Time-resolved flow cytometry(TRFC)was used to measure metabolic differences in estrogen receptor-positive breast cancer cells.This specialty cytometry technique measures fluorescence lifetimes as a single-cell paramet...Time-resolved flow cytometry(TRFC)was used to measure metabolic differences in estrogen receptor-positive breast cancer cells.This specialty cytometry technique measures fluorescence lifetimes as a single-cell parameter thereby providing a unique approach for high-throughput cell counting and screening.Differences in fluorescence lifetime were detected and this was associated with sensitivity to the commonly prescribed therapeutic tamoxifen.Differences in fluorescence lifetime are attributed to the binding states of the autofluorescent metabolite NAD(P)H.The function of NAD(P)H is well described and in general involves cycling from a reduced to oxidized state to facilitate electron transport for the conversion of pyruvate to lactate.NAD(P)H fluorescence lifetimes depend on the bound or unbound state of the metabolite,which also relates to metabolic transitions between oxidative phosphorylation and glycolysis.To determine if fundamental metabolic profiles differ for cells that are sensitive to tamoxifen compared to those that are resistant,large populations of MCF-7 breast cancer cells were screened and fluorescence lifetimes were quantified.Additionally,metabolic differences associated with tamoxifen sensitivity were measured with a Seahorse HS mini metabolic analyzer(Agilent Technologies Inc.Santa Clara,CA)and confocal imaging.Results show that tamoxifen-resistant breast cancer cells have increased utilization of glycolysis for energy production compared to tamoxifen-sensitive breast cancer cells.This work is impacting because it establishes an early step toward developing a reliable screening technology in which large cell censuses can be differentiated for drug sensitivity in a label-free fashion.展开更多
Hydroxyapatite luminescent nanocrystallines doped with 6 mol.%Tb^(3+)(Tb-HA)were prepared via chemical deposition method and calcined at different temperature,and the effects of calcinations temperature on the lumines...Hydroxyapatite luminescent nanocrystallines doped with 6 mol.%Tb^(3+)(Tb-HA)were prepared via chemical deposition method and calcined at different temperature,and the effects of calcinations temperature on the luminescence intensity and fluorescent lifetime were studied.TEM image of Tb-HA revealed that the shape of nanocrystallines changed from needle-like to short rod-like and sphere-like with the increase of calcinations temperature;while the particles sizes decreased from 190 nm to 110 nm.the crystallinity degree increased.the typical emission peaks attributed to Tb^(3+) ions were observed in emission spectra of 6 mol.%Tb-HA under 378 nm excitation.the luminescent intensity of Tb-HA,which showed the fluorescence quenching,firstly enhanced and then decreased at 700℃;while the fluorescent lifetime increased firstly and then decreased after 600℃.Furthermore,the ratio of intensity between 545 nm and 490 nm corresponding to electric-dipole and magnetic-dipole transition(I_(R):I_(O))increases firstly and then decreases,which revealed that the proportion of substitute type and site of Ca^(2+) ions by Tb^(3+) ions were helpful to realize the substitute process and functional structure design.展开更多
Fluorescence litime imaging(FLIM)is an effective noninvasive bioanalytical tol based onmeasuring fuorescent lifetime of fuorophores.A growing number of FLIM studies utilizes ge-netically engineered fluorescent protein...Fluorescence litime imaging(FLIM)is an effective noninvasive bioanalytical tol based onmeasuring fuorescent lifetime of fuorophores.A growing number of FLIM studies utilizes ge-netically engineered fluorescent proteins targeted to specific subcellular structures to probe localmolecular environment,which opens new directions in cell science.This paper highlights theunconventional applications of FLIM for studies of molecular processes in diverse organelles oflive cultured cells.展开更多
Absolute quantum yield （Ф） is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x（TTA）3phens are synthesized with the ratio of Gd3＋ dopant concentrati...Absolute quantum yield （Ф） is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x（TTA）3phens are synthesized with the ratio of Gd3＋ dopant concentration ranging from 10% to 90% to improve the absolute quantum yield. EuxGd1-x（TTA）3phens possess similar infrared and ultraviolet spectra, showing that they have similar molecular structures. The absolute emission quantum yields of EuxGd1-x（TTA）3phens are determined using a fluoromax-4 spectrofluorometer equipped with an integrating sphere. The fluorescence lifetimes of the EuxGd1-x（TTA）3phens are measured in the same experiment. It was found that both absolute quantum yields and fluorescence lifetimes of EuxGd1-x（TTA）3phens are of quasi-periodic variation with the change of the Gd3. dopant concentrations. The absolute quantum efficiency and fluorescence lifetime vary with respect to the Gd content in an opposite fashion, indicating that the rate of energy absorption by the EuxGd1-x（TTA）3phens and the conversion to light energy is critical for the absolute quantum efficiency. The radiative rate constant Kr and non-radiative rate constant Knr are calculated. The dependence of Kr and Knr on the Gd3＋ dopant concentrations is very similar to that of absolute quantum efficiency. The radiation rate constant Kr and absolute quantum efficiency have a linear relationship.展开更多
In the current study novel magnetic BiOBr-Gd^(3+)doped CoFe_(2)O_(4)heterojunction nanocomposites fabricated by chemical precipitation method for Acid Violet 7(AV 7)and Reactive Red 120(RR 120)dye degradation under su...In the current study novel magnetic BiOBr-Gd^(3+)doped CoFe_(2)O_(4)heterojunction nanocomposites fabricated by chemical precipitation method for Acid Violet 7(AV 7)and Reactive Red 120(RR 120)dye degradation under sunlight are presented.The samples were well characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),scanning electron microscopy(SEM),energy dispersive X-ray analysis(EDAX),UV-visible near infrared(NIR),photoluminescence(PL),TRF,EIS,Mott-Schottky,and BET analysis.X-ray diffractograms of BiOBr-Gd^(3+)doped CoFe_(2)O_(4)nanocomposites authenticate the formation of the composite composed of diffraction peaks of both BiOBr and Gd^(3+)doped CoFe_(2)O_(4)samples.Photoluminescence(PL),Time Resolved Fluorescence Spectrocopy(TRF)and Electrochemical Impedance Spectroscopy(EIS)investigations were explored to examine the transfer efficiency of photoinduced charge carriers.Among the synthesized materials,the BiOBr-Gd^(3+)doped CoFe_(2)O_(4)-2 nanocomposite presents superior degradation capability for RR 120 of 87.34%and AV 7 dyes of 98.41%.The apparent rate constant(k)value of 0.1317 min^(-1)for AV 7 is sixteen times higher and RR 120(0.0135 min^(-1))is 2 times higher than pristine BiOBr.The radical trapping experiments also proved the role of photogenerated h^(+),O_(2)·^(-),and·OH radicals in the degradation mechanism.The superior performance of BiOBr-Gd^(3+)doped CoFe_(2)O_(4)-2 is ascribed to the formation of the heterostructure,the in-built electric field,and energy-band alignment,which thermodynamically and kinetically favors the photoactivity and stability of the heterojunction.展开更多
