Fluorescence Emission Research Articles

A Novel Rhodamine-Based Fluorescent Sensor for Detection of Cu2.

In this work, a new fluorescent sensor for detecting Cu2 + was developed based on the Rhodamine derivative. It displayed strong fluorescence enhancement upon the addition of Cu2+, and other common metal ions do not significantly affect the optical properties of the sensor. This optical signal change caused solely by Cu2 + is due to the opening of the lactone amide spiro ring structure, resulting in fluorescence emission. This specific recognition endows the sensor with the ability to qualitatively and quantitatively detect Cu2+, and the conclusion was also verified through density functional theory calculations. Simultaneously, the cell imaging and zebrafish experiments proved the potential application value in biological systems.

Position Optimization of Bulky Tetraphenylsilane in Multiple Resonance Molecules for Highly Efficient Narrowband OLEDs.

Multiple resonance (MR)-type thermally activated delayed fluorescence (TADF) emitters have garnered significant interest due to their narrow full width at half maximum (FWHM) and high electroluminescence efficiency. However, the planar structures and large singlet-triplet energy gaps (ΔESTs) characteristic of MR-TADF molecules pose challenges to achieving high-performance devices. Herein, two isomeric compounds, p-TPS-BN and m-TPS-BN, are synthesized differing in the connection modes between a bulky tetraphenylsilane (TPS) group and an MR core. This strategy aims to suppress intermolecular interactions, reduce ΔEST values, and investigate how connection positions influence photoelectric properties. Both compounds exhibit remarkably small ΔEST values (0.08-0.09eV) and high internal quantum yields (95.0-97.8%). Notably, p-TPS-BN demonstrates a faster reverse intersystem crossing (RISC) with a rate constant of 2.54×10⁵s⁻¹, attributed to its optimal long-range charge transfer (LRCT) process. A narrowband device employing p-TPS-BN achieves a maximum external quantum efficiency of 35.8% with an FWHM of 36nm. This work offers an effective framework for studying structure-property relationships in MR molecules, paving the way for the development of high-efficiency electroluminescent devices.

Indocyanine green dyed gauze-guided minimum invasive surgery for anatomical landmarks and preventing gauze remnants: a pilot study.

We aimed to develop a novel fluorescent surgical gauze dyed with indocyanine green (ICG) to guide surgeons to the target anatomical destination during surgery for real-time navigation and to prevent gauze remnants after surgery. Surgical gauze was dyed with an aqueous solution of ICG (5.0 × 10- 5 mol L- 1 for Steraze, 1.5 × 10- 4 mol L- 1 for BK-Opeze) at 132°C (inside pressure: 2.82atm, 286kPa) for 15min using an autoclave, followed by washing with distilled water, drying at room temperature, and sterilizing at 132°C for 8min before surgery. Fluorescence (FL) intensity was examined preclinically in the resected specimens using the SPY PHI (Stryker) system. Fourteen patients who underwent laparoscopic- and robotic-assisted gastroenterological surgery at Showa University Hospital were included. Fluorescent emission of ICG-dyed gauze was clearly observed through resected specimens with a thickness of approximately 10mm or more. In a clinical trial, the ICG-dyed gauze was detected earlier with near-infrared (near-IR) FL imaging than under white light during seven cases of laparoscopic and robotic surgery, which could become a precise marker for surgeons to locate the dissection site despite overlaying tissues and nearby disturbances. Additionally, no seepage of ICG from the gauze was observed in all surgical fields. We successfully developed ICG-dyed gauze exhibiting bright near-IR FL which can guide surgeons to the target anatomical destination and prevent gauze remnants during surgery. This invention would be a powerful support for real-time navigation surgery.

Targeted Theranostic Nanoprobes Assisted In Vivo NIR-II Fluorescence Imaging-Guided Surgery Therapy for Alveolar Echinococcosis.

