Triple-negative breast cancer (TNBC) is an aggressive and often fatal disease, especially since the brain metastasis of TNBC has been a particularly severe manifestation. However, brain metastasis in TNBC at early sta...Triple-negative breast cancer (TNBC) is an aggressive and often fatal disease, especially since the brain metastasis of TNBC has been a particularly severe manifestation. However, brain metastasis in TNBC at early stages often lacks noticeable symptoms, making it challenging to detect. Near-infrared II (NIR-II) fluorescence microscopic imaging obtains long wavelength, which enables reduced scattering, high spatial resolution and minimal autofluorescence, it is also a favorable imaging method for tumor diagnosis. PbS@CdS quantum dots (QDs) are one of the popular NIR-II fluorescence nanoprobes for well brightness. In this study, NIR-II emissive PbS@CdS QDs were utilized and further encapsulated with thiol-terminated poly(ethylene oxide) (SH-PEG, MW = 5000) to form PbS@CdS@PEG QDs nanoparticles (NPs). The obtained PbS@CdS@PEG QDs NPs were then characterized and further studied in detail. The PbS@CdS@PEG QDs NPs had large absorption spectra, exhibited strong NIR-II fluorescence emission at approximately 1300nm, and possessed good NIR-II fluorescence properties. Then, the mice model of early-stage brain metastases of TNBC was established, and the PbS@CdS@PEG QDs NPs were injected into the tumor-bearing mice for NIR-II fluorescence microscopic bioimaging. The brain vessels and tumors of the living mice were detected with high spatial resolution under the NIR-II fluorescence microscopic imaging system with irradiation of 808nm laser. The tumor tissues were further restricted and prepared as thin slices. The NIR-II fluorescence signals were collected from the tumor slices with high spatial resolution and signal-to-background ratio (SBR). Thus, the PbS@CdS@PEG QDs NPs-assisted NIR-II fluorescence microscopic system can effectively achieve targeting brain metastases of TNBC imaging, offering a novel and promising approach for TNBC-specific diagnosis.展开更多
The leaf structure, content and the storage location of aloin in the leaves of six species of Aloe L. were studied by means of semi-thin section, high performance liquid chromatography (HPLC) and fluorescent microscop...The leaf structure, content and the storage location of aloin in the leaves of six species of Aloe L. were studied by means of semi-thin section, high performance liquid chromatography (HPLC) and fluorescent microscope. Results showed that all leaves consisted of epidermis, chlorenchyma, aquiferous tissue and vascular bundles. The leaves had the xeromorphic characteristics, including thickened epidermal cell wall, thickened cuticle, sunken stomata and well-developed aquiferous tissue. With the exception of thus, there were remarkable differences in leaf structure among the six species. The chlorenchyma cells were similar to palisade tissues in Aloe arborescens Mill. and A. mutabilis Pillans, but isodiametric in A. vera L., A. vera L. var. chinensis Berg., A. saponaria Hawer and A. greenii Bali. A. arborescens, A. mutabilis, A. very and A. vera var. chinensis included large parenchymatous cells at the vascular bundles, whereas no such cells were observed at the vascular bundles of A. saponaria and A. greenii. In A. arborescens, A. mutabilis and A. vera, the aquiferous tissue sheaths were present and composed of a layer of small parenchymatous cells without chloroplasts around the aquiferous tissue. While there were no aquiferous tissue sheaths in A. vera var. chinensis, A. saponaria and A. greenii. The HPLC revealed that the content of aloin was high in A. arborescens, low in A. vera, and very low in A. saponaria among the six species. The fluorescent microscopy showed that the yellow-green globule only appeared in the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath, but not in the chlorenchyma and aquiferous tissue. Consequently, the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath were the storage location of aloin. They were positively correlated with the content of aloin.展开更多
A new multiphoton fluorescence microscope has been developed,offering cellular resolution across a large field of view deep within biological tissues.This opens new possibilities across a range of biological sciences,...A new multiphoton fluorescence microscope has been developed,offering cellular resolution across a large field of view deep within biological tissues.This opens new possibilities across a range of biological sciences,particularly within neuroscience where optical approaches can reveal signaling in real time throughout an extended network of cells distributed through the brain of an awake,behaving mouse.展开更多
