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
Interaction of procainamide hydrochloride（PAH） with human serum albumin（HSA） is of great significance in understanding the pharmacokinetic and pharmacodynamic mechanisms of the drug. Multi-spectroscopic techniques...Interaction of procainamide hydrochloride（PAH） with human serum albumin（HSA） is of great significance in understanding the pharmacokinetic and pharmacodynamic mechanisms of the drug. Multi-spectroscopic techniques were used to investigate the binding mode of PAH to HSA and results revealed the presence of static type of quenching mechanism. The number of binding sites, binding constants and thermodynamic parameters were calculated. The results showed a spontaneous binding of PAH to HSA and hydrophobic interactions played a major role. In addition, the distance between PAH and the Trp–214 was estimated employing the F？rster＇s theory. Site marker competitive experiments indicated that the binding of PAH to HSA primarily took place in subdomain IIA（Sudlow＇s site I）. The influence of interference of some common metal ions on the binding of PAH to HSA was studied. Synchronous fluorescence spectra（SFS）, 3D fluorescence spectra and circular dichroism（CD） results indicated the conformational changes in the structure of HSA.展开更多
A spectrometric setup to perform total internal reflection fluorescence (TIRF) and synchronous TIRF measurements at solid/liquid interfaces is presented. The combination of TIRF and synchronous fluorescence was propo...A spectrometric setup to perform total internal reflection fluorescence (TIRF) and synchronous TIRF measurements at solid/liquid interfaces is presented. The combination of TIRF and synchronous fluorescence was proposed to analyze simultaneously different components at interfaces. The TIRF excitation, emission and synchronous spectra of a watersoluble porphyrin were obtained from water/glass interface using this setup without the existence of a surfactant.展开更多
[ Objective] This study aimed to establish a simultaneous detection method of shrimp viruses by real-time fluorescence quantitative RT-PCR, to improve the efficiency of inspection and quarantine. [ Method] A novel rea...[ Objective] This study aimed to establish a simultaneous detection method of shrimp viruses by real-time fluorescence quantitative RT-PCR, to improve the efficiency of inspection and quarantine. [ Method] A novel real-time fluorescence quantitative RT-PCR assay was established and optimized for simultaneously detecting DNA/RNA of four shrimp viruses （WSSV, IHHNV, TSV and YHV ）. [ Result] The optimized real-time fluorescence quantitative RT-PCR system gener- ated typical amplification curves with high amplification efficiencies （E = 1.06, 1.07, 0.92 and 0.92, respectively）, good hnear relationship （ r = 1 ）, uniform repeatability （ standard deviation = 0.05 - 0.46 ; variation coefficient = 0.26% - 1.62% ） and high sensitivity, exhibiting no significant differences compared with re- al-time fluorescence quantitative PCR （average error of Ct value = 0.04 -0.40; T = 0.53 -2.50; P 〉 0.05 ）. The total detection time was about 1 h. [ Conclusion] The optimized real-time fluorescence quantitative RT-PCR system can be used for rapid detection of WSSV, IHHNV, TSV and YHV.展开更多
<div style="text-align:justify;"> Peanut oil oxidation was to monitor and quantify combining synchronous fluorescence spectroscopy and chemometrics. Peanut oil was subjected to an accelerated oxidation...<div style="text-align:justify;"> Peanut oil oxidation was to monitor and quantify combining synchronous fluorescence spectroscopy and chemometrics. Peanut oil was subjected to an accelerated oxidation testing. The spectral and related chemical indicators were caught during oxidation induce testing. Fluorescence spectra were gained for each sample with simultaneous excitation from 200 to 800 nm and the offsets (Δλ) of 10 to 180 nm during the oxidation process. The results showed the induce period (IP) of the peanut oil was 16.45 h. Parallel factor analysis (PARAFAC) was performed to select the best Δλ interval of 70 nm, which spectral data was the most suitable for interval partial least square (iPLS) and synergy interval PLS (siPLS) modeling and forecast. The study presented all interval selection methods had the better results than the global spectrum modelling. iPLS reached the best into 10 intervals with a ratio of prediction to deviation (RPD) of 2.10. siPLS that separated the whole spectrum into 15 intervals and combined the third intervals (282 to 320 nm, 362 to 400 nm, and 761 to 800 nm) had a ratio of RPD of 2.26. The results showed the optimal siPLS model performed a little better than iPLS. The established model lying on interval selection could improve the prediction accuracy. It could provide a quick, accurate method to monitor oil oxidation process. </div>展开更多
The synchronous fluorescence spectroscopy of three polymiclear aromatic hydrocarbons was studied. It was shown that the specific Δλ of the spectra were 10nm for benzo(k) fluoranthene, 25 nm for benzo(a) pyrene, and ...The synchronous fluorescence spectroscopy of three polymiclear aromatic hydrocarbons was studied. It was shown that the specific Δλ of the spectra were 10nm for benzo(k) fluoranthene, 25 nm for benzo(a) pyrene, and 40 nm for pyrene. The peaks of the spectra were at 407, 404, and 373 nm for the three chemicals, respectively. Benzo(k) fluoranthene, benzo(a) pyrene, and pyrene in the urine samples from smokers were identified by high pressure liquid chromatography combined with the synchronous fluorescence spectroscopy.展开更多
Total internal reflection fluorescence spectroscopy (TIRF) and synchronous scanning technique were combined to study the adsorption behavior of the meso-tetrakis (4-sulfonatophenyl) porphyrin (TPPS) at the glass-water...Total internal reflection fluorescence spectroscopy (TIRF) and synchronous scanning technique were combined to study the adsorption behavior of the meso-tetrakis (4-sulfonatophenyl) porphyrin (TPPS) at the glass-water interface without any surfactant. The pH dependence of synchronous fluorescence signal at the interface was analyzed. Both unprotonated (TPPS4-) and diprotonated (H2TPPS2-) forms of TPPS were observed at the interface. But the interface favored the adsorption of. The apparent estimated pKa2 value shifted from 5.00 in the bulk solution to 2.7 at the interface. STIRF provides a good technique to study multi-component systems at the interface.展开更多
A rapid method of determination of BaP in various environmental samples,using synchronous fluorescence spectroscopy scanning in defined range of dual-wavelengths(SFDW)is described in this paper.
Rapid simultaneous determination of chlorophyll a and chlorophyll b by reverse variable-angle synchronous spectrofluorimetry has been studied on a laboratory-constructed microcomputer-controlled versatile spectrofluor...Rapid simultaneous determination of chlorophyll a and chlorophyll b by reverse variable-angle synchronous spectrofluorimetry has been studied on a laboratory-constructed microcomputer-controlled versatile spectrofluorimeter.A method in estimation of scan parameters for the determination of two-component system by variable-angle synchronous spectrofluorimetry has been suggested展开更多
Dissolved organic matter (DOM) can be originated from autochthonous or allochthonous sources, where allochthonous DOM can be from pedogenic sources (humic substances—HSs) or anthropogenicsources (wastewater). The ana...Dissolved organic matter (DOM) can be originated from autochthonous or allochthonous sources, where allochthonous DOM can be from pedogenic sources (humic substances—HSs) or anthropogenicsources (wastewater). The analysis of fluorescence emission, excitation, synchronous or excitation-emission matrix (EEM) have been used to identify the main source or probable contribution of dissolved compounds, such as humic acids (HA), fulvic acids (FA) and dissolved organic carbon (DOC) from sewage, but