Alveolar echinococcosis (AE) is a serious parasitic infectious disease that is highly invasive and destructive to the liver and has a high mortality rate. However, currently, there is no effective targeted imaging and treatment method for the precise detection and therapy of AE. We proposed a new two-step targeting strategy (TSTS) for AE based on poly(lactic-co-glycolic acid) (PLGA). We designed and constructed a novel type of ICG@PLGA@Lips nanoprobe with integrated imaging and treatment properties. First, we used the characteristics of PLGA gluconeogenic raw material to target the liver during blood circulation. Then, we utilized the characteristics of PLGA specifically penetrating the AE shell to achieve specific identification of AE in the liver. Under 808 nm laser excitation, ICG@PLGA@Lips effectively achieved accurate imaging of AE based on near-infrared II (NIR-II, 900-1700 nm) fluorescence imaging methods and achieved AE treatment through PDT effects. PLGA improved the optical properties of ICG, while liposomes further improved the biocompatibility of the nanoprobe. As ICG@PLGA@Lips showed strong NIR-II fluorescence emission and good biocompatibility, ICG@PLGA@Lips showed advantages in the specific fluorescence navigation of AE surgical resection lesions. Thus, with the assistance of ICG@PLGA@Lips, we achieved precise targeted and real-time NIR-II fluorescence imaging of AE for the first time. We successfully obtained in vivo NIR-II fluorescence imaging-guided photodynamic/surgical therapy of AE. This TSTS-based AE imaging and treatment exploration provided a new strategy for accurate imaging and treatment of early AE, which is expected to significantly improve the prognosis of patients.

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.

Computational Chemistry Study of pH-Responsive Fluorescent Probes and Development of Supporting Software

This study employs quantum chemical computational methods to predict the spectroscopic properties of fluorescent probes 2,6-bis(2-benzimidazolyl)pyridine (BBP) and (E)-3-(2-(1H-benzo[d]imidazol-2-yl)vinyl)-9-(2-(2-methoxyethoxy)ethyl)-9H-carbazole (BIMC). Using time-dependent density functional theory (TDDFT), we successfully predicted the fluorescence emission wavelengths of BBP under various protonation states, achieving an average deviation of 6.0% from experimental excitation energies. Molecular dynamics simulations elucidated the microscopic mechanism underlying BBP’s fluorescence quenching under acidic conditions. The spectroscopic predictions for BIMC were performed using the STEOM-DLPNO-CCSD method, yielding an average deviation of merely 0.57% from experimental values. Based on Einstein’s spontaneous emission formula and empirical internal conversion rate formulas, we calculated fluorescence quantum yields for spectral intensity calibration, enabling the accurate prediction of experimental spectra. To streamline the computational workflow, we developed and open-sourced the EasySpecCalc software v0.0.1 on GitHub, aiming to facilitate the design and development of fluorescent probes.

Sensitive Fluorescent Probe for Al3+, Cr3+ and Fe3+: Application in Real Water Samples and Logic Gate.

Construction of single probes for simultaneous detection of common trivalent metal ions has attracted much attention due to higher efficiency in analysis and cost. A naphthalimide-based fluorescent probe K1 was synthesized for selective detection of Al3+, Cr3+ and Fe3+ ions. Fluorescence emission intensity at 534nm of probe K1 in DMSO/H2O (9:1, v/v) was significantly enhanced upon addition of Al3+, Cr3+ and Fe3+ ions while addition of other metal ions (Li+, Na+, K+, Ag+, Cu2+, Fe2+, Zn2+, Co2+, Ni2+, Mn2+, Sr2+, Hg2+, Ca2+, Mg2+, Ce3+, Bi3+ and Au3+) did not bring about substantial change in fluorescence emission. The calculated detection limits were 0.32 µM, 0.81 µM, and 0.27 µM for Al3+, Cr3+, and Fe3+, respectively. Probe K1 displayed strong anti-interference ability, a large Stokes shift, rapid response, and applicability in a wide pH range for the simultaneous detection of Al3+, Cr3+ and Fe3+ in real water samples. Job's plot test showed that the stoichiometric ratio of the complexes formed between probe K1 and the trivalent metal ions was 1:1. The reversible application of probe K1 was realized by addition of Na2EDTA. A molecular logic gate was built based on the input-output information. This approach may provide a basis for highly selective and sensitive detection of common trivalent cations and for design of memory devices.

Theoretical Study on the Internal Conversion Decay Pathways of Bithiophene-Fused Isoquinolines.