The synthesis of fluorescent nanomaterials has received considerable attention due to the great potential of these materials for a wide range of applications, from chemical sensing through bioimaging to optoelectron- ...The synthesis of fluorescent nanomaterials has received considerable attention due to the great potential of these materials for a wide range of applications, from chemical sensing through bioimaging to optoelectron- ics. Herein, we report a facile and scalable approach to prepare fluorescent carbon dots （FCDs） via a one-pot reaction of citric acid with ethylenediamine at 150 ℃ under ambient air pressure. The resultant FCDs pos- sess an optical bandgap of 3.4 eV and exhibit strong excitation-wavelength-independent blue emission （λEm = 450 nm） under either one- or two-photon excitation. Owing to their low cytotoxicity and long fluorescence lifetime, these FCDs were successfully used as internalized fluorescent probes in human cancer cell lines （HeLa cells） for two-photon excited imaging of cells by fluorescence lifetime imaging microscopy with a high-contrast resolution. They were also homogenously mixed with commercial inks and used to draw fluo- rescent patterns on normal papers and on many other substrates （e.g., certain flexible plastic films, textiles, and clothes）. Thus, these nanomaterials are promising for use in solid-state fluorescent sensing, security labeling, and wearable optoelectronics.展开更多
Digestive tract tumors acount for 15%and 19.3%of the cancer incidence and deaths,respec-tively.Early detection of digestive tract tumors is crucial to the reduction of global cancer burden.Two-photon excitation fuores...Digestive tract tumors acount for 15%and 19.3%of the cancer incidence and deaths,respec-tively.Early detection of digestive tract tumors is crucial to the reduction of global cancer burden.Two-photon excitation fuorescence lifetime imaging microscopy(TP-FLIM)allows non-invasive,label free,three-dimensional,high-resolution imaging of living tisues with not only histological but also biochemical characterization ability in both qualitative and quantitative way.Benefiting from these advantages,this technology is protmising for clinical diagnosis of digestive tract tumors.In recent years,many efforts have'been made in this field and some remarkable progress has been achieved.In this paper,we overview the recent progress of TP-FLIM-based researches on digestive tract tumor detection.Among them,our latest results on the gastric cancer and esophageal cancer are elaborately depicted.Finally,we outlook and discuss the potential advantages and challenges of TP-FLIM in future clinical applications.展开更多
Compared with visible light,near infrared(NIR)light has deeper penetration in biological tisues.Three-photon fuorescence microscopy(3PFM)can effectively utilize the NIR excitation to obtain high-contrast images in the...Compared with visible light,near infrared(NIR)light has deeper penetration in biological tisues.Three-photon fuorescence microscopy(3PFM)can effectively utilize the NIR excitation to obtain high-contrast images in the deep tisue.However,the weak three photon fluorescence signals may be not well presented in the traditional fuorescence intensity imaging mode.Fluorescence lifetime of certain probes is insensitive to the intensity of the excitation laser.Moreover,fluorescence lifetimne imaging microscopy(FLIM)can detect weak signals by utilizing time correlated single photon counting(TCSPC)technique.Thus,it would be an improved strategy to combine the 3PFM imaging with the FLIM together.Herein,DCDPP-2TPA,a novel agegation-induced emission luminogen(AIEgen),was adopted as the fluorescent probes.The three-photon absorption cros-section of the AlEgen,which has a deep-red fluorescence emission,was proved to be large.DCDPP-2TPA nanoparticles were synthesized,and the three photon fluorescence lifetime of which was measured in water.Moreover,in vrivo thre-photon fuorescence lifetime microscopic imaging of a craniotomy mouse was conducted via a home made optical system.High contrast cerebrovascular images of different vertical depths were obtained and the maximun depth was about 600 pumn.Even reaching the depth of 600 pum,tiny capillary vessels as small as 1.9 pum could still be distinguished.The three photon fuorescence lifetimes of the capillaries in some representative images were in accord with that of DCDPP-2TPA nanoparticles in water.A vivid 3D reconstruction was further organized to present a wealth of lifetime information.In the future,the combination strategy of 3PFM and FLIM could be further applied in the brain functional imaging.展开更多
Fluorescence lifetime imaging microscopy(FLIM)is increasingly used in biomedicine,material science,chemistry,and other related research fields,because of its advantages of high specificity and sensitivity in monitorin...Fluorescence lifetime imaging microscopy(FLIM)is increasingly used in biomedicine,material science,chemistry,and other related research fields,because of its advantages of high specificity and sensitivity in monitoring cellular microenvironments,studying interaction between proteins,metabolic state,screening drugs and analyzing their efficacy,characterizing novel materials,and diagnosing early cancers.Understandably,there is a large interest in obtaining FLIM data within an acquisition time as short as possible.Consequently,there is currently a technology that advances towards faster and faster FLIM recording.However,the maximum speed of a recording technique is only part of the problerm.The acquisition time of a FLIM image is a complex function of many factors.These include the photon rate that can be obtained from the sample,the amount of information a technique extracts from the decay functions,the fficiency at which it determines fluorescence decay parameters from the recorded photons,the demands for the accuracy of these parameters,the number of pixels,and the lateral and axial resolutions that are obtained in biological materials.Starting from a discussion of the parameters which determine the acquisition time,this review will describe existing and emerging FLIM techniques and data analysis algo-rithms,and analyze their performance and recording speed in biological and biomedical applications.展开更多
