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A reversible fluorescent probe for directly monitoring protein-small molecules interaction utilizing vibration-induced emission
摘要： The interactions between proteins and small molecules play an important role in the regulation of various cellular processes and modern drug discovery. Herein, we have developed a novel strategy for real-time monitoring the protein-ligand interaction based on vibration-induced emission (VIE) mechanism. These results demonstrated that the probe DPAC-DB could directly visualize the binding process in biotin-avidin system, which was undisturbed to other environmental stimuli, such as pH, interference species and temperature. Furthermore, the unique VIE effect caused by dramatic and reversible intramolecular vibrations enabled our strategy possible to build up the bio-logic gate. This method to efficiently control the emission of VIE-based probe through the reversible noncovalent protein-small molecules interactions opens new avenues for the development of potent protein pharmaceuticals and small molecule drugs.
关键词： Reversible,Vibration-induced emission (VIE),Biotin-avidin system,Bio-logic gate
更新于2025-09-04 15:30:14
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Alkyl chain-dependent cyano-stilbene derivative's molecular stacking, emission enhancement and fluorescent response to the mechanical force and thermal stimulus
摘要： Two cyano-stilbene derivatives with butyl (C4MPA) and octyl groups (C8MPA) were synthesized to investigate the effects of alkyl chains on molecular stacking, emission enhancement, and mechanofluorochromism. The two compounds displayed weak emissions in monomolecular state and emitted an enhanced fluorescence in crystal state. However, the fluorescence quantum yield of C4MPA (19%) was lower than that of C8MPA (76%). Face-to-face dimer stacking was found only in the C4MPA crystal, in which molecules adopted a nonplanar configuration. The C8MPA crystal presented two kinds of antiparallel 1D arrangement. One involved the antiparallel stacking of nonplanar aromatic moieties. The other consisted of coplanar molecules without π-π stacking, which were responsible for the higher luminescence yield. Moreover, the emission of the C4MPA solid was quenched under mechanical force, whereas the C8MPA solid still emitted a strong fluorescence after grinding. C8MPA lost fluorescence when heated at above 60 °C because of its low melting point, and the supercooling viscous liquid without fluorescence was observed even the sample was cooled to room temperature for 10 h, meaning a very slowly crystallization process. Such non-emissive supercooling viscous liquid might rapidly transform into strongly emissive solid under the mechanical force shearing stimulus. Thus, C8MPA films could be used as sensors for mechanical force and thermal stimuli.
关键词： mechanofluorochromism,emission enhancement,molecular stacking,thermal stimulus,cyano-stilbene derivatives,alkyl chains
更新于2025-09-04 15:30:14
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Super-resolution microscopy and empirically validated autocorrelation image analysis discriminates microstructures of dairy derived gels
摘要： The food industry must capitalise on advancing technologies in order to optimise the potential from emerging ingredient technologies. These can aid in product optimisation and provide quantitative empirical data to which there is a fundamental physical understanding. Super-resolution microscopy provides a tool to characterise the microstructure of complex colloidal materials under near native conditions. Coherent Anti-Stokes Raman Scattering (CARS) microscopy was used to show the presence of fluorescent dye required for imaging does not affect gel microstructure and super-resolution Stimulated Emission Depletion (STED) microscopy is used to image four dairy derived gels. Image analysis has been developed based on 2D spatial autocorrelation, and a model that extracts parameters corresponding to a typical length of the protein domains and the inter pore distance. The model has been empirically validated through the use of generated images to show the fitting parameters relate to precise physical features. The fractal dimension is extracted from Fourier space analysis. The combination of STED microscopy and image analysis is sensitive enough to significantly differentiate samples based on whether gels were made from fresh or reconstituted milk, and whether gelation was induced through acidification or rennet addition. Rheometry shows that the samples exhibit different macroscopic behaviours, and these differences become increasingly significant with time. Samples can be differentiated earlier in the gelation process with imaging as compared to rheometry. This highlights the potential of STED imaging and image analysis to characterise the size of protein domains, pore spacing and the fractal dimensions of microstructures to aid product optimisation.