In this study, the radiative and nonradiative decay pathways from the first singlet excited states (denoted as S1) of three bithiophene-fused isoquinolines were investigated by using the mixed-reference spin-flip time-dependent density functional theory approach. These isoquinolines, which are prepared via [2 + 2 + 2] cycloaddition reactions between three types of bithiophene-linked diynes and nitriles, exhibit different fluorescence quantum yields in response to the positions of their sulfur atoms. The decay processes, including the fluorescence emission and internal conversion, were considered. In the internal conversion pathway, the minimum energy conical intersection structures between the ground and first singlet excited states (denoted as S0/S1 MECI) of the ring strain for the isoquinoline skeleton and the ring opening of the thiophene skeleton were systematically explored. Dewar-type ring strain resulted in the smallest energy barrier from the equilibrium geometries of the ground state (denoted as S0) to the MECI structures between the S0 and S1 states. The energy difference between the three types of bithiophene-fused isoquinolines at the transition state geometries of the S1 state varies owing to the steric effects between the methyl groups and the hydrogen atom of the thiophene ring, and the excitation energy increases owing to a decrease in aromaticity. In addition, the oscillator strengths of the S0 and S1 states were evaluated at the equilibrium geometries of the S1 state to determine the contribution of the fluorescence process. The obtained theoretical results are consistent with the experimental results.

N-Doped Carbon Nanodots as Temperature Sensors and Fluorescent Probes for the Detection of Tinidazole in Milk.

In this study, nitrogen-doped carbon nanodots (N-CDs) with temperature and fluorescence sensing were prepared via hydrothermal method using L-lysine and ethylenediamine as precursors. The synthesized N-CDs exhibited spherical morphology with sizes ranging from 2.8 to 5.2nm, with an average diameter of 4.03nm. Maximum fluorescence emission was observed at 390nm upon excitation at 320nm, with the excitation spectrum closely overlapping the absorption spectrum of tinidazole (TNZ). In the temperature range of 20 ~ 50°C, the fluorescence intensity of N-CDs decreased linearly with the increase of temperature. TNZ was detected based on inner filter effect (IFE) using N-CDs as a fluorescent probe. The fluorescence quenching degree had a good linear correlation with the TNZ concentration in the range of 1~100 µM (r = 0.9970), and the detection limit was 0.362 µM. In addition, the detection limits of other nitroimidazole antibiotics, including metronidazole (MNZ), Ornidazole (OMZ) and Seknidazole (SNZ), were 0.324 µM, 0.345 µM and 0.341 µM, respectively. Importantly, this method exhibits minimal interference from ions present in milk and has been validated in real milk samples, with recovery rates ranging from 92.56 to 107.27%. These results highlight the method's strong potential for application in food analysis.

Advanced Dual-Mode Microfluidic Sensing Platform Based on Amphiphilic Polymer-Capped Perovskite Nanozymes Induced Photoelectrochemical Signal Amplification and Fluorescence Emission.

A novel dual-mode microfluidic sensing platform integrating photoelectrochemical (PEC) and fluorescence (FL) sensors was developed for the sensitive monitoring of heart fatty acid binding protein (h-FABP). First, BiVO4/AgInS2 (BVAIS) composites with excellent photoelectric activity were synthesized as sensing matrices. The BVAIS heterojunction with a well-matched internal energy level structure provided a stable photocurrent. Second, an innovative signal amplification strategy based on octylamine-modified poly(acrylic acid) (OPA)-capped CsPbBr3 (OPCB) nanocrystals (NCs) with excellent catalytic activity and fluorescence property was proposed. On the OPCB nanozyme possessing ascorbate oxidase-like catalytic activity could catalyze the oxidation of ascorbic acid, which achieved quenching of the photocurrent signals by competitively consuming the electron donor. On the other hand, the OPCB NCs that overcame the water stability defect processed good luminescence performance and were able to produce obvious FL signals. Mutually verified dual-response signals effectively enhance the precision of test outcomes and avoid false-positive or false-negative results. Finally, the constructed microfluidic sensing platform realized sensitive detection of h-FABP in the linear range of 0.0001-150 ng/mL (PEC mode) and 0.001-150 ng/mL (FL mode), with detection limits of 36 fg/mL and 0.32 pg/mL, respectively. The present work provided a new perspective for designing an efficient dual-mode sensing strategy to achieve sensitive detection of disease markers.

Enhanced Near-Infrared Fluorescence Emission near a Graphene-Metal Hybrid Structure.

