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Fluorescence coupled with electrochemical approach at the bulk and the interface region of hydrogen-bonding self assemblies of urea derivatives with DDP dye in aqueous solution
摘要： Photophysical and electrochemical techniques were employed to hydrogen-bonding self assemblies forming solutes (Urea, Dimethylurea and Tetramethylurea) in the presence of 4-dicyanomethylene 2, 6-dimethyl-4H-pyran (DDP) dye. Addition of urea derivatives to DDP dye (Intramolecular Charge Transfer (ICT)) results in a fluorescence enhancement accompanied with a significant shift. Fluorescence lifetime behavior exhibits a tri-exponential decay with a large variation in the fluorescence lifetime and relative amplitude distribution. The co-existence of three different fluorescence lifetime components of DDP with urea derivatives signifies the existence of heterogeneous micro environment. The dye is surrounded by varying proportion of solute and water molecules are established from fluorescence lifetime studies. Urea derivatives govern the excited state characteristics of DDP dye resulting in the formation and promotion of different microenvironment which are clearly distinguishable. The existence of multi environment attributed to urea-water structural behaviour is authenticated by electrochemical impedance spectral studies (EIS). A large variation in the contour pattern, shape and intensity in 3D fluorescence contour spectra of dye with urea validate the existence of dye in a heterogeneous micro environment. The hydrophobicity of urea derivatives along with the hydrogen-bonding properties of urea-water and urea-urea influence the photophysical and electrochemical nature of dye is emphasized.
关键词： Hydrogen-bonding,Urea derivatives,Fluorescence lifetime,Electrochemical impedance spectra,Fluorescence emission,DDP dye
更新于2025-09-12 10:27:22
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Distinct metabolic profiles in Drosophila sperm and somatic tissues revealed by two-photon NAD(P)H and FAD autofluorescence lifetime imaging
摘要： Metabolic profiles vary across all levels of biological diversity, from cells to taxa. Two-photon fluorescence lifetime imaging microscopy (FLIM) facilitates metabolic characterisation of biological specimens by assaying the intrinsic autofluorescence of the ubiquitous coenzymes NAD(P)H and FAD. the potential of this method for characterising the diversity of organismal metabolism remains largely untapped. Using FLIM in Drosophila melanogaster, we show tissue-specificity in fluorescence lifetime that reflects variation in redox patterns. In particular, sperm cells exhibited elevated glycolysis relative to other tissues. We also show that sperm metabolism is phenotypically plastic: compared to male-stored sperm, sperm stored in the female’s storage organ showed a substantial reduction in the protein-bound FAD lifetime fraction but no change in the NAD(P)H profile. This study represents the first ex vivo investigation of sperm metabolism using FLIM.
关键词： two-photon fluorescence lifetime imaging microscopy,FAD,Drosophila melanogaster,NAD(P)H,glycolysis,sperm metabolism,OxPHOS
更新于2025-09-12 10:27:22
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A Quantum Dot-Based FLIM Glucose Nanosensor
摘要： In the last few years, quantum dot (QD) nanoparticles have been employed for bioimaging and sensing due to their excellent optical features. Most studies have used photoluminescence (PL) intensity-based techniques, which have some drawbacks, especially when working with nanoparticles in intracellular media, such as fluctuations in the excitation power, fluorophore concentration dependence, or interference from cell autofluorescence. Some of those limitations can be overcome with the use of time-resolved spectroscopy and fluorescence lifetime imaging microscopy (FLIM) techniques. In this work, CdSe/ZnS QDs with long decay times were modified with aminophenylboronic acid (APBA) to achieve QD-APBA conjugates, which can act as glucose nanosensors. The attachment of the boronic acid moiety on the surface of the nanoparticle quenched the PL average lifetime of the QDs. When glucose bonded to the boronic acid, the PL was recovered and its lifetime was enhanced. The nanosensors were satisfactorily applied to the detection of glucose into MDA-MB-231 cells with FLIM. The long PL lifetimes of the QD nanoparticles made them easily discernible from cell autofluorescence, thereby improving selectivity in their sensing applications. Since the intracellular levels of glucose are related to the metabolic status of cancer cells, the proposed nanosensors could potentially be used in cancer diagnosis.
