Aggregation-Induced Emission (AIE), Life and Health

Sensitive fluorescence-responsive photonic crystals fabricated from AIE molecule embedded nanospheres for application in dual anti-counterfeiting textiles

The preparation of anti-counterfeiting textiles is usually associated with laborious processes, high cost and environmental risks. In this work, the core-shell colloidal nanospheres composed of the polystyrene (PS) core with embedded aggregation-induced emission (AIE) molecules of tetraphenylethene (TPE) and the shell of densely crosslinked PS ((PS-TPE)@CPS) were designed and synthesized via emulsion polymerization. The patterned fluorescence-responsive photonic crystals (FRPCs) were then constructed using the (PS-TPE)@CPS nanospheres as building blocks on textile substrates via screen printing. Thanks to the compatibility and affinity of TPE with PS and its own AIE property, the TPE molecules enriched in the PS core and then aggregated and embedded within (PS-TPE)@CPS colloidal nanospheres. Confined by the polymer chains, the TPE molecules formed π-π stacking and exhibited AIE effect, while maintaining a stable conjugated structure. The FRPC anti-counterfeiting patterns constructed with the (PS-TPE)@CPS nanospheres exhibited angle-dependent structural colors under visible light and sensitive responsive fluorescence characteristic under ultraviolet light, realizing the double anti-counterfeiting effect. This approach to achieve anti-counterfeiting textile is simple, cost-effective, and environmentally friendly. The obtained FRPC patterns possess excellent optical properties and anti-counterfeiting functions, meeting the requirements for the sustainable structural coloration of textiles, and also promoting the practical application of responsive photonic crystal anti-counterfeiting textiles.

Rapid identification of multiplexed pathogens via a two-step dual-channel fluorescence turn-on array

Bacterial infections have been an increasingly serious threat to human health. However, the rapid identification of multiplexed bacteria remains challenging due to their intricate composition. Herein, we developed a two-step, dual-channel fluorescence "turn-on" sensor array that sequentially amplifies signals via Indicator Displacement Analysis (IDA) and Aggregation-Induced Emission (AIE). Three weakly fluorescent, positively charged conjugated fluorophores (A1-A3) with AIE properties were designed to form electrostatic complexes (C1-C3) with negatively charged graphene oxide (GO). Upon addition of bacteria, fluorophores were released from the electrostatic complexes via IDA, resulting in fluorescence turn-on. These fluorophores then aggregated on the bacterial surface, further enhancing fluorescence. This array accurately differentiated among 10 distinct bacterial strains, achieving 98.3 % classification accuracy within 30 s. Finally, the approach facilitated semi-quantitative bacterial analysis, multiplex identification, and robust differentiation in artificial urine samples, presenting a promising method for early infectious disease diagnosis.

Precise and selective detection of perchlorate at trace level using side-chain engineered perylene sensor: From probe to platform

The importance of onsite perchlorate detection in real water matrices at trace level (ng/L) has been recognized to ensure drinking water safety, which however faces certain issues (i.e., sensitivity, accuracy, selectivity, etc.). In this study, we meticulously designed an aggregation-induced emission (AIE) luminescent sensor by covalently coupling twisted perylene and alkyl pyridine, demonstrating a high affinity for perchlorate with binding energy of -79.09 kcal/mol. Importantly, the incorporated alkyl pyridine acts as a crucial recognition site, enhancing fluorescence emission through multivalent-driven weak interactions and restricting the skeleton distortion of the AIE probe for precise perchlorate detection. As a result, the optimized perchlorate-specific probe (Per-4C6) characterized a record-breaking selectivity (Kij∼219), a rapid response (<2 min), high sensitivity (2026.9 a.u./mM), an impressive limit of detection (6.37 nM), and robust anti-interference capabilities. Its practical application has been validated by integrating the Per-4C6 probe into a smartphone-based platform. Overall, this study highlights the potential of our AIE probe for reliable and efficient onsite detection of perchlorate at trace level, contributing to the broader goal of sustainable water management.

NIR-II aggregation-induced emission nanoparticles camouflaged with preactivated macrophage membranes for phototheranostics of pulmonary tuberculosis

Phototheranostics, which allows simultaneous diagnosis and therapy, offers notable advantages in terms of noninvasiveness, controllability and negligible drug resistance, presenting a promising approach for disease treatment. By integrating second near-infrared (NIR-II, 1,000-1,700 nm) phototheranostic agents characterized by aggregation-induced emission (AIE) and cell membranes with specific targeting capacity, we have developed a versatile type of biomimetic nanoparticle (NP) for precise phototheranostics of pulmonary tuberculosis (TB). Coating the phototheranostic agents with preactivated macrophage membranes results in the formation of biomimetic NPs, which exhibit specific binding to TB through a lesion-pathogen dual-targeting strategy, allowing the accurate detection of Mycobacterium tuberculosis via NIR-II fluorescence imaging and precise photothermal therapy using the irradiation of a 1,064 nm laser. In comparison with traditional treatments, small individual granulomas (0.2 mm in diameter) in TB-infected mice are visualized, and improved antibacterial effects are achieved upon NP administration. Here we present a standardized workflow for the synthesis of the NIR-II AIE agents, their use for the fabrication of the biomimetic NPs and their in vitro and in vivo applications as phototheranostics against M. tuberculosis. The preparation and characterization of the NIR-II AIE agents requires ~8 d, the synthesis and characterization of the phototheranostic NPs requires ~8 d, the validation of in vitro targeting capacity and photothermal eradication requires ~26 d, and the in vivo NIR-II fluorescence imaging and imaging-guided photothermal therapy requires ~74 d. All procedures are straightforward and suitable for clinicians or researchers with prior training in organic synthesis and biomedical engineering.

Thioflavin T Inspirations: On the Photophysical and Aggregation Properties of Fluorescent Difluoroborates Based on the Benzothiazole Core

In this work, we investigated a novel series of fluorescent dyes based on benzothiazole core substituted with a palette of donor groups that differ in size, shape, and character (alkyl vs aromatic). These dyes exhibit an intramolecular charge transfer state in their electronic structure. The photophysical properties of the newly synthesized dyes were studied with an eye toward aggregation effects in solvents and mixtures of solvents differing in polarity. Moreover, multiphoton absorption studies were performed to determine the potential of the dyes in two-photon microscopy. The results of spectroscopic measurements were supported by electronic structure calculations using coupled-cluster theory. Overall, the results provide an indication regarding the optimal substituents to achieve bright emission in various media and how these properties are related to aggregation effects.

Modeling the Vertical Transport of Copepod Fecal Particles under Nano/Microplastic Exposure

Nano- and microplastics (NMPs) may significantly impact the marine carbon cycle, and fecal pellets produced by the copepods are crucial for vertical carbon transport. In this study, we investigated the effects of NMP size, concentration, and diatom supply on the production and settling of fecal pellets by the marine copepod Parvocalanus crassirostris. By employing an aggregation-induced emission fluorescence imaging technique, we visualized the distribution of NMPs in fecal pellets, measured their size and production rate, and developed a fluid dynamic model to simulate the settling process of fecal pellets in the water column. Our results indicated that NPs and MPs exhibited uniform and nonuniform distributions in the produced fecal materials, respectively. NMPs reduced both the size and integrity of copepod fecal pellets. Copepods ingested MPs in the absence of diatoms, but exposure to 5000 μg/L of NMPs decreased the fecal pellet production by 52% in the presence of diatoms due to feeding selectivity. The sinking rates of fecal pellets of varying sizes, as obtained from modeling simulations, ranged from 10.9 to 103.1 m/day. When the proportion of participating polystyrene (PS) reached 50%, the sinking velocity decreased by 34%. Our study provides new insights into the vertical transport of copepod fecal pellets under NMP pollution.

