As a promising signaling transduction approach, fluorescence polarization(FP)/fluorescence anisotropy(FA), provides a powerful quantitative tool for the rotational motion of fluorescently labeled molecules in chemical...As a promising signaling transduction approach, fluorescence polarization(FP)/fluorescence anisotropy(FA), provides a powerful quantitative tool for the rotational motion of fluorescently labeled molecules in chemical or biological homogeneous systems. Unlike fluorescence intensity, FP/FA is almost independent the concentration or quantum of fluorophores, but they are highly dependent on the size or molecular weight of the molecules or materials attached to fluorophores. Recently, significant progress in FP/FA was made, due to the introduction of some nanomaterials as FP/FA enhancers. The detection sensitivity is thus greatly improved by using nanomaterials as FP/FA enhancers, and nanomaterial-based FP/FA is currently used successfully in immunoassay, and analysis of protein, nucleic acid, small molecule and metal ion.Nanomaterial-based FP/FA provides a new kind of strategy to design fluorescent sensors and establishes innovative analytical methods. In this review, we summarize the scientific publications in the field of FP/FA sensor in recent five years, and first introduce the recent progress of FP/FA sensor based on nanomaterial. Subsequently, the various analytical applications of FP/FA based on nanomaterial are discussed. Finally, we provide perspectives on the current challenges and future prospects in this promising field.展开更多
Fluorescence polarization is related to the dipole orientation of chromophores,making fuores-cence polarization microscopy possible to_reveal structures and functions of tagged cellularorganelles and biological macrom...Fluorescence polarization is related to the dipole orientation of chromophores,making fuores-cence polarization microscopy possible to_reveal structures and functions of tagged cellularorganelles and biological macromolecules.Several recent super resolution techniques have beenapplied to fluorescence polarization microscopy,achieving dipole measurement at nanoscale.In this review,we summarize both difraction limited and super resolution fluorescence polari-zation microscopy techniques,as well as their applications in biological imaging.展开更多
A fluorescence polarization immunoassay （FPIA） was developed for the analysis ofaflatoxins （AFs） using an anti-aflatoxin B1 （AFB1） monoclonal antibody and a novel fluorescein-labeled AFB1 tracer. The FPIA showed...A fluorescence polarization immunoassay （FPIA） was developed for the analysis ofaflatoxins （AFs） using an anti-aflatoxin B1 （AFB1） monoclonal antibody and a novel fluorescein-labeled AFB1 tracer. The FPIA showed an IC50 value of 23.33 ng/mL with a limit of detection of 13.12 ng/mL for AFB1. The cross-reactivities of AFB1, AFB2, AFG1, AFG2, AFM1, and AFM2 with the antibody were 100%, 65.7%, 143%, 23.5%, 111.4%, and 2%, respectively. The group-specificity of anti-AFB1mAb indicated that the FPIA could potentially be used in a screening method for the detection of total AFs, albeit not AFG2 and AFM2. The total time required for analyzing 96 samples in one microplate was less than 5 rain. This study demonstrates the potential usefulness of the FPIA as a rapid and simple technique for monitoring AFs.展开更多
Polarization variable-angle synchronous fluorescence spectrometry was proposed to determine samples in turbid solution. A mixture of fluorescein, rhodamine 6G and rhodamine B was used to evaluate the technique. The ba...Polarization variable-angle synchronous fluorescence spectrometry was proposed to determine samples in turbid solution. A mixture of fluorescein, rhodamine 6G and rhodamine B was used to evaluate the technique. The background caused by scattering light was decreased remarkably. The limits of detection were 0.6 ng/ml for fluorescein, 2.3 ng/ml for rhodamine 6G and 4.1 ng/ml for rhodamine B, respectively.展开更多
When measuring reflectance spectra, it is very important to accurately extract chlorophyll fluorescence from elastic-scattering light in water-leaving radiance. The elastic scattering of light by water particles produ...When measuring reflectance spectra, it is very important to accurately extract chlorophyll fluorescence from elastic-scattering light in water-leaving radiance. The elastic scattering of light by water particles produces partially polarized light. In contrast, chlorophyll fluorescence in planktonic algae yields completely unpolarized light. These properties can be used to separate fluorescent signals from the water-leaving radiance and thus to determine chlorophyll concentration. The algal species Aureococcus anophagefferens was used to conduct a laboratory polarization experiment. For the tests, we used a field spectroradiometer and a polarizer; measurements were collected using two different observation modes. The chlorophyll fluorescence curve extracted through polarization shows an excellent match with the results obtained using the fluorospectro photometer for both measurement modes, suggesting that polarization-based chlorophyll fluorescence extraction may be feasible. The extracted fluorescence is more reliable at incident zenith angles ranging from 30? to 60?. For algae-containing water, the results improve with increasing chlorophyll concentration. This method could help improve chlorophyll concentration measurement and the remote-sensing detection of resulting harmful algae blooms.展开更多