关键词： fluorescence lifetime imaging,intracellular sensing,quantum dots,nanoparticles,glucose,photoluminescence
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Spectral Luminescence Properties of Ho <sup>3+</sup> Ions in Active Media Codoped with Tb <sup>3+</sup> , Pr <sup>3+</sup> and Yb <sup>3+</sup> for Mid-Infrared Laser Development
摘要： Lasers operating in mid-infrared spectral region specifically with 3 m wavelength attract a lot of attention due to their various applications in atmospheric monitoring, medical surgery, remote sensing and scientific research. Such laser can be used as an efficient and high-quality radiation source for optical parametric oscillators and converters to longer IR wavelengths. Laser active media doped with Ho3+ ions are of interest for obtaining the radiation in this spectral range. However the realization of the laser radiation at 5I6 → 5I7 optical transition in Ho3+ ions is a complicated task due to the lack of commercially available laser diodes for efficient pumping of Ho3+ ions. Yb3+ ion is known as an efficient sensitizer for Ho3+ ions in various laser active crystals. The scheme with the excitation transfer from Yb3+ to Ho3+ was realized in Cr:Yb:Ho:YSGG and Cr:Yb:Ho:Eu:YAP lasers with flash lamp pumping [1, 2] and Ho:Yb:GGG and Ho:Yb:YSGG lasers with diode pumping [3]. In addition 5I6 → 5I7 optical transition is known as a “self-terminating” one because the fluorescence lifetime of the lower laser level 5I7 is considerably larger than that of the upper laser level 5I6. Codoping of Ho3+ active media with Tb3+ or Pr3+ ions can accelerate the deactivation process of the lower laser level. The concentration set of CaF2 crystal doped with Ho3+, Yb3+, Tb3+, Pr3+ ions was grown using the Bridgman technique. The number of Gd2O3, Y2O3 single crystal fibers doped with the same ions was successfully obtained by laser-heated pedestal growth method. Absorption spectra of Yb:Ho:Gd2O3 and Yb:Ho:Pr:Gd2O3 crystals showed that Yb3+ doping increased the absorption coefficient within 850-1050nm spectral region and make Yb doped media suitable for efficient pumping by commercially available laser diodes. The fluorescence lifetime of 5I6 and 5I7 manifolds of Ho3+ ions was investigated in CaF2 crystals codoped with Tb3+ and Pr3+ ions. It was found that this codoping resulted in the depopulation of the lower laser level 5I7 in Ho3+ ions and at the same time had little influence on the upper laser level 5I6 (Table 1). The lifetime of the lower laser level reduced from 17.5 ms for Yb:Ho:CaF2 crystal to 0.75 ms for Yb:Ho:Tb:CaF2. Deactivation effect of lower laser level 5I7 in Ho3+ was also observed in Yb3+:Ho3+:Pr3+:Gd2O3 and Yb3+:Ho3+:Tb3+:Gd2O3 single crystal fibers. The lifetime of the lower laser level 5I7 decreased from 8.25 ms to 1.04 ms and to 0.67 ms with a codoping of 0.5 at.% Pr3+ and 0.5 at.% Tb3+ ions, respectively. The use of Yb3+, Tb3+ or Pr3+ codoping with Ho3+ to enhance the laser properties of Ho3+ ions at 5I6→5I7 optical transition at the wavelength of ~2.8-3 μm were investigated in the Gd2O3, Y2O3 single crystal fiber for the first time. Obtained results indicate that single crystal fiber Yb3+:Ho3+:Tb3+:Gd2O3 and CaF2 :Yb3+:Ho3+:Tb3+ crystal is a promising laser medium for developing compact LD-pumped lasers operating at the wavelength of 2.8-3 μm.