Size-Tunable Fluorescent Unimolecular Nanoparticles (FUNs) for Bright Cancer Imaging

Fluorescent nanoparticles such as quantum dots, carbon dots, and polymeric fluorophore conjugates have shown promising applications for biomedical imaging. It is desirable to develop new fluorescent probes with well-defined particle size, bright fluorescence, high biocompatibility, and easy functionalization. Here, a facile and controllable method is first reported to prepare size-tunable fluorescent unimolecular nanoparticles (FUNs) for biomedical imaging. The FUNs are constructed by the rapid ring-opening polymerization (ROP) of amino acid N-carboxyanhydrides monomers using a fluorescent dye-cored polylysine dendritic macromolecule as the macroinitiator. By precisely adjusting the ratio of the monomer to the macroinitiator, the study customizes FUNs with particle sizes of 30, 60, 90, or 130 nm. The fluorescence quantum yield of the FUNs is up to 6.6-fold of the small molecule dye. It is shown that the particle size-dependent cellular uptake, blood circulation, and tumor entrance by optical imaging with the glutamic acids (Glu)-modified FUNs (FUNs-Glu). The FUNs-Glu with sizes of 30 and 60 nm exhibited superior blood circulation, tumor accumulation, and penetration. These FUNs dendritic dots have the merits of tunable particle size, single-molecule structure, excellent fluorescence properties, and ample groups for surface functionalization, which have great potential for various biomedical imaging.

From Molecule to Aggregate: Designing AIE Nanocrystals for Low-Power Backward Third-Harmonic Generation Angiography

Organic materials featuring third harmonic generation (THG) hold great promise for deep-tissue bioimaging due to their good biocompatibility and second near-infrared excitation. However, minimizing photodamage from the incident light necessitates significant improvements in the third-order nonlinear susceptibility. Herein, an organic luminogen called OTBP is developed as a backward THG (BTHG) contrast agent for second near-infrared (NIR-II) angiography. OTBP's intense absorption at 433 nm resonantly enhances its BTHG efficiency when excited by a 1300 nm femtosecond laser. In the aggregate state, the robust intermolecular interactions among OTBP molecules realize excellent crystallinity and the facile preparation of nanocrystals (NCs) with a high refractive index of 1.78. By leveraging Mie scattering theory, the best size of OTBP NCs for BTHG collection is attained. These integrated properties result in a high BTHG efficiency of OTBP NCs. Encapsulating the NCs with F-127 enables ultralow-power but high-contrast 3D vasculature imaging with negligible photodamage and background interference. Further elevating the laser power to 60 mW enables the visualization of microvessels at 500 µm with a high SNR of 143. This study offers insights into material design strategies toward efficient organic BTHG contrast agents and paves the way for the materials-oriented non-linear optics.

Aggregation-induced emission-based phototheranostics to combat bacterial infection at wound sites: A review

The healing of chronic wounds infected by bacteria has attracted increasing global concerns. In the past decades, antibiotics have certainly brought hope to cure bacteria-infected chronic wounds. However, the misuse of antibiotics leads to the emergence of numerous multidrug-resistant bacteria, which aggravate the health threat to clinical patients. To address these increasing challenges, scientists are committed to creating novel non-antibiotic strategies to kill bacteria and promote bacteria-infected chronic wound healing. Fortunately, with the quick development of nanotechnology, the representatives of phototherapy, such as photothermal therapy (PTT) and photodynamic therapy (PDT), exhibit promising possibilities in promoting bacteria-infected wound healing. Well-known, photothermal agents and photosensitizers largely determine the effects of PTT and PDT. A common problem for these molecules is the aggregation-induced quenching effect, which highly limits their further applicability in biomedical and clinical fields. Fortunately, the occurrence of aggregation-induced emission luminogens (AIEgens) efficiently overcomes the photobleaching and exhibit advantages, such as strongly aggregated emission, superior photostability, aggregation-enhanced reactive oxygen species (ROS), and heat generation, which makes great sense to the development of PTT and PDT. This article reviews various studies conducted on novel AIEgen-based materials that can mediate potent PDT, PTT, and a combination of PDT and PTT to promote bacteria-infected chronic wound healing.

An AIE-active Janus filter membrane for highly efficient detection and elimination of bioaerosols

Highly efficient detection and sterilization techniques for bioaerosol prevention and control are urgently needed. Herein, we present an AIE-active Janus air filter membrane (AIE-HAFM) that features water-dissolvable micro-nano porous network architecture and aggregation-induced emission (AIE) activity constructed by the asymmetrical surface modification with an amphiphilic AIE photosensitizer (MeOTTVP). The all-round AIE-HAFM can not only provide low pressure drop and high interception efficiency for bioaerosol sampling but also perfectly inherit the AIE functions of MeOTTVP, which allows for intensive near-infrared (NIR) emission and efficient production of reactive oxygen species. The airborne pathogens can be effectively captured, collected, transferred, and released by AIE-HAFM for subsequent quantitative detection with colony counting and ATP bioluminescence, as well as stained by the incorporated MeOTTVP for NIR fluorescence imaging-guided visual detection. Meanwhile, AIE-HAFM enables on-demand and surface-dependent photodynamic effects for reliable bacterial eradication under white light irradiation due to the surface-concentrated MeOTTVP, consequently achieving the smart prevention and control of bioaerosols both in the simulated and real-world bioaerosol environment. The versatility of AIE-HAFM in handling diverse airborne pathogens may bring about a transformative solution to address the bioaerosol contamination problems.

Fluorescence-guided Surgery for Hepatocellular Carcinoma: From Clinical Practice to Laboratories

Fluorescence navigation is a novel technique for accurately identifying hepatocellular carcinoma (HCC) lesions during hepatectomy, enabling real-time visualization. Indocyanine green-based fluorescence guidance has been commonly used to demarcate HCC lesion boundaries, but it cannot distinguish between benign and malignant liver tumors. This review focused on the clinical applications and limitations of indocyanine green, as well as recent advances in novel fluorescent probes for fluorescence-guided surgery of HCC. It covers traditional fluorescent imaging probes such as enzymes, reactive oxygen species, reactive sulfur species, and pH-sensitive probes, followed by an introduction to aggregation-induced emission probes. Aggregation-induced emission probes exhibit strong fluorescence, low background signals, excellent biocompatibility, and high photostability in the aggregate state, but show no fluorescence in dilute solutions. Design strategies for these probes may offer insights for developing novel fluorescent probes for the real-time identification and navigation of HCC during surgery.

Phosphinylation/cyclization of propynolaldehydes to isobenzo-furanylic phosphine oxides displaying AIE properties

Investigating organic reactions to synthesize novel molecules that exhibit aggregation-induced emission (AIE) characteristics is becoming a research hotspot. Herein, we develop a one-pot phosphinylation/cyclization reaction between propynolaldehydes and diarylphosphine oxides to generate isobenzofuran-substituted phosphine oxides (IBFPOs) displaying AIE properties. Such a reaction possesses benefits such as metal-free synthesis, simple operation and wide substrate applicability. Further structural modifications of the products have been implemented through the palladium-catalyzed Sonogashira reaction, Ullmann coupling and Diels-Alder addition. Furthermore, these AIE luminogens (AIEgens), which have satisfactory quantum yields and tunable emission covering the entire visible region, can be employed for the cell imaging of lipid droplets in HeLa cells. Notably, quantitative evaluation of the phototherapy effect demonstrates that one of these presented AIEgens, namely IBFPO-3j, displays high type-I reactive oxygen species (ROS) generation efficiency, enabling its effective application in photodynamic therapy in a hypoxic environment.

Aggregation-induced emission-based aptasensors for the detection of various targets: Recent progress

The advancement of aptasensors utilizing aggregation-induced emission (AIE) has progressed remarkably in recent years, owing to various unique benefits provided by aggregation-induced emission luminogens (AIEgens) as a novel category of fluorescent substances and aptamers as exceptional recognition components. AIE refers to a photophysical phenomenon identified in certain luminogens that show minimal or absent emission in dilute solutions, yet display considerable emission when in aggregate or solid states. Fluorescent sensing is an effective technique for the detection of various targets; however, many traditional dyes frequently demonstrate an aggregation-caused quenching (ACQ) effect in solid form, which limits their applicability on a larger scale. In contrast, fluorescent probes that leverage AIE characteristics have garnered considerable interest, owing to their elevated fluorescence quantum yields and ease of fabrication. This review discusses the application of various AIEgens in the design of diverse sensitive and selective AIE-based aptasensors for monitoring various targets, with a particular focus on recent advances. The AIE-based aptasensors exploit the supreme affinity of the aptamers to their targets and the remarkable properties of AIEgen, including its photostability and high quantum yield, and the interaction between AIEgen and DNA. The objective is to acquaint researchers with the various categories of materials exhibiting AIE characteristics and their potential applications in the creation of different aptasensors, enabling them to introduce novel kinds of innovative AIEgens and AIE-integrated aptasensors.