Objective: To develop a new high sensitivity, rapid and simple mycobacterium tuberculosis DNA detection method using fluorescence polarization technology. Methods: In our asymmetric PCR protocol, 100 times mole of TB-...Objective: To develop a new high sensitivity, rapid and simple mycobacterium tuberculosis DNA detection method using fluorescence polarization technology. Methods: In our asymmetric PCR protocol, 100 times mole of TB-R primer was added than in the usual symmetric PCR to get enough single strands PCR product. The probe TB-5′-TAMRA and PCR products were mixed in a tube and incubate for 5-15 min at 46 ℃.The polarization (mp) was measured using victor2 Multilabel Plate Reader. Results: Asymmetric and symmetric PCR products were analyzed by the FP method. Asymmetric PCR products are detected more sensitively than symmetric ones. The polarization values of probe associated with asymmetric products were much higher than with symmetric products. Conclusion: This fluorescence polarization assay in conjunction with asymmetric PCR is a powerful and widely applicable method for the rapid and sensitive detection of micro-organisms in clinical laboratories.展开更多
Objective: To develop a new method for the detection of TPMT gene mutations and determine the frequencies of four TPMT alleles, TPMT *1, *3A , *3B and *3C in a healthy Chinese population. Methods: A TDI-FP assay syste...Objective: To develop a new method for the detection of TPMT gene mutations and determine the frequencies of four TPMT alleles, TPMT *1, *3A , *3B and *3C in a healthy Chinese population. Methods: A TDI-FP assay system was set up in out lab. To evaluate this system, 220 healthy individuals were analyzed for the polymorphic sites at positions 460(G→A)and 719(A→G)of the TPMP gene using our new TDI–FP method. Results: Three TPMP*3C(G 460→G 719) heterozygotes were identified, TPMP *3A and TPMP *3B were not found. All mutations were confirmed by conventional DNA sequencing analysis. Conclusion: TDI-FP method has proven to be very efficient as a rapid and accurate approach for TPMP genotyping. TPMP *3C was the only polymorphism identified in this clinical samples we have registered.展开更多
Objective: Peroxisome proliferator-activated receptor -γ(PPAR-γ) plays a critical role in adipocyte differentiation and the development of type 2 diabetes mellitus (T2DM). Numerous studies across several populations...Objective: Peroxisome proliferator-activated receptor -γ(PPAR-γ) plays a critical role in adipocyte differentiation and the development of type 2 diabetes mellitus (T2DM). Numerous studies across several populations have indicated that Pro12Ala polymorphism of PPAR-γ is associated with decreased insulin resistance and decreased risk of T2DM. The aims of this study are to develop a simple and sensitive detection of Pro12Ala polymorphism and examined the distribution of this polymorphism in Chinese population. Methods: The PPAR-γ gene fragment containing Pro12Ala variant of 101 T2DM patients and 104 controls were amplified by PCR amplification and the extension reaction was performed using primer that adjacent to the single nucleotide polymorphic site in presence of two different dye-labeled terminators. The primer's specially extending reactions make the increase of their fluorescence polarization (FP) that mean special genotype. The variant frequencies of the two groups were compared. Results: We detected the Pro12Ala variant successfully by TDI-FP method and we found no significant association between this polymorphism and T2DM in case-control study. Conclusion: The TDI-FP technology is a new specific and sensitive method that is suitable for automatic detection of large number of clinical samples. Prol2Ala mutation in PPAR--@2 gene does not play a significant role in T2DM risk in Chinese population.展开更多
In this paper,we propose a new fluorescence emission difference microscopy(FED)technique based on polarization modulation.An electro-optical modulator(EOM)is used to switch the excitation beam between the horizontal a...In this paper,we propose a new fluorescence emission difference microscopy(FED)technique based on polarization modulation.An electro-optical modulator(EOM)is used to switch the excitation beam between the horizontal and vertical polarization states at a high frequency,which leads to solid-and donut-shaped beams after spatial light modulation.Experiment on the fluorescent nanoparticles demonstrates that the proposed method can achieve~λ=4 spatial resolution.Using the proposed system,the dynamic imaging of subcellular structures in living cells over time is achieved.展开更多
Purpose To propose a method for simultaneous fluorescence and Compton scattering computed tomography by using linearly polarized X-rays.Methods Monte Carlo simulations were adopted to demonstrate the feasibility of th...Purpose To propose a method for simultaneous fluorescence and Compton scattering computed tomography by using linearly polarized X-rays.Methods Monte Carlo simulations were adopted to demonstrate the feasibility of the proposed method.In the simulations,the phantom is a polytetrafluoroethylene cylinder inside which are cylindrical columns containing aluminum,water,and gold(Au)-loaded water solutions with Au concentrations ranging between 0.5 and 4.0 wt%,and a parallel-hole collimator imaging geometry was adopted.The light source was modeled based on a Thomson scattering X-ray source.The phantom images for both imaging modalities were reconstructed using a maximumlikelihood expectation maximization algorithm.Results Both the X-ray fluorescence computed tomography(XFCT)and Compton scattering computed tomography(CSCT)images of the phantom were accurately reconstructed.A similar attenuation contrast problem for the different cylindrical columns in the phantom can be resolved in the XFCT and CSCT images.The interplay between XFCT and CSCT was analyzed,and the contrast-to-noise ratio(CNR)of the reconstruction was improved by correcting for the mutual influence between the two imaging modalities.Compared with K-edge subtraction imaging,XFCT exhibits a CNR advantage for the phantom.Conclusion Simultaneous XFCT and CSCT can be realized by using linearly polarized X-rays.The synergy between the two imaging modalities would have an important application in cancer radiation therapy.展开更多