Image restoration phase-filtering lateral superresolution confocal microscopy, a new approach, is proposed to achieve lateral superresolution using a confoeal microscope. This approach uses a lateral superresolution p...Image restoration phase-filtering lateral superresolution confocal microscopy, a new approach, is proposed to achieve lateral superresolution using a confoeal microscope. This approach uses a lateral superresolution pupil filter to preliminarily improve its lateral resolution and uses a siagle-image superresolution restoration technique based on a maximum likelihood estimate to further improve its lateral resolution. The new approach has the advantages of a low cost and the remarkable superresolution effect without excessive system complexity. Experiments indicate that the proposed approach can improve the lateral resolution of a confocal microscope from 0.3μm to less than 0.1 μm when λ = 632.8 nm and NA=0.85.展开更多
A critical function of flow cytometry is to count the concentration of blood cells,which helps in the diagnosis of certain diseases.However,the bulky nature of commercial flow cytometers makes such tests only availabl...A critical function of flow cytometry is to count the concentration of blood cells,which helps in the diagnosis of certain diseases.However,the bulky nature of commercial flow cytometers makes such tests only available in hospitals or laboratories,hindering the spread of point-of-care testing(POCT),especially in underdeveloped areas.Here,we propose a smart Palm-size Optofluidic Hematology Analyzer based on a miniature fluorescence microscope and a microfluidic platform to lighten the device to improve its portability.This gadget has a dimension of 35×30×80 mm and a mass of 39 g,less than 5%of the weight of commercially available flow cytometers.Additionally,automatic leukocyte concentration detection has been realized through the integration of image processing and leukocyte counting algorithms.We compared the leukocyte concentration measurement between our approach and a hemocytometer using the Passing-Bablok analysis and achieved a correlation coefficient of 0.979.Through Bland-Altman analysis,we obtained the relationship between their differences and mean measurement values and established 95%limits of agreement,ranging from−0.93×10^(3)to 0.94×10^(3)cells/μL.We anticipate that this device can be used widely for monitoring and treating diseases such as HIV and tumors beyond hospitals.展开更多
Since the solvent evaporation of a droplet on a hydrophobically pretreated glass slide, femtomole amount of fluorescent materials is carried by the evaporation and results in outward capillary flow to the perimeter of...Since the solvent evaporation of a droplet on a hydrophobically pretreated glass slide, femtomole amount of fluorescent materials is carried by the evaporation and results in outward capillary flow to the perimeter of the droplet spot where the solute deposits, and forms a fluorescent ring like deposit (RLD) with submicrometer-scale structures.展开更多
Background:Fluorescence Microscope is a promising analytical method for the examination of the sequence of strokes of writing inks of different colours,brands,and models in a questioned document.Aims and Objectives:In...Background:Fluorescence Microscope is a promising analytical method for the examination of the sequence of strokes of writing inks of different colours,brands,and models in a questioned document.Aims and Objectives:In the present article,an attempt has been made to categorize the writing inks of different brands and colours on the basis of their fluorescence.Materials and Methods:Atotal of 36 writing inks were used to make the different intersections on a standard A4 sheet which were then analyzed under the excitation filters of the Fluorescence Microscope.Results:The results indicated that the different inks can be characterized optically based on the luminescent components of the ink present in crossed lined intersections.Conclusions:Fluorescence Microscopy is a relatively simple,fast,inexpensive,and non-destructive technology that can be used in conjunction with other,more complex,and expensive technologies to identify the sequence of line crossing.It can provide a novel way of analysis based on the assessment of microelement analysis and the characteristics of diverse ink handwriting samples.展开更多