Apoptosis is very important for the maintenance of cellular homeostasis and is closely related to the occurrence and treatment of many diseases.Mitochondria in cells play a crucial role in programmed cell death and re...Apoptosis is very important for the maintenance of cellular homeostasis and is closely related to the occurrence and treatment of many diseases.Mitochondria in cells play a crucial role in programmed cell death and redox processes.Nicotinamide adenine dinucleotide(NAD(P)H)is the primary producer of energy in mitochondria,changing NAD(P)H can directly reflect the physiological state of mitochondria.Therefore,NAD(P)H can be used to evaluate metabolic response.In this paper,we propose a noninvasive detection method that uses two-photon fluorescence lifetime imaging microscopy(TP-FLIM)to characterize apoptosis by observing the binding kinetics of cellular endogenous NAD(P)H.The result shows that the average fluorescence lifetime of NAD(P)H and the fluorescence lifetime of protein-bound NAD(P)H will be affected by the changing pH,serum content,and oxygen concentration in the cell culture environment,and by the treatment with reagents such as H2O2 and paclitaxel.Taxol(PTX).This noninvasive detection method realized the dynamic detection of cellular endogenous substances and the assessment of apoptosis.展开更多
Fluorescence lifetime(FLT)of fluorophores is sensitive to the changes in their surrounding microenvironment,and hence it can quantitatively reveal the physiological characterization of the tissue under investigation.F...Fluorescence lifetime(FLT)of fluorophores is sensitive to the changes in their surrounding microenvironment,and hence it can quantitatively reveal the physiological characterization of the tissue under investigation.Fluorescence lifetime imaging microscopy(FLIM)provides not only morphological but also functional information of the tisse by producing spatially resolved image of fuorophore lifetime,which can be used as a signature of disorder and/or malignancy in diseased tissues.In this paper,we begin by introducing the basic principle and common detection methods of FLIM.Then the recent advances in the FLIM-based diagnosis of three different skin cancers,including basal cell carcinoma(BCC),squamous cell carcinoma(SCC)and malignant melanoma(MM)are reviewed.Furthermore,the potential advantages of FLIM in skin cancer diagnosis and the challenges that may be faced in the future are prospected.展开更多
Fluorescence lifetime is not only associated with the molecular structure f fuorophores,but alsostrongly depends on the environment around them,which llows fuorescence lifetime imagingmicroscopy(FLIM)to be used as a t...Fluorescence lifetime is not only associated with the molecular structure f fuorophores,but alsostrongly depends on the environment around them,which llows fuorescence lifetime imagingmicroscopy(FLIM)to be used as a tool for precise measurement of the cell or tisue microenvironment,This review introduces the basic principle of fuorescence lifetime imagingtechnology and its application in clinical medicine,including research and diagnosis of diseases inskin,brain,eyes,mouth,bone,blood vessels and cavity organs,and drug evaluation.As anoninvasive,nontoxic and nonionizing radiation technique,FLIM demonstrates excellent per-formance with high sensitivity and specificity,which allows to determine precise position of thelesion and,thus,has good potential for application in biomedical research and clinical diagnosis.展开更多
The fluorescence lifetime of nicotinamide adenine dinucleotide(NADH),a key endogenous coenzyme and metabolic biomarker,can reflect the metabolic state of cells.To implement metabolic imaging of brain tissue at high re...The fluorescence lifetime of nicotinamide adenine dinucleotide(NADH),a key endogenous coenzyme and metabolic biomarker,can reflect the metabolic state of cells.To implement metabolic imaging of brain tissue at high resolution,we assembled a two-photon fluorescence lifetime imaging microscopy(FLIM)platform and verified the feasibility and stability of NADH-based two-photon FLIM in paraformaldehydefixed mouse cerebral slices.Furthermore,NADH based metabolic state oscillation was observed in cerebral nuclei suprachiasmatic nucleus(SCN).The free NADH fraction displayed a relatively lower level in the daytime than at the onset of night,and an ultradian oscillation at night was observed.Through the combination of high-resolution imaging and immunostaining data,the metabolic tendency of different cell types was detected after the first two hours of the day and at night.Thus,two-photon FLIM analysis of NADH in paraformaldehyde-fixed cerebral slices provides a high-resolution and label-free method to explore the metabolic state of deep brain regions.展开更多
Fluorescence lifetime and anisotropy has become a prevalent tool to detect the structure change and motility property of proteins. YgaP is the only membrane-integrated rhodanese in E. coli. The sulfur transfer process...Fluorescence lifetime and anisotropy has become a prevalent tool to detect the structure change and motility property of proteins. YgaP is the only membrane-integrated rhodanese in E. coli. The sulfur transfer process has been characterized by various studies. However, the mechanism of the outward transportation of SCN-remains unclear. In this work, we examined the fluorescence lifetime and anisotropy of site-specific incorporated unnatural amino acid 7-HC to study the conformational change of YgaP upon SCN-binding. We also compared the fluorescence changes between detergent-wrapped environment in DPC and intact native membrane environment in SMA. Our results suggested the presence of at least two different conformations in YgaP protein. Both the residues in the middle of TMH2 and the residues near extracellular side play important roles in the binding and/or output of SCN-. SMA is a good material to reflect the in situ conformation changes of protein than micelles.展开更多
Fluorescence microscopy, as a sensitive method to detect microenvironment of molecules, is widely used in protein conformation and dynamic studies in live cells. Fluorescence lifetime imaging microscopy（FLIM）, which...Fluorescence microscopy, as a sensitive method to detect microenvironment of molecules, is widely used in protein conformation and dynamic studies in live cells. Fluorescence lifetime imaging microscopy（FLIM）, which is independent of fluorophore concentrations, scattering and bleaching, is a suitable tool to analyze membrane proteins in a single cell. Ferroportin（FPN）, a multi-ion exporter in vertebrates, was modulated by metal ions with unknown mechanism. Herein, we fused green fluorescence protein on Cterminal of FPN（FPN-eGFP） and applied fluorescence lifetime to monitor conformation changes of FPN in a live cell. The fluorescence lifetime distribution showed a shift to shorter lifetime upon Mn^（2＋） treatment,suggesting a preference conformation of FPN in Mn^（2＋） exposure. It is also observed that the lifetime（rather than intensity） measurement was not strongly influenced by laser power. The observed fluorescence lifetime changes of FPN-eGFP upon Mn^（2＋） treatments indicated that extracellular metal ions can modulate FPN through conformation exchanges between several different states.展开更多
