Aggregation-induced emission of 1-methyl-1,2,3,4,5-pentaphenylsilole

Activatable second-near-infrared-window multimodal luminogens with aggregation-induced-emission and aggregation-caused-quenching properties for step-imaging guided tumor therapy

Traditional organic luminogens, such as aggregation-caused quenching or aggregation-induced emission luminogens, only suitable to exhibit bright luminescence in the single state (i.e., solution or aggregated state), restricting their applications in heterogeneous environments. Herein, we propose a class of luminogens, aggregation-caused quenching / aggregation-induced emission dual property multimodal luminogens, which can simultaneously balance radiative and non-radiative decay processes in both the solution and aggregation states, bridging the gap between aggregation-caused quenching and aggregation-induced emission luminogens. By manipulating the rigidity planes and twisted groups of the molecules, we successfully develop a series of dual-property multimodal dyes DPM-HD1-3 with excellent second near-infrared window (NIR-II) fluorescent, photoacoustic, and photothermal properties signals. Based on the dual-property multimodal characteristics of DPM-HD3, we construct a CO-activated multimodal luminogen, DPM-HD3-CO, for the step-imaging guided therapy in the tumor-bearing mice. DPM-HD3-CO can overcome the interference of tumor heterogeneity, and reveal the relationship between CO levels and treatment response in the different treatment steps via multimodal imaging. We expect that the introduction of the concept of dual-property multimodal luminogens would open up a innovative avenue for dye chemistry, offering greater possibilities for future widespread applications in the areas such as chemistry, biomedical imaging, and energy.

Interfacing Flexible Design and Social Self-Sorting Enables Comprehensive Control over Photophysical and Self-Assembly Properties of Supramolecular Polymers

Supramolecular self-assembly offers an intriguing approach to construct microarchitectures, which combine properties of their molecular constituents with dynamic supramolecular features. Control over intermolecular interactions and their resulting properties can sometimes be achieved by targeted design. However, it is often unfeasible to transfer the insights gained from a specific supramolecular synthon to another chromophore without tedious synthetic work guided by trial and error. Herein we demonstrate how a flexible molecular design approach enables access to a diverse library of photophysical properties, which can be further diversified by social self-sorting strategies using a second supramolecular building block as a modulator. By intercalation into the supramolecular polymer the modulator can disrupt interchromophore interactions and modulate the ensembles emissive properties across the visible color space by simply adjusting the ratio between the two building blocks. Furthermore, by combining a chromophore appended synthon with a different morphology than the modulator the mesoscopic size distribution of the coassemblies can be modified to resemble either of its constituents. Crucially, this moldability is not only achievable for systems under thermodynamic control, but can be also employed to tune photophysical properties and thermal stability profiles of kinetically controlled states. Finally, the thermodynamic stability of the modulated polymers can be adjusted by varying the amount of solubilizing alkyl chains in the ensemble. This peripheral stabilization approach does not affect the engineered photophysical or supramolecular properties. Our results demonstrate how flexible molecular design enriched by a supramolecular modulator can offer access to a wide variety of photophysical properties and enable unique fine-tuning of various supramolecular properties.

Multifunctional red-emissive AIEgens as DNA-intercalating ligands: dual sensing of pH and viscosity accompanied by tissue imaging

The best antimicrobials and cancer therapies intercalate DNA-binding compounds to target DNA-processing proteins. We developed a DNA intercalator ligand that addresses the aggregation to speed up the development of novel intercalating medications. This DNA-intercalating ligand allows cellular imaging with little background interference due to its aggregation-induced emission (AIE) and colorimetric pH-responsiveness. These properties make it a versatile biosensor. The ligand exhibits robust intercalative binding with DNA at a 52.6 nM concentration and a high affinity of 55.46 × 106 M-1, ensuring sensitivity to low DNA concentrations. By changing its emission intensity and spectrum features with viscosity, the ligand may sense its microenvironment's physical parameters. It also changes color when pH changes, making pH monitoring easy and noticeable. We studied its DNA interaction using absorbance, fluorescence, and circular dichroism spectroscopy. To determine the mechanism, we performed dye-displacement tests, melting temperature investigations, and iodide quenching. Red fluorescence, high-affinity DNA intercalation, aggregation-induced emission (AIE), viscosity sensitivity, and pH-dependent colorimetric response make this ligand a promising candidate for DNA-targeted imaging and pH-sensitive biosensing in biological and environmental applications. Plant cell tissue imaging has also proved successful.

Heptene end-capped Thiele hydrocarbons with tunable configuration and emission and on-surface transformation via annulation

We report a para-quinodimethane skeleton (p-QDM)-based polycyclic aromatic hydrocarbon (PAH) with heptenes as end-capping groups and F-substituents in the central six-membered ring. This compound shows the syn-configuration in one crystal form with relative strong emission (ΦF = 0.25), and the anti-configuration in another crystal form with weak emission. Furthermore, this compound was transformed into the more annulated PAHs via on-surface C-F bond activations.

Tuning Optical Properties of Organic Thin Films through Intermolecular Interactions - Fundamentals, Advances and Strategies

In applications ranging from photon-energy conversion into electrical or chemical forms (such as photovoltaics or photocatalysis) to numerous sensor technologies based on organic solids, the role of supramolecular structures and chromophore interactions is crucial. This review comprehensively examines the critical intermolecular interactions between organic dyes and their impact on optical properties. We explore the range of changes in absorption or emission properties observed in molecular aggregates compared to single molecules. Each effect is dissected to reveal its physicochemical foundations, relevance to different application domains, and documented examples from the literature that illustrate the potential modulation of absorption or emission properties by molecular and supramolecular structural adjustments. This work aims to serve as a concise guide for exploiting supramolecular phenomena in the innovation of novel optical and optoelectronic organic materials, with emphasis on strategic application and exploitation.

Designing Multifunctional AIEgens by Molecular Engineering of Imidazo[1,2-a]pyridine For Color Tunable Molecular Salts, Anti-Counterfeit Applications and Sensing of Mn2+, Ag+, and Fe3

Mechanochromic materials, known for their ability to change color in response to mechanical stimuli such as pressure, stretching, grinding, or rubbing, hold significant importance due to their diverse applications. In this study, we synthesized and characterized two novel pyridine-tethered imidazo[1,2-a]pyridine mechanoresponsive luminogens with appended tetraphenylethene, named GBY-10 and GBY-11. GBY-10 exhibited reversible mechanofluorochromism, while GBY-11 did not revert to its original color after solvent fuming. The photophysical properties of these luminogens were significantly influenced by the position of the terminal pyridine. Additionally, we created color-tunable mechanoresponsive molecular salts by co-grinding GBY-11 with various aryl acid derivatives. Co-grinding GBY-11 with pentafluorobenzoic acid resulted in a significant bathochromic shift of the emission maxima by 66 nm, compared to 37 nm and 12 nm shift for benzoic acid and para-nitrobenzoic acid, respectively. This counter-ion-dependent luminescence suggests strong electronic interactions between the counter ions. These luminogens also demonstrated reversible pH-responsive behaviour, making them suitable for anti-counterfeiting applications. Furthermore, the pyridine-functionalized luminogen, GBY-10, showed metal ion detection (Mn2+, Ag+, Fe3+) ability in water, with detection limits as low as 0.0043, 0.015, and 0.0029 mM, respectively. This report opens new avenues for designing promising AIE-active materials for potential applications in anti-counterfeiting, sensing, optoelectronics, and biomedicine. A de-novo approach of engineering imidazo[1,2-a]pyridine scaffold to mechanoresponsive AIE-active molecules for anti-counterfeiting and metal sensing applications. By co-grinding the designed luminogens with various aryl acid derivatives, color tuneable mechanoresponsive molecular salts can be further developed.