关键词： Pr3+ ions,Tb3+ ions,mid-infrared laser,fluorescence lifetime,laser active media,Ho3+ ions,Yb3+ ions
更新于2025-09-11 14:15:04
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Fluorescence Lifetime-Based Tumor Contrast Enhancement Using an EGFR Antibody–Labeled Near-Infrared Fluorophore
摘要： Purpose: Imaging techniques for highly specific detection of cancer cells in vivo can have applications ranging from preclinical drug discovery studies to clinical cancer diagnosis and surgical therapy. Although fluorescence imaging using cancer-targeted antibodies has shown promise, nonspecific probe accumulation in tissue results in significant background fluorescence, reducing detection sensitivity using traditional intensity–based continuous-wave (CW) fluorescence imaging. Here we demonstrate that fluorescence lifetime (FLT) imaging can provide significant tumor contrast enhancement over CW intensity in preclinical models of human breast cancer. Experimental Design: Mice bearing MDA-MB-231 tumors were injected with anti-EGFR antibody conjugated to the fluorescent dye IRDye 800CW (anti-EGFR-800). Time domain fluorescence imaging was performed in vivo and in situ up to 48 hours after dye injection. Results: Mice injected with anti-EGFR-800 showed a significantly longer FLT (0.7 ± 0.03 ns) compared with the FLT of nonspecific probe uptake in liver (0.63 ± 0.05 ns), providing a dramatic improvement in sensitivity and specificity compared with CW intensity. IgG antibody–conjugated IRDye 800CW did not show an increased FLT compared with normal tissue, suggesting that the FLT increase of anti-EGFR-800 in tumors was associated with receptor expression. Using serial surgery, we show that FLT allows the detection of smaller residual tumors in the surgical bed than possible using CW intensity. Conclusions: Our data suggest that FLT can significantly enhance tumor contrast using fluorescently labeled antibodies, thereby accelerating the efficient clinical application of these probes for margin assessment in image-guided surgery and for highly specific detection of tumor receptors in vivo.
关键词： near-infrared fluorophore,EGFR,fluorescence lifetime imaging,image-guided surgery,tumor contrast
更新于2025-09-11 14:15:04
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Assessment of Gate Width Size on Lifetime-Based F?rster Resonance Energy Transfer Parameter Estimation
摘要： F?rster Resonance Energy Transfer (FRET) enables the observation of interactions at the nanoscale level through the use of fluorescence optical imaging techniques. In FRET, fluorescence lifetime imaging can be used to quantify the fluorescence lifetime changes of the donor molecule, which are associated with proximity between acceptor and donor molecules. Among the FRET parameters derived from fluorescence lifetime imaging, the percentage of donor that interacts with the acceptor (in proximity) can be estimated via model-based fitting. However, estimation of the lifetime parameters can be affected by the acquisition parameters such as the temporal characteristics of the imaging system. Herein, we investigate the effect of various gate widths on the accuracy of estimation of FRET parameters with focus on the near-infrared spectral window. Experiments were performed in silico, in vitro, and in vivo with gate width sizes ranging from 300 ps to 1000 ps in intervals of 100 ps. For all cases, the FRET parameters were retrieved accurately and the imaging acquisition time was decreased three-fold. These results indicate that increasing the gate width up to 1000 ps still allows for accurate quantification of FRET interactions even in the case of short lifetimes such as those encountered with near-infrared FRET pairs.
关键词： fluorescence lifetime,F?rster Resonance Energy Transfer (FRET),gated ICCD,near infrared (NIR) dyes,time-resolved imaging,gate width,in vivo imaging
更新于2025-09-10 09:29:36
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Metabolic imaging with the use of?fluorescence lifetime imaging microscopy (FLIM) accurately detects mitochondrial dysfunction in?mouse oocytes
摘要： To determine whether metabolic imaging with the use of fluorescence lifetime imaging microscopy (FLIM) identifies metabolic differences between normal oocytes and those with metabolic dysfunction. Experimental study. Academic research laboratories. None. Oocytes from mice with global knockout of Clpp (caseinolytic peptidase P; n ? 52) were compared with wild-type (WT) oocytes (n ? 55) as a model of severe oocyte dysfunction. Oocytes from old mice (1 year old; n ? 29) were compared with oocytes from young mice (12 weeks old; n ? 35) as a model of mild oocyte dysfunction. FLIM was used to measure the naturally occurring nicotinamide adenine dinucleotide dehydrogenase (NADH) and flavin adenine dinucleotide (FAD) autofluorescence in individual oocytes. Eight metabolic parameters were obtained from each measurement (4 per fluorophore): short (t1) and long (t2) fluorescence lifetime, fluorescence intensity (I), and fraction of the molecule engaged with enzyme (F). Reactive oxygen species (ROS) levels and blastocyst development rates were measured to assess illumination safety. In Clpp-knockout oocytes compared with WT, FAD t1 and t2 were longer and I was higher, NADH t2 was longer, and F was lower. In old oocytes compared with young ones, FAD t1 was longer and I was lower, NADH t1 and t2 were shorter, and I and F were lower. FLIM did not affect ROS levels or blastocyst development rates. FLIM parameters exhibit strong differentiation between Clpp-knockout versus WT, and old versus young oocytes. FLIM could potentially be used as a noninvasive tool to assess mitochondrial function in oocytes.
