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Fighting aggregation-caused quenching and leakage of dyes in fluorescent polymer nanoparticles: universal role of counterion
摘要： Dye-loaded polymer nanoparticles (NPs) emerge as a powerful tool for bioimaging applications, owing to their exceptional brightness and controlled small size. However, aggregation-caused quenching (ACQ) and leakage of dyes at high loading remain important challenges of these nanomaterials. The use of bulky hydrophobic counterions has been recently proposed as an effective approach to minimize ACQ and dye leakage, but the role of counterion structure is still poorly understood. Here, a systematic study based on ten counterions, ranging from small hydrophilic perchlorate up to large hydrophobic tetraphenylborate derivatives, reveals how counterion nature can control encapsulation and emission of a cationic dye (rhodamine B octadecyl ester) in NPs prepared by nanoprecipitation of a biodegradable polymer, poly-lactide-co-glycolide (PLGA). We found that increase in counterion hydrophobicity enhances dye encapsulation efficiency and prevents dye adsorption at the particle surface. Cellular imaging studies revealed that ≥95% encapsulation efficiency, achieved with most hydrophobic counterions (fluorinated tetraphenylborates), is absolutely required, because non-encapsulated dye species at the NPs surface are the origin of dye leakage and strong background in cells. The size of counterions is found to be essential to prevent ACQ, where the largest species, serving as effective spacer between dyes, provide the highest fluorescence quantum yield. Moreover, we found that the most hydrophobic counterions favor dye-dye coupling inside NPs, leading to ON/OFF fluorescence switching of single particles. By contrast, less hydrophobic counterions tend to disperse dyes in the polymer matrix favoring stable emission of NPs. The obtained structure-property relationships validate the counterion-based approach as a mature concept to fight ACQ and dye leakage in the development of advanced polymeric nanomaterials with controlled optical properties.
关键词： dye-loaded polymer nanoparticles,fluorescent nanoparticles,bulky hydrophobic counterion,aggregation-caused quenching,bioimaging
更新于2025-09-23 15:23:52
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Reducing aggregation caused quenching effect through co-assembly of PAH chromophores and molecular barriers
摘要： The features of well-conjugated and planar aromatic structures make π-conjugated luminescent materials suffer from aggregation caused quenching (ACQ) effect when used in solid or aggregated states, which greatly impedes their applications in optoelectronic devices and biological applications. Herein, we reduce the ACQ effect by demonstrating a facile and low cost method to co-assemble polycyclic aromatic hydrocarbon (PAH) chromophores and octafluoronaphthalene together. Significantly, the solid photoluminescence quantum yield (PLQYs) for the as-resulted four micro/nanococrystals are enhanced by 254%, 235%, 474 and 582%, respectively. Protection from hydrophilic polymer chains (P123 (PEO20-PPO70-PEO20)) endows the cocrystals with superb dispersibility in water. More importantly, profiting from the above-mentioned highly improved properties, nano-cocrystals present good biocompatibility and considerable cell imaging performance. This research provides a simple method to enhance the emission, biocompatibility and cellular permeability of common chromophores, which may open more avenues for the applications of originally non- or poor fluorescent PAHs.
关键词： cocrystals,aggregation caused quenching,bioimaging,polycyclic aromatic hydrocarbon,photoluminescence quantum yield
更新于2025-09-23 15:23:52
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The electrical signal-induced systemic photosynthetic response is accompanied by changes in the photochemical reflectance index in pea
摘要： Plants can be affected by numerous environmental stressors with spatially heterogeneous actions on their bodies. A fast systemic photosynthetic response, which is connected with long-distance electrical signalling, plays an important role in the adaptation of higher plants to the action of stressors. Potentially, measurement of the response by using a photochemical reflectance index (PRI) could be the basis of monitoring photosynthesis under spatially heterogeneous stressors; however, the method has not been previously used for investigating the systemic photosynthetic response. We investigated changes in PRI and photosynthetic parameters (quantum yields of PSI and PSII and nonphotochemical quenching) in intact leaves of pea (Pisum sativum L.) after local heating of another leaf and the propagation of electrical signals through the plant body. We showed that electrical signals decreased the quantum yields of PSI and PSII and increased the nonphotochemical quenching of intact leaves in times ranging from minutes to tens of minutes; the changes were strongly connected with changes in PRI. Additional analysis showed that changes in PRI were caused by an increase of the energy-dependent quenching induced by electrical signals. Thus PRI can be potentially used for monitoring the systemic photosynthetic response connected with long-distance electrical signalling.