Leading edge biosensing applications based on AIE technology

Luminescent materials provide a unique method for biological imaging. Luminescent probes can label molecules of interest and present luminescent signals. Bioluminescence bioimaging has shown great efficacy in environmental, live cell and animal studies. Light-emitting materials play a very wide role in the field of light-emitting devices and biosensing. Luminescent materials are usually used as solid films or aggregate states. However, it is difficult to monitor the selectivity and sensitivity of various ions and small molecules in living cells with ordinary luminescent materials due to the changes in various aspects of analytes. Organic luminescent materials exhibit aggregation-induced quenching (ACQ) on molecular aggregation, and the ACQ effect is very common, which greatly limits the application of luminescent materials in chemical sensing, especially in biological imaging. Academician Tang Benzhong proposed "aggregation-induced emission (AIE)" as a powerful method to solve the ACQ problem for the first time. In this paper, the working principle of AIE is reviewed, and the research on the core working mechanism of AIE technology is not only of great fundamental significance, but also can pave the way for practical innovation of AIE technology applications. In this review, we outline the current basic understanding of the working mechanism of AIE, collate the cutting-edge biosensing applications based on AIE technology, including applications based on AIE in substance detection, biological detection, and disease detection. At last, we discuss the future development of AIE research.

Experimental and Computational Optoelectrochemical Investigation of Quinoxaline Based Charge Transfer Derivatives: Green-Orange Emissive, AIEE Active Materials

2,3-Diphenylquinoxalin-6-yl based dyes were synthesized and characterized using 1H, 13C, HRMS and NOSEY spectroscopic technique. The comprehensive photophysical, aggregation-induced emission enhancement (AIEE) activity, electrochemical and theoretical studies of dyes explored. The intramolecular charge transfer transition (ICT) at 380-386 nm in absorption spectra suggest weak push-pull feature of dyes. Dyes show emission in green to orange region (λmax: 561-588 nm) in solvent as well as solid state. The Stokes shift of dyes is 7979-9167 cm-1. The minimal positive solvatochromism (slight variation in λemi) own by dyes, suggest environment stability of dyes in various solvent polarity. AIEE activity with good emission at solid-state make the dyes suitable candidature for solid state OLED's application. Further Dynamic Light Scattering (DLS) studies of dye 1 validate reverse correlation of emission behavior of nanoaggregate formed at high water fraction of THF-H2O mixture with its particle size. The good thermal stability of dyes reflected by decomposition temperature i.e., 221°C-357°C (292°C-372°C) for 5(10)% weight loss. The LUMO (-3.68 to -3.83 eV) of derivatives are lower than LUMO of reported n-type materials (-3.0 to -3.30 eV). Thus, photophysical with AIEE activity and electrochemical properties obtained for dyes signify suitability of it in organic electronics.

Water-soluble AIE photosensitizer in short-wave infrared region for albumin-enhanced and self-reporting phototheranostics

Organic photosensitizers (PSs) play important roles in phototheranostics, and contribute to the fast development of precision medicine. However, water-soluble and highly emissive organic PSs, especially those emitting in the short-wave infrared region (SWIR), are still challenging. Also, it's difficult to prepare self-reporting PSs for visualizing the treatment via stimulated emission depletion (STED) nanoscopy. Thus, in this work, a water-soluble molecule of DTPAP-TBZ-I with aggregation-induced emission features is designed for the self-reporting photodynamic therapy (PDT) in an ultra-high resolution. In contrast to single molecule, its complex (DTPAP-TBZ-I@BSA) shows much enhanced fluorescence properties and reactive oxygen species (ROS) generation in SWIR window. Their photoluminescence quantum yield is determined to be ∼20.6 % and the enhancement of ROS generation is ∼18-fold. During the PDT, immigration of the complex from cytoplasm to nucleus is also observed via STED nanoscopy with a resolution of 66.11 nm, which allows self-report in the PDT treatment. DTPAP-TBZ-I@BSA is finally utilized for the imaging-guided PDT in vivo with a tumor inhibition rate of 84 %. This is the first work in albumin-enhanced water-soluble organic PSs in SWIR window for self-reporting phototheranostics at ultra-high resolutions, providing an ideal solution for the next generation of photosensitizers for precise medicine.

Aggregation-Mediated Photoacoustic/NIR-II and Photodynamic Properties of pH-Reversible Thiopyrylium Agents: A Computational and Experimental Approach

Aggregation profoundly influences the photophysical properties of molecules. Here, a new series of thiopyrylium-based hemicyanine near-infrared II (NIR-II) fluorophores is developed by meticulously adjusting their aggregation states. Notably, the star molecule HTPA exhibits a remarkable pH-responsive behavior and a significant increase in photoacoustic (PA) intensity when aggregated. Additionally, their behavior and pH reversibility during aggregation formation are systematically investigated, including computational optimization, femtosecond transient absorption spectroscopy, NMR analysis, and single crystal analysis. Finally, an innovative "off " nanoparticle specifically is designed for effective tumor-targeted PA/NIR-II dual-modal imaging and photodynamic therapy by utilizing a pH-responsive polymer. The signal-to-background ratio (SBR) of PA signals significantly increased to 169 in the region of interest (ROI) in the mouse model when irradiated at 1064 nm. These findings not only provide a promising avenue for future studies of NIR-II small molecules but also pave the way for significant advances in the field of integrated cancer diagnosis and therapy.

Innovations in aggregation-induced emission materials for theranostics in the musculoskeletal system

Aggregation-induced emission (AIE) offers a promising solution for achieving lower background and more reliable signals in biomedical imaging. AIE materials also exhibiting photostability and resistance to photobleaching. These characters are crucial for monitoring musculoskeletal functions and offering targeted therapies for related diseases. This review compiles research on AIEgens targeting various molecules, cells, or tissues within the musculoskeletal system under physiological or pathological conditions and classifies them according to different clinical applications. A sort of AIEgens is applied in monitoring osteogenic differentiation and bone component analysis. Additionally, AIEgens targeting intra-articular inflammatory or rheumatic related molecules, such as reactive oxygen species, enable early-stage diagnosis and targeted therapies of arthritis. Researchers have also developed novel materials containing AIEgens for joint tissue repair. This review highlights the advantages of these applications while also exploring future demands and development directions in musculoskeletal system imaging and treatment, aiming to promote further design of AIEgens and their clinical applications in musculoskeletal diseases.

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.