关键词： Stimulated Emission Depletion (STED) microscopy,Super-resolution microscopy,Fractal dimension,Coherent Anti-stokes Raman Scattering (CARS) microscopy,2D spatial autocorrelation analysis
更新于2025-09-04 15:30:14
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Carbon Nitride Dots: A Selective Bioimaging Nanomaterial
摘要： In contrast to the recent immense attention in carbon nitride quantum dots (CNQDs) as a heteroatom-doped carbon quantum dot (CQD), their biomedical applications have not thoroughly investigated. The targeted cancer therapy is a prominently researched area in biomedical field. Here, the ability of CNQDs as a selective bioimaging nanomaterial was investigated to assist the targeted cancer therapy. CNQDs were first synthesized using four different precursor sets, involving urea derivatives and the characteristics were compared to select the best candid material for bioapplications. Characterization techniques such as UV-vis, luminescence X-ray photoelectron spectroscopy, nuclear magnetic resonance spectroscopy and transmission electron microscopy were used. These CNQDs were analyzed in in vitro studies of bioimaging and labeling using pediatric glioma cells (SJGBM2) for possible selective biolabeling and nano-distribution inside the cell membrane. The in vitro cellular studies were conducted under long-wavelength emission without the interference of blue autofluorescence. Thus, excitation-dependent emission of CNQDs was proved to be advantageous. Importantly, CNQDs selectively entered SJGBM2 tumor cells while it did not disperse in to normal human embryonic kidney cells (HEK293). The distribution studies in the cell cytoplasm indicated that CNQDs disperse into lysosomes within approximately 6 h after the incubation. The CNQDs exhibited great potential as a possible nanomaterial in selective bioimaging and drug-delivery for targeted cancer therapy.
关键词： Pediatric glioma cells,Long-wavelength emission,Urea derivatives,Carbon nitride Quantum dots,Fluorescence,Selective bioimaging
更新于2025-09-04 15:30:14
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Structural and Luminescence Properties of Anthracene- and Biphenyl-Based Lanthanide Bisphosphonate Ester Coordination Polymers
摘要： Coordinative networks containing lanthanide ions attached via phosphonate ester functionalities provide remarkable luminescence properties. On the basis of ditopic phosphonic ester ligands with biphenylene and 9,10-anthracenylene bridges, a series of compounds with formal composition {[M(NO3)3]L}n or {[M(NO3)3]2(L1)3}n (L = C28H40O6P2; L1 = C26H40O6P2) with M = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y have been synthesized, structurally characterized, and the luminescence behavior was explored in the visible and NIR spectral regions, where applicable. In contrast to closely related networks based on biphenyl bisphosphonate esters from previous work, no evidence for ligand-to-metal energy transfer could be observed, despite strong near-infrared emission in some cases. Unique behavior is found for the Eu derivative with the 9,10-anthracenylene bridge, which is nonemissive, showing neither ligand- nor metal-based emission.
关键词： lanthanide,phosphonate ester,luminescence,NIR emission,coordination polymers
更新于2025-09-04 15:30:14
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Fluorescence Behavior of Bis(cyanostyryl)pyrrole Derivatives Depending on Substituent Position of Cyano Groups in Solution and in Solid State
摘要： We synthesized a novel fluorophores of distyrylpyrrole derivatives possessing cyano groups at different position on olefin. Their fluorescence properties in solution and solid state were investigated by photoluminescence quantum yield and lifetime measurement, which provided radiative decay constant (kf) and nonradiative decay constant (knr). The derivative with cyano groups at inner position of molecule, inner isomer, shows high fluorescence quantum yield (Φf = 0.43) in solution while another derivative with cyano group at outer position, outer isomer, hardly shows fluorescence (Φf < 0.01) due to the large nonradiative decay (knr > 10 ns?1). Upon formation of single crystal or nanoparticles, these difference were inverted; the quantum yield of outer and inner isomer was enhanced and diminished, respectively. We explained these differences between in solution and solid state by means of analysis of single X-ray structure and computation study.
关键词： solid emission,pyrrole derivatives,substituent effect,Solid-state luminescence enhancement
更新于2025-09-04 15:30:14
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Conformational change due to intramolecular hydrophobic interaction leads to large blue-shifted emission from single molecular cage solutions
摘要： We demonstrate a unique negative solvatochromic emission (NSE) process from a conformational change of a coordination cage in response to solvent composition. The cationic cage contains two tetra-(4-pyridylphenyl)ethylene (TPPE) luminogens on two opposite faces, linked by Pt(PEt3)2 and isophthalate. When the solvent changes from acetone/acetonitrile/methanol to water, the emission of single cages gradually shifts to short wavelength (NSE) with a drastic value of B60 nm. Small angle X-ray scattering (SAXS) measurements indicate a molecular conformational change during the process and intramolecular p–p stacking and hydrophobic interaction between the TPPE planes could be the driving forces. As a comparison, a cage with a longer inter-fluorophore distance does not have such strong intramolecular interactions and only shows regular positive solvatochromic emission (PSE) under the same conditions.