Estrone has been identified as a potential endocrine-disrupting chemical （EDC）[1]. Estrone is usually quantified by gas chromatography-mass spectrometry （GC-MS）, GC-MS/MS, high performance liquid chromatography （...Estrone has been identified as a potential endocrine-disrupting chemical （EDC）[1]. Estrone is usually quantified by gas chromatography-mass spectrometry （GC-MS）, GC-MS/MS, high performance liquid chromatography （HPLC）, HPLC- MS, and HPLC-MS/MS, etc.[2-3]. Meanwhile, several immunoassays based on radioimmunoassay, enzyme linked immunosorbent assay （ELISA） or chemiluminescence immunoassay （CLIA） for determination of estrone in real samples have been developed[2＇4]. Although these methods are sensitive, they need multistage separation and are thus time-consuming and laborious. A very promising way for the simplification of immunoassays for routine applications is a shift from heterogeneous methods （with separation） to homogeneous assays （without separation）[5]. Fluorescence polarization immunoassay （FPIA） is one of the homogeneous techniques that meets the requirements of a simple, reliable, fast, and cost-effective analysis[6]. Therefore, the present study is focused on the development of FPIA in order to analyze estrone based on antibody production.展开更多
Serology is the foundation of any brucellosis control and eradication program worldwide, thus it is important to define accuracy diagnostics assays and cut-off of those assays, due to variations from country to countr...Serology is the foundation of any brucellosis control and eradication program worldwide, thus it is important to define accuracy diagnostics assays and cut-off of those assays, due to variations from country to country and even among specific areas in the country. The variation of cutoff values depended on: prevalence of disease, vaccination status, animal management, and control and eradication programs. Therefore, a cut-off for the diagnosis of bovine brucellosis through fluorescence polarization assay (FPA) in Carchi—Ecuador was determined. The survey has been carried out in Carchi province of Ecuador, who is considered a province of high prevalence of brucellosis and the vaccination status is unknown due to the lack of registers. Sera samples (n = 200) were obtained from individual cows from randomly selected herds. Blood sera were tested through Fluoresce Polarization Assay (FPA) and competitive enzyme-linked inmunosorbent assay (cELISA) as confirmatory test, and then receiver operating characteristic (ROC) analysis was done. The sensitivity and specificity values of FPA were 88.7% and 92.50% respectively using a cut-off of 89.90 mP. Moreover, the area under the curve showed that 92.2% is the probability accuracy of the test. The advantage of the FPA is that it is a test with good characteristics of sensitivity and specificity as well as a simple and quick test.展开更多
Bisphenol A(BPA)is one of the environmental endocrine disruptors(EDCs),and BPA contamination in environment can cause high risks to human health.Rapid determination of BPA on sites is in high demand in environmental a...Bisphenol A(BPA)is one of the environmental endocrine disruptors(EDCs),and BPA contamination in environment can cause high risks to human health.Rapid determination of BPA on sites is in high demand in environmental analysis.Taking advantage of aptamers as affinity ligands and fluorescence anisotropy(FA)analysis,we developed a simple and rapid FA assay for BPA by employing a single tetramethylrhodamine(TMR)labeled short 35-mer DNA aptamer against BPA.The assay is based on the BPA-binding induced conformation change of TMR-labeled aptamer and alteration of interaction between TMR and guanine bases,resulting in change of FA signals.We screened the FA change of aptamer probes having TMR label on a specific site of the aptamer upon BPA addition.The aptamer with a TMR label on the 22nd T base showed large FA-decreasing response to BPA and maintained good binding affinity to BPA.By using this TMR-labeled aptamer,we achieved FA detection of BPA with a detection limit of 0.5μmol/L under the optimized conditions.This assay was selective towards BPA and enabled the detection of BPA spiked in tap water sample,showing the potential applications on water samples.展开更多