Pressure-Modulated Luminescence Enhancement and Quenching in a Hydrogen-Bonded Organic Framework

Light emission in the solid state is central for illumination, sensing, and imaging applications. Unlike luminescence in dilute solutions, where the excited states are unimolecular in nature, intermolecular interaction plays a significant role in the quantum yield of solid-state luminophores, manifested as competing aggregation-caused quenching (ACQ) and aggregation-induced enhancement (AIE). Both effects are extensively studied in various systems; however, it remains unclear how their competition depends on molecular conformation and intermolecular stacking. Here the direct observation of pressure-modulated AIE-ACQ competition in a crystalline hydrogen-bonded organic framework (HOF) is reported. Using in situ spectroscopies and computational modeling, the intramolecular vibration and intermolecular π-π stacking directly responsible for the non-radiative decay of the excited state are identified. The extent of these two contributions is modulated by hydrostatic pressure and guest molecules in the HOF pores. This work demonstrates a physically neat model system to understand and control solid-state luminescence, and a potential material platform for piezoluminescent sensing.

Multiscale and stimuli-responsive biosensing in biomedical applications: Emerging biomaterials based on aggregation-induced emission luminogens

Biosensors play a critical role in the diagnosis, treatment, and prognosis of diseases, with diverse applications ranging from molecular diagnostics to in vivo imaging. Conventional fluorescence-based biosensors, however, often suffer from aggregation-caused emission quenching (ACQ), limiting their effectiveness in high concentrations and complex environments. In contrast, the phenomenon of aggregation-induced emission (AIE) has emerged as a promising alternative, where luminescent materials exhibit strong emission in the aggregated state with good photostability, biocompatibility, large Stokes shift, high quantum yield, and tunable emission. This review article discusses the development of AIEgen-based biosensors for multiscale biosensing in biomedical applications. The integration of AIEgens with nanomaterials, such as graphene oxide and stimuli-responsive nanomaterials, can further improve the selectivity and multifunctionality of biomolecule detection. By careful molecular design, the affinity between AIEgens and specific biomolecules can be tuned, enabling the selective detection of targets like DNA, RNA, and proteins ex vivo, in vitro and in vivo, which can be applied across multiple scales, from detecting biomolecules and cellular structures to analyzing tissues and organs, underscoring their growing importance in disease diagnosis. Furthermore, we explore the potential integration of AIEgen-based biosensors with artificial intelligence (AI) technologies, offering promising avenues for future advancements in this field.

Aggregation-Induced Emissive Scintillators: A New Frontier for Radiation Detection and Imaging

Aggregation-induced emission (AIE) is a unique phenomenon where certain organic materials exhibit enhanced luminescence in their aggregated states, overcoming the typical quenching observed in conventional organic materials. Since its discovery in 2001, AIE has driven significant advances in fields like OLEDs and biological imaging, earning recognition in fundamental research. However, its application in high-energy radiation detection remains underexplored. Organic scintillators, though widely used, face challenges such as low light yield and poor radiation attenuation. AIE materials offer promising solutions by improving light yield, response speed, and radiation attenuation. This review summarizes the design strategies behind AIE scintillators and their very recent applications in X-ray, γ-ray, and fast neutron detection. We highlight their advantages in enhancing detection sensitivity, reducing background noise, and achieving high-resolution imaging. By addressing the current challenges, we believe AIE materials will play a pivotal role in advancing future radiation detection and imaging technologies.

Unveiling the Role of Alkyl Chain in Boosting Antibacterial Selectivity and Cell Biocompatibility

Cationic amphiphiles have been demonstrated to be superior targeted antibacterial agents whose antibacterial activity exhibits a close relationship with their alkyl chain substituents. However, a systematic and deep investigation of the structure-property relationship is still pending. Meanwhile, cationic amphiphiles have a risk of accumulating in living mammalian cells, which poses a great threat to biosafety and clinical applications. In this study, a series of cationic amphiphilic aggregation-induced emission luminogens (AIEgens) with different alkyl chains (TPD-4, TPD-6, and TPD-12) have been developed with selective and variable antibacterial activity against Gram-positive bacteria depending on the alkyl chain length. Among them, TPD-6 with the intermediate alkyl chain length exhibited superior Gram-positive antibacterial performance. In addition, these cationic amphiphilic AIEgens had negligible invasiveness to mammalian cells. Molecular dynamics simulations revealed that the binding and deforming capabilities of the cationic amphiphilic AIEgens to the phospholipid bilayer of bacteria are responsible for their antibacterial activity. In vivo experiments indicated that TPD-6 also exhibited significant antibacterial and wound-healing abilities against Gram-positive bacteria.

Novel Lead Halide Perovskite and Copper Iodide Materials for Fluorescence Sensing of Oxygen

The most commonly used optical oxygen sensing materials are phosphorescent molecules and functionalized nanocrystals. Many exploration studies on oxygen sensing have been carried out using the fluorescence or phosphorescence of semiconductor nanomaterials. Lead halide perovskite nanocrystals, a new type of ionic semiconductor, have excellent optical properties, making them suitable for use in optoelectronic devices. They also show promising applications in analytical sensing and biological imaging, especially manganese-doped perovskite nanocrystals for optical oxygen sensing. As a class of materials with diverse sources, copper iodide cluster semiconductors have rich structural and excellent luminescent properties, and have attracted attention in recent years. These materials have adjustable optical properties and sensitive stimulus response properties, showing great potential for optical sensing applications. This review paper provides a brief introduction to traditional oxygen sensing using organic molecules and introduces research on oxygen sensing using novel luminescent semiconductor materials, perovskite metal halides and copper iodide hybrid materials in recent years. It focuses on the mechanism and application of these materials for oxygen sensing and evaluates the future development direction of these materials for oxygen sensing.

Organic Luminescent Cocrystals Based on Benzotriazole Derivatives: Synthesis, Characterization, Crystal Structure and Fluorescence Behavior

Organic cocrystals have garnered significant research attention owing to their distinctive properties and promising applications. However, challenges in molecular structure design and control of intermolecular interactions continue to impede further advancements. In this study, two novel cocrystals were successfully formed from a series of synthesized benzotriazole derivatives. The resulting cocrystals exhibit bright green and yellow fluorescence under 365 nm light. To elucidate the microstructure of the obtained cocrystals, systematic characterization techniques such as solid-state fluorescence emission spectroscopy, Single-crystal X-ray diffraction (SCXRD), Power X-ray diffraction (PXRD) and density functional theory (DFT) were performed. These benzotriazole-based cocrystals demonstrate distinct fluorescent responses to alkaline and acidic environments, respectively. Additionally, preliminary tests for fingerprint recognition yielded satisfactory results. These findings suggest that the two cocrystals hold potential applications in acid-alkali sensing, anti-counterfeiting labels, and smart material development, while also providing valuable insights for the design and optimization of solid-state luminescent materials.

Design strategies and biomedical applications of organic NIR-IIb fluorophores

The introduction of fluorescence imaging (FLI) in near-infrared II sub-channels (NIR-IIb, 1500-1700 nm) has revolutionized the ability to explore complex patho-physiological settings in vivo. Despite the transformative potentials, the development of organic NIR IIb dyes encounters considerable difficulties, and only a limited number of such fluorophores have been developed so far. This review systematically introduces design strategies of organic NIR-IIb fluorophores classified by molecular scaffolds, mainly including cyanine dyes and D-A-D small molecule dyes. The design strategies of cyanine dyes involve repurposing of the existing NIR dyes, conjugate reinforcement and regulation of the aggregation state. For D-A-D small molecule dyes, strategies mainly incorporate the extension of the conjugate skeleton, introduction of shielding units, and acceptor/donor engineering. We further describe recent biomedical applications including biomedical imaging and imaging-guided therapy, and conclude by clarifying the current challenges and prospects of NIR-IIb FLI.