Octadecylamine was derivatized with dansyl chloride (5-dimethylaminonaphthalene-1-sulfonyl chloride) In order to simplify and understand the LB films of fluorescent probe labeling proteins. its monolayer and multilaye...Octadecylamine was derivatized with dansyl chloride (5-dimethylaminonaphthalene-1-sulfonyl chloride) In order to simplify and understand the LB films of fluorescent probe labeling proteins. its monolayer and multilayers in the absence and presence of stearic acid were deposited by LB technique. Fluorescence spectra and lifetimes of the fluorescent products were studied to elucidate the microenvironment of molecules in the LB films.展开更多
Due to photoluminescence intermittency of single tional exponential fluorescence lifetime analysis is colloidal quantum dots （QDs）, the tradinot perfect to characterize QDs＇ fluores- cent emission behavior. In this...Due to photoluminescence intermittency of single tional exponential fluorescence lifetime analysis is colloidal quantum dots （QDs）, the tradinot perfect to characterize QDs＇ fluores- cent emission behavior. In this work we used the time-tagged time-resolved （TTTR） mode to record the fluorescent photons from single QDs. We showed that this method is compatible with the traditional lifetime analysis. In addition, by constructing the trajectory over time and the distribution of average arrival time （AAT） of the fluorescent photons, inore details about the emission behavior of QDs were revealed.展开更多
Objective：To study the mitochondrial redox state in experimental animals to sensitively detect early signs of mitochondrial function in pathophysiologieal conditions, such as isehemia. Methods： Fluorescence of nieot...Objective：To study the mitochondrial redox state in experimental animals to sensitively detect early signs of mitochondrial function in pathophysiologieal conditions, such as isehemia. Methods： Fluorescence of nieotinamide adenine dinucleotide （phosphate） , or NAD（P）H, the principal electron donor in mitochondrial respiration responsible for vital ATP supply of cardiomyocytes, is studied for non-invasive fluorescent probing of the mitochondrial function. Examination of NAD （P）H fluorescence in living cardiomyocytes following excitation by UV-pulsed laser diode and detection by spectrally-resolved time-correlated single photon counting （TCSPC） , is based on the simultaneous measurement of the fluorescence spectra and lifetime. Results ： The dynamic characteristics of NAD （P） H fluorescence decay in living rat cardiomyocytes show that at least a 3-exponential decay model, with 0.4 - 0.7 ns, 1.2 - 1.9 ns and 8.0 - 13.0 ns lifetimes, is necessary to describe cardiomyocyte autofluorescenee （AF）. Decay-associated spectra （DSA） revealed the presence of 4 spectrally-distinct populations of NADH molecules in eardiomyocytes with spectral maximum at 470 nm for short-lifetime pool for the first time, and emission peaks at 450 nm, 470 nm and 490 nm for intermediate and long-lifetime pools. Increased mitochondrial NADH content ratio by ketone bodies enhanced the AF intensity, without the significant change in fluorescent lifetimes. Rotenone, the inhibitor of Complex I of the mitochondrial respiratory chain, increased AF and shortened the average fluorescence lifetime. Dinitrophenol （DNP）, an uncoupling agent of the mitochondrial oxidative phosphorylation, lowered AF,broadened the spectral shoulder at 520 nm and increased the average lifetime. These effects, comparable to the changes in the concentration and in the rate of dehydrogenation of NADH in vitro, were also examined under ischemia-mimetic conditions. Conclusion： Our findings anticipate a contribution of both conformational NADH changes and energy transfer from NADH to lipoamide dehydrogenase （LipDH）-bound flavins, to explain observed fluorescence kinetics. Presented spectrally resolved fluorescence lifetime approach provides promising new tool for analysis of mitochondrial NAD （P） H in living cardiomyocytes, and hence for investigation of energy metabolism and mitoehondrial dysfunction at a cellular level.展开更多
Fluorescence imaging in the second near-infrared window(NIR-II,900–1880 nm)with less scattering background in biological tissues has been combined with the confocal microscopic system for achieving deep in vivo imagi...Fluorescence imaging in the second near-infrared window(NIR-II,900–1880 nm)with less scattering background in biological tissues has been combined with the confocal microscopic system for achieving deep in vivo imaging with high spatial resolution.However,the traditional NIR-IIfluorescence confocal microscope with separate excitation focus and detection pinhole makes it possess low confocal e±ciency,as well as di±cultly to adjust.Two types of upgraded NIR-IIfluorescence confocal microscopes,sharing the same pinhole by excitation and emission focus,leading to higher confocal e±ciency,are built in this work.One type is-ber-pinhole-based confocal microscope applicable to CW laser excitation.It is constructed forfluorescence intensity imaging with large depth,high stabilization and low cost,which could replace multiphotonfluorescence microscopy in some applications(e.g.,cerebrovascular and hepatocellular imaging).The other type is air-pinhole-based confocal microscope applicable to femtosecond(fs)laser excitation.It can be employed not only for NIR-IIfluorescence intensity imaging,but also for multi-channelfluorescence lifetime imaging to recognize different structures with similarfluorescence spectrum.Moreover,it can be facilely combined with multiphotonfluorescence microscopy.A single fs pulsed laser is utilized to achieve up-conversion(visible multiphotonfluorescence)and down-conversion(NIR-II one-photonfluorescence)excitation simultaneously,extending imaging spectral channels,and thus facilitates multi-structure and multi-functional observation.展开更多
Er^(3+),Na^(+)co-doped CaF_(2) transparent ceramics with Er^(3+)dopant concentration of 3% and Na^(+) of 0%,0.5%,1.0%,1.5% and 2.0% were fabricated by the vacuum hot pressing method with 16 mm in diameter and 3 mm in ...Er^(3+),Na^(+)co-doped CaF_(2) transparent ceramics with Er^(3+)dopant concentration of 3% and Na^(+) of 0%,0.5%,1.0%,1.5% and 2.0% were fabricated by the vacuum hot pressing method with 16 mm in diameter and 3 mm in thickness.The average grain size of the obtained Er,Na∶CaF_(2) powders varied from 28 nm to 36 nm with the shape of sphere.The effects of Na^(+) doping on the transmittance,microstructure and spectral properties of Er^(3+)∶CaF_(2) transparent ceramics were investigated.The transmittance of all the obtained ceramic samples is above 84%in the wavelength of 1000 nm.The results show that after introducing Na^(+)into Er^(3+)∶CaF_(2) transparent ceramics,charge-neutralized Er^(3+)-Na^(+) structure formed which prevent Er^(3+) from clustering.The emission spectra of Er^(3+) in CaF_(2) transparent ceramics at around 1.5 and 2.7μm could be modulated by adjusting the concentration of Na^(+) and the near-infrared fluorescence lifetime at around 1.5μm increase with the increasing of Na^(+) concentration,reaching a maximum of 56.75 ms.展开更多
基金the National Institute of Health for supporting this research under grants NIH R35GM152076,NIH 1SC1GM127175-01,NIH T32GM148394.