Rapid antibiotic biosensors based on multiple molecular recognition elements

The extensive use of antibiotics poses significant public health concerns, including the increase in drug-resistant bacteria and environmental pollution, underscoring the urgent need for rapid, sensitive, and specific antibiotic detection methods. Most current reviews on antibiotic detection primarily focus on categorizing antibiotics based on their types or the classification of sensors used, such as electrochemical, optical, or colorimetric sensors. In contrast, this review proposes a novel and systematic theoretical framework for the detection of antibiotics using sensors using seven popular molecular recognition elements-antibodies, aptamers, microorganisms, cells, peptides, molecularly imprinted polymers (MIPs), metal-organic frameworks (MOFs) and direct recognition modalities and briefly discusses the mechanism of molecular recognition elements and antibiotic recognition. Additionally, it explores biosensors developed using these elements, offering a detailed analysis of their strengths and limitations in terms of sensitivity, specificity, and practicality. The review concludes by addressing current challenges and future directions, providing a comprehensive perspective essential for enhancing food safety and protecting public health.

Biological AIE Molecules: Innovations in Synthetic Design and AI-Driven Discovery

Biological aggregation -induced emission (AIE) molecules offer significant advantages over synthetic organic fluorophores, particularly in biocompatibility, environmental sustainability, and emission properties in biological systems. Derived from biomolecules such as peptides, proteins, and nucleic acids, biological AIE molecules hold great promise for applications in biosensing, bioimaging, and target drug delivery. This review explores the design principles, mechanistic insights, and functional properties of biological AIE molecules whiles highlighting the role of artificial intelligence (AI) in accelerating their discovery and optimization. AI-driven approaches, including machine learning and computational modeling, are transforming the identification and synthesis of AIE molecules by enabling precise structural modifications and enhanced fluorescence efficiency. These advancements are paving the way for the integration of AIE molecules in next-generation smart biomedical devices, personalized medicine and sustainable technological applications. Emerging trends, including hybrid biomaterials, Ai-guided molecular engineering, and advanced imaging techniques, are expanding the scope of biological AIE molecules in healthcare and environmental monitoring. The synergy between AI and biological AIE molecules is unlocking new frontiers in biomedical technology, enabling transformative advancements in material science and healthcare applications, and shaping the future of fluorescence- based diagnostics and therapeutics.

Design strategies for tetrazine fluorogenic probes for bioorthogonal imaging

Tetrazine fluorogenic probes play a critical role in bioorthogonal chemistry, selectively activating fluorescence upon reaction to enhance precision in imaging and sensing within complex biological environments. Recent structural innovations-such as varied fluorophore choices, spacer optimization, and direct tetrazine integration within a fluorophore's π-conjugated system-have expanded their spectral range from visible to NIR, enhancing adaptability across various applications. This review examines advancements in the rational design and synthesis of these probes. We examine key fluorogenic mechanisms, such as energy transfer, internal conversion, and electron/charge transfer, that significantly influence fluorescence activation. We also highlight representative applications in live-cell imaging, super-resolution microscopy, and therapeutic monitoring, underscoring the expanding role of tetrazine probes in biomedical research and diagnostics. Collectively, these insights provide a strategic foundation for developing next-generation tetrazine probes with tailored properties to address evolving diagnostic and therapeutic challenges.

Aggregation-Induced Emission in Bridged (E,E)-1,4-Diphenyl-1,3-butadiene Derivatives with Six- and Seven-Membered Rings

Recently, we developed a new aggregation-induced emission (AIE) luminogen (AIEgen), bridged stilbene, by incorporating a propylene group into the C=C bond of the luminescent phenyl stilbene. This bridged structure, featuring a seven-membered ring, induces a significant conformational change, causing the C=C bond to twist in the excited state, thereby enhancing non-radiative decay in solution. In this study, we introduced bridged structures with alkylene groups of varying lengths into (E,E)-1,4-diphenyl-1,3-butadiene (DPB). The variation in the bridged structures of the synthesized DPB derivatives notably influenced the environmental sensitivity of fluorescence. Whereas the compound with two six-membered ring structures exhibited emission in solution and in the polycrystalline state, derivatives with a seven-membered ring exhibited AIE properties. Specifically, BDPB[7,7], featuring two seven-membered ring structures, demonstrated AIE characteristics with solid-state luminescence originating from J-aggregates. However, the fluorescence quantum yield was low in poly(methyl methacrylate) (PMMA) dispersion films, where molecular motion was restricted. These findings open new possibilities for designing unique AIEgens that remain nonluminescent even in highly viscous or confined environments, such as PMMA films.

Urease-powered micro/nanomotors: Current progress and challenges

Enzyme-powered micro/nanomotors (MNMs) (EMNMs) use natural enzymes to facilitate the decomposition of fuels, including hydrogen peroxide (H2O2), glucose, triglycerides, and urea to provide power. EMNMs can achieve self-propulsion through the in situ utilization of biofuels without additional fuels, exhibiting excellent biocompatibility and significant potential for application in the biomedical field. Compared with H2O2, which may cause oxidative damage to the body, urea exhibits superior biosafety characteristics. Presently, urease-powered MNMs (UMNMs) have made notable progress in their applications in the biomedical field and have garnered considerable attention from researchers. In this review, we present the latest advancements in the biomedical field of UMNMs, primarily focusing on: 1) diverse materials used for constructing the fundamental framework of motors; 2) control of motor movement through the regulation of enzymatic reaction rates; and 3) research directions for the clinical application of motors, including in vivo imaging, biomarker detection, cancer treatment, optical therapy, overcoming biological barriers, antibacterial interventions, antithrombotic strategies, and gastric disease management. Despite showing immense potential in biomedical applications, there are still several challenges impeding its practical implementation, such as maintaining activity in the in vivo environment while accurately targeting specific sites to achieve the desired clinical therapeutic effects.

Aggregation-induced emission(AIE)for next-generation biosensing and imaging: A review

Luminescence technology is a powerful analytical tool for biomedical research as well as for marker detection. Luminescent materials with aggregation-induced emission (AIE) properties have attracted extensive research interest, and their unique luminescence characteristics, biocompatibility, and sensitivity make them useful for the development of fluorescence-turn-on biosensors with superior sensitivity. While numerous reviews have focused on the design of AIEgens, comprehensive summaries on the strategies for biosensor preparation and application fields remain limited. In this review, we provide a concise introduction to the discovery and mechanism of the AIE phenomenon and summarize the working principles of classic AIE molecules. We discuss luminescence tuning strategies and functionalization methods for AIEgens, along with the design and preparation of AIE-based biosensors. Typical applications of AIE in biosensing and imaging are outlined, and we analyze the current limitations and future research directions of AIE technology in these fields. We hope this review will serve as a valuable reference for researchers in this rapidly developing field. The insights provided may facilitate the rational design of next-generation biosensors based on AIE technology, exhibiting promising avenues of biomedical applications and vast potential for growth.

Rational design of AIEgens through π-bridge engineering for dual-modal photodynamic and photothermal therapy

A series of aggregation-induced emission luminogens (AIEgens) with donor-π-acceptor (D-π-A) architecture were rationally designed and synthesized through π-bridge engineering for dual-modal photodynamic and photothermal therapy. The AIEgens (TPT, TFT, and TTT) were constructed using methoxy-substituted tetraphenylene as the electron donor and tricyanofuran as the electron acceptor, connected via different π-bridges (phenyl, furan, or thiophene). These compounds exhibited red-shifted absorption (460-545 nm) and emission (712-720 nm) with remarkable aggregation-induced emission characteristics. Among them, TTT demonstrated superior photophysical properties and was successfully encapsulated into amphiphilic calixarene-based nanoparticles (T@Q NPs) with uniform morphology. The T@Q NPs showed efficient reactive oxygen species generation and photothermal conversion (η = 6.98 %), enabling effective tumor cell ablation through combined photodynamic and photothermal therapy. In vivo studies revealed that T@Q NPs achieved 70 % tumor growth inhibition in 4T1 tumor-bearing mice without obvious systemic toxicity. This work presents an effective strategy for designing AIEgens-based phototherapeutic agents through π-bridge engineering, offering promising candidates for clinical translation in tumor phototherapy.