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.

Stimuli-responsive benzothiazole-phenothiazine derivatives: mechanochromism, AIE, acid sensing, and anticancer efficacy in benzo[a]pyrene-induced cancer models

Mechanofluorochromic (MFC) materials are emerging as a versatile candidate for optoelectronic and biomedical applications. In the present work, we designed and synthesized four MFC materials, namely BT-PTZ-1, BT-PTZ-2, BT-PTZO-1, and BT-PTZO-2, using Suzuki cross-coupling reaction. These materials possess benzothiazole (BT) as an acceptor moiety and different donors, including phenothiazine (PTZ) and triphenylamine (TPA), with variations in their spacer units. The photophysical properties of these derivatives have been explored, revealing solvatochromism, aggregation-induced emission (AIE), acid sensing, and mechanochromic behaviour. Single crystal X-ray analysis of BT-PTZO-2 provides crucial structural insights, revealing the twisted conformation of the TPA donor and the bent structure of the PTZ oxide spacer. The biological studies of these BT derivatives reveal the therapeutic potential against benzo[a]pyrene (B[a]P)-induced carcinogenesis in A549 (lung) and HEK293 (kidney) cells. Treatment with BT-PTZ-2 reflects anti-cancerous properties, with significant up-regulation of p53 and down-regulation of β-catenin and pNF-κB. Additionally, downregulation of mitochondrial fission protein (DRP1) and oxidative stress through DCFDA staining in lung cells are observed with BT-PTZ-2 treatment. These findings strongly suggest that BT-PTZ-2 can inhibit lung cancer cell proliferation and survival, suggesting it to be a promising anti-cancer agent. This comprehensive study of these MFC materials provides insights into their design, synthesis, and properties, in addition to their potential applications in various optoelectronic and biomedical fields.

Recent advances in optical heavy water sensors

D2O and H2O, as two important solvents with very similar properties, play a pivotal role in nuclear industrial production, life and scientific research. Unfortunately, D2O and H2O are highly susceptible to contamination by each other, so effective qualitative and quantitative analyses of both are necessary. This review comprehensively discusses the progress in optical sensing for the detection of a trace amount of H2O in heavy water or vice versa, mainly including five types of analytical systems: inorganic nanocrystals, carbon-based nanomaterials, lanthanide complexes, organic polymers, and organic small molecules. The whole article is divided into several sub-sections based on multiple mechanisms underlying the design of heavy water optical sensors, i.e., the difference in binding energy, the difference in quenching efficacy of oscillator types and the difference in acid-base of H2O and D2O. The working mechanism, advantages and disadvantages, analytical performance and applications of the reported sensors in recent years were analyzed in detail, and the future development is envisioned for the optical sensors towards distinguishing D2O and H2O.

Through-space conjugation driven luminescence enhancement in crystalline butterfly architectures

Through-space conjugation in organic chromophores offers significant potential for developing highly efficient luminescent materials. Herein, we investigate the luminescencent properties of crystalline tetra-naphthalene connected dihydropentacene isomers, 1-NP and 2-NP, using both experimental and theoretical approaches, establishing the presence of through-space conjugation mediated luminescence enhancement.

A comprehensive review of atomically precise metal nanoclusters with emergent photophysical properties towards diverse applications

Atomically precise metal nanoclusters (MNCs) composed of a few to hundreds of metal atoms represent an emerging class of nanomaterials with a precise composition. With the size approaching the Fermi wavelength of electrons, their energy levels are well-separated, leading to molecule-like properties, like discrete single electronic transitions, tunable photoluminescence (PL), inherent structural anisotropy, and distinct redox behavior. Extensive synthetic efforts and electronic structure revelation have expanded applicability of MNCs in catalysis, optoelectronics, and biology. This review highlights the intriguing photophysical and electrochemical behaviors of MNCs and their regulatory parameters and applications. Initially, we present a brief discussion on the evolution of MNCs from gas-phase naked metal clusters to monolayer ligand-protected MNCs along with representative studies on their electronic structure. Due to their quantized molecular orbitals, they often exhibit PL, which can be regulated based on their capping ligands, number of atoms, crystal packing, presence of heterometal, and surrounding environment. Apart from PL, the relaxation pathways of MNCs on an ultrafast time scale have been extensively studied, which significantly differ from that of plasmonic metal nanoparticles. Moreover, their interaction with high-intensity light results in unique non-linear optical properties. The synergy between MNCs in a hierarchical self-assembled structure has been exploited to enhance their PL by precisely tuning their non-covalent interactions. Moreover, several NC-based hybrids have been designed to exhibit efficient electron or energy transfer in the photoexcited state. In the next section, we briefly focus on the redox behavior of NCs and facile electron transfer to suitable substrates, which result in enzyme-like catalytic activity. Utilizing these photophysical and electrochemical behaviors, NCs are widely employed in catalysis, optical sensing, and light-harvesting applications, which are also discussed in this review. In the final section, conclusions and open questions for the NC research community are included. This review will provide a comprehensive view of the emerging physicochemical properties of MNCs, thereby enabling an understanding for their precise modulation in future.

Comprehensive review of protein imaging with AIEgens conjugated probes: From concentration to conformation

Proteins are an essential component of living organisms, and the study of their structure and function is of great importance in biological and medical research. In recent years, the remarkable phenomenon of aggregation-induced emission (AIE) has been extensively utilized in protein detection. Significant progress has been made in the development of aggregation-induced emission luminogens (AIEgens), which have proven invaluable in protein imaging. This review highlights AIEgen-conjugated probes for imaging proteins in tumor cells through various mechanisms, including physical interactions, ligand binding, and enzymatic cleavage. These probes exploit the AIE effect to enhance the signal-to-noise ratio, providing important tools for protein research. Additionally, these probes can be used to study structural changes in intracellular protein phase separation processes, such as unfolded, misfolded, fibrous, and amorphous aggregates. The above research achievements presented lay the foundation for the widespread application of AIEgen-conjugated probes in the biomedical field and are expected to stimulate further development in related research.

Red fluorescent AIE bioprobes with a large Stokes shift for droplet-specific imaging and fatty liver diagnosis

Lipid droplets (LDs) as spherical dynamic subcellular organelles, play an important role in various cellular functions such as protein degradation, lipid metabolism, energy storage, signal transduction, and membrane formation. Abnormal function of LDs will lead to a series of diseases and hence monitoring the status of LDs is particularly important. In this study, we synthesized a water-insoluble red fluorescent emitting small molecule fluorescent probe (TPE-TCF), which exhibited aggregation-induced emission (AIE) properties and enabled highly selective real-time imaging of LDs (Pearson's R value was 0.90). More interestingly, this probe was able to track the dynamic processes of LDs in living cells, including lipophagy, and monitor fatty liver disease in mice. Therefore, TPE-TCF with red fluorescence emission, good biocompatibility, large Stokes shift, AIE properties, LDs imaging, and fatty liver recognition capabilities can be practically used in more LDs-related diseases.