Recent experiments have shown that hole traps could be suppressed in polymer light-emitting diodes under current stress by diluting the light-emitting conjugated polymers within an“inert”large-bandgap host material....Recent experiments have shown that hole traps could be suppressed in polymer light-emitting diodes under current stress by diluting the light-emitting conjugated polymers within an“inert”large-bandgap host material.However,it is unclear why there is an enhanced dilution effect in partially miscible blends rather than fully miscible blends,as intuition would suggest that better miscibility leads to better dilution.In this work,we propose a cascade analysis by combining multiple fluorescence microscopic techniques and all-atom molecular dynamics simulations to study the solid-to-solid dilution of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene](MEH-PPV)inMEH-PPV/polystyrene(PS)blends and MEH-PPV/poly(vinylcarbazole)(PVK)blends.By varying the molecular weights of PS and PVK,we can regulate their miscibility with MEH-PPV.The results corroborate that the dilution effect is enhanced in partially miscible blends rather than fully miscible ones.This is because,in partially miscible blends undergoing phase separation,the concentration of MEH-PPV is notably decreased in the phase occupying the majority of the volume,leading to an overall greater dilution effect than in fully miscible blends.Moreover,MEH-PPV could adopt the more extended conformation in the fully miscible blend,causing a shorter intermolecular distance to further undermine the dilution effect.These findings explain the seemingly counterintuitive more effective dilution effect observed in the recently reported partially miscible blends and provide guidance for further enhancing the performance of future generations of polymer light-emitting diodes.展开更多
Stimulated emission depletion(STED) microscope is one of the most prominent super-resolution bio-imaging instruments, which holds great promise for ultrahigh-resolution imaging of cells. To construct a STED microscope...Stimulated emission depletion(STED) microscope is one of the most prominent super-resolution bio-imaging instruments, which holds great promise for ultrahigh-resolution imaging of cells. To construct a STED microscope, it is challenging to realize temporal synchronization between the excitation pulses and the depletion pulses. In this study, we present a simple and low-cost method to achieve pulse synchronization by using a condensed fluorescent dye as a depletion indicator. By using this method, almost all the confocal microscopes can be upgraded to a STED system without losing its original functions. After the pulse synchronization,our STED system achieved sub-100-nm resolution for fluorescent nanospheres and single-cell imaging.展开更多
MicroRNAs(miRNAs),especially exosomal miRNAs,are promising noninvasive biomarkers in early-stage cancer diagnosis and disease treatment monitoring.However,their precise and sensitive quantification remains challenging...MicroRNAs(miRNAs),especially exosomal miRNAs,are promising noninvasive biomarkers in early-stage cancer diagnosis and disease treatment monitoring.However,their precise and sensitive quantification remains challenging due to their small size and low abundance.Herein,we have developed a nanoparticle-confined DNA walker strategy for the specific detection of miRNA.In the existence of the target miRNA;the on-particle DNA walking reaction will be initiated,providing a fluorescence-positive nanoparticle.Otherwise,the nanoparticle would be fluorescence-negative.Utilizing the total internal reflection fluorescent microscope(TIRFM)to digitally count the fluorescence-positive nanoparticles,the proposed method possesses a detection limit of 0.2 pmol/L miRNA and can accurately distinguish the single-base mismatched target.This design combines the merits of the DNA walker for signal amplification and the TIRFM for highly sensitive detection,paving a new way for the digital counting-based analysis of exosomal miRNAs.展开更多