NIR-II AIEgen nanocomplex with suppressed nonradiative decay and intersystem crossing for high-contrast mesenteric vascular imaging

The prompt assessment of the mesenteric vasculature is crucial for the diagnosis of lethal mesenteric ischemia, underscoring the need for real-time mesenteric vascular imaging using small organic molecules that radiate fluorescence within the second near-infrared spectrum (NIR-II) due to its deep penetration and elevated signal-to-background ratio (SBR), which have been rarely reported. Unfortunately, numerous NIR-II dyes exhibit low quantum yields (QYs) when employed in practical applications, highlighting the need for QY enhancement. For this research, a NIR-II fluorescent AIEgen, termed TPETPA-TQT, was rationally designed by incorporating tetraphenylethylene (TPE)-fused triphenylamine (TPA) into the robust, high QY core of 6,7-di(thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline (TQT). We further encapsulated this dye within F127 to form the TPETPA-TQT F127 nanocomplex, which exhibits a 6.5-fold enhancement in fluorescence intensity over the TPA-TQT dye encapsulated with DSPE-PEG2000, attributed to the suppression of molecular nonradiative decay and intersystem crossing. The abdominal vasculature and microvessels on the intestinal wall surface, as narrow as 0.41 mm, can real-time visualization using TPETPA-TQT F127 nanocomplex, and exhibit a 94 % improvement of SBR versus ICG. Our findings will push forward the progress of high-brightness NIR-II contrast agents for enhanced mesenteric vasculature imaging and mesenteric ischemia diagnosis.

Aggregation-induced enhanced emission (AIEE), pH sensing and selective detection of sulfuric acid of novel imidazole-based surrogates made via microwave-assisted synthesis

A novel series of imidazole derivatives (4a-d) was synthesized via a microwave-assisted synthesis and whose structures were elucidated using 1H and 13C NMR, ESI-HRMS, and FT-IR spectroscopy. Photophysical characterization revealed absorption peaks around 305 nm and 327-365 nm, with strong photoluminescence (PL) emission maxima ranging between 435 and 453 nm. Aggregation-induced enhanced emission (AIEE) behavior was observed in THF/H2O mixtures, where 4a-c showed maximal fluorescence at certain solvent ratios, indicating aggregate formation. 4d disclosed a wavelength shift from 408 to 460 nm along with an enhanced emission, which is attributed to restricted intramolecular rotation (RIR), as confirmed by viscosity studies. Fluorescence lifetime and dynamic light scattering (DLS) measurements further supported the aggregation process, with particle sizes between 100 nm and 720 nm. Density functional theory (DFT) calculations validated electronic conjugation, showing HOMO-LUMO bandgaps (ΔE) of approximately 2.01-2.23 eV for 4a-d. Compound 4a exhibited the largest HOMO-LUMO energy gap of 2.23 eV, indicating greater electronic stability and enhanced emission efficiency upon aggregation. In contrast, compound 4d, with the smallest energy gap of 2.01 eV, suggests higher reactivity and better sensitivity to aggregation phenomena. This characteristic renders 4d particularly advantageous for sensing applications where rapid responsiveness to environmental variations is critical. pH sensing studies demonstrated the stability of 4a-d over a broad pH range, with 4d showing a 47 nm red shift in highly acidic conditions besides a selectivity for sulfuric acid detection. Investigation of sulfuric acid detection limit was studied, revealing a capacity for 4a-d to detect an acidic concentration as low as 16.5 μM. Stability and practical applicability of 4d compound as a sensor are further confirmed through reversibility and repeatability tests which reveal the possibility to regenerate the imidazole derivative even after several uses.

Eradication of Antibiotic-Resistant Gram-Positive Bacteria and Biofilms by Rationally Designed AIE-Active Iridium(III) Complexes Derived from Cyclometalating 2-Phenylquinoline and Ancillary Bipyridyl Ligands

Antibiotic resistance caused by Gram-positive bacteria is a growing global human health threat. Selective discrimination and eradication of Gram-positive bacteria and their biofilms is challenging. Therapeutic strategies with multiple modes of action are urgently needed to address the increase in Gram-positive bacteria-resistant nosocomial infections. In this work, we have presented rationally designed aggregation-induced emission (AIE)-active cationic cyclometalated iridium(III) complexes derived from 2-phenylquinoline and 2,2'-bipyridine ligands for Gram-positive antibacterial studies. The AIE properties of these complexes were exploited for selective discrimination between Gram-positive and Gram-negative bacteria. These complexes displayed good antimicrobial activity against critical Gram-positive ESKAPE pathogens with minimum inhibitory concentrations in the low micromolar range but were inactive against Gram-negative pathogens. Importantly, the complexes can inhibit biofilm formation and eradicate bacteria from mature biofilms, which are major causes of persistent infections and antibiotic resistance and are more difficult to eliminate. In addition, these complexes showed low hemolytic activity against mammalian cells and a high therapeutic index, indicating good selectivity. Interestingly, the complexes kill bacteria through a variety of modes of mechanism, including ROS generation, cell membrane disruption, and depolarization and the loss of bacterial membrane integrity. These findings offer opportunities for designing metal AIEgens to treat Gram-positive bacterial infections effectively.

Side Chain Phenyl Isomerization-Induced Spatial Conjugation for Achieving Efficient Near-Infrared II Phototheranostic Agents

The contradiction of near-infrared II (NIR-II) emission and photothermal effects limits the development of phototheranostic agents (PTAs) in many emerging cutting-edge applications. Organic aggregates present a promising opportunity for the balance of competitive relaxation processes through the manipulation of molecular structure and packing. Herein, side chain phenyl isomerization-induced spatial conjugation was proposed for constructing A-D-A type NIR-II PTAs with simultaneous enhancement of fluorescence brightness and photothermal properties. Three pairs of mutually isomeric fluorophores, whose phenyls respectively located at the outside (o-series) and inside (i-series) of the side chain, were designed and synthesized. The positional isomerization of the phenyl endows the o-series crystals with strong spatial conjugation between the phenyl group on the side chain and the backbone, as well as interlocked planar network, which is different to that observed in the i-series. Thus, all o-series nanoparticles (NPs) exhibit red-shifted absorption, enhanced NIR-II emission, and superior photothermal properties than their i-series counterparts. A prominent member of the o-series, o-ITNP NPs, demonstrated efficacy in facilitating NIR-II angiography, tumor localization, and NIR-II imaging-guided tumor photothermal therapy. The success of this side chain phenyl isomerization strategy paves the way for precise control of the aggregation behavior and for further development of efficient NIR-II PTAs.

Synthesis and Optoelectronic Properties of Perylene Diimide-Based Liquid Crystals

Perylene diimide (PDI), initially synthesized and explored as an organic dye, has since gained significant recognition for its outstanding optical and electronic properties. Early research primarily focused on its vibrant coloration; however, the resolution of solubility challenges has revealed its broader potential. PDIs exhibit exceptional optical characteristics, including strong absorption and high fluorescence quantum yield, along with remarkable electronic properties, such as high electron affinity and superior charge carrier mobility. Furthermore, the robust π-π stacking interactions and liquid crystalline behavior of PDIs facilitate precise their self-assembly into highly ordered structures, positioning them as valuable materials for advanced applications in optoelectronics, photonics, and nanotechnology. This article provides a comprehensive review of the progress made in the design, synthesis, and optoelectronic performance of PDI-based liquid crystals. It explores how various substituents and their placement on the PDI core impact the properties of these liquid crystal molecules and discusses the challenges and opportunities that shape this rapidly evolving class of optical materials. This review is strictly focused on PDIs and does not cover their elongated or laterally extended derivatives, nor does it include monoimide or ester compounds.