Aggregation-induced emission (AIE) of Au(I)-GSH complexes activated by cationic polymer for sensitive foodborne pathogens detection and inactivation

Aggregation-induced emission (AIE) is a novel signal output method but is limited in pathogen sensing. Herein, a multifunctional biosensor based on the AIE properties of Au(I)-GSH complexes as signal conversion tags was firstly constructed for rapid and sensitive total bacteria. Bacteria were captured by the boronic acid group of MNPs@Au@4-MPBA (MAu@MPBA) through recognition of peptidoglycan on their surface. Simultaneously, cationic polymer Poly (diallyldimethylammonium chloride) (PDDA) were electrostatic absorb on bacteria. After magnetic separation, the remaining PDDA induced Au(I)-GSH complexes aggregation to produce strong red fluorescence, which was linearly with the quantity of bacteria. Under optimized conditions, quantitative detection of bacteria can be achieved within 60 min, with a minimum detection concentration of 18 CFU/mL. Moreover, 90 % bacteria can be effectively inactivated while being detected. This strategy is capable of sensitively detecting and killing foodborne pathogens and can be successfully applied to food safety monitoring.

Advances in aggregation-induced emission luminogens for biomedicine: From luminescence mechanisms to diagnostic applications

Advancements in early detection have demonstrated the significance of biomarkers as indicators of health and disease. Traditional detection methods often face limitations, such as low sensitivity and time consumption. Fluorescence-based techniques are considered promising approaches because of their noninvasiveness and rapid response. However, these conventional methods have some drawbacks, such as low quantum yield, photobleaching, and aggregation-caused quenching. Recently, aggregation-induced emission (AIE) has emerged as a potential alternative, characterized by luminous emission upon aggregation, thus improving detection sensitivity and stability. This review explores the recent advancements in AIE luminogens (AIEgens) in biomedical engineering, with a particular focus on their application in biomarker detection. Here, we discuss the different types of AIE mechanisms and their advantages in disease diagnosis and imaging. In addition, we summarize the development of various AIEgen-based probes for the detection of diverse biomarkers. Finally, we address the remaining challenges and future directions for AIE materials in modern biomedical engineering, emphasizing the potential of AIEgens in biomarker detection and disease diagnosis strategies.

Rapid and simple fluorescent detection of chlorogenic acid in Aidi injection using aggregation-induced emission (AIE) nanoclusters

Chlorogenic acid (CGA) is a key component in Aidi injection, known for its anti-cancer properties and ability to reduce toxicity. Therefore, accurate detection of CGA levels in Aidi injection is essential for monitoring therapeutic efficacy and minimizing adverse effects. This study presents a rapid and simple fluorescent method for detecting CGA in Aidi injection using aggregation-induced emission (AIE) nanoclusters, i.e. D(-)-penicillamine (DPA)-capped bimetallic gold/copper nanoclusters (DPA-Au/CuNCs). Upon the addition of CGA, the aggregation state of DPA-Au/CuNCs was disrupted through hydrogen bond formation and ligand exchange, leading to fluorescence quenching. The prepared DPA-Au/CuNCs exhibited a rapid response time of 0.5 min, and demonstrated good sensitivity for CGA, with a limit of detection of 3.75 μg/mL, and a linear detection range of 12.5-200 μg/mL. This method was successfully applied for the analysis of CGA in Aidi injection and plasma with good recovery rates and minimal matrix effect, highlighting its potential for the applications in pharmaceutical products and clinical samples.

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.

A novel multifunctional fluorescent probe with ESIPT and AIE effects for the detection of Co2+ and HClO

We developed a novel fluorescent probe featuring excited-state intramolecular proton transfer (ESIPT) and aggregation-induced emission (AIE) effects, which displayed dual-channel fluorescence emission. The probe detected both Co2+ and HClO with naked eye under daylight as well as through a fluorescence spectrophotometer. The probe exhibited a low detection limit for Co2+ at 2.823 μM, while the detection limit for HClO was 11.55 μM. When the probe (10 μM) was mixed with Co2+, the fluorescence intensity at 556 nm rapidly decreased within 10 minutes and stabilized after 40 minutes, while for HClO, it took 960 min to observe the same decrease in intensity within 960 min. The probe (10 μM) achieved naked-eye detection of Co2+ recognition under daylight; however, achieving naked-eye detection of HClO under daylight necessitated higher concentrations (500 μM). Thus, this probe shows promising potential for environmental monitoring and water quality detection.

Thermally stable strongly fluorescent multi-stimuli responsive carbazole zwitterionic fluorophores: Alkyl chain length dependent thermofluorochromism and latent fingerprinting

Carbazole-picoline based π-conjugated zwitterionic fluorophores, (E)-3-(4-(4-(9H-carbazol-9-yl)styryl)pyridin-1-ium-1-yl)propane-1-sulfonate (Cz-PS) and (E)-4-(4-(4-(9H-carbazol-9-yl)styryl)pyridin-1-ium-1-yl)butane-1-sulfonate (Cz-BS) were synthesized and investigated the stimuli-responsive solid-state fluorescence properties. Cz-PS and Cz-BS displayed enhanced fluorescence in the solid-state (555 and 542 nm) with the quantum yield (Φf) of 32.9 and 28.5 %, respectively. Thermogravimetric analysis (TGA) indicated good thermal stability up to 300 °C for both Cz-PS and Cz-BS. Single crystal structural analysis of Cz-BS confirmed twisted molecular conformation and supramolecular interactions induced network structure, which lead to increase of solid-state fluorescence. Cz-BS showed mechanical stimuli-induced reversible/self-reversible fluorescence switching between two fluorescence states whereas Cz-PS did not show mechanofluorochromism. But both Cz-PS and Cz-BS showed acid/base dependent on-off reversible fluorescence switching in solution as well as solid-state. Further, both compounds also displayed reversible thermofluorochromism by heating and cooling. The yellow fluorescence of Cz-PS and Cz-BS was transformed to orange upon heating at 110 °C and cooling reversed the fluorescence to initial state. The good thermal stability and enhanced solid-state fluorescence of Cz-PS and Cz-BS were utilized for latent fingerprinting (LFP) application on various solid substrate. Particularly, LFP images of Cz-BS showed finger marks with well-defined features. Thus, integrating zwitterionic functionality produced strong solid-state fluorescence with multi-functional applications.