文摘Time-resolved flow cytometry(TRFC)was used to measure metabolic differences in estrogen receptor-positive breast cancer cells.This specialty cytometry technique measures fluorescence lifetimes as a single-cell parameter thereby providing a unique approach for high-throughput cell counting and screening.Differences in fluorescence lifetime were detected and this was associated with sensitivity to the commonly prescribed therapeutic tamoxifen.Differences in fluorescence lifetime are attributed to the binding states of the autofluorescent metabolite NAD(P)H.The function of NAD(P)H is well described and in general involves cycling from a reduced to oxidized state to facilitate electron transport for the conversion of pyruvate to lactate.NAD(P)H fluorescence lifetimes depend on the bound or unbound state of the metabolite,which also relates to metabolic transitions between oxidative phosphorylation and glycolysis.To determine if fundamental metabolic profiles differ for cells that are sensitive to tamoxifen compared to those that are resistant,large populations of MCF-7 breast cancer cells were screened and fluorescence lifetimes were quantified.Additionally,metabolic differences associated with tamoxifen sensitivity were measured with a Seahorse HS mini metabolic analyzer(Agilent Technologies Inc.Santa Clara,CA)and confocal imaging.Results show that tamoxifen-resistant breast cancer cells have increased utilization of glycolysis for energy production compared to tamoxifen-sensitive breast cancer cells.This work is impacting because it establishes an early step toward developing a reliable screening technology in which large cell censuses can be differentiated for drug sensitivity in a label-free fashion.
基金The authors gratefully acknowledge the financial support of International S&T Cooperation Program of China(No.2009DFR50520)Natural Science Foundation of China(NO.51472151).
文摘Hydroxyapatite luminescent nanocrystallines doped with 6 mol.%Tb^(3+)(Tb-HA)were prepared via chemical deposition method and calcined at different temperature,and the effects of calcinations temperature on the luminescence intensity and fluorescent lifetime were studied.TEM image of Tb-HA revealed that the shape of nanocrystallines changed from needle-like to short rod-like and sphere-like with the increase of calcinations temperature;while the particles sizes decreased from 190 nm to 110 nm.the crystallinity degree increased.the typical emission peaks attributed to Tb^(3+) ions were observed in emission spectra of 6 mol.%Tb-HA under 378 nm excitation.the luminescent intensity of Tb-HA,which showed the fluorescence quenching,firstly enhanced and then decreased at 700℃;while the fluorescent lifetime increased firstly and then decreased after 600℃.Furthermore,the ratio of intensity between 545 nm and 490 nm corresponding to electric-dipole and magnetic-dipole transition(I_(R):I_(O))increases firstly and then decreases,which revealed that the proportion of substitute type and site of Ca^(2+) ions by Tb^(3+) ions were helpful to realize the substitute process and functional structure design.
基金supported by the National Basic Research Program of China(2015CB352005)the National Natural Science Foundation of China(61525503/61378091/61620106016)+2 种基金Guangdong Natural Science Foundation Innovation Team(2014A030312008)Hong Kong,Macao and Taiwan cooperation innovation platform and major projects of international cooperation in Colleges and Universities in Guangdong Province(2015KGJHZ002)Shenzhen Basic Research Project(JCYJ20150930104948169/JCYJ20160328144746940/GJHZ 20160226202139185).
文摘Fluorescence litime imaging(FLIM)is an effective noninvasive bioanalytical tol based onmeasuring fuorescent lifetime of fuorophores.A growing number of FLIM studies utilizes ge-netically engineered fluorescent proteins targeted to specific subcellular structures to probe localmolecular environment,which opens new directions in cell science.This paper highlights theunconventional applications of FLIM for studies of molecular processes in diverse organelles oflive cultured cells.
基金supported by the National Natural Science Foundation of China(No.50973003)Anhui Science and TechnologyProgram(Nos.KJ2012B135,KJ2012A217,KJ2012B136,KJ2011A210, 1301042112)+1 种基金Natural Science Foundation of Fuyang Normal College (Nos.2011HJJC02ZD,2011HJJC01ZD,2011HJJC04YB,2010FSKJ01ZD, 2013FSKJ03ZD)Incubator Fund of Scientific and Technological achievements of Fuyang Normal College(Nos.2013KJFH03, 2013KJFH01)
文摘Absolute quantum yield （Ф） is one of the most important parameters to evaluate the potential of novel materials. Lanthanide complexes EuxGd1-x（TTA）3phens are synthesized with the ratio of Gd3＋ dopant concentration ranging from 10% to 90% to improve the absolute quantum yield. EuxGd1-x（TTA）3phens possess similar infrared and ultraviolet spectra, showing that they have similar molecular structures. The absolute emission quantum yields of EuxGd1-x（TTA）3phens are determined using a fluoromax-4 spectrofluorometer equipped with an integrating sphere. The fluorescence lifetimes of the EuxGd1-x（TTA）3phens are measured in the same experiment. It was found that both absolute quantum yields and fluorescence lifetimes of EuxGd1-x（TTA）3phens are of quasi-periodic variation with the change of the Gd3. dopant concentrations. The absolute quantum efficiency and fluorescence lifetime vary with respect to the Gd content in an opposite fashion, indicating that the rate of energy absorption by the EuxGd1-x（TTA）3phens and the conversion to light energy is critical for the absolute quantum efficiency. The radiative rate constant Kr and non-radiative rate constant Knr are calculated. The dependence of Kr and Knr on the Gd3＋ dopant concentrations is very similar to that of absolute quantum efficiency. The radiation rate constant Kr and absolute quantum efficiency have a linear relationship.
文摘In the current study novel magnetic BiOBr-Gd^(3+)doped CoFe_(2)O_(4)heterojunction nanocomposites fabricated by chemical precipitation method for Acid Violet 7(AV 7)and Reactive Red 120(RR 120)dye degradation under sunlight are presented.The samples were well characterized by X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),transmission electron microscopy(TEM),scanning electron microscopy(SEM),energy dispersive X-ray analysis(EDAX),UV-visible near infrared(NIR),photoluminescence(PL),TRF,EIS,Mott-Schottky,and BET analysis.X-ray diffractograms of BiOBr-Gd^(3+)doped CoFe_(2)O_(4)nanocomposites authenticate the formation of the composite composed of diffraction peaks of both BiOBr and Gd^(3+)doped CoFe_(2)O_(4)samples.Photoluminescence(PL),Time Resolved Fluorescence Spectrocopy(TRF)and Electrochemical Impedance Spectroscopy(EIS)investigations were explored to examine the transfer efficiency of photoinduced charge carriers.Among the synthesized materials,the BiOBr-Gd^(3+)doped CoFe_(2)O_(4)-2 nanocomposite presents superior degradation capability for RR 120 of 87.34%and AV 7 dyes of 98.41%.The apparent rate constant(k)value of 0.1317 min^(-1)for AV 7 is sixteen times higher and RR 120(0.0135 min^(-1))is 2 times higher than pristine BiOBr.The radical trapping experiments also proved the role of photogenerated h^(+),O_(2)·^(-),and·OH radicals in the degradation mechanism.The superior performance of BiOBr-Gd^(3+)doped CoFe_(2)O_(4)-2 is ascribed to the formation of the heterostructure,the in-built electric field,and energy-band alignment,which thermodynamically and kinetically favors the photoactivity and stability of the heterojunction.