Using seismic data recorded by Yunnan Telemetry Seismic Network from January 1, 2000 to December 31, 2003, the dominant polarization directions of fast shear-waves are obtained at 10 digital seismic stations by SAM te...Using seismic data recorded by Yunnan Telemetry Seismic Network from January 1, 2000 to December 31, 2003, the dominant polarization directions of fast shear-waves are obtained at 10 digital seismic stations by SAM technique, a systematic analysis method on shear-wave splitting, in this study. The results show that dominant directions of polarizations of fast shear-waves at most stations are mainly at nearly N-S or NNW direction in Yunnan. The dominant polarization directions of fast shear-waves at stations located on the active faults are consistent with the strike of active faults, directions of regional principal compressive strains measured from GPS data, and basically consistent with regional principal compressive stress. Only a few of stations.show complicated polarization pattern of fast shear-waves, or are not consistent with the strike of active faults and the directions of principal GPS compressive strains, which are always located at junction of several faults. The result reflects complicated fault distribution and stress field. The dominant polarization direction of fast shear-wave indicates the direction of the in-situ maximum principal compressive stress is controlled by multiple tectonic aspects such as the regional stress field and faults.展开更多
Fluorescence anisotropy(FA)assay in homogenous solution is simple,sensitive and reproducible.Here,we reported an aptamer structure switch FA assay for detection of aflatoxin B1(AFB1),one of the most toxic mycotoxins,b...Fluorescence anisotropy(FA)assay in homogenous solution is simple,sensitive and reproducible.Here,we reported an aptamer structure switch FA assay for detection of aflatoxin B1(AFB1),one of the most toxic mycotoxins,by using tetra methylrhodamine(TMR)-labeled aptamer probe and its complementary DNA(cDNA)with tandem G bases extension,to meet the demand in sensitive and selective detection of AFB1,The hybridization of aptamer and cDNA drew TMR close to the repeated guanine(G)bases,and a high FA value was induced due to TMR-G inte raction and re stricted local rotation of TMR.In the presence of AFB1,aptamer bound to AFB1 instead of the cDNA due to competition.Thus,the TMR-G interaction was eliminated,and FA value of TMR decreased.This assay enabled the detection of AFB1 with detection limit of 125 pmol/L and dynamic range from 125 pmol/L to 31.2 nmol/L.展开更多
Fluorescence mode is influenced by the substituents, the polarity of the solvent, the steric factor and even the aggregation state of molecules in solvent under the testing environment. By comparing the fluorescent be...Fluorescence mode is influenced by the substituents, the polarity of the solvent, the steric factor and even the aggregation state of molecules in solvent under the testing environment. By comparing the fluorescent behavior of three anthracene derivatives, we observe that the hydrophobic interaction and steric effect in structures reduce fluorescence intensity, quantum yield and fluorescence lifetime. The emitting mode of two amphiphilic salts changes from aggregation emission in weak polar solvent to monomer emission in strong polar solvent and gives the similar variety in mixed solvent.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
Based on an analytical solution for the current point source in an anisotropic half-space,we study the apparent resistivity and apparent chargeability of a transversely isotropic medium with vertical and horizontal ax...Based on an analytical solution for the current point source in an anisotropic half-space,we study the apparent resistivity and apparent chargeability of a transversely isotropic medium with vertical and horizontal axes symmetry,respectively.We then provide a simple derivation of the anisotropy paradoxes in direct current resistivity and time-domain induced polarization methods.Analogous to the mean resistivity,we propose a formulation for deriving the mean polarizability.We also present a three-dimensional finite element algorithm for modeling the direct current resistivity and time-domain induced polarization using an unstructured tetrahedral grid.Finally,we provide the apparent resistivity and apparent chargeability curves of a tilted,transversely isotropic medium with diff erent angles,respectively.The subsequent results illustrate the anisotropy paradoxes of direct current resistivity and time-domain induced polarization.展开更多
Fluorescence Anisotropy(FA)is an effective biochemical detection method based on molecular rotations.Graphene oxide(GO)has been extensively used as an FA amplifier.However,the enhancement of FA by GO alone is limited ...Fluorescence Anisotropy(FA)is an effective biochemical detection method based on molecular rotations.Graphene oxide(GO)has been extensively used as an FA amplifier.However,the enhancement of FA by GO alone is limited and the strong scattering of GO will easily make the measurement of FA inaccurate.In order to address these problems,an octopus-like DNA nanostructure(ODN)was designed and coupled with GO to enhance the FA together in this work.By mimicking the multi-clawed structure of the octopus,the ODN can be adsorbed on GO tightly,which not only could improve the sensitivity because of the double FA enhancement abilities of GO and ODN,but also could improve the specificity due to the decrease of the nonspecific interaction in complex samples.Furthermore,ODN could maintain a certain distance between the fluorophore and GO to reduce the fluorescence quenching efficiency of GO,which could improve the accuracy.This method has been applied for the detection of hepatitis B virus DNA(HBV-DNA)in a range of 1-50 nmol/L and the limit of detection(LOD)was 330 pmol/L.In addition,the proposed method has been successfully utilized to detect HBV-DNA in human serum,indicating that this method has a great practical application prospect.展开更多