Stepwise Lighting Up Gold(I)-Thiolate Complexes from AIE Nanoaggregates to AIEE Nanoprobes with a ZIF-8 Shell for Glucose Biosensing

Aggregation-induced emission (AIE) or aggregation-induced emission enhancement (AIEE) has endowed gold species with responsive fluorescent properties, favoring their potential applications in sensing, imaging, and therapy. However, it remains an interesting challenge to fabricate fluorophores with both AIE and AIEE effects. Herein, we presented highly luminescent Au(I) thiolate nanocomplex-based biosensors with Zn2+ induced-AIE and zeolite imidazolate framework (ZIF-8) induced-AIEE effects. The nonemissive monovalent gold-glutathione complexes (AuI-SGs) were obtained to synthesize the core-shell Zn2+/AuI-SG@ZIF-8 composites with strong luminescence via the coordination-assisted self-assembly strategy. By immobilizing GOx on the surface of Zn2+/AuI-SG@ZIF-8, Zn2+/AuI-SG@ZIF-8/GOx biosensors exhibited effective responsiveness to glucose, showing a "turn-off" detection model. The mechanism study revealed that the robust luminescence of Zn2+/AuI-SG@ZIF-8 to glucose sensing was attributed to the acid-stimulated degradation of the probe facilitated by H+ generated from the glucose oxidase (GOx)-catalyzed oxidation process. To achieve noninvasive and intelligent blood glucose detection, the Zn2+/AuI-SG@ZIF-8/GOx-loaded microneedle (MN)-patch fluorescent platform was further developed. The MN-patch-based sensing platform had promising performance for on-needle capture and in situ glucose detection. This study demonstrated a universal and feasible protocol to construct luminescent biosensors for glucose detection and their potential for the development of MN-based analytical devices.

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.

Recent advances and design strategies for organic afterglow agents to enhance autofluorescence-free imaging performance

Long-lasting afterglow luminescence imaging that detects photons slowly being released from chemical defects has emerged, eliminating the need for real-time photoexcitation and enabling autofluorescence-free in vivo imaging with high signal-to-background ratios (SBRs). Organic afterglow nano-systems are notable for their tunability and design versatility. However, challenges such as unsatisfactory afterglow intensity, short emission wavelengths, limited activatable strategies, and shallow tissue penetration depth hinder their widespread biomedical applications and clinical translation. Such contradiction between promising prospects and insufficient properties has spurred researchers' efforts to improve afterglow performance. In this review, we briefly outline the general composition and mechanisms of organic afterglow luminescence, with a focus on design strategies and an in-depth understanding of the structure-property relationship to advance afterglow luminescence imaging. Furthermore, pending issues and future perspectives are discussed.

Strength in Numbers: A Giant NIR-II AIEgen with One-for-All Phototheranostic Features for Exceptional Orthotopic Bladder Cancer Treatment

One-for-all phototheranostics that allows the simultaneous implementations of multiple optical imaging and therapeutic modalities by utilizing a single component, is growing into a sparkling frontier in cancer treatment. Of particular interest is phototheranostic agent with emission in the second near-infrared (NIR-II) window. Nevertheless, the practical uses of those conventional NIR-II agents are severely impeded by their unsatisfactory features including insufficient stability, low synthetic yield, to be extended absorption/ emission wavelengths, and inefficient phototheranostic outcomes. Developing exceptional phototheranostic agents is thus highly desirable yet remains formidably challenging. Herein, we synthesized two novel N-heteroacenes-based NIR-II luminogens, namely 2TT-PPT and 4TT-PBPT, by respectively employing pyrene-fused phenaziothiadiazoles and pyrene-fused bisphenaziothiadiazoles as acceptor skeletons. There is strength in numbers by increasing the fusing rings in N-heteroacenes moieties and numbers of appended donors. Compared to less ring-fused 2TT-PPT, the giant molecule 4TT-PBPT shows improved photophysical characteristics, such as enhanced light absorbance, red-shifted wavelengths, higher brightness, favorable reactive oxygen species (ROS) generation, and elevated photothermal conversion efficiency, which render 4TT-PBPT nanoparticles excellent fluorescence-photoacoustic-photothermal trimodal imaging guided photodynamic-photothermal synergistic therapy for orthotopic bladder cancer.

Wash-free fluorescent tools based on organic molecules: Design principles and biomedical applications

Fluorescence-assisted tools based on organic molecules have been extensively applied to interrogate complex biological processes in a non-invasive manner with good sensitivity, high resolution, and rich contrast. However, the signal-to-noise ratio is an essential factor to be reckoned with during collecting images for high fidelity. In view of this, the wash-free strategy is proven as a promising and important approach to improve the signal-to-noise ratio, thus a thorough introduction is presented in the current review about wash-free fluorescent tools based on organic molecules. Firstly, generalization and summarization of the principles for designing wash-free molecular fluorescent tools (WFTs) are made. Subsequently, to make the thought of molecule design more legible, a wash-free strategy is highlighted in recent studies from four diverse but tightly binding aspects: (1) special chemical structures, (2) molecular interactions, (3) bio-orthogonal reactions, (4) abiotic reactions. Meanwhile, biomedical applications including bioimaging, biodetection, and therapy, are ready to be accompanied by. Finally, the prospects for WFTs are elaborated and discussed. This review is a timely conclusion about wash-free strategy in the fluorescence-guided biomedical applications, which may bring WFTs to the forefront and accelerate their extensive applications in biology and medicine.

Amidine-functionalized aggregation-induced emission luminogen and a 3D-printed digital sensor platform for ultrafast and visual detection of heparin

BACKGROUND

Heparin is a widely used anticoagulant in clinic. However, improper dosing can increase the risk of thromboembolic events, potentially leading to life-threatening complications. Clinic monitoring of heparin is very important for its use safety. Rapid and accurate point-of-care testing can significantly reduce the risk of thrombotic events. The detection of heparin using fluorescent probes has emerged as a significant area of research, driven by the need for rapid, sensitive, and selective methods for monitoring this crucial anticoagulant in clinical settings. However, the absence of convenient and user-friendly heparin testing methods continues to pose a challenge.

RESULTS

In this work, a tetraphenylethylene derivatives with four amidine active groups (TPE-4+) was prepared. TPE-4+ has obvious aggregation-induced emission (AIE) effect on the heparin with a 127-fold enhancement occurring within just 3 s. The molecular docking simulation showed that TPE-4+ was closely embedded in the heparin by the electrostatic force between four amidine of TPE-4+ and sulfate ester group of heparin, restricted intramolecular motion of TPE-4+, and causing obvious AIE features. The fluorescence intensity of TPE-4+ was line with the concentration of heparin in the range of 0-2.0 U/mL with a lowest detection limit of 0.0038 U/mL. The possible interference in the serum samples had no influence on the determination of heparin. Using 3D printing technology, a compact, portable digital sensor platform for straightforward monitoring of heparin levels was fabricated.

SIGNIFICANCE

The proposed innovative platform provides a powerful tool to make portable and real-time monitoring of heparin possible, and thereby contributing to achieve point-of-care testing and decrease the risk of thrombotic events. This novel method of combining the probe with the sensing platform simplifies the detection process and enhances patient care by providing more accurate diagnostic capabilities.

Wet Photolithography From Hydrogen Abstraction of a Quasi-Orthogonal Aggregation-Induced Emitter

A new aggregation-induced emission (AIE) luminogen is obtained by dimerizing acridin-9(10H)-one (Ac), an aggregation-caused quenching (ACQ) effect monomer via an N─N bond and forming 9H,9'H-[10,10'-biacridine]-9,9'-dione (DiAc) with D2d symmetry. The quenching of DiAc in solution is ascribed to the enhanced basicity promoting hydrogen bonding and then a hydrogen abstraction (HA) reaction and/or an unallowed transition in frontier orbitals with the same symmetry facilitating intersystem crossing. It is found that emissive Ac is one product of the non-emissive DiAc solution in the HA reaction activated by UV irradiation. By exploiting the AIE properties and the HA reaction of DiAc, photolithographic patterning is demonstrated with a paper wetted with DiAc solution.