文摘The synthesis of fluorescent nanomaterials has received considerable attention due to the great potential of these materials for a wide range of applications, from chemical sensing through bioimaging to optoelectron- ics. Herein, we report a facile and scalable approach to prepare fluorescent carbon dots （FCDs） via a one-pot reaction of citric acid with ethylenediamine at 150 ℃ under ambient air pressure. The resultant FCDs pos- sess an optical bandgap of 3.4 eV and exhibit strong excitation-wavelength-independent blue emission （λEm = 450 nm） under either one- or two-photon excitation. Owing to their low cytotoxicity and long fluorescence lifetime, these FCDs were successfully used as internalized fluorescent probes in human cancer cell lines （HeLa cells） for two-photon excited imaging of cells by fluorescence lifetime imaging microscopy with a high-contrast resolution. They were also homogenously mixed with commercial inks and used to draw fluo- rescent patterns on normal papers and on many other substrates （e.g., certain flexible plastic films, textiles, and clothes）. Thus, these nanomaterials are promising for use in solid-state fluorescent sensing, security labeling, and wearable optoelectronics.
基金supports from the National Key Research and Development Program of China(2017YFC0110200)Program 973(2015CB755502)+4 种基金the National Natural Science Foundation of China(NSFC)(81571724,81701744,81822023)the Natural Science Foundation of Guangdong Province(2014A030312006,2017A 030310308)the Scientific Instrument Innovation Team of Chinese Academy of Sciences(GJJSTD 20180002)the Shenzhen Science and Technology Program(JCYJ20170818164343304,JCYJ20170818155006471,JCYJ20160608214524052,JCYJ20180507182432303)the SIAT Innovation Program for Excellent Young Researchers(201821).
文摘Digestive tract tumors acount for 15%and 19.3%of the cancer incidence and deaths,respec-tively.Early detection of digestive tract tumors is crucial to the reduction of global cancer burden.Two-photon excitation fuorescence lifetime imaging microscopy(TP-FLIM)allows non-invasive,label free,three-dimensional,high-resolution imaging of living tisues with not only histological but also biochemical characterization ability in both qualitative and quantitative way.Benefiting from these advantages,this technology is protmising for clinical diagnosis of digestive tract tumors.In recent years,many efforts have'been made in this field and some remarkable progress has been achieved.In this paper,we overview the recent progress of TP-FLIM-based researches on digestive tract tumor detection.Among them,our latest results on the gastric cancer and esophageal cancer are elaborately depicted.Finally,we outlook and discuss the potential advantages and challenges of TP-FLIM in future clinical applications.
基金supported by National Natural Science Foundation of China(61735016)Zhejiang Provincial Natural Science Foundation of China(LR17F050001).
文摘Compared with visible light,near infrared(NIR)light has deeper penetration in biological tisues.Three-photon fuorescence microscopy(3PFM)can effectively utilize the NIR excitation to obtain high-contrast images in the deep tisue.However,the weak three photon fluorescence signals may be not well presented in the traditional fuorescence intensity imaging mode.Fluorescence lifetime of certain probes is insensitive to the intensity of the excitation laser.Moreover,fluorescence lifetimne imaging microscopy(FLIM)can detect weak signals by utilizing time correlated single photon counting(TCSPC)technique.Thus,it would be an improved strategy to combine the 3PFM imaging with the FLIM together.Herein,DCDPP-2TPA,a novel agegation-induced emission luminogen(AIEgen),was adopted as the fluorescent probes.The three-photon absorption cros-section of the AlEgen,which has a deep-red fluorescence emission,was proved to be large.DCDPP-2TPA nanoparticles were synthesized,and the three photon fluorescence lifetime of which was measured in water.Moreover,in vrivo thre-photon fuorescence lifetime microscopic imaging of a craniotomy mouse was conducted via a home made optical system.High contrast cerebrovascular images of different vertical depths were obtained and the maximun depth was about 600 pumn.Even reaching the depth of 600 pum,tiny capillary vessels as small as 1.9 pum could still be distinguished.The three photon fuorescence lifetimes of the capillaries in some representative images were in accord with that of DCDPP-2TPA nanoparticles in water.A vivid 3D reconstruction was further organized to present a wealth of lifetime information.In the future,the combination strategy of 3PFM and FLIM could be further applied in the brain functional imaging.
基金support from the National Key R&D Program of China(2017YFA0700500)National Natural Science Foundation of China(61775144/61525503/61620106016/61835009/81727804)+2 种基金(Key)Project of Department of Education of Guangdong Province(2015KGJHZ002/2016KCXTD007)Guangdong Natural Science Foundation(2014A030312008,2017A030310132,2018A030313362)Shenzhen Basic Research Project(JCYJ20170818144012025/JCYJ20170818141701667/JCYJ20170412105003520/JCYJ20150930104948169).
文摘Fluorescence lifetime imaging microscopy(FLIM)is increasingly used in biomedicine,material science,chemistry,and other related research fields,because of its advantages of high specificity and sensitivity in monitoring cellular microenvironments,studying interaction between proteins,metabolic state,screening drugs and analyzing their efficacy,characterizing novel materials,and diagnosing early cancers.Understandably,there is a large interest in obtaining FLIM data within an acquisition time as short as possible.Consequently,there is currently a technology that advances towards faster and faster FLIM recording.However,the maximum speed of a recording technique is only part of the problerm.The acquisition time of a FLIM image is a complex function of many factors.These include the photon rate that can be obtained from the sample,the amount of information a technique extracts from the decay functions,the fficiency at which it determines fluorescence decay parameters from the recorded photons,the demands for the accuracy of these parameters,the number of pixels,and the lateral and axial resolutions that are obtained in biological materials.Starting from a discussion of the parameters which determine the acquisition time,this review will describe existing and emerging FLIM techniques and data analysis algo-rithms,and analyze their performance and recording speed in biological and biomedical applications.