基金the financial support provided by the National Natural Science Foundation of China (Nos. 21822407, 21405163)the top priority program of “OneThree-Five” Strategic Planning of Lanzhou Institute of Chemical Physics, CAS
文摘As a promising signaling transduction approach, fluorescence polarization(FP)/fluorescence anisotropy(FA), provides a powerful quantitative tool for the rotational motion of fluorescently labeled molecules in chemical or biological homogeneous systems. Unlike fluorescence intensity, FP/FA is almost independent the concentration or quantum of fluorophores, but they are highly dependent on the size or molecular weight of the molecules or materials attached to fluorophores. Recently, significant progress in FP/FA was made, due to the introduction of some nanomaterials as FP/FA enhancers. The detection sensitivity is thus greatly improved by using nanomaterials as FP/FA enhancers, and nanomaterial-based FP/FA is currently used successfully in immunoassay, and analysis of protein, nucleic acid, small molecule and metal ion.Nanomaterial-based FP/FA provides a new kind of strategy to design fluorescent sensors and establishes innovative analytical methods. In this review, we summarize the scientific publications in the field of FP/FA sensor in recent five years, and first introduce the recent progress of FP/FA sensor based on nanomaterial. Subsequently, the various analytical applications of FP/FA based on nanomaterial are discussed. Finally, we provide perspectives on the current challenges and future prospects in this promising field.
基金supported by the National Instrument Development Special Program(2013YQ03065102)the Natural Science Foundation of China(614-75010,61428501)Science and Technology Commission of Shanghai Municipality(16DZ-1100300).
文摘Fluorescence polarization is related to the dipole orientation of chromophores,making fuores-cence polarization microscopy possible to_reveal structures and functions of tagged cellularorganelles and biological macromolecules.Several recent super resolution techniques have beenapplied to fluorescence polarization microscopy,achieving dipole measurement at nanoscale.In this review,we summarize both difraction limited and super resolution fluorescence polari-zation microscopy techniques,as well as their applications in biological imaging.
基金supported by grants from the International Science&Technology Cooperation Program of China(2009DFA32330)the Special Fund for Agro-scientific Research in the Public Interest(No.201203040)
文摘A fluorescence polarization immunoassay （FPIA） was developed for the analysis ofaflatoxins （AFs） using an anti-aflatoxin B1 （AFB1） monoclonal antibody and a novel fluorescein-labeled AFB1 tracer. The FPIA showed an IC50 value of 23.33 ng/mL with a limit of detection of 13.12 ng/mL for AFB1. The cross-reactivities of AFB1, AFB2, AFG1, AFG2, AFM1, and AFM2 with the antibody were 100%, 65.7%, 143%, 23.5%, 111.4%, and 2%, respectively. The group-specificity of anti-AFB1mAb indicated that the FPIA could potentially be used in a screening method for the detection of total AFs, albeit not AFG2 and AFM2. The total time required for analyzing 96 samples in one microplate was less than 5 rain. This study demonstrates the potential usefulness of the FPIA as a rapid and simple technique for monitoring AFs.
文摘Polarization variable-angle synchronous fluorescence spectrometry was proposed to determine samples in turbid solution. A mixture of fluorescein, rhodamine 6G and rhodamine B was used to evaluate the technique. The background caused by scattering light was decreased remarkably. The limits of detection were 0.6 ng/ml for fluorescein, 2.3 ng/ml for rhodamine 6G and 4.1 ng/ml for rhodamine B, respectively.
基金supported by the National Natural Science Foundation of China (Nos.41406199,41506197)the Program Foundation of Nanjing University of Information Science and Technology (No.KHYS1301)+1 种基金the Doctoral Scientific Research Foundation of Liaoning Province (No.201501190)the Fundamental Research Funds for the Central Universities (No.3132015081)
文摘When measuring reflectance spectra, it is very important to accurately extract chlorophyll fluorescence from elastic-scattering light in water-leaving radiance. The elastic scattering of light by water particles produces partially polarized light. In contrast, chlorophyll fluorescence in planktonic algae yields completely unpolarized light. These properties can be used to separate fluorescent signals from the water-leaving radiance and thus to determine chlorophyll concentration. The algal species Aureococcus anophagefferens was used to conduct a laboratory polarization experiment. For the tests, we used a field spectroradiometer and a polarizer; measurements were collected using two different observation modes. The chlorophyll fluorescence curve extracted through polarization shows an excellent match with the results obtained using the fluorospectro photometer for both measurement modes, suggesting that polarization-based chlorophyll fluorescence extraction may be feasible. The extracted fluorescence is more reliable at incident zenith angles ranging from 30? to 60?. For algae-containing water, the results improve with increasing chlorophyll concentration. This method could help improve chlorophyll concentration measurement and the remote-sensing detection of resulting harmful algae blooms.
