confirmed by optical, NMR, AFM and DLS techniques. HBT 2 was also used for the detection of Cu[sup.2+] ions in real water samples collected from different regions of Punjab. HBT 2 was successfully used for the bio-imaging of Cu[sup.2+] ions in live A549 and its anticancer activity was checked on different cancer cell lines, such as MG63, and HeLa, and normal cell lines such as L929. We successfully utilized HBT 2 to develop security labels for anticounterfeiting applications.

Light has been sought and explored by human since ancient times. As the most important form of light, fluorescence is significant to applications in bioimaging and optoelectronic devices. However, fluorescence quenching problem constitutes a serious bottleneck in materials creation. Inspired from the core–shell structure in nature, we report an effective strategy to overcome this long‐standing problem by utilizing a molecular core–shell structure. With an emissive core and multifunctional shell fragments, these compounds show aggregation‐induced delayed fluorescence (AIDF) properties by restricting singlet oxygen (1O2) generation and suppressing the triplet–triplet annihilation (TTA). Protected by the functional shell, the aggregation‐induced emission luminogens (AIEgens) exhibit strong emission with high photoluminescent quantum yield and exciton utilization. Furthermore, because the shell materials can form exciplex with electron‐transport materials, the fully solution‐processed organic light‐emitting diodes (OLEDs) based on these core–shell materials show low turn‐on voltages, excellent device performance with current efficiency of 61.4 cd A–1 and power efficiency of 42.8 lm W–1, which is a record‐breaking efficiency based on all‐solution processed organic multilayer systems among the AIE‐OLEDs so far. This simple visualization strategy based on molecular core–shell structure provides a promising platform for AIEgens used in the fully wet‐processed optoelectronic field. Core–shell molecules are firstly designed and proposed to achieve aggregation‐induced delayed fluorescence (AIDF) by stabilizing and protecting the triplet exciton, then the fully solution‐processed OLEDs based on the core–shell structural emitters demonstrate superior device performance with maximum luminance of 30,000 cd m–2, excellent EL efficiencies of up to 21.8%, 61.4 cd A–1 and 42.8 lm W–1.

Urinary microalbumin (mALB) serves as an exceptionally sensitive indicator for the early detection of kidney damage, playing a pivotal role in identifying chronic renal failure and kidney lesions in individuals. Nevertheless, the current fluorescent methodologies for point‐of‐care (POC) diagnosis of mALB in real urine still exhibit suboptimal performance. Herein, the development and synthesis of QM‐N2, an albumin‐activated near‐infrared (NIR) aggregation‐induced emission (AIE) fluorescent probe, are presented. The strategic incorporation and positioning of quaternary ammonium salts within the quinoline‐malononitrile (QM) scaffold significantly influence solubility and luminescence characteristics. Specifically, the quaternary ammonium salt‐free variant, QM‐OH, and the quaternary ammonium salt integrated at the donor function group (DFG) site, QM‐N1, display limited solubility in aqueous solutions while demonstrating a distinct fluorescence signal. Conversely, the incorporation of quaternary ammonium salt at the conformational functional group (CFG) site in QM‐N2 imparts superior dispersibility in water and reduces the initial fluorescence. Furthermore, the integration of a well‐defined D‐π‐A structure within QM‐N2 enables itself with near‐infrared emission, which is crucial for mitigating interference from autofluorescence present in urine samples. Upon interaction with albumin, QM‐N2 forms a tight bond with the IIA site of the subdomain of human serum albumin (HSA), inducing alterations in protein configuration and constraining the intrinsic motion of fluorescent molecules. This interaction induces fluorescence, facilitating the sensitive detection of trace albumin. Ultimately, QM‐N2 is applied for POC testing of mALB using portable equipment, particularly in the diagnosis of mALB‐related diseases, notably chronic renal failure. This positioning underscores its potential as an ideal candidate for self‐health measurement at home or in community hospitals. An albumin‐activated near‐infrared (NIR) aggregation‐induced emission (AIE) fluorescent probe QM‐N2 is designed, aiming to achieve rapid and accurate fluorescence detection of urinary microalbumin. Through a comprehensive analysis of numerous human urine samples, the fluorescence enhancement exhibited a robust correlation with the concentration of urinary microalbumin, positioning QM‐N2 as a promising tool for the diagnosis of mALB‐related kidney diseases.

Aggregation‐induced emission (AIE) carbon dot (CDs) in solid state with tunable multicolor emissions have sparked significant interest in multidimensional anti‐counterfeiting. However, the realization of solid‐state fluorescence (SSF) by AIE effect and the regulation of fluorescence wavelength in solid state is a great challenge. In order to solve this dilemma, the AIE method to prepare multi‐color solid‐state CDs with fluorescence wavelengths ranging from bright blue to red emission is employed. Specifically, by using thiosalicylic acid and carbonyl hydrazine as precursors, the fluorescence wavelength can be accurately adjusted by varying the reaction temperature from 150 to 230 °C or changing the molar ratio of the precursors from 1:1 to 1:2. Structural analysis and theoretical calculations consistently indicate that increasing the sp2 domains or doping with graphite nitrogen both cause a redshift in the fluorescence wavelength of CDs in the solid state. Moreover, with the multi‐dimensional and adjustable fluorescence wavelength, the application of AIE CDs in the fields of multi‐anti‐counterfeiting encryption, ink printing, and screen printing is demonstrated. All in all, this work opens up a new way for preparing solid‐state multi‐color CDs using AIE effect, and further proposes an innovative strategy for controlling fluorescence wavelengths. Herein, they proposed an efficient and precise wavelength tuning mechanism for the Aggregation‐induced emission (AIE) carbon dots (CDs). Specifically, by using thiosalicylic acid and carbonyl hydrazine as precursors, they can accurately adjust the fluorescence wavelength by varying the reaction temperature or changing the molar ratio of the precursors. Moreover, the application of AIE CDs in the fields of multi anti‐counterfeiting encryption has been demonstrated.