It is of great significance to study the brain structure and function in deep-tissue for neuroscience research and bio-medical applications because of the urgent demand for precise theranostics.Three-photon fluorescen...It is of great significance to study the brain structure and function in deep-tissue for neuroscience research and bio-medical applications because of the urgent demand for precise theranostics.Three-photon fluorescence microscopic(3PFM)bioimaging excited by the light in near-infrared IIb(NIR-IIb,1,500–1,700 nm)spectral region is one of the most promising imaging techniques with the advantages of high spatial resolution,large imaging depth,and reduced scattering.Herein,a type of NIR-IIb light excitable deep-red emissive semiconducting polymer dots(P-dots)with bright 3PF and large three-photon absorption cross-section(σ3)at 1,550 nm was prepared.Then the P-dots were functionalized with polystyrene polymer polystyrene graft ethylene oxide functionalized with carboxyl groups(PS-PEG-COOH)and modified with NH2-poly(ethylene glycol)(PEG)to synthesis photochemically stable and biocompatible P-dots nanoparticles(NPs).Further the P-dots NPs were utilized for in vivo 3PFM bioimaging of cerebral vasculature with and without the brain skull under 1,550 nm femtosecond(fs)laser excitation.In vivo 3PFM bioimaging of the mice cerebral vasculature at various vertical depths was obtained.Moreover,a vivid three-dimensional structure of the mice vascular architecture beneath the skull was reconstructed.At the depth of 350μm beneath the brain skull,3.8μm blood vessels could still be clearly recognized.NIR-IIb excitable P-dots assisted 3PFM bioimaging has great potential in accurate deep tissue bioimaging.展开更多
This study developed a method on detecting methyl viologen(paraquat)using a CdTe-paper-based visual sensor.The CdTe Qdots were immobilized on the paper using glycerin.The volume percentages of CdTe in glycerin were op...This study developed a method on detecting methyl viologen(paraquat)using a CdTe-paper-based visual sensor.The CdTe Qdots were immobilized on the paper using glycerin.The volume percentages of CdTe in glycerin were optimized to be 50%.The sensing principle is that the methyl viologen quenches the fluorescence intensity of CdTe Qdots in a concentration dependent manner.The sensor is linearly response to the logarithm concentration of the methyl viologen in the range from 0.39μmol/L to 3.89 mmol/L with a detection limit of 0.16μmol/L and the corre-lation coefficient R^(2) of 0.99.Three parallel experiments at the methyl viologen concentration of 38.89μmol/L give a relative error of 2.45%,which indicates a good reproducibility.The sensor is not disturbed by other pestisides in-cluding omethoate,anilofos,machete and glyphosate isopropylamine salt.The advantages of this sensor are dis-posable,stable,convenient,and easy to operate.展开更多
Detennining the sequence of document production and stamping is one of the most important issues in the field of questioned document identification.In China,whether a contract or a document is legal or not,highly depe...Detennining the sequence of document production and stamping is one of the most important issues in the field of questioned document identification.In China,whether a contract or a document is legal or not,highly depends on the relationship between the generation time of the document?s content and its stamping.Usually,a formal(legal)document would become effective once a seal is affixed,and normally,the content of the document is generated first and then subsequently stamped after being approved by the relevant personnel.Therefore,correctly identifying the sequence used to produce a document is necessary to detennine whether it is authentic or whether it may have been forged.However,because of the interference of many factors,the identification of such kind of forged documents has long been considered one of the most difficult technical issues in the field of questioned document identification.In this work,four nondestructive approaches to determine the order of photocopying and stamping were investigated:The stereomicroscope method,fluorescence microscopy,the three-dimensional pseudo-color method,and the contour ring method.Each method is associated with its own advantages and disadvantages,but all have been shown to produce some useful results relevant for determining the sequence of photocopying and stamping.展开更多
基金supported by the National Natural Science Foundation of China(NSFC)under Grant Nos.62035011,82202220 and 82060326State Key Laboratory of Pathogenesis,Prevention and treat ment of High Incident Diseases in central Asia(Nos.SKL-HIDCA-2022-3 and SKL-HIDCA-2022-GJ1)+3 种基金the Xinjiang Uygur Autonomous Region Regional Collaborative Innovation Special Science and Technology Assistance Program(No.2022E02130)Xinjiang Uygur Autonomous Region Natural Sci ence Foundation Key Project(No.2022D01D40)Outstanding Youth Project(2023D01E06)Y.Gao and C.Zhang authors contributed equally to this work.