关键词： Pisum sativum,nonphotochemical quenching,long-distance electrical signalling
更新于2025-09-23 15:23:52
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Insights into anti-thermal quenching of photoluminescence from SrCaGa4O8 based on defect state and application in temperature sensing
摘要： Herein, a self-activated phosphor SrCaGa4O8 with excellent thermal stability was synthesized by high temperature solid state reaction method. It exhibited the broad emission range from 300 to 600 nm under 220 nm excitation, which may be caused by the intrinsic defects of host. Specifically, with the temperature increasing, the photoluminescence (PL) color changed from bluish to yellow-green and the maximum of PL intensity at 550 nm was obtained when reaching 493 K. From thermoluminescence curves and high temperature spectra, it was found that the anti-thermal quenching phenomenon could be dependent on the self-compensation of the carriers. Accordingly, the results of temperature-dependent intensity ratio and sensitivity show that SrCaGa4O8 may have potential in the optical temperature sensing.
关键词： Energy transfer,Self-activated phosphor,Optical properties,Anti-thermal quenching,Sensors
更新于2025-09-23 15:22:29
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Photoinduced electron transfer in non-covalent free-base octaethylporphyrin and 2-nitrofluorene donor-acceptor system: A combined experimental and quantum chemical study
摘要： Photosynthetic reaction center functions through non-covalent incorporation into a well-defined transmembrane proteins. In the context of exploring photoinduced electron transfer (PET) in non-covalent donor-acceptor systems, we have investigated electron transfer from free-base octaethylporphyrin (OEP) donor to 2-nitrofluorene (2NF) acceptor in acetonitrile (ACN), a polar solvent. Steady-state and time-resolved emission spectroscopic studies in conjunction with density functional theory (DFT) calculations were employed to explore the electron transfer process. Quenching of the fluorescence emission intensity as well as fluorescence lifetime of the OEP upon excitation at the Q band of OEP at 300 K, is attributed to the PET from OEP to 2NF. Our DFT [wB97XD functional and 6-31G (d,p) basis set] calculations also support the interaction between donor and acceptor and also reveals the co-facial π-π interaction energy of ?24.6 kcal/mol with intermolecular distance b4 ?. Our results are expected to shed light on PET in non-covalent donor acceptor systems.
关键词： Marcus theory,Photoinduced electron transfer,Octaethylporphyrin,Second-order bimolecular fluorescence quenching constant,2-Nitrofluorene,DFT study by wB97XD/6-31G(d,p),Time-resolved emission spectroscopy
更新于2025-09-23 15:22:29
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A Signal-On Fluorosensor Based on Quench-Release Principle for Sensitive Detection of Antibiotic Rapamycin
摘要： An antibiotic rapamycin is one of the most commonly used immunosuppressive drugs, and also implicated for its anti-cancer activity. Hence, the determination of its blood level after organ transplantation or tumor treatment is of great concern in medicine. Although there are several rapamycin detection methods, many of them have limited sensitivity, and/or need complicated procedures and long assay time. As a novel fluorescent biosensor for rapamycin, here we propose “Q’-body”, which works on the fluorescence quench-release principle inspired by the antibody-based quenchbody (Q-body) technology. We constructed rapamycin Q’-bodies by linking the two interacting domains FKBP12 and FRB, whose association is triggered by rapamycin. The fusion proteins were each incorporated position-specifically with one of fluorescence dyes ATTO520, tetramethylrhodamine, or ATTO590 using a cell-free translation system. As a result, rapid rapamycin dose-dependent fluorescence increase derived of Q’-bodies was observed, especially for those with ATTO520 with a lowest detection limit of 0.65 nM, which indicates its utility as a novel fluorescent biosensor for rapamycin.
关键词： rapamycin,fluorescent biosensor,fluorescence quenching,photoinduced electron transfer,antibiotics
更新于2025-09-23 15:22:29
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Bonded-luminescent foam based on europium complexes as a reversible copper (II) ions sensor in pure water
摘要： Developing novel lanthanide complexes to rapidly and reliably sensing Cu2+ ions in pure water is highly challenging. Here, a series long luminescence lifetime luminescent Eu-complex polyurethane foams (Eu-PUFs) porous material by simple one-step co-polycondensation reaction has been successfully assembled. The photoluminescence (PL) results indicated that the pure red emission from Eu3+ ions is selectively quenched upon addition of Cu2+ ions, and barely any interference by other metal ions in pure water, thus making Eu-PUFs as a potential Cu2+ ions sensing material. The original luminescent intensity of Eu3+ ions located 617nm can be recovered about 84% by washing of ethylenediaminetetraacetic acid (EDTA) there times, indicating the sensing ability of Eu-PUFs is highly reversible. Due to the probe molecules Eu (TTA)3 ? Phen-NH2 was bonded into Eu-PUFs through covalent bond linker, so the Eu-PUFs sensors can be utilized to detection of Cu2+ ions in pure water multiple times (more than 20 times) without much effect on the sensitivity, and the limitation of detection (LOD) for Cu2+ in pure water is as low as 0.28 μM. All above mentioned results revealed these Eu-PUFs are excellent and potential Cu2+ ions sensing material in pure water and will be widely used in analytical and biological application fields.