基金supported in part by the National Key R&D Program of China(2017YFA0700402)National Natural Science Foundation of China(61961136005/61935012/62175163/61835009)+1 种基金Shenzhen Key projects(JCYJ20200109105404067)Shenzhen International Cooperation Project(GJHZ 20190822095420249).
文摘Apoptosis is very important for the maintenance of cellular homeostasis and is closely related to the occurrence and treatment of many diseases.Mitochondria in cells play a crucial role in programmed cell death and redox processes.Nicotinamide adenine dinucleotide(NAD(P)H)is the primary producer of energy in mitochondria,changing NAD(P)H can directly reflect the physiological state of mitochondria.Therefore,NAD(P)H can be used to evaluate metabolic response.In this paper,we propose a noninvasive detection method that uses two-photon fluorescence lifetime imaging microscopy(TP-FLIM)to characterize apoptosis by observing the binding kinetics of cellular endogenous NAD(P)H.The result shows that the average fluorescence lifetime of NAD(P)H and the fluorescence lifetime of protein-bound NAD(P)H will be affected by the changing pH,serum content,and oxygen concentration in the cell culture environment,and by the treatment with reagents such as H2O2 and paclitaxel.Taxol(PTX).This noninvasive detection method realized the dynamic detection of cellular endogenous substances and the assessment of apoptosis.
基金supported by The 111 Project(B17035)Open Research Fund Program of the State Key Laboratory of Low Dimensional Quantum Physics(KF201713)+1 种基金State Key Laboratory of Transient Optics and Photonics,Chinese Academy of Sciences(SKLST201804)the Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province(GD201711).
文摘Fluorescence lifetime(FLT)of fluorophores is sensitive to the changes in their surrounding microenvironment,and hence it can quantitatively reveal the physiological characterization of the tissue under investigation.Fluorescence lifetime imaging microscopy(FLIM)provides not only morphological but also functional information of the tisse by producing spatially resolved image of fuorophore lifetime,which can be used as a signature of disorder and/or malignancy in diseased tissues.In this paper,we begin by introducing the basic principle and common detection methods of FLIM.Then the recent advances in the FLIM-based diagnosis of three different skin cancers,including basal cell carcinoma(BCC),squamous cell carcinoma(SCC)and malignant melanoma(MM)are reviewed.Furthermore,the potential advantages of FLIM in skin cancer diagnosis and the challenges that may be faced in the future are prospected.
基金funded by the Science and Technology Planning Fundamental Research Project of Shenzhen(No.JCYJ20150324140036853)National Natural Science Foundation of China(No.61378091)+1 种基金Ningbo Natural Science Foundation Project(No.2016A610032)the Central University Basic Scientic Research Business Expenses Project(No.NSIY051405).
文摘Fluorescence lifetime is not only associated with the molecular structure f fuorophores,but alsostrongly depends on the environment around them,which llows fuorescence lifetime imagingmicroscopy(FLIM)to be used as a tool for precise measurement of the cell or tisue microenvironment,This review introduces the basic principle of fuorescence lifetime imagingtechnology and its application in clinical medicine,including research and diagnosis of diseases inskin,brain,eyes,mouth,bone,blood vessels and cavity organs,and drug evaluation.As anoninvasive,nontoxic and nonionizing radiation technique,FLIM demonstrates excellent per-formance with high sensitivity and specificity,which allows to determine precise position of thelesion and,thus,has good potential for application in biomedical research and clinical diagnosis.
基金supported by the National Key R&D Program of China(Nos.2016YFA0400900 and 2017YFA0505301)National Natural Science Foundation of China(No.U1832181)。
文摘The fluorescence lifetime of nicotinamide adenine dinucleotide(NADH),a key endogenous coenzyme and metabolic biomarker,can reflect the metabolic state of cells.To implement metabolic imaging of brain tissue at high resolution,we assembled a two-photon fluorescence lifetime imaging microscopy(FLIM)platform and verified the feasibility and stability of NADH-based two-photon FLIM in paraformaldehydefixed mouse cerebral slices.Furthermore,NADH based metabolic state oscillation was observed in cerebral nuclei suprachiasmatic nucleus(SCN).The free NADH fraction displayed a relatively lower level in the daytime than at the onset of night,and an ultradian oscillation at night was observed.Through the combination of high-resolution imaging and immunostaining data,the metabolic tendency of different cell types was detected after the first two hours of the day and at night.Thus,two-photon FLIM analysis of NADH in paraformaldehyde-fixed cerebral slices provides a high-resolution and label-free method to explore the metabolic state of deep brain regions.
基金supported by the National Key R&D Program of China (Nos. 2016YFA0400900, 2017YFA0505300)the Instrument Developing Project of the Chinese Academy of Sciences (No. YZ201564)
文摘Fluorescence lifetime and anisotropy has become a prevalent tool to detect the structure change and motility property of proteins. YgaP is the only membrane-integrated rhodanese in E. coli. The sulfur transfer process has been characterized by various studies. However, the mechanism of the outward transportation of SCN-remains unclear. In this work, we examined the fluorescence lifetime and anisotropy of site-specific incorporated unnatural amino acid 7-HC to study the conformational change of YgaP upon SCN-binding. We also compared the fluorescence changes between detergent-wrapped environment in DPC and intact native membrane environment in SMA. Our results suggested the presence of at least two different conformations in YgaP protein. Both the residues in the middle of TMH2 and the residues near extracellular side play important roles in the binding and/or output of SCN-. SMA is a good material to reflect the in situ conformation changes of protein than micelles.
基金supported by the National Key R&D Program of China (Nos. 2016YFA0400900, 2017YFA0505300)the Instrument Developing Project of the Chinese Academy of Sciences (No. YZ201564)
文摘Fluorescence microscopy, as a sensitive method to detect microenvironment of molecules, is widely used in protein conformation and dynamic studies in live cells. Fluorescence lifetime imaging microscopy（FLIM）, which is independent of fluorophore concentrations, scattering and bleaching, is a suitable tool to analyze membrane proteins in a single cell. Ferroportin（FPN）, a multi-ion exporter in vertebrates, was modulated by metal ions with unknown mechanism. Herein, we fused green fluorescence protein on Cterminal of FPN（FPN-eGFP） and applied fluorescence lifetime to monitor conformation changes of FPN in a live cell. The fluorescence lifetime distribution showed a shift to shorter lifetime upon Mn^（2＋） treatment,suggesting a preference conformation of FPN in Mn^（2＋） exposure. It is also observed that the lifetime（rather than intensity） measurement was not strongly influenced by laser power. The observed fluorescence lifetime changes of FPN-eGFP upon Mn^（2＋） treatments indicated that extracellular metal ions can modulate FPN through conformation exchanges between several different states.