Plasmon resonance plays an important role in improving the detection of biomolecules, and it is one of the focuses of research to use metal plasmon resonance to achieve fluorescence enhancement and to improve detection sensitivity. However, the problems of nondynamic tuning and fluorescence quenching of metal plasmon resonance need to be solved. Graphene surface plasmon resonance can be dynamically controlled, and the graphene adsorption of fluorescent molecules can avoid fluorescence quenching and greatly improve the fluorescence emission intensity. The graphene-metal hybrid structure designed in this work can solve the above two problems well, and the plasmon resonance can improve the fluorescence emission efficiency of molecules on the surface of graphene and improve the sensitivity of biological detection. At the same time, graphene nanoribbons in our hybrid structure do not require patterning, which greatly lowers the threshold for graphene application in biosensing.

Modulation of Donor in Purely Organic Triplet Harvesting AIE-TADF Photosensitizer for Image-guided Photodynamic Therapy.

Image-guided photodynamic therapy is acknowledged as one of the most demonstrative therapeutic modalities for cancer treatment because of its high precision, non-invasiveness, and improved imaging ability. A series of purely organic photosensitizers denoted as BTMCz, BTMPTZ, and BTMPXZ, have been designed and synthesized and are found to exhibit both thermally activated delayed fluorescence and aggregation-induced emission simultaneously. Experimental and theoretical studies are combined to reveal that modulation of the donor of the photosensitizer enables distinct thermally activated delayed fluorescence via a second-order spin-orbit perturbation mechanism involving lowest singlet charge-transfer and higher-lying triplet locally excited states, respectively. Further, different donor strengths and unique aggregations (H-, J- and X-type packings) greatly influence their color-tunable up-converted luminescence and endow them with superb dispersibility in water. The confocal microscopy-based cellular uptake study confirms the successful internalization of the nano-probes, while BTMCz enables the generation of reactive oxygen species (singlet oxygen) under white-light irradiation, enabling the efficient killing of cancer cells.

Synthesis, structural characterization, and optical properties of two Co(II)-based coordination compounds

Two new Co(II)-based coordination compounds, [Co(Hmctrz)2(H2O)2] (1) and [Co(Hdctrz)(H2O)2]n (2), were synthesized via routine or hydrothermal reactions using cobalt salts, triazole derivatives, and auxiliary reagents. Characterizations, including single-crystal X-ray diffraction, elemental analysis, IR spectroscopy, TGA, and PXRD, confirmed their formation. UV-Vis and fluorescence studies revealed distinct optical properties, with 1 and 2 exhibiting UV absorption peaks at 353 and 370 nm, respectively, and concentration-dependent fluorescence emission, indicating potential for optoelectronic and biological imaging applications. Additionally, adsorption studies showed excellent dye removal capabilities, with 1 achieving 98% removal of methylene blue (MB) and 93% of methyl orange (MO), outperforming 2, which removed 95% of MB and 87% of MO. These results highlight the compounds’ potential in both environmental remediation and advanced material applications.

Gold nanomaterials capped with bovine serum albumin for cell and extracellular vesicle imaging

Bovine serum albumin-capped gold nanoclusters (AuNC@BSA) are ionic, ultra-small, and eco-friendly nanomaterials that exhibit red fluorescence emission. Upon modification, these nanomaterials can serve as imaging probes with multimodal functionality. Owing to their nanoscale properties, AuNC@BSA-based nanomaterials can be readily endocytosed by cells for imaging. With the increasing interest in cell therapy, extracellular vesicles (EVs) have attracted considerable attention from researchers; however, effective methods for imaging EVs remain limited. Although several studies have explored imaging strategies for cells and EVs using compounds, nuclear pharmaceuticals, nanoparticles, or genetic constructs, the use of AuNC@BSA-based nanomaterials for labeling EVs and their parental cells has rarely been discussed, with even less attention paid to their multimodal potential. To address this gap, we utilized three types of AuNC@BSA-based derivatives: AuNC@BSA, AuNC@BSA-Gd, and AuNC@BSA-Gd-I. Our findings demonstrate that these derivatives can effectively label both cells and EVs using a simple direct labeling approach, which is particularly notable for EVs, as they typically require more complex labeling procedures. Furthermore, the multimodal potential of labeled cells and EVs was evaluated, revealing their capabilities for multimodal imaging. In summary, this study presents an effective strategy for labeling EVs and their parental cells using multimodal nanomaterials. These findings will contribute to accelerating the development of drug delivery systems, cell- and EV-based therapies, and advanced imaging strategies.

Dual-mode ratiometric optical sensor for rapid visual detection of Hg2+ with poly(adenine)-assisted silver nanoclusters anchoring on tetrahedral DNA framework.