关键词： copper (II) ions detection,fluorescence quenching,Europium complexes,Bonded-luminescent foam
更新于2025-09-23 15:22:29
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Bichromophoric pyrazoline derivative with solvent-selective photoluminescence quenching
摘要： The quenching of fluorescence in the presence of chloromethanes, which is an unprecedented effect for pyrazolines, has been evidenced for the first time in the case of 1,3-diphenyl-5-{4-[(4-vinylbenzyl)oxy]phenyl}-4,5-dihydropyrazole. The detailed synthesis of this aryl trisubstituted pyrazoline that combines two chromophoric units in a non-conjugated manner is presented. The compound has been extensively characterized from a structural point of view, and its crystal structure has been determined by single crystal X-ray crystallography. The fluorescence study has evidenced the particular behavior of this pyrazoline derivative in solutions of chloromethanes, and the insight gained from the experimental data has been useful in elaborating a plausible fluorescence quenching mechanism. The investigated compound was modeled by Density Functional Theory (DFT) to point out the particularities of the electron transitions in gas phase as well as in the implicit solvents. Also, the HOMO-LUMO energy gap, mapped electrostatic potential, electronic density, dipole moment and polarizability have been reported for the pyrazoline derivative.
关键词： Fluorescence,Synthesis,Quenching,Molecular modelling,Bichromophore,Pyrazoline
更新于2025-09-23 15:22:29
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A high-performance fluorescent probe for dopamine detection based on g-C3N4 nanofibers
摘要： A novel fluorescent sensor based on g-C3N4 nanofibers for the sensitive detection of dopamine (DA) has been proposed. We synthesized g-C3N4 nanofibers by directly hydrolyzing bulk g-C3N4 in the alkaline atmosphere (3 M NaOH). The obtained ultrathin g-C3N4 nanofibers were verified by characterizations of Transmission electronic microscope (TEM), X-ray diffractometer (XRD), Fourier transformation-infrared (FT-IR) and X-Ray photoelectron spectroscopy (XPS). It was found that the fluorescence intensity of g-C3N4 nanofibers was obviously quenched by DA. Fluorescence resonance energy transfer (FRET) between DA and g-C3N4 nanofibers led to the fluorescence reduction of g-C3N4 nanofibers. The fluorescent probe based on g-C3N4 nanofibers exhibits linear responses to the concentration of DA in the range from 0 to 4 μM and 4 to 20 μM, the limit of detection is 17 nM. The fluorescent probe shows excellent stability, good selectivity with its application in serums.
关键词： dopamine,g-C3N4 nanofibers,quenching,fluorescent probe
更新于2025-09-23 15:22:29
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Dual Quenching Electrochemiluminescence Strategy Based on 3D Metal-organic Frameworks for Ultrasensitive Detection of Amyloid-β
摘要： We have proposed a dual quenching electrochemiluminescence (ECL) strategy which based on Ru(bpy)3 2+ as chromophores caged in 3D Zn-oxalate metal-organic frameworks (Ru(bpy)3 2+/Zn-oxalate MOFs) for ultrasensitive detection of amyloid-β (Aβ). The three-dimensional chromophore connectivity in Zn-oxalate MOFs provided a network for rapid excited state energy transfer migration among Ru(bpy)3 2+ units which shielded the chromophores from solvent molecules and led to a high energy Ru emission efficiency. In addition, we found that both Au nanoparticles and NiFe-based nanocube MOFs could contribute to the reduction of the ECL intensity of chromophore. And the ECL emission spectra of 3D Ru(bpy)3 2+/Zn-oxalate MOFs overlapped appropriately with the ultraviolet visible (UV-vis) absorption spectra of Au@NiFe-MOFs composites, which could trigger the resonance energy transfer (RET) behavior between Ru(bpy)3 2+/Zn-oxalate MOFs (donor) and Au@NiFe-MOFs (acceptor), achieving the dual quenching effect of Ru(bpy)3 2+ encapsulated in 3D Zn-oxalate MOFs and significantly boosting the sensitivity of the Aβ-detection immunosensor. In order to examine the clinical practicability, we have applied it to verify the content of Aβ solution ranging from 100 fg mL-1 to 50 ng mL-1 and obtained the calibration cure with high correlation coefficient, along with the low limit of detection of 13.8 fg mL-1. Above all, this work demonstrated an approach of constructing dual quenching effect ECL immunosensors in whole 3D MOFs system and its application in ECL methodology.
关键词： Ru(bpy)3 2+,Dual quenching electrochemiluminescence,Au@NiFe nanocube,3D Zn-oxalate metal-organic frameworks,Amyloid-β detection
更新于2025-09-23 15:22:29