基金the National Natural Science Foundation of China (296333010) and The President Science Foundation of the Chinese Academy of Scie
文摘Octadecylamine was derivatized with dansyl chloride (5-dimethylaminonaphthalene-1-sulfonyl chloride) In order to simplify and understand the LB films of fluorescent probe labeling proteins. its monolayer and multilayers in the absence and presence of stearic acid were deposited by LB technique. Fluorescence spectra and lifetimes of the fluorescent products were studied to elucidate the microenvironment of molecules in the LB films.
基金supported by the National Science Foundation CAREER award(CHE-1554800)
文摘Due to photoluminescence intermittency of single tional exponential fluorescence lifetime analysis is colloidal quantum dots （QDs）, the tradinot perfect to characterize QDs＇ fluores- cent emission behavior. In this work we used the time-tagged time-resolved （TTTR） mode to record the fluorescent photons from single QDs. We showed that this method is compatible with the traditional lifetime analysis. In addition, by constructing the trajectory over time and the distribution of average arrival time （AAT） of the fluorescent photons, inore details about the emission behavior of QDs were revealed.
基金Canadian Institute for Health Researchgrant number:MOP74600+3 种基金Canadian Foundation for Innovationgrant number:N°9b84Groupe de Recherche Universitaire sur Mdicament grant to AC,FRSQ-NSFCgrant number:N°5540
文摘Objective：To study the mitochondrial redox state in experimental animals to sensitively detect early signs of mitochondrial function in pathophysiologieal conditions, such as isehemia. Methods： Fluorescence of nieotinamide adenine dinucleotide （phosphate） , or NAD（P）H, the principal electron donor in mitochondrial respiration responsible for vital ATP supply of cardiomyocytes, is studied for non-invasive fluorescent probing of the mitochondrial function. Examination of NAD （P）H fluorescence in living cardiomyocytes following excitation by UV-pulsed laser diode and detection by spectrally-resolved time-correlated single photon counting （TCSPC） , is based on the simultaneous measurement of the fluorescence spectra and lifetime. Results ： The dynamic characteristics of NAD （P） H fluorescence decay in living rat cardiomyocytes show that at least a 3-exponential decay model, with 0.4 - 0.7 ns, 1.2 - 1.9 ns and 8.0 - 13.0 ns lifetimes, is necessary to describe cardiomyocyte autofluorescenee （AF）. Decay-associated spectra （DSA） revealed the presence of 4 spectrally-distinct populations of NADH molecules in eardiomyocytes with spectral maximum at 470 nm for short-lifetime pool for the first time, and emission peaks at 450 nm, 470 nm and 490 nm for intermediate and long-lifetime pools. Increased mitochondrial NADH content ratio by ketone bodies enhanced the AF intensity, without the significant change in fluorescent lifetimes. Rotenone, the inhibitor of Complex I of the mitochondrial respiratory chain, increased AF and shortened the average fluorescence lifetime. Dinitrophenol （DNP）, an uncoupling agent of the mitochondrial oxidative phosphorylation, lowered AF,broadened the spectral shoulder at 520 nm and increased the average lifetime. These effects, comparable to the changes in the concentration and in the rate of dehydrogenation of NADH in vitro, were also examined under ischemia-mimetic conditions. Conclusion： Our findings anticipate a contribution of both conformational NADH changes and energy transfer from NADH to lipoamide dehydrogenase （LipDH）-bound flavins, to explain observed fluorescence kinetics. Presented spectrally resolved fluorescence lifetime approach provides promising new tool for analysis of mitochondrial NAD （P） H in living cardiomyocytes, and hence for investigation of energy metabolism and mitoehondrial dysfunction at a cellular level.
基金supported by National Natural Science Foundation of China(61975172,82001874 and 61735016).
文摘Fluorescence imaging in the second near-infrared window(NIR-II,900–1880 nm)with less scattering background in biological tissues has been combined with the confocal microscopic system for achieving deep in vivo imaging with high spatial resolution.However,the traditional NIR-IIfluorescence confocal microscope with separate excitation focus and detection pinhole makes it possess low confocal e±ciency,as well as di±cultly to adjust.Two types of upgraded NIR-IIfluorescence confocal microscopes,sharing the same pinhole by excitation and emission focus,leading to higher confocal e±ciency,are built in this work.One type is-ber-pinhole-based confocal microscope applicable to CW laser excitation.It is constructed forfluorescence intensity imaging with large depth,high stabilization and low cost,which could replace multiphotonfluorescence microscopy in some applications(e.g.,cerebrovascular and hepatocellular imaging).The other type is air-pinhole-based confocal microscope applicable to femtosecond(fs)laser excitation.It can be employed not only for NIR-IIfluorescence intensity imaging,but also for multi-channelfluorescence lifetime imaging to recognize different structures with similarfluorescence spectrum.Moreover,it can be facilely combined with multiphotonfluorescence microscopy.A single fs pulsed laser is utilized to achieve up-conversion(visible multiphotonfluorescence)and down-conversion(NIR-II one-photonfluorescence)excitation simultaneously,extending imaging spectral channels,and thus facilitates multi-structure and multi-functional observation.
基金National Key R&D Program of China(2023YFB3507400)。
文摘Er^(3+),Na^(+)co-doped CaF_(2) transparent ceramics with Er^(3+)dopant concentration of 3% and Na^(+) of 0%,0.5%,1.0%,1.5% and 2.0% were fabricated by the vacuum hot pressing method with 16 mm in diameter and 3 mm in thickness.The average grain size of the obtained Er,Na∶CaF_(2) powders varied from 28 nm to 36 nm with the shape of sphere.The effects of Na^(+) doping on the transmittance,microstructure and spectral properties of Er^(3+)∶CaF_(2) transparent ceramics were investigated.The transmittance of all the obtained ceramic samples is above 84%in the wavelength of 1000 nm.The results show that after introducing Na^(+)into Er^(3+)∶CaF_(2) transparent ceramics,charge-neutralized Er^(3+)-Na^(+) structure formed which prevent Er^(3+) from clustering.The emission spectra of Er^(3+) in CaF_(2) transparent ceramics at around 1.5 and 2.7μm could be modulated by adjusting the concentration of Na^(+) and the near-infrared fluorescence lifetime at around 1.5μm increase with the increasing of Na^(+) concentration,reaching a maximum of 56.75 ms.