文摘Triple-negative breast cancer (TNBC) is an aggressive and often fatal disease, especially since the brain metastasis of TNBC has been a particularly severe manifestation. However, brain metastasis in TNBC at early stages often lacks noticeable symptoms, making it challenging to detect. Near-infrared II (NIR-II) fluorescence microscopic imaging obtains long wavelength, which enables reduced scattering, high spatial resolution and minimal autofluorescence, it is also a favorable imaging method for tumor diagnosis. PbS@CdS quantum dots (QDs) are one of the popular NIR-II fluorescence nanoprobes for well brightness. In this study, NIR-II emissive PbS@CdS QDs were utilized and further encapsulated with thiol-terminated poly(ethylene oxide) (SH-PEG, MW = 5000) to form PbS@CdS@PEG QDs nanoparticles (NPs). The obtained PbS@CdS@PEG QDs NPs were then characterized and further studied in detail. The PbS@CdS@PEG QDs NPs had large absorption spectra, exhibited strong NIR-II fluorescence emission at approximately 1300nm, and possessed good NIR-II fluorescence properties. Then, the mice model of early-stage brain metastases of TNBC was established, and the PbS@CdS@PEG QDs NPs were injected into the tumor-bearing mice for NIR-II fluorescence microscopic bioimaging. The brain vessels and tumors of the living mice were detected with high spatial resolution under the NIR-II fluorescence microscopic imaging system with irradiation of 808nm laser. The tumor tissues were further restricted and prepared as thin slices. The NIR-II fluorescence signals were collected from the tumor slices with high spatial resolution and signal-to-background ratio (SBR). Thus, the PbS@CdS@PEG QDs NPs-assisted NIR-II fluorescence microscopic system can effectively achieve targeting brain metastases of TNBC imaging, offering a novel and promising approach for TNBC-specific diagnosis.
文摘The leaf structure, content and the storage location of aloin in the leaves of six species of Aloe L. were studied by means of semi-thin section, high performance liquid chromatography (HPLC) and fluorescent microscope. Results showed that all leaves consisted of epidermis, chlorenchyma, aquiferous tissue and vascular bundles. The leaves had the xeromorphic characteristics, including thickened epidermal cell wall, thickened cuticle, sunken stomata and well-developed aquiferous tissue. With the exception of thus, there were remarkable differences in leaf structure among the six species. The chlorenchyma cells were similar to palisade tissues in Aloe arborescens Mill. and A. mutabilis Pillans, but isodiametric in A. vera L., A. vera L. var. chinensis Berg., A. saponaria Hawer and A. greenii Bali. A. arborescens, A. mutabilis, A. very and A. vera var. chinensis included large parenchymatous cells at the vascular bundles, whereas no such cells were observed at the vascular bundles of A. saponaria and A. greenii. In A. arborescens, A. mutabilis and A. vera, the aquiferous tissue sheaths were present and composed of a layer of small parenchymatous cells without chloroplasts around the aquiferous tissue. While there were no aquiferous tissue sheaths in A. vera var. chinensis, A. saponaria and A. greenii. The HPLC revealed that the content of aloin was high in A. arborescens, low in A. vera, and very low in A. saponaria among the six species. The fluorescent microscopy showed that the yellow-green globule only appeared in the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath, but not in the chlorenchyma and aquiferous tissue. Consequently, the large parenchymatous cells of vascular bundles, vascular bundle sheath and aquiferous tissue sheath were the storage location of aloin. They were positively correlated with the content of aloin.