文摘Objective: To develop a new high sensitivity, rapid and simple mycobacterium tuberculosis DNA detection method using fluorescence polarization technology. Methods: In our asymmetric PCR protocol, 100 times mole of TB-R primer was added than in the usual symmetric PCR to get enough single strands PCR product. The probe TB-5′-TAMRA and PCR products were mixed in a tube and incubate for 5-15 min at 46 ℃.The polarization (mp) was measured using victor2 Multilabel Plate Reader. Results: Asymmetric and symmetric PCR products were analyzed by the FP method. Asymmetric PCR products are detected more sensitively than symmetric ones. The polarization values of probe associated with asymmetric products were much higher than with symmetric products. Conclusion: This fluorescence polarization assay in conjunction with asymmetric PCR is a powerful and widely applicable method for the rapid and sensitive detection of micro-organisms in clinical laboratories.
文摘Objective: To develop a new method for the detection of TPMT gene mutations and determine the frequencies of four TPMT alleles, TPMT *1, *3A , *3B and *3C in a healthy Chinese population. Methods: A TDI-FP assay system was set up in out lab. To evaluate this system, 220 healthy individuals were analyzed for the polymorphic sites at positions 460(G→A)and 719(A→G)of the TPMP gene using our new TDI–FP method. Results: Three TPMP*3C(G 460→G 719) heterozygotes were identified, TPMP *3A and TPMP *3B were not found. All mutations were confirmed by conventional DNA sequencing analysis. Conclusion: TDI-FP method has proven to be very efficient as a rapid and accurate approach for TPMP genotyping. TPMP *3C was the only polymorphism identified in this clinical samples we have registered.
文摘Objective: Peroxisome proliferator-activated receptor -γ(PPAR-γ) plays a critical role in adipocyte differentiation and the development of type 2 diabetes mellitus (T2DM). Numerous studies across several populations have indicated that Pro12Ala polymorphism of PPAR-γ is associated with decreased insulin resistance and decreased risk of T2DM. The aims of this study are to develop a simple and sensitive detection of Pro12Ala polymorphism and examined the distribution of this polymorphism in Chinese population. Methods: The PPAR-γ gene fragment containing Pro12Ala variant of 101 T2DM patients and 104 controls were amplified by PCR amplification and the extension reaction was performed using primer that adjacent to the single nucleotide polymorphic site in presence of two different dye-labeled terminators. The primer's specially extending reactions make the increase of their fluorescence polarization (FP) that mean special genotype. The variant frequencies of the two groups were compared. Results: We detected the Pro12Ala variant successfully by TDI-FP method and we found no significant association between this polymorphism and T2DM in case-control study. Conclusion: The TDI-FP technology is a new specific and sensitive method that is suitable for automatic detection of large number of clinical samples. Prol2Ala mutation in PPAR--@2 gene does not play a significant role in T2DM risk in Chinese population.
基金supported in part by the National Natural Science Foundation of China(61827825,62125504,and 61735017)Major Program of the Natural Science Foundation of Zhejiang Province(LD21F050002)+2 种基金Key Research and Development Program of Zhejiang Province(2020C01116)Zhejiang Lab(2020MC0AE01)China Postdoctoral Science Foundation(BX2021272).
文摘In this paper,we propose a new fluorescence emission difference microscopy(FED)technique based on polarization modulation.An electro-optical modulator(EOM)is used to switch the excitation beam between the horizontal and vertical polarization states at a high frequency,which leads to solid-and donut-shaped beams after spatial light modulation.Experiment on the fluorescent nanoparticles demonstrates that the proposed method can achieve~λ=4 spatial resolution.Using the proposed system,the dynamic imaging of subcellular structures in living cells over time is achieved.