Aggregation Induced Emission Based Luminogenic (AIEgenic) Probes for the Biomarker Detection

Various biomarkers such as proteins play key roles in controlling crucial biochemical processes. The critical concentration of the biomarkers is important to maintain a healthy life. In fact, imbalance in concentration or irregular activity of these can lead to various diseases like Cancer, Alzheimer's etc. Therefore, the disease related biomarkers and their timely detection are key to control the illness. In the literature, a few activity-based probes for the detection of such biomarkers are available. As per the requirement an ideal probe should be very specific to recognize the target analyte and that could be achieved by virtue of having a robust structure and stimuli responsive nature. In this regard, several fluorescent probes are of great choice. Although these fluorescent probes face certain challenges such as aggregation caused quenching, which heavily affects the sensitivity and photostability is another major concern for many fluorescent probes. To overcome these challenges aggregation-induced emissive fluorescent probes found to be an excellent alternative. Aggregation induced emissive luminogens (AIEgens) offer higher signal to noise ratios and found to possess better photostability during sensing and imaging. In the present review we have summarized the development of AIEgenic probes for sensing and imaging of disease related biomarkers. We believe this review could be a guide to design efficient AIEgenic probes for the diagnostics development.

Chitosan as a fluorescent probe for the detection of the AIE-active food colorant quinoline yellow

The greenish-yellow synthetic dye quinoline yellow (Qy) is widely used in the food and pharmaceutical industries. However, this dye may lead to health and environmental problems. Therefore, investigating how Qy interacts with biological macromolecules is of great interest. In this work, Qy was found to be a novel AIEgen having strong solid-state emission and water-solubility. Adding tetrahydrofuran to an aqueous solution of Qy induced Qy to form nanoaggregates, which increased its fluorescence intensity. Moreover, we found that Qy was able to interact with typical biological macromolecules, such as chitosan, BSA, and DNA, and quench these biomolecules' intrinsic fluorescence. Therefore, chitosan was chosen as a probe for Qy detection. The results showed that chitosan could detect Qy in the presence of interfering ions, other dyes, and sucrose, as well as in an acidic environment. Finally, chitosan was used to determine the quantity of Qy in orange juice and wine. This is the first report of the identification of a food colorant as an AIEgen, and this AIE activity has been wisely harnessed to visualize molecular interactions between Qy and biological macromolecules, as well as to detect Qy in beverages.

Ultrasmall metal nanoclusters as efficient luminescent probes for bioimaging

Ultrasmall metal nanoclusters (NCs, <2 nm) have emerged as a novel class of luminescent probes due to their atomically precise size and tailored physicochemical properties. The rapid advancements in the design and utilization of metal NC-based luminescent probes are facilitated by the atomic-level manipulation of metal NCs. This review article explores (i) the engineering of metal NCs' functions for bioimaging applications, and (ii) the diverse uses of metal NCs in bioimaging. We begin by presenting an overview of the engineering functions of metal NCs as luminescent probes for bioimaging applications, highlighting key strategies for enhancing NCs' luminescence, biocompatibility and targeting capabilities towards biological specimens. Our discussion then centers on the bioimaging applications of metal NCs in subcellular organelles, individual cells, tissues, and entire organs. Finally, we offer a perspective on the challenges and potential developments in the future use of metal NCs for bioimaging applications.

In situ dressing based on a D-π-A structured aggregation-induced emission photosensitizer for healing infected wounds

Photodynamic antimicrobial therapy (aPDT) can effectively kill bacteria without promoting drug resistance. However, the phototoxicity of photosensitizers in aPDT against normal cells hinders their practical applications. In this work, we report the utilization of an aggregation-induced emission (AIE)-active photosensitizer, DTTPB, to develop antibacterial dressing for effective eradication of both Gram-positive and Gram-negative bacteria. The D-π-A structure of DTTPB facilitates efficient ROS generation in the aggregate state, addressing the limitations of a traditional photosensitizer. Notably, DTTPB demonstrates good biocompatibility towards normal cells, which minimizes its phototoxicity to normal tissues. To demonstrate its practical implications, DTTPB is combined with Carbomer 940 to create an injectable hydrogel dressing (DTTPB@gel). DTTPB@gel not only adheres to wounds but also maintains the antimicrobial properties of DTTPB, which together contributes to its enhanced wound-healing performance. Biocompatibility and toxicity assessments confirm the safety of this novel material, highlighting its potential as a practical and effective treatment for bacterial infections in wounds. The results underscore the importance of innovative antimicrobial strategies in fighting against antibiotic resistance, paving the way for safer and more effective therapeutic options.

Aggregation-induced emission in novel multilayered 3D polymers: development of a fluorescent probe for selective metal ion detection

This study presents the characterization of a novel multilayered three-dimensional (3D) polymer exhibiting aggregation-induced emission (AIE) properties when excited at a low wavelength of 280 nm. Utilizing fluorescence spectroscopy, we demonstrate that the polymer displays a marked enhancement in luminescence upon aggregation, a characteristic behavior that distinguishes AIE-active materials from conventional fluorophores. Furthermore, we explore the potential application of this multilayered 3D polymer as a fluorescent probe for the selective detection of specified metal ions. By incorporating chelating functional groups into the polymer matrix, we facilitate specific interactions with target metal ions, leading to significant fluorescence intensity changes that correlate with ion concentration. According to their cyclic voltammetry characteristics, the polymers have potential applications in cutting-edge electrical and optoelectronic systems. Our findings indicate that this multilayered 3D polymer serves as an effective fluorescent sensor and offers tunable optical properties, paving the way for innovative applications in environmental monitoring and biomedical diagnostics. The results underscore the utility of AIE-active polymers in developing advanced materials for sensitive and selective detection of metal ions, contributing to the growing field of smart sensing technologies.

Aggregation-Induced Emission Luminogens Realizing High-Contrast Bioimaging

A revolutionary transformation in biomedical imaging is unfolding with the advent of aggregation-induced emission luminogens (AIEgens). These cutting-edge molecules not only overcome the limitations of traditional fluorescent probes but also improve the boundaries of high-contrast imaging. Unlike conventional fluorophores suffering from aggregation-caused quenching, AIEgens exhibit enhanced luminescence when aggregated, enabling superior imaging performance. This review delves into the molecular mechanisms of aggregation-induced emission (AIE), demonstrating how strategic molecular design unlocks exceptional luminescence and superior imaging contrast, which is crucial for distinguishing healthy and diseased tissues. This review also highlights key applications of AIEgens, such as time-resolved imaging, second near-infrared window (NIR-II), and the advancement of AIEgens in sensitivity to physical and biochemical cue-responsive imaging. The development of AIE technology promises to transform healthcare from early disease detection to targeted therapies, potentially reshaping personalized medicine. This paradigm shift in biophotonics offers efficient tools to decode the complexities of biological systems at the molecular level, bringing us closer to a future where the invisible becomes visible and the incurable becomes treatable.

Nonconventional Full-Color Luminescent Polyurethanes: Luminescence Mechanism at the Molecular Orbital Level

The study of structure-activity relationships is a top priority in the development of nontraditional luminescent materials. In this work, nonconjugated polyurethanes (PUs) with full-color emission (red, green, and blue) are easily obtained by control of the diol monomer structure and the polymerization conditions. Selected diol monomers introduced single, double, or triple bond repeating units into the main chain of the PUs, in order to understand how unsaturated bonds and H-bonds affect their luminescence from a molecular orbital viewpoint. Detailed experimental and theoretical results show that the PUs have different temperature-dependent behaviors related to the interplay of H-bonding, through-space n-π interactions, and aggregation properties. The potential applications of PUs in colorful displays, covert information transmission, and multifunctional bioimaging have been verified. This work provides a new general protocol for the simple preparation of multifunctional nonconventional fluorescent polymers and deepens the understanding of their luminescence mechanisms.