关键词： Mitochondria,aging,mitochondrial unfolded protein response,fluorescence lifetime imaging microscopy,CLPP,FLIM,oocyte
更新于2025-09-10 09:29:36
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Fluorescent Chemosensor for Quantitation of Multiple Atmospheric Gases
摘要： Recently, the sensing and monitoring of gases from ambient as well as industrial sources has gained a great importance in order to ensure occupational hygiene, public health, and societal welfare. The development of new technologies for visualizing and detecting gases at trace levels is imperative for various applications. There exist several established traditional methods to detect different gases. In this article, we review the latest trends in the area of fluorescence sensing of gas molecules, which is a high sensitivity technique with minimum or negligible interferences. The gas sensors fabricated with the use of fluorescent nanoparticles as detecting elements possess special feature, like high surface-to-volume ratios, ultra sensitivity, enhanced selectivity, cost effectiveness, and fast response. The inherent properties of the related systems, e.g. a large fluorescence lifetime, nanoscale particle size and a tunable zeta potential, make it possible to devise fluorescent sensors with an attractive pathway of fluorescence ‘off–on’. Several fluorimetric methods are known to detect specific gases from the atmospheric gaseous samples with satisfactory detection results. Modern fluorescent gas sensors are did not cause interference from the co-pollutants thus making the fluorimetric sensing process to be quantitative as well as specific.
关键词： Atmospheric environmental sample,Fluorescent gas sensor,Job’s plot,Fluorescent organic nanoparticles,Analytical method,Fluorescence lifetime
更新于2025-09-04 15:30:14
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High Pressure effect on fluorescence lifetime <i>τ</i> for magnetic dipole <sup>5</sup> D <sub/>0</sub> → <sup>5</sup> F <sub/>1</sub> transitions in YAG:Eu <sup>3+</sup>
摘要： The fluorescence lifetime for magnetic dipole 5D0→7F1 transition in yttrium aluminum garnet doped with Eu3+ (YAG:Eu3+) crystal was studied under the pressure of up to 10.4 GPa at room temperature. The fluorescence lifetime τ (5D0→7F1 transition) slowly decreased with pressure. The pressure effect on τ (5D0→7F1 transition) was explained with a model which considered pressure effect on line position: inter-ionic distance, ion volume, molecular volume, ion polarizability, molecular polarizability, sample refractive index, and surrounding hydrostatic medium refractive index. The fluorescence lifetime τ calculated by the presented model was in close correspondence with the experimental values.
关键词： rare earth,fluorescence lifetime,YAG:Eu3+,optical properties,glass ceramics,High pressure
更新于2025-09-04 15:30:14
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[Methods in Molecular Biology] BCL-2 Family Proteins Volume 1877 (Methods and Protocols) || Rapid Imaging of BCL-2 Family Interactions in Live Cells Using FLIM-FRET
摘要： The Bcl-2 proteins control cell death via interchanging interactions within the Bcl-2 family. Fluorescence lifetime imaging microscopy (FLIM) is used to detect F?rster resonance energy transfer (FRET) between two fluorescent-fusion proteins in live cells. FLIM-FRET has been used to detect specific interactions and their disruption, for Bcl-2 family proteins. To date, this has been possible only in low throughput, due to the time required for serial data acquisition. We developed an automated optical system with eight parallel detectors for rapid and efficient data collection. Here we describe how to use this system for FLIM-FRET imaging of Bcl-2 family protein interactions in a 384-well plate format.
关键词： BH3 mimetic,FLIM Hyperspectral,FLIM-FRET,Bcl-2 family,mCerulean3,High throughput,Fluorescence lifetime imaging microscopy
更新于2025-09-04 15:30:14