文摘A new multiphoton fluorescence microscope has been developed,offering cellular resolution across a large field of view deep within biological tissues.This opens new possibilities across a range of biological sciences,particularly within neuroscience where optical approaches can reveal signaling in real time throughout an extended network of cells distributed through the brain of an awake,behaving mouse.
基金Supported by the National Natural Science Foundation of China under Grant No 50475035, and the Research Fund for the Doctoral Programme of Higher Education of China under Grant No 20050213035.
文摘Image restoration phase-filtering lateral superresolution confocal microscopy, a new approach, is proposed to achieve lateral superresolution using a confoeal microscope. This approach uses a lateral superresolution pupil filter to preliminarily improve its lateral resolution and uses a siagle-image superresolution restoration technique based on a maximum likelihood estimate to further improve its lateral resolution. The new approach has the advantages of a low cost and the remarkable superresolution effect without excessive system complexity. Experiments indicate that the proposed approach can improve the lateral resolution of a confocal microscope from 0.3μm to less than 0.1 μm when λ = 632.8 nm and NA=0.85.
基金supported by the National Natural Science Foundation of China (grant no.62305083 to W.Z.,grant no.T2222009 to H.L.,grant no.32227802 to H.L.)China Postdoctoral Science Foundation (grant no.2023T160163 to W.Z.grant no.2022M720971 to W.Z.)+2 种基金the Heilongjiang Provincial Postdoctoral Science Foundation (grant no.LBH-Z22027 to W.Z.)the National Key Research and Development Program of China (grant no.2022YFC3400600 to H.L.)the Natural Science Foundation of Heilongjiang Province (grant no.YQ2021F013 to H.L.).
文摘A critical function of flow cytometry is to count the concentration of blood cells,which helps in the diagnosis of certain diseases.However,the bulky nature of commercial flow cytometers makes such tests only available in hospitals or laboratories,hindering the spread of point-of-care testing(POCT),especially in underdeveloped areas.Here,we propose a smart Palm-size Optofluidic Hematology Analyzer based on a miniature fluorescence microscope and a microfluidic platform to lighten the device to improve its portability.This gadget has a dimension of 35×30×80 mm and a mass of 39 g,less than 5%of the weight of commercially available flow cytometers.Additionally,automatic leukocyte concentration detection has been realized through the integration of image processing and leukocyte counting algorithms.We compared the leukocyte concentration measurement between our approach and a hemocytometer using the Passing-Bablok analysis and achieved a correlation coefficient of 0.979.Through Bland-Altman analysis,we obtained the relationship between their differences and mean measurement values and established 95%limits of agreement,ranging from−0.93×10^(3)to 0.94×10^(3)cells/μL.We anticipate that this device can be used widely for monitoring and treating diseases such as HIV and tumors beyond hospitals.
文摘Since the solvent evaporation of a droplet on a hydrophobically pretreated glass slide, femtomole amount of fluorescent materials is carried by the evaporation and results in outward capillary flow to the perimeter of the droplet spot where the solute deposits, and forms a fluorescent ring like deposit (RLD) with submicrometer-scale structures.
文摘Background:Fluorescence Microscope is a promising analytical method for the examination of the sequence of strokes of writing inks of different colours,brands,and models in a questioned document.Aims and Objectives:In the present article,an attempt has been made to categorize the writing inks of different brands and colours on the basis of their fluorescence.Materials and Methods:Atotal of 36 writing inks were used to make the different intersections on a standard A4 sheet which were then analyzed under the excitation filters of the Fluorescence Microscope.Results:The results indicated that the different inks can be characterized optically based on the luminescent components of the ink present in crossed lined intersections.Conclusions:Fluorescence Microscopy is a relatively simple,fast,inexpensive,and non-destructive technology that can be used in conjunction with other,more complex,and expensive technologies to identify the sequence of line crossing.It can provide a novel way of analysis based on the assessment of microelement analysis and the characteristics of diverse ink handwriting samples.