From Molecule to Aggregate: Understanding AIE through Multiscale Experimental and Computational Techniques

Aggregation-induced emission (AIE) phenomena have garnered significant attention due to their applications in various fields, ranging from materials science to biomedicine. Despite substantial progress, the underlying mechanism governing the AIE activity of molecules remains elusive. This study employs a comprehensive and multiscale approach, combining experimental and theoretical methodologies, to discern the determinants of AIE activity. Our investigations involve synthesizing four organic molecules with D-π-A-D architecture, accompanied by quantum mechanics (QM) and molecular dynamics (MD) simulations, providing a deep understanding of the interactions within aggregates. The symmetry-adapted perturbation theory (SAPT) calculations further corroborate our findings, revealing a clear correlation between AIE activity and the type of aggregate formed. Specifically, we demonstrate that AIE-active molecules exhibit a distinctive J-type aggregation characterized by enhanced emission from the S1 state. In contrast, AIE-inactive molecules adopt an H-type aggregate configuration, where the emission from the S1 state is constrained. In addition, we investigated the subcellular localization of the molecules, revealing localization within the lipid droplets. Our findings contribute to the fundamental understanding of AIE phenomena and provide insights into the design principles for AIE-active materials with potential applications in advanced sensing and imaging technologies.

Recent Progress in Nanomedicine for the Diagnosis and Treatment of Alzheimer's Diseases

Alzheimer's disease (AD) is a neurodegenerative disease that causes memory loss and progressive and permanent deterioration of cognitive function. The most challenging issue in combating AD is its complicated pathogenesis, which includes the deposition of amyloid β (Aβ) plaques, intracellular hyperphosphorylated tau protein, neurofibrillary tangles (NFT), etc. Despite rapid advancements in mechanistic research and drug development for AD, the currently developed drugs only improve cognitive ability and temporarily relieve symptoms but cannot prevent the development of AD. Moreover, the blood-brain barrier (BBB) creates a huge barrier to drug delivery in the brain. Therefore, effective diagnostic tools and treatments are urgently needed. In recent years, nanomedicine has provided opportunities to overcome the challenges and limitations associated with traditional diagnostics or treatments. Various types of nanoparticles (NPs) play an essential role in nanomedicine for the diagnosis and treatment of AD, acting as drug carriers to improve targeting and bioavailability across/bypass the BBB or acting as drugs directly on AD lesions. This review categorizes different types of NPs and summarizes their applications in nanomedicine for the diagnosis and treatment of AD. It also discusses the challenges associated with clinical applications and explores the latest developments and prospects of nanomedicine for AD.

Disulfide-Bridged Cationic Dinuclear Ir(III) Complex with Aggregation-Induced Emission and Glutathione-Consumption Properties for Elevating Photodynamic Therapy

The ability of photosensitizers (PSs) to generate reactive oxygen species (ROS) is crucial for photodynamic therapy (PDT). However, many traditional PSs face the drawbacks that aggregation-caused quenching (ACQ) and highly expressed glutathione (GSH) in the tumor microenvironment seriously limit their ROS generation ability. Herein, we report two cationic dinuclear iridium complexes, Ir-C-C-Ir and Ir-S-S-Ir, which possess aggregation-induced emission (AIE). Ir-S-S-Ir was constructed for GSH consumption by introducing a disulfide linkage between the two auxiliary ligands with imine units. Quantum chemical calculations revealed that Ir-C-C-Ir and Ir-S-S-Ir possess many degenerate states, which provide more channels for singlet-to-triplet exciton transitions, and then the intersystem crossing rate is increased due to the heavy atom effect of the iridium and sulfur atoms. The ROS production experiments indicated that the singlet oxygen yield of Ir-S-S-Ir was 33 times more than that of the ACQ mononuclear iridium complex Ir-C. Most importantly, Ir-S-S-Ir consumed GSH through a thiol-disulfide exchange reaction, as demonstrated by mass spectrometry and high-performance liquid chromatography. Cell experiments testified that Ir-S-S-Ir consumes GSH in tumor cells, possesses good ROS production capacity, and exhibits an extraordinary PDT effect. This is the first report of an AIE dinuclear iridium complex with a GSH-consuming function.

Berberine-doped montmorillonite nanosheet for photoenhanced antibacterial therapy and wound healing

Bacterial infections pose a substantial threat to human health, particularly with the emergence of antibiotic-resistant strains. Therefore, it is essential to develop novel approaches for the efficient treatment of bacterial diseases. This study presents a therapeutic approach involving BBR@MMT nanosheets (NSs), wherein montmorillonite (MMT) was loaded with berberine (BBR) through an ion intercalation reaction to sterilize and promote wound healing. BBR@MMT exhibits nano-enzymatic-like catalytic activity, is easy to synthesize, and requires low reaction conditions. This nanocomplex showed photodynamic properties and superoxide dismutase (SOD) activity. The in vitro experiments indicated that BBR@MMT was able to effectively inhibit the growth of Gram-positive bacteria (S. aureus) and Gram-negative bacteria (E. coli) through the production of ROS when exposed to white light. Meanwhile, BBR@MMT inhibited the secretion of pro-inflammatory factors and scavenged free radicals via its SOD-like activity. In vivo results showed that BBR@MMT NSs were capable of effectively promoting the wound-healing process in infected mice under white light irradiation. Hence, it can be concluded that photodynamic therapy based on BBR@MMT NSs with nano-enzymatic activity has the potential to be used in treating infections and tissue repair associated with drug-resistant microorganisms.

Modeling the differential functional responses and selectivity of a marine copepod to nano/microplastics in mixture

Nano- and microplastics (NMPs) pollution is widespread in the oceans, posing potential risks to marine species. This study examined the accumulation capacity and selectivity potentials of NMPs by a marine copepod Parvocalanus crassirostris under different food mixtures by modeling the combined biokinetic and functional response. We investigated two sizes of NMPs (200 nm and 5 µm) across a concentration gradient (0 - 5000 µg/L) and varying diatom abundances (0, 104, 105 cells/mL). Fluorescence imaging and quantification revealed that P. crassirostris actively ingested NMPs at low concentration. Accumulation increased with NMPs concentration but eventually saturated due to gut capacity limits, following a Holling type II functional response (i.e., hyperbolic curve). Our novel functional response model estimated the key parameters and demonstrated that the maximum accumulation reached 5.3 % of dry weight with averaged half-saturation constants of 229 µg/L. The size of NMPs did not significantly affect the total accumulation or satiety levels. The presence of diatoms influenced the feeding selectivity and decreased the microplastic accumulation by 73 % at 105 cells/mL, while facilitating nanoplastic accumulation by 81 % at 104 cells/mL. This study enhanced our understanding of NMPs bioavailability and environmental fate in marine ecosystems.

Photocatalytic therapy via photoinduced redox imbalance in biological system

Redox balance is essential for sustaining normal physiological metabolic activities of life. In this study, we present a photocatalytic system to perturb the balance of NADH/NAD+ in oxygen-free conditions, achieving photocatalytic therapy to cure anaerobic bacterial infected periodontitis. Under light irradiation, the catalyst TBSMSPy+ can bind bacterial DNA and initiate the generation of radical species through a multi-step electron transfer process. It catalyzes the conversion from NADH to NAD+ (the turnover frequency up to 60.7 min-1), inhibits ATP synthesis, disrupts the energy supply required for DNA replication, and successfully accomplishes photocatalytic sterilization in an oxygen-free environment. The catalyst participates in the redox reaction, interfering with the balance of NADH/NAD+ contents under irradiation, so we termed this action as photoinduced redox imbalance. Additionally, animal experiments in male rats also validate that the TBSMSPy+ could effectively catalyze the NADH oxidation, suppress metabolism and stimulate osteogenesis. Our research substantiates the concept of photoinduced redox imbalance and the application of photocatalytic therapy, further advocating the development of such catalyst based on photoinduced redox imbalance strategy for oxygen-free phototherapy.