Cytosine-rich and poly(adenine)-tailed tetrahedral DNA framework (TDF) is designed as template (A8-TDF) for anchoring silver nanoclusters (AgNCs) and igniting the dual-color fluorescence of AgNCs. The resultant DNA-AgNCs simultaneously emits red and green fluorescence, and the quantum yield of red fluorescence is as high as 44.8%. The red fluorescence can be selectively quenched by Hg2+ within 2 min due to the redox reaction between Hg2+ and Ag0 as well as the subsequent Ag amalgamation. Meanwhile, the green fluorescence is enhanced. Thus a ratiometric fluorescence sensor is constructed for rapid and visual Hg2+ detectionbased on the synchronous change of two fluorescence signals. In addition, the resultant AgNCs probe also provides ratiometric colorimetric sensing of Hg2+ and simultaneously shows a visible color change from pink to yellow along with increasing content of Hg2+. The detection limits of ratiometric fluorescence and colorimetric modes are 0.24 nM and 1.32 nM, respectively. The method has been applied to the determinationof Hg2+ in water samples, and recoveries ranged between 94.1 and 108.7%. This study not only provides a new guideline to modulate the fluorescence emission of AgNCs by scientifically designing terminal DNA sequence but also provides a facile and efficient single-probe and dual-mode ratiometric sensing platform for the routine determination and field monitoring of Hg2+.

Excited-State and Steric Hindrances Engineering Enable Fast Spin-Flip Narrowband Thermally Activated Delayed Fluorescence Emitters with Enhanced Quenching Resistance.

Multi-resonance thermally activated delayed fluorescence (MR-TADF) materials have great potential for applications in ultrahigh-definition (UHD) organic light-emitting diode (OLED) displays, that benefit from their narrowband emission characteristic. However, key challenges such as aggregation-caused quenching (ACQ) effect and slow triplet-to-singlet spin-flip process, especially for blue MR-TADF materials, continue to impede their development due to planar skeletons and relatively large ΔESTs. Here, an effective strategy that incorporates multiple carbazole donors into the parent MR moieties is proposed, synergistically engineering their excited states and steric hindrances to enhance both the spin-flip process and quenching resistance. As expected, the designed materials namely 5Cz-BNO and 5Cz-BN exhibit bright blue and green emissions with narrow full-width at half-maximums (FWHMs) around 23 nm, together with significantly improved reverse intersystem crossing (RISC) rates. The OLEDs based on 5Cz-BNO and 5Cz-BN with doping concentrations from 5 to 20 wt% achieve high maximum external quantum efficiency (EQEmax) values exceeding 30% with suppressed efficiency roll-offs and improved operational stability. This work offers an effective approach for designing doping-insensitive blue and green MR-TADF materials with fast spin-flip processes by integrating the engineering of excited states and steric hindrances.

Two Transition Metal Coordination Polymers: Potential Adsorbents for Contaminant Removal and Photoluminescent Properties.

Methylene blue (MB) contamination has become a significant environmental issue due to its widespread presence in industrial effluents, posing serious threats to ecosystems and human health. As a result, there is an urgent need for the development of novel adsorbent materials that can effectively remove these pollutants from water sources. In this context, the present study focuses on the design and synthesis of two coordination polymers (CPs) containing Zn(II) and Mn(II), namely, {[Mn3(L)2(tib)2]·4H2O}n (1) and [Zn(L)(3,5-bibp)]n (2), using a combined-ligand approach under solvothermal conditions. The ligands, H3L is 4-(3,5-dicarboxylatobenzyloxy)benzoic acid), 1,3,5-tris(1-imidazolyl)benzene and 3,5-bibp is 3,5-bis(imidazol-1-yl)biphenyl), were carefully selected to enhance the properties of the resulting polymers. These CPs were thoroughly characterized using a variety of techniques, including IR spectroscopy, elemental analysis (EA), single-crystal X-ray diffraction, thermogravimetric analysis (TGA), and powder X-ray diffraction (PXRD). Both CPs demonstrated ligand-dependent blue fluorescence emissions, suggesting their potential for use as photoluminescent materials in various applications. Furthermore, the adsorption capabilities of CP1 and CP2 for methylene blue (MB) were evaluated. The results revealed that both CPs exhibited excellent adsorption efficiencies, with CP1 achieving a 77.6% adsorption efficiency within 1h and completely removing 20mg/L of MB within 6h. These findings highlight the significant potential of CP1 as a highly effective adsorbent for organic dyes, particularly for environmental remediation applications. The ability of these coordination polymers to adsorb MB efficiently underscores the urgent need for the development of innovative and efficient materials to address the growing challenges of water pollution.