An Ultra-low Detection Limit Fe3+ Optical Fiber Fluorescent Sensor Based on a Anti-B18H22 Derivative with Aggregation-induced Emission Enhancement

A fluorescent Fe3+ probe ((C10H7NO2)2B18H20, M1) by introducing two isoquinoline-1-carboxylic acid group into the 6,9-position of anti-B18H22 was designed and synthesized. The structure of M1 was investigated by 1H NMR, MS, FT-IR and theoretical calculation, and its optical properties were characterized with UV-Vis and PL. M1 showed aggregation induced emission enhancement (AIEE) properties in THF/H2O solution, and exhibited an excellent selectivity toward Fe3+ in THF/H2O (v/v, ƒw = 95%) solution with a detection limit of 1.93 × 10-5 M. The interaction mechanism of probe for detecting Fe3+ is attributed to the involvement of intramolecular charge transfer (ICT) process. Furthermore, a optical fiber fluorescent Fe3+ sensor based on M1 sensing film was developed, the detection limit of the optical fiber Fe3+ fluorescent sensor could be improved to13.8 pM, the ultra-low detection limit is superior to most reported fluorescent probes (or sensors) towards Fe3+. This method has the advantages of high sensitivity, anti-interference and easy to operate, and has great potential in the field of the analysis of environmental and biological samples.

Peptide Fluorescent Probes Based on Aggregation-Induced Emission for the Detection of Ni2+ and Zn2+ in Different Buffer Systems

Heavy metal contamination has emerged as a significant global environmental concern. The contamination of Ni2+ and Zn2+ has attracted increasing attention, not only because of the pollution it causes but also because of the potential risks it poses to human health. It is of great importance to explore sensitive and rapid analytical methods for the accurate detection of Ni2+ and Zn2+. This paper presents the design and synthesis of a peptide fluorescent probe, TPE-HN (TPE-Pro-Trp-His-Glu-Phe-Gln-NH2), coupled with a peptide to tetraphenylethylene (TPE). The aggregation-induced emission (AIE) effect has been employed to construct a rapid 'turn-on' assay for Ni2+and Zn2+ peptide fluorescent probes. The probe is capable of qualitatively detecting Ni2+ and Zn2+ in different buffer systems and can be distinguished by changes in buffer systems. The limit of detection for Ni2+ and Zn2+ in a 15% buffer solution was 9.613 mM (R2 = 0.9924), whereas the limit of detection for Ni2+ in a 20% buffer solution was 1.215 mM (R2 = 0.9922). The probe exhibits high sensitivity, high cell permeability and low biotoxicity, rendering it suitable for live-cell imaging under biological conditions. This demonstrates that TPE-HN is capable of detecting Ni2+ and Zn2+ in biological environments.

Theoretical guiding with molecular docking for the screening of high-sensitive AIE probes for specific protein detection

The detection of proteins is crucial in the fields of disease diagnosis and drug development. Detection of proteins by aggregation-induced emission (AIE) probes is a quick and convenient method. However, the current AIE probes for the specific protein detection mainly depended on experimental test, lacking a guiding strategy. This study presented a novel approach to design AIE probes for detecting protein using molecular docking depending on AIE luminescence mechanism of the restriction of intramolecular motions. As an example to show its feasibility, three AIE probes with pyrrolo[3,2-b]pyrrole motif were designed and synthesized. The binding of the three probes to nine common proteins were predicted in advance using the molecular docking technique, obtaining information including intermolecular forces, binding energy, and binding sites between probes with proteins. The prediction results were verified through experimental data, and the mutual comparation of experimental and molecular docking results confirmed the reliability of the information provided by the molecular docking technique. Furthermore, the probes TPPP-2Na and TPPP-4Na exhibited limit of detection as low as 0.33 μg/mL for BSA and 0.35 μg/mL for HSA, respectively. The study revealed an innovative approach for the screening and molecular design of AIE probes for the detection of proteins.

The Effect of the Position of a Phenyl Group on the Luminescent and TNP-Sensing Properties of Cationic Iridium(III) Complexes

Three cationic Ir(III) complexes, 1, 2, and 3, were successfully synthesized and characterized by tuning the position of a phenyl group at the pyridyl moiety in 2-phenylpyridine. All three complexes exhibited typical aggregation-induced phosphorescence emission (AIPE) properties in CH3CN/H2O. The AIPE property was further utilized to achieve the highly sensitive detection of 2,4,6-trinitrophenol (TNP) in aqueous media with low limit of detection (LOD) values of 164, 176, and 331 nM, respectively. This suggests that the different positions of the phenyl group influence the effectiveness of 1, 2, and 3 in the detection of TNP. In addition, 1, 2, and 3 showed superior selectivity and anti-interference properties for the detection of TNP and were observed to have the potential to be used to detect TNP in practical applications. The changes in the luminescence lifetime and UV-Vis absorption spectra of 1, 2, and 3 before and after the addition of TNP indicate that the corresponding quenching process is a combination of static and dynamic quenching. Additionally, the proton nuclear magnetic resonance spectra and results of spectral studies show that the detection mechanism is photo-induced electron transfer (PET).

Dual-Emissive Iridium(III) Complex with Aggregation-Induced Emission: Mechanistic Insights into Electron Transfer for Enhanced Hypoxia Detection in 3D Tumor Models

Accurate oxygen detection and measurement of its concentration is vital in biological and industrial applications, necessitating highly sensitive and reliable sensors. Optical sensors, valued for their real-time monitoring, nondestructive analysis, and exceptional sensitivity, are particularly suited for precise oxygen measurements. Here, we report a dual-emissive iridium(III) complex, IrNPh2, featuring "aggregation-induced emission" (AIE) properties and used for sensitive oxygen sensing. IrNPh2 exhibits dual emissions at 450 and 515 nm, with 515 nm triplet-state emission demonstrating remarkable oxygen sensitivity due to its long-lived excited state (12.12 μs) and high quantum yield (68%). Stern-Volmer analysis reveals a notable quenching constant (Ksv = 12.44%-1) and an ultralow detection limit of 0.0397%, emphasizing its superior performance. The oxygen quenching mechanism is driven by electron transfer (ET), supported by computational studies showing the lowest-unoccupied molecular orbital (LUMO) alignment of IrNPh2 with the πg* orbitals of triplet oxygen, leading to superoxide radical (O2•-) formation. Electron paramagnetic resonance (EPR) studies further confirm this pathway. Biological evaluations using a three-dimensional (3D) U87-MG glioma spheroid model highlight the ability of IrNPh2 to detect hypoxic regions, with significant fluorescence enhancement under hypoxia and minimal cytotoxicity (>80% viability at 100 μM). With high sensitivity, low detection limits, and biocompatibility, IrNPh2 emerges as a promising candidate for oxygen sensing in environmental and biomedical applications, especially tumor hypoxia detection.