Supramolecular assemblies with aggregation-induced emission for in situ active imaging-guided photodynamic therapy of cancer cells

Photodynamic therapy (PDT) has attracted widespread attention as a novel non-invasive anticancer approach. However, the diminished photosensitivity and limited oxygen exposure caused by the aggregation of traditional photosensitizers greatly impair its overall therapeutic efficacy. Herein, a series of water-soluble aggregation-induced emission luminogens (AIEgens) with triphenylamine as skeleton were synthesized and exhibited bright Near-infrared (NIR) emission and strong reactive oxygen species (ROS) generation. Through host-guest complexation between the multicharged triphenylamine units on AIEgens and cucurbit[10]uril (CB[10]) host molecule, supramolecular nanoassemblies were constructed and exhibited negligible phototoxicity to normal cells due to their limited oxygen contact. In contrast, the efficient release of AIEgens from nanoassemblies through competitive binding of overexpressed peptides in cancer cells with CB[10], enabled the full exploitation of the photosensitivity of AIEgens to produce highly efficient ROS, achieving selective ablation of cancer cells. Moreover, due to the restriction of intramolecular motion (RIM) upon anchored on organelle membranes through electrostatic interactions, the cationic AIEgens with weak fluorescence in physiological environment exhibited intense fluorescence emission, thus realizing imaging-guided PDT. This work may open up an avenue for the development of simple and feasible smart responsive nanomaterials for cancer treatment using supramolecular host-guest complexation strategy.

Highly stable and near-infrared responsive phase change materials for targeted enzyme delivery toward cancer therapy

Natural enzyme-based catalytic cascades have garnered increasing attention in cancer therapy, but their clinical utility is greatly limited due to loss of function during in vivo delivery. Here, we developed an enzyme delivering nanoplatform (GCI@RPCM) with great in vivo stability and achieve NIR-triggered enzyme dynamic therapy. This nanoplatform is created with encapsulation of nature enzymes (glucose oxidase and chloroperoxidase) and photothermal agent (indocyanine green) within tumor targeting and thermo-responsive phase change materials (RPCMs). With NIR irradiation for 10 min, GCI@RPCM can release 41 % of the enzymes and generate abundant reactive oxygen species (ROS), which showed significant tumor cell inhibition. After intravenous injection, GCI@RPCM can efficiently accumulate at the tumor site and local NIR treatment resulted in complete tumor eradication without detectable systemic toxicity. This study provides a highly stable and NIR-controllable smart delivery system and achieve enzyme dynamic therapy for enhanced breast cancer therapy.

Exploration of Alkyne-Based Multilayered 3D Polymers and Oligomers: Subtle Aggregation-Induced Emission, Chromium(VI) Ion Detection, and Chiral Properties Characterization

This study investigates the synthesis and characterization of alkyne-based multilayered three-dimensional (3D) polymers, which exhibit a subtle aggregation-induced emission (AIE) phenomenon. The polymers demonstrate significant potential as fluorescent probes for the selective detection of chromium (VI) ions (Cr6⁺), showcasing their utility in environmental sensing applications. Additionally, the circular dichroism (CD) spectra reveal a pronounced cotton effect, indicative of chiral properties, while scanning electron microscopy (SEM) and dynamic light scatting (DLS) analysis reveal a distinctive rock-like surface morphology and Cr6+ sensitive anti-aggregation. These findings highlight the multifunctional capabilities of alkyne-based multilayered 3D polymers, suggesting their applicability in both fluorescence-based sensing and materials science. The insights gained from this research contribute to the development of advanced materials with tailored optical properties for environmental monitoring and other practical applications.

Excited State Dynamics of Geometrical Evolution of α-Substituted Dibenzoylmethanatoboron Difluoride Complex with Aggregation-Induced Emission Property

Organic molecules with an aggregation-induced emission (AIE) property have been attracting much attention from the viewpoint of application to solid state emissive materials. For the AIE mechanism, quantum mechanical studies proposed the restriction of the intramolecular motion (RIM) model with the contribution of the conical intersection (CI) and deduced the importance of the restricted access to a conical intersection (RACI) in the potential energy surface (PES). Although these theoretical studies have contributed to the elucidation of AIE phenomena, direct detection of the reaction dynamics is indispensable to clarify the actual PES and the deactivation mechanism. Along this line, we investigated excited state dynamics of the AIE molecule with dibenzoylmethanatoboron difluoride complexes using time-resolved absorption spectroscopies in both visible and infrared (IR) regions. While the reference system of 1,3-bis(4-methoxyphenyl)methanatoboron difluoride (2aBF2) showed strong emission in solution, the methyl-substituted derivative at the α-position of the dioxaborine ring (2amBF2) led to the very weak fluorescence in solution but strong emission in the solid state. Time-resolved visible absorption measurements revealed a peak shift and broadening of the stimulated emission in the solution of 2amBF2, owing to the rapid change of the molecular geometry. With the temporal evolution of time-resolved IR absorption signals and density functional theory (DFT) calculation of these systems, it was deduced that 2amBF2 has two stable geometries, namely, planar and bending, in the S1 state and the bending geometry in the S1 state led to rapid conversion to the S0 state. These results support the RACI model in the aggregated states, leading to the AIE properties.

A new luminescent nickel nanocluster with solvent and ion induced emission enhancement toward heavy metal analysis

Expanding the family of fluorescent metal clusters beyond gold, silver, and copper has always been an issue for researchers to solve. In this study, a novel type of cysteine-capped nickel nanoclusters (Cys-Ni NCs) with bright turquoise emission was developed. The as-synthesized Ni NCs showed aggregation-induced emission enhancement (AIEE) properties across Cd2+ and various polar organic solvents. Concurrently, solvents with different viscosities were used to explore the principle of solvent-induced AIEE of Cys-Ni NCs, revealing a positive correlation between fluorescence intensity and solution viscosity. In addition, the concentration of Cd2+ that induced the AIEE effect was reduced by nearly two orders of magnitude in highly viscous solvents, indicating the possibility of Cys-Ni NCs as a promising nanomaterial platform for Cd2+ sensing analysis. Moreover, we propose a novel fluorescent sensing method for rapid detection of Cu2+ based on the carboxyl group of Cys-Ni NCs coupling with Cu2+. Further, validation of Cu2+ detecting methodologies in environmental water samples with the accuracy up to 93.94% underscores their potential as robust and efficient sensing platforms. This study expands the repertoire of fluorescent metal nanoclusters for highly sensitive and selective sensing of hazardous ions and paves the way for further exploration and wide applications in Cu2+ detection in biological and medicine fields.

Conceptually innovative fluorophores for functional bioimaging

Fluorophore chemistry is at the forefront of bioimaging, revolutionizing the visualization of biological processes with unparalleled precision. From the serendipitous discovery of mauveine in 1856 to cutting-edge fluorophore engineering, this field has undergone transformative evolution. Today, the synergy of chemistry, biology, and imaging technologies has produced diverse, specialized fluorophores that enhance brightness, photostability, and targeting capabilities. This review delves into the history and innovation of fluorescent probes, showcasing their pivotal role in advancing our understanding of cellular dynamics and disease mechanisms. We highlight groundbreaking molecules and their applications, envisioning future breakthroughs that promise to redefine biomedical research and diagnostics.

A mitochondria targeting, de novo designed, aggregation-induced emission probe for selective detection of neurotoxic amyloid-β aggregates

A striking issue is the scarcity of imaging probes for the early diagnosis of Alzheimer's disease. For the development of Aβ biomarkers, a mitochondria targeting, de novo designed, aggregation-induced emission (AIE) probe Cou-AIE-TPP+ is constructed by engineering the aromatic coumarin framework into the bridge of electron donor-acceptor-donor tethered with a lipophilic cationic triphenylphosphonium (TPP+) group. The synthesized Cou-AIE-TPP+ probe exhibits biocompatibility, noncytotoxicity, and a huge Stokes shift (124 nm in PBS). Cou-AIE-TPP+ has respectable fluorescence augmentation inside the aggregated Aβ40 in comparison with monomeric Aβ40 with a high binding affinity (Kd = 83 nM) to Aβ40 aggregates, is capable of detecting the kinetics of amyloid aggregation, and is superior to the gold standard probe thioflavin T. Fluorescence lifetime and brightness are also augmented when the probe Cou-AIE-TPP+ binds with Aβ aggregates in PBS. Cou-AIE-TPP+ (λem 604 nm) selectively targets and images neuronal cell mitochondria, is useful to monitor mitochondrial morphology alteration and damage during Aβ40-induced neurotoxicity, recognizes neurotoxic Aβ fibrils, and is highly colocalized with thioflavin T, showing a decent Pearson correlation coefficient of 0.91 in the human neuroblastoma SH-SY5Y cell line. These findings indicate that the mitochondria targeting, de novo designed, functional AIE-based solvatofluorochromic Cou-AIE-TPP+ probe is a promising switch on biomarkers for fluorescence imaging of Aβ aggregates and to monitor mitochondrial morphology change and dysfunction during Aβ-induced neurotoxicity, which may offer imperative direction for the advancement of compelling AIE biomarkers for targeted early stage Aβ diagnosis in the future.