AIE-active Circularly Polarized Thermally Activated Delayed Fluorescence Emitters for Stable Solution-Processed Circularly Polarized Electroluminescence.

Circularly polarized organic light-emitting diodes (CP-OLEDs) have significant promise for naked-eye 3D displays. However, most devices are fabricated using vacuum deposition technology, and development of efficient solution-processed CP-OLEDs, particularly those exhibiting low efficiency roll-off, remains a formidable challenge. This research successfully designed and synthesized two pairs of thermally activated delayed fluorescence (TADF) enantiomers through isomer engineering, namely (R/S)-N-5-TPA and (R/S)-N-4-TPA, which features fifth and fourth substitution sites of phthalimide (acceptor) by tri-phenylamine (donor), respectively. Both molecules displayed aggregation-induced emission (AIE) properties. Notably, the CP-OLED devices, fabricated by solution-process, exhibited vivid blue-green and green emission with the maximum current efficiency of 7.4 and 29.6 cd A-1, the external quantum efficiency of 2.7% and 10.2%, and the low efficiency roll-off of 3.7% and 16.7%. Moreover, these devices demonstrated CP-EL signals with gEL values of +6.61 × 10-4 /-6.84 × 10-4 and +1.13 × 10-3/-1.25 × 10-3, respectively.

Yellow fluorescent UV-curable epoxy acrylate/VTMS-modified GQDs coatings: study of UV-blocking and viscoelastic properties

Polymer coatings decompose in the presence of UV radiation from sunlight and beget economic and environmental losses. Hence, it is necessary to reinforce the polymer coatings with UV-blocking nanoparticles and to convert the UV light into visible light. In this research work, the surface of graphene quantum dots (GQDs) was modified by vinyltrimethoxysilane (VTMS). VTMS-modified GQDs (VmGQDs) including 0, 0.3 and 0.6 wt% were taken into account to synthesize UV-curable epoxy acrylate/VmGQDs (Ep/VmGQDs) nanocomposite coatings. Surface modification, UV-blockage, fluorescence features and viscoelastic properties of Ep/VmGQDs coatings were analyzed by various spectrometry tests. The existence of VmGQDs (0.3 wt% and 0.6 wt%) in the polymer matrix led to absorption of UV rays in UV regions and fluorescence emission in the visible area with 578 nm wavelength (yellow fluorescence). Appearance of strong absorption bands at 250, 285 and 365 nm by the coatings with VmGQDs confirmed that a large portion of UV rays was absorbed and blocked. The intensity of UV-blockage by Ep/VmGQDs 0.6 wt% was recorded >99%. Furthermore, reinforcement of the coatings with VmGQDs resulted in increase in storage modulus, cross-linking density and Tg value.

Intramolecular Repulsive Interactions Enable High Efficiency of NIR-II Aggregation-Induced Emission Luminogens for High-Contrast Glioblastoma Imaging.

Strategies to acquire high-efficiency luminogens that emit in the second near-infrared (NIR-II, 1000-1700 nm) range are still rare due to the impediment of the energy gap law. Herein, a feasible strategy is pioneered by installing large-volume encumbrances in a confined space to intensify the repulsive interactions arising from overlapping electron densities. The experimental results, including smaller coordinate displacement, reduced reorganization energy, and suppressed internal conversion, demonstrate that the repulsive interactions assist in the inhibition of radiationless deactivation. Meanwhile, the configuration and hybridization form of the donor units are transformed along with the repulsive interactions, bringing about improved oscillator strength. A 3.8-fold higher luminescence efficiency is realized via the synergistic effect. Furthermore, the repulsive interactions endow the NIR-II fluorophores with a highly twisted conformation, superior AIE activity, and cascaded improvement of fluorescence emission from isolated molecules to aggregates. By utilizing a brain-targeting peptide to functionalize the NIR-II nanoparticles, accurate detection and high-contrast imaging of orthotopic glioblastoma are realized. This work not only explores a fundamental principle to handle the intractable energy gap law but also provides potential applications of NIR-II luminogens in high-contrast bioimaging and glioblastoma detection.