基金support from the National Natural Science Foundation of China(no.22073091)the National Key Research and Development Program of China(no.2021YFC2101700)+2 种基金the Youth Growth Science and Technology Program of Jilin Province(no.20220508023RC)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(no.ZDBS-LY-SLH033)the Technological Innovation Project of Instrument and Equipment Function Development,Chinese Academy of Sciences.
文摘Recent experiments have shown that hole traps could be suppressed in polymer light-emitting diodes under current stress by diluting the light-emitting conjugated polymers within an“inert”large-bandgap host material.However,it is unclear why there is an enhanced dilution effect in partially miscible blends rather than fully miscible blends,as intuition would suggest that better miscibility leads to better dilution.In this work,we propose a cascade analysis by combining multiple fluorescence microscopic techniques and all-atom molecular dynamics simulations to study the solid-to-solid dilution of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene](MEH-PPV)inMEH-PPV/polystyrene(PS)blends and MEH-PPV/poly(vinylcarbazole)(PVK)blends.By varying the molecular weights of PS and PVK,we can regulate their miscibility with MEH-PPV.The results corroborate that the dilution effect is enhanced in partially miscible blends rather than fully miscible ones.This is because,in partially miscible blends undergoing phase separation,the concentration of MEH-PPV is notably decreased in the phase occupying the majority of the volume,leading to an overall greater dilution effect than in fully miscible blends.Moreover,MEH-PPV could adopt the more extended conformation in the fully miscible blend,causing a shorter intermolecular distance to further undermine the dilution effect.These findings explain the seemingly counterintuitive more effective dilution effect observed in the recently reported partially miscible blends and provide guidance for further enhancing the performance of future generations of polymer light-emitting diodes.
基金supported by the National Natural Science Foundation of China (21227804, 21390414, 61378062, 21505148)National Key Research and Development Program (2016YFA0400902)the Natural Science Foundation of Shanghai (15ZR1448400, 14ZR1448000)
文摘Stimulated emission depletion(STED) microscope is one of the most prominent super-resolution bio-imaging instruments, which holds great promise for ultrahigh-resolution imaging of cells. To construct a STED microscope, it is challenging to realize temporal synchronization between the excitation pulses and the depletion pulses. In this study, we present a simple and low-cost method to achieve pulse synchronization by using a condensed fluorescent dye as a depletion indicator. By using this method, almost all the confocal microscopes can be upgraded to a STED system without losing its original functions. After the pulse synchronization,our STED system achieved sub-100-nm resolution for fluorescent nanospheres and single-cell imaging.
基金the National Natural Science Foundation of China(Nos.22074088 and 21904083)the Program for Changjiang Scholars and Innovative Research Team in University(IRT_15R43)the Fundamental Research Funds for the Central Universities(Nos.GK202003038,GK201901003,2020TS089,GK202101001).
文摘MicroRNAs(miRNAs),especially exosomal miRNAs,are promising noninvasive biomarkers in early-stage cancer diagnosis and disease treatment monitoring.However,their precise and sensitive quantification remains challenging due to their small size and low abundance.Herein,we have developed a nanoparticle-confined DNA walker strategy for the specific detection of miRNA.In the existence of the target miRNA;the on-particle DNA walking reaction will be initiated,providing a fluorescence-positive nanoparticle.Otherwise,the nanoparticle would be fluorescence-negative.Utilizing the total internal reflection fluorescent microscope(TIRFM)to digitally count the fluorescence-positive nanoparticles,the proposed method possesses a detection limit of 0.2 pmol/L miRNA and can accurately distinguish the single-base mismatched target.This design combines the merits of the DNA walker for signal amplification and the TIRFM for highly sensitive detection,paving a new way for the digital counting-based analysis of exosomal miRNAs.
基金This work was supported by the National Natural Science Foundation of China(Nos.61735016,61975172,and 91632105)Zhejiang Provincial Natural Science Foundation of China(Nos.LR17F050001 and LY17C090005)the Fundamental Research Funds for the Central Universities and State Key Laboratory of Pathogenesis,Prevention and Treatment of High Incidence Diseases in Central Asia Fund(No.SKL-HIDCA-2019-3).
文摘It is of great significance to study the brain structure and function in deep-tissue for neuroscience research and bio-medical applications because of the urgent demand for precise theranostics.Three-photon fluorescence microscopic(3PFM)bioimaging excited by the light in near-infrared IIb(NIR-IIb,1,500–1,700 nm)spectral region is one of the most promising imaging techniques with the advantages of high spatial resolution,large imaging depth,and reduced scattering.Herein,a type of NIR-IIb light excitable deep-red emissive semiconducting polymer dots(P-dots)with bright 3PF and large three-photon absorption cross-section(σ3)at 1,550 nm was prepared.Then the P-dots were functionalized with polystyrene polymer polystyrene graft ethylene oxide functionalized with carboxyl groups(PS-PEG-COOH)and modified with NH2-poly(ethylene glycol)(PEG)to synthesis photochemically stable and biocompatible P-dots nanoparticles(NPs).Further the P-dots NPs were utilized for in vivo 3PFM bioimaging of cerebral vasculature with and without the brain skull under 1,550 nm femtosecond(fs)laser excitation.In vivo 3PFM bioimaging of the mice cerebral vasculature at various vertical depths was obtained.Moreover,a vivid three-dimensional structure of the mice vascular architecture beneath the skull was reconstructed.At the depth of 350μm beneath the brain skull,3.8μm blood vessels could still be clearly recognized.NIR-IIb excitable P-dots assisted 3PFM bioimaging has great potential in accurate deep tissue bioimaging.
基金supported by the National Natural Science Foundation of China(Nos.21273059,21003032)the State Key Laboratory of Urban Water Resource and Environment(Harbin Institute of Tech-nology)(No.2014DX09)+1 种基金the Fundamental Research Funds for the Central Universities(No.HIT.KISTP.201407)Harbin Science and Technology Research Council(No.2014RFXXJ063).
文摘This study developed a method on detecting methyl viologen(paraquat)using a CdTe-paper-based visual sensor.The CdTe Qdots were immobilized on the paper using glycerin.The volume percentages of CdTe in glycerin were optimized to be 50%.The sensing principle is that the methyl viologen quenches the fluorescence intensity of CdTe Qdots in a concentration dependent manner.The sensor is linearly response to the logarithm concentration of the methyl viologen in the range from 0.39μmol/L to 3.89 mmol/L with a detection limit of 0.16μmol/L and the corre-lation coefficient R^(2) of 0.99.Three parallel experiments at the methyl viologen concentration of 38.89μmol/L give a relative error of 2.45%,which indicates a good reproducibility.The sensor is not disturbed by other pestisides in-cluding omethoate,anilofos,machete and glyphosate isopropylamine salt.The advantages of this sensor are dis-posable,stable,convenient,and easy to operate.
文摘Detennining the sequence of document production and stamping is one of the most important issues in the field of questioned document identification.In China,whether a contract or a document is legal or not,highly depends on the relationship between the generation time of the document?s content and its stamping.Usually,a formal(legal)document would become effective once a seal is affixed,and normally,the content of the document is generated first and then subsequently stamped after being approved by the relevant personnel.Therefore,correctly identifying the sequence used to produce a document is necessary to detennine whether it is authentic or whether it may have been forged.However,because of the interference of many factors,the identification of such kind of forged documents has long been considered one of the most difficult technical issues in the field of questioned document identification.In this work,four nondestructive approaches to determine the order of photocopying and stamping were investigated:The stereomicroscope method,fluorescence microscopy,the three-dimensional pseudo-color method,and the contour ring method.Each method is associated with its own advantages and disadvantages,but all have been shown to produce some useful results relevant for determining the sequence of photocopying and stamping.