关键词： coordination cage,intramolecular hydrophobic interaction,small angle X-ray scattering,TPPE luminogens,negative solvatochromic emission
更新于2025-09-04 15:30:14
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Color-tunable lanthanide metal–organic framework gels
摘要： Fluorescence signi?cantly improves the performance of gels. Various strategies, such as embedment and crosslinking, have been used to integrate extrinsic luminophores into gel systems, but the procedures are usually complex. Herein, for the ?rst time, we report gels with intrinsic and tunable emission color prepared with 5-boronoisophthalic acid (5-bop) and Eu3+, Tb3+, and/or Dy3+ similar to the procedure for the preparation of metal–organic frameworks (MOFs). The single-metal gels exhibit intrinsic trichromatic ?uorescence, due to which full-color emissions are readily obtained by tuning the type and/or ratio of Ln3+ ions to prepare mixed-metal gels. The emission is governed by an antenna e?ect and is thus excited with single-wavelength at 275 nm. The nucleation-growth mechanism reveals that the Ln3+ ions and 5-bop produce separated layers, which then grow anisotropically to form nanoribbons by high coordinated valence of Ln3+ ions and biased carboxyl distribution as well as steric hindrance and hydrogen bonds of the boric acid group in 5-bop. The nanoribbons entangle together to generate chemical-physical hybrid gels. To the best of our knowledge, this is the ?rst example of gels with inherent and tunable emission color. Due to their optical and viscoelastic properties, the gels have numerous potential applications such as tunable emission and multi-target detection.
关键词： metal–organic frameworks,lanthanide,gels,tunable emission,Fluorescence
更新于2025-09-04 15:30:14
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On/off rhodamine-BODIPY based fluorimetric/colorimetric sensor for detection of mercury(II) in half-aqueous medium
摘要： A turn on/off rhodamine-BODIPY (RB) fluorescent sensor has been designed for selective and sensitive detection of Hg(II) cation in half-aqueous solution. For this purpose, a Bodipy derivative having dual-cores is bilaterally bound to a rhodamine containing dual-amine moieties. The newly prepared sensor reacts with mercury (II) salt to generate a product with different optical parameters. These are changes confirmed by both absorption, emission and excitation measurements. “A blue shift is observed as the ‘Turn-off’ change the pink color to transparent upon the addition of Hg (II) ions which is assigned to suppression of fluorescence resonance energy transfer (FRET) upon mercury (II) ion affinity. Selectivity towards Hg(II) ion is found to depend upon cavity size created of the amino moieties of rhodamine and the carbonyls of Bodipy to the metal ion. Sensor RB is selective and sensitive to Hg(II) with a detection limit (1.94 (?0.2) 10-8 M). The three-way fluorescent probe can be selectively applied for the detection of mercury (II) ion in real water samples.
关键词： Bodipy,emission,mercury,absorption,fluorescent,Rhodamine
更新于2025-09-04 15:30:14
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Confidence interval constraint based regularization framework for PET quantization
摘要： In this paper, a new generic regularized reconstruction framework based on confidence interval constraints for tomographic reconstruction is presented. As opposed to usual state-of-the-art regularization methods that try to minimize a cost function expressed as the sum of a data-fitting term and a regularization term weighted by a scalar parameter, the proposed algorithm is a two-step process. The first step concentrates on finding a set of images that relies on direct estimation of confidence intervals for each reconstructed value. Then, the second step uses confidence intervals as a constraint to choose the most appropriate candidate according to a regularization criterion. Two different constraints are proposed in this paper. The first one has the main advantage of strictly ensuring that the regularized solution will respect the interval-valued data-fitting constraint, thus preventing over-smoothing of the solution while offering interesting properties in terms of spatial and statistical bias/variance trade-off. Another regularization proposition based on the design of a smoother constraint also with appealing properties is proposed as an alternative. The competitiveness of the proposed framework is illustrated in comparison to other regularization schemes using analytical and GATE-based simulation and real PET acquisition.
关键词： confidence intervals,constrained regularization,Image reconstruction,total variation,positron emission tomography
更新于2025-09-04 15:30:14