基金supported by the National Natural Science Foundation of China(Nos.12375157,12027902,and 11905011)。
文摘Purpose To propose a method for simultaneous fluorescence and Compton scattering computed tomography by using linearly polarized X-rays.Methods Monte Carlo simulations were adopted to demonstrate the feasibility of the proposed method.In the simulations,the phantom is a polytetrafluoroethylene cylinder inside which are cylindrical columns containing aluminum,water,and gold(Au)-loaded water solutions with Au concentrations ranging between 0.5 and 4.0 wt%,and a parallel-hole collimator imaging geometry was adopted.The light source was modeled based on a Thomson scattering X-ray source.The phantom images for both imaging modalities were reconstructed using a maximumlikelihood expectation maximization algorithm.Results Both the X-ray fluorescence computed tomography(XFCT)and Compton scattering computed tomography(CSCT)images of the phantom were accurately reconstructed.A similar attenuation contrast problem for the different cylindrical columns in the phantom can be resolved in the XFCT and CSCT images.The interplay between XFCT and CSCT was analyzed,and the contrast-to-noise ratio(CNR)of the reconstruction was improved by correcting for the mutual influence between the two imaging modalities.Compared with K-edge subtraction imaging,XFCT exhibits a CNR advantage for the phantom.Conclusion Simultaneous XFCT and CSCT can be realized by using linearly polarized X-rays.The synergy between the two imaging modalities would have an important application in cancer radiation therapy.
基金supported by Natural Science Foundation of China(U1301214)Guangdong Natural Science Foundation(S2013030013338)+1 种基金the PhD Programs Foundation of Ministry of Education of China(20114404130002)National Department Public Benefit Research Foundation(201003008-08)
文摘Estrone has been identified as a potential endocrine-disrupting chemical （EDC）[1]. Estrone is usually quantified by gas chromatography-mass spectrometry （GC-MS）, GC-MS/MS, high performance liquid chromatography （HPLC）, HPLC- MS, and HPLC-MS/MS, etc.[2-3]. Meanwhile, several immunoassays based on radioimmunoassay, enzyme linked immunosorbent assay （ELISA） or chemiluminescence immunoassay （CLIA） for determination of estrone in real samples have been developed[2＇4]. Although these methods are sensitive, they need multistage separation and are thus time-consuming and laborious. A very promising way for the simplification of immunoassays for routine applications is a shift from heterogeneous methods （with separation） to homogeneous assays （without separation）[5]. Fluorescence polarization immunoassay （FPIA） is one of the homogeneous techniques that meets the requirements of a simple, reliable, fast, and cost-effective analysis[6]. Therefore, the present study is focused on the development of FPIA in order to analyze estrone based on antibody production.
文摘Serology is the foundation of any brucellosis control and eradication program worldwide, thus it is important to define accuracy diagnostics assays and cut-off of those assays, due to variations from country to country and even among specific areas in the country. The variation of cutoff values depended on: prevalence of disease, vaccination status, animal management, and control and eradication programs. Therefore, a cut-off for the diagnosis of bovine brucellosis through fluorescence polarization assay (FPA) in Carchi—Ecuador was determined. The survey has been carried out in Carchi province of Ecuador, who is considered a province of high prevalence of brucellosis and the vaccination status is unknown due to the lack of registers. Sera samples (n = 200) were obtained from individual cows from randomly selected herds. Blood sera were tested through Fluoresce Polarization Assay (FPA) and competitive enzyme-linked inmunosorbent assay (cELISA) as confirmatory test, and then receiver operating characteristic (ROC) analysis was done. The sensitivity and specificity values of FPA were 88.7% and 92.50% respectively using a cut-off of 89.90 mP. Moreover, the area under the curve showed that 92.2% is the probability accuracy of the test. The advantage of the FPA is that it is a test with good characteristics of sensitivity and specificity as well as a simple and quick test.
基金supported by the National Natural Science Foundation of China(Nos.21874146,21575153,21435008)。
文摘Bisphenol A(BPA)is one of the environmental endocrine disruptors(EDCs),and BPA contamination in environment can cause high risks to human health.Rapid determination of BPA on sites is in high demand in environmental analysis.Taking advantage of aptamers as affinity ligands and fluorescence anisotropy(FA)analysis,we developed a simple and rapid FA assay for BPA by employing a single tetramethylrhodamine(TMR)labeled short 35-mer DNA aptamer against BPA.The assay is based on the BPA-binding induced conformation change of TMR-labeled aptamer and alteration of interaction between TMR and guanine bases,resulting in change of FA signals.We screened the FA change of aptamer probes having TMR label on a specific site of the aptamer upon BPA addition.The aptamer with a TMR label on the 22nd T base showed large FA-decreasing response to BPA and maintained good binding affinity to BPA.By using this TMR-labeled aptamer,we achieved FA detection of BPA with a detection limit of 0.5μmol/L under the optimized conditions.This assay was selective towards BPA and enabled the detection of BPA spiked in tap water sample,showing the potential applications on water samples.
基金National Natural Science Foundation of China (40274011).