Colorimetric Xylenol Orange: A Long-Buried Aggregation-Induced Emission Dye and Restricted Rotation for Dual-Mode Sensing of pH and Metal Ions

As the third largest class of dyes in the world, triphenylmethane dyes are widely applied in colorimetric sensing. However, triphenylmethane dyes are commonly nonfluorescent, which limits their sensing applications. It is worthwhile to study the fluorescence off/on control of triphenylmethane dyes and promote the applications of triphenylmethane dyes in sensing technology. In this work, the fluorescence off/on control was investigated by employing a triphenylmethane dye xylenol orange (XO), which is a colorimetric indicator for pH and metal ions. It was discovered that XO exhibited aggregation-induced emission (AIE), and thus, its fluorescence off/on was controlled by intramolecular rotation. This discovery broadens the optical properties of XO and transforms XO from a colorimetric dye to a colorimetric/fluorescent dual-mode AIE dye. It was further verified that the AIE-based fluorescence off/on control improved the sensing performance of XO. A bovine serum albumin-based rotation suppression method was applied to enhance the fluorescence emission of XO for colorimetric/fluorescent dual-mode indication of pH and metal ions. Compared with colorimetric sensing, colorimetric/fluorescent dual-mode sensing exhibits higher accuracy, ascribed to the self-validation effect. This work uncovers AIE-based fluorescence off/on control of triphenylmethane dyes and breathes new life into the sensing applications of triphenylmethane dyes.

Bioconjugation of Podophyllotoxin and Nanosystems: Approaches for Boosting Its Biopharmaceutical and Antitumoral Profile

Podophyllotoxin is a natural compound belonging to the lignan family and is well-known for its great antitumor activity. However, it shows several limitations, such as severe side effects and some pharmacokinetics problems, including low water solubility, which hinders its application as an anticancer agent. Over the past few years, antitumor research has been focused on developing nanotechnology-based medicines or nanomedicines which allow researchers to improve the pharmacokinetic properties of anticancer compounds. Following this trend, podophyllotoxin nanoconjugates have been obtained to overcome its biopharmaceutical drawbacks and to enhance its antitumor properties. The objective of this review is to highlight the advances made over the past few years (2017-2023) regarding the inclusion of podophyllotoxin in different nanosystems. Among the huge variety of nanoconjugates of diverse nature, drug delivery systems bearing podophyllotoxin as cytotoxic payload are organic nanoparticles mainly based on polymer carriers, micelles, and liposomes. Along with the description of their pharmacological properties as antitumorals and the advantages compared to the free drug in terms of biocompatibility, solubility, and selectivity, we also provide insight into the synthetic procedures developed to obtain those podophyllotoxin-nanocarriers. Typical procedures in this regard are self-assembly techniques, nanoprecipitations, or ionic gelation methods among others. This comprehensive perspective aims to enlighten the medicinal chemistry community about the tendencies followed in the design of new podophyllotoxin-based drug delivery systems, their features and applications.

Assessment of the Microbiological Potential and Spectroscopic Properties of New Imino-1,3,4-Thiadiazoles Showing the ESIPT Effect Strongly Enhanced by Aggregation

There is currently a growing interest in imino derivatives of compounds such as thiadiazoles and other groups of compounds whose extended π-electron systems enhance their photophysical properties. These compounds also show low toxicity and strong antifungal activity, making them effective against fungal pathogens in crops. For the above reasons, in the first part of the paper, the structure of the selected analogs was considered, and detailed spectroscopic analyses were conducted focusing on the excited state intramolecular proton transfer (ESIPT) process taking place in the same. Measurements were taken in terms of absorption spectroscopy and electron fluorescence, synchronous spectra, and fluorescence lifetimes, as well as calculations of fluorescence quantum efficiency in selected solvents and concentrations. In the spectral observations, the ESIPT process was manifested in several solvents as very distinct dual fluorescence. Moreover, in selected molecules, this phenomenon was strongly related to molecular aggregation, which was associated with not very efficient but nonetheless visible fluorescence of the AIE (Aggregation-Induced Emission) type. In the second part of the paper, a detailed preliminary study is presented exploring the microbiological properties of selected imino-1,3,4-thiadiazole derivatives in the context of their potential applicability as inhibitors affecting the development and growth of some of the most important fungal pathogens attacking cereal crops and posing an increasing threat to modern agriculture. Overall, the research presented in this article provides a detailed, experimental analysis of the spectroscopic properties of selected imino-thiadiazoles and points to their potential use as novel and effective solutions capable of limiting the growth and development of fungal pathogens in cereals.

Nanomaterial-based synergistic strategies for combating dental caries: progress and perspectives

Dental caries, as the predominant global oral disease, remains a critical public health issue worldwide, particularly in socioeconomically disadvantaged communities. However, common caries prevention approaches (e.g., oral health education, mechanical plaque removal, and delivery of fluoride agents) are still insufficient for optimal caries management, and therefore, alternative regimens that can supplement existing strategies are highly warranted. Nanomaterials exhibit considerable potential in combating cariogenic pathogens and biofilms owing to their promising antimicrobial capacity, improved penetration into biofilms, targeted precision delivery, and versatile physicochemical properties. As unifunctional materials are limited in caries management, this review underscores the latest advancement in multifunctional anti-caries nanomaterials/nanomedicines. It highlights the cutting-edge materials developed or engineered to (i) incorporate diagnostic capabilities to prevent caries at an early stage, thus enhancing treatment efficiency, (ii) integrate mechanical "brushing" with anti-caries approaches to mechanochemically eradicate biofilms, (iii) exert antimicrobial/antibiofilm effects while preserving dental hard tissue. The current work also outlines future directions for optimizing nanosystems in the management of dental caries while emphasizing the need for innovative solutions to improve preventive and therapeutic efficacies.

π-Spacer Engineering: Driving Near-infrared Aggregation Induced-emission and Mechanofluorochromism in Carbazole-biscyanostilbenes

In this study, we report the design and synthesis of two novel carbazole-based bis-cyanostilbenes incorporating phenyl and thiophene π-spacer units to investigate their distinct impacts on photophysical properties. Notably, the thiophene-based derivative exhibits remarkable far-red/near-infrared (NIR) solid-state emission, with an emission peak at 732 nm, which shifts to 750 nm upon mechanical grinding, demonstrating pronounced mechanochromic fluorescence in the NIR region. Although its quantum yield is moderate, the ability to modulate its emission through mechanical stimuli opens exciting opportunities for stimuli-responsive NIR applications. Conversely, the phenyl-based analogue shows excellent solid-state emission at 596 nm, achieving significantly higher quantum yields, due to suppressing π-π interactions. Both compounds also exhibit strong AIE, with the thiophene system emitting at 730 nm and the phenyl-based analogue at 580 nm in the aggregate state. In addition to their optical properties, both derivatives demonstrate remarkable thermal stability and reversible MFC. These intriguing behaviors highlight the critical role of π-spacer engineering in fine-tuning solid-state emission, enhancing stimuli-responsive capabilities, and ensuring robust thermal performance. Overall, our findings provide valuable insights into the design of next-generation NIR-emissive materials, with promising potential for advancing applications in optoelectronics, bioimaging, and smart sensing technologies.