Modulating the photodynamic modality of Au22 nanoclusters through surface conjugation of arginine for promoted healing of bacteria-infected wounds

Developing novel antibacterial agents without drug resistance is highly desired but challenging. In this study, an Au nanocluster (NC)-based photodynamic antibacterial agent with aggregation-induced emission (AIE) has been designed to promote the healing of bacteria-infected wounds by conjugating arginine (Arg) on the surface of Au22 NCs. The conjugation of Arg not only endows the NCs with enhanced visible light absorption, increased photoluminescence (PL) intensity, and prolonged PL lifetime, but it also enables switching the photodynamic production mode of reactive oxygen species (ROS) and extra production of reactive nitrogen species (RNS). These enhancements allow the Arg-Au22 NCs to combine ROS/RNS-mediated antibacterial action with the enhanced inherent antibacterial properties of Au NCs, resulting in outstanding antibacterial efficacy against both Gram-negative and Gram-positive bacteria. In vivo experiments demonstrate the effective treatment of bacteria-infected wounds by the Arg-Au22 NCs, leading to the photodynamic eradication of bacterial infections and reduced inflammation in the wound area without causing systemic harm or impairing blood and liver functions. This study introduces a novel approach to designing metal NC-based photodynamic antibacterials with multiple antibacterial actions, contributing to deeper understanding of ROS/RNS-mediated antibacterial mechanisms, and future utilization of metal NCs in antibacterial therapies.

Reengineering of Donor-Acceptor-Donor Structured Near-Infrared II Aggregation-Induced Emission Luminogens for Starving-Photothermal Antitumor and Inhibition of Lung Metastasis

Electron acceptor possessing strong electron-withdrawing ability and exceptional stability is crucial for developing donor-acceptor-donor (D-A-D) structured aggregation-induced emission luminogens (AIEgens) with second near-infrared (NIR-II) emission. Although 6,7-diphenyl-[1,2,5] thiadiazolo [3,4-g] quinoxaline (PTQ) and benzobisthiadiazole (BBT) are widely employed as NIR-II building blocks, they still suffer from limited electron-withdrawing capacity or inadequate chemo-stability under alkaline conditions. Herein, a boron difluoride formazanate (BFF) acceptor is utilized to construct NIR-II AIEgen, which exhibits a better overall performance in terms of NIR-II emission and chemo-stability compared to the PTQ- and BBT-derived fluorophores. With finely tuned intramolecular motions and strong D-A interaction strength, TPE-BFF simultaneously exhibits high molar extinction coefficient (ε= 4.31 × 104 M-1cm-1), strong NIR-II emission (Φ = 0.49%) and photothermal effect (η = 58.5%), as well as high stability. Thanks to these merits, the thermosensitive nanoparticles constructed by integrating TPE-BFF and the antiglycolytic agent 2-deoxy-d-glucose (2DG) are successfully utilized for imaging-guided photothermal antitumor lung metastasis by regulating glycolysis and reducing ATP-dependent heat shock proteins. Combining experimental results and theoretical calculations, BFF proves to be an outstanding electron acceptor for the design of versatile NIR-II AIEgens. Overall, this study offers a promising alternative for developing multifunctional NIR-II AIEgens in biomedical applications.

Aggregation-Induced Emission Luminogen: Role in Biopsy for Precision Medicine

Biopsy, including tissue and liquid biopsy, offers comprehensive and real-time physiological and pathological information for disease detection, diagnosis, and monitoring. Fluorescent probes are frequently selected to obtain adequate information on pathological processes in a rapid and minimally invasive manner based on their advantages for biopsy. However, conventional fluorescent probes have been found to show aggregation-caused quenching (ACQ) properties, impeding greater progresses in this area. Since the discovery of aggregation-induced emission luminogen (AIEgen) have promoted rapid advancements in molecular bionanomaterials owing to their unique properties, including high quantum yield (QY) and signal-to-noise ratio (SNR), etc. This review seeks to present the latest advances in AIEgen-based biofluorescent probes for biopsy in real or artificial samples, and also the key properties of these AIE probes. This review is divided into: (i) tissue biopsy based on smart AIEgens, (ii) blood sample biopsy based on smart AIEgens, (iii) urine sample biopsy based on smart AIEgens, (iv) saliva sample biopsy based on smart AIEgens, (v) biopsy of other liquid samples based on smart AIEgens, and (vi) perspectives and conclusion. This review could provide additional guidance to motivate interest and bolster more innovative ideas for further exploring the applications of various smart AIEgens in precision medicine.

Self-Assembly of Silole-Based Aggregation-Induced Emission Compounds with Green Fluorescent Protein under Physiological Conditions for Traceable and Versatile Drug Delivery

Biomacromolecules are viewed as promising drugs due to their specific functions in biological processes, biocompatibility, and pharmacological efficacy. Injective administration, chosen to avoid intestinal barriers, may in turn lead to immediate decay in the circulation system, unreliable targeting performance, or the induction of immune responses. For some biomacromolecules, chemically modified proteins have been developed for practical use. Various cargo or carrier systems are under development but have been delayed by technical difficulties. We present self-assembled nanocapsules with diameters ranging from 100 to 500 nm that can be deployed in physiological buffers to enclose various substances present in the buffers at the same time. Our amphiphilic nanocapsule, consisting of silole-core dendrimer products as the hydrophobic part and green fluorescent protein (GFP) derivatives as the hydrophilic part, connects and assembles spontaneously when mixed in solutions while engulfing dissolved or dispersed compounds together in a dose-dependent manner and shows unique optical characteristics because the dendrimer products exhibit aggregation-induced emission. Furthermore, the emission of the dendrimer causes considerable fluorescence resonance energy transfer (FRET) to GFP derivatives upon association. We could easily monitor assemblies by FRET states and particle sizes and have confirmed a stable presence in the buffer for at least a month. Further tracking of nanocapsules by fluorescence confirmed efficient uptake into some cancer cells. Nanocapsules based on GFP variants with or without a cell-surface-specific tag demonstrated that the tag improved the potential for specific targeted delivery. There were also indications that the nanocapsules became unstable after cellular uptake in the intracellular environment. We report here the simple preparation of traceable, stable, and biocompatible self-assembled nanocapsules as the basis for a versatile drug delivery system.

Nonconjugated Polyurethane Derivatives with Aggregation-Induced Luminochromism for Multicolor and White Photoluminescent Films

A simple and effective strategy to obtain solid-state multicolor emitting materials is a particularly attractive topic. Nonconventional/nonconjugated polymers are receiving widespread attention because of their advantages of rich structural diversity, low cost, and good processability. However, it is difficult to control the molecular conformation or to obtain the crystal structure of amorphous molecules, which means it is a challenge to obtain nontraditional polymeric materials with multicolor emission. In this work, a polyurethane derivative (PUH) with red-shifted emission was synthesized by a simple one-pot polymerization reaction. By exploiting the aggregation-induced luminochromism of PUH, a series of plastic films with tunable emission from blue to orange, and white-light emission, was obtained by doping different amounts of PUH into poly(methyl methacrylate) (PMMA), thereby changing the aggregation degree of PUH. This work demonstrates the excellent promise of polyurethane derivatives for the simple fabrication of large-scale flexible luminescent films.