文摘Using seismic data recorded by Yunnan Telemetry Seismic Network from January 1, 2000 to December 31, 2003, the dominant polarization directions of fast shear-waves are obtained at 10 digital seismic stations by SAM technique, a systematic analysis method on shear-wave splitting, in this study. The results show that dominant directions of polarizations of fast shear-waves at most stations are mainly at nearly N-S or NNW direction in Yunnan. The dominant polarization directions of fast shear-waves at stations located on the active faults are consistent with the strike of active faults, directions of regional principal compressive strains measured from GPS data, and basically consistent with regional principal compressive stress. Only a few of stations.show complicated polarization pattern of fast shear-waves, or are not consistent with the strike of active faults and the directions of principal GPS compressive strains, which are always located at junction of several faults. The result reflects complicated fault distribution and stress field. The dominant polarization direction of fast shear-wave indicates the direction of the in-situ maximum principal compressive stress is controlled by multiple tectonic aspects such as the regional stress field and faults.
基金the National Natural Science Foundation of China(Nos.21874146,21575153,21435008)Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDB14030200)。
文摘Fluorescence anisotropy(FA)assay in homogenous solution is simple,sensitive and reproducible.Here,we reported an aptamer structure switch FA assay for detection of aflatoxin B1(AFB1),one of the most toxic mycotoxins,by using tetra methylrhodamine(TMR)-labeled aptamer probe and its complementary DNA(cDNA)with tandem G bases extension,to meet the demand in sensitive and selective detection of AFB1,The hybridization of aptamer and cDNA drew TMR close to the repeated guanine(G)bases,and a high FA value was induced due to TMR-G inte raction and re stricted local rotation of TMR.In the presence of AFB1,aptamer bound to AFB1 instead of the cDNA due to competition.Thus,the TMR-G interaction was eliminated,and FA value of TMR decreased.This assay enabled the detection of AFB1 with detection limit of 125 pmol/L and dynamic range from 125 pmol/L to 31.2 nmol/L.
基金Supported by the Natural Science Foundation of Gansu(2016 Gansu Science and Technology Support Project)(1610RJZA072)the Key Laboratory of Traditional Chinese Medicine Quality and Standard,Gansu Province(Gansu University of Chinese Medicine)(ZYZL18-006)
文摘Fluorescence mode is influenced by the substituents, the polarity of the solvent, the steric factor and even the aggregation state of molecules in solvent under the testing environment. By comparing the fluorescent behavior of three anthracene derivatives, we observe that the hydrophobic interaction and steric effect in structures reduce fluorescence intensity, quantum yield and fluorescence lifetime. The emitting mode of two amphiphilic salts changes from aggregation emission in weak polar solvent to monomer emission in strong polar solvent and gives the similar variety in mixed solvent.
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the special funding of Guiyang science and technology bureau and Guiyang University[GYUKY-[2021]]the National Key Research and Development Program of China-Geophysical Comprehensive Exploration and Information Extraction of Deep Mineral Resources(2016YFC0600505)the National K&D Program(2018YFC1504901,2018YFC1504904).
文摘Based on an analytical solution for the current point source in an anisotropic half-space,we study the apparent resistivity and apparent chargeability of a transversely isotropic medium with vertical and horizontal axes symmetry,respectively.We then provide a simple derivation of the anisotropy paradoxes in direct current resistivity and time-domain induced polarization methods.Analogous to the mean resistivity,we propose a formulation for deriving the mean polarizability.We also present a three-dimensional finite element algorithm for modeling the direct current resistivity and time-domain induced polarization using an unstructured tetrahedral grid.Finally,we provide the apparent resistivity and apparent chargeability curves of a tilted,transversely isotropic medium with diff erent angles,respectively.The subsequent results illustrate the anisotropy paradoxes of direct current resistivity and time-domain induced polarization.
基金supported by the National Natural Science Foundation of China(Nos.21974109,22322409)the Natural Science Foundation of Chongqing(No.CSTB2022NSCQ-MSX1662)the Fundamental Research Funds for the Central Universities(No.XDJK2019TY003)。
文摘Fluorescence Anisotropy(FA)is an effective biochemical detection method based on molecular rotations.Graphene oxide(GO)has been extensively used as an FA amplifier.However,the enhancement of FA by GO alone is limited and the strong scattering of GO will easily make the measurement of FA inaccurate.In order to address these problems,an octopus-like DNA nanostructure(ODN)was designed and coupled with GO to enhance the FA together in this work.By mimicking the multi-clawed structure of the octopus,the ODN can be adsorbed on GO tightly,which not only could improve the sensitivity because of the double FA enhancement abilities of GO and ODN,but also could improve the specificity due to the decrease of the nonspecific interaction in complex samples.Furthermore,ODN could maintain a certain distance between the fluorophore and GO to reduce the fluorescence quenching efficiency of GO,which could improve the accuracy.This method has been applied for the detection of hepatitis B virus DNA(HBV-DNA)in a range of 1-50 nmol/L and the limit of detection(LOD)was 330 pmol/L.In addition,the proposed method has been successfully utilized to detect HBV-DNA in human serum,indicating that this method has a great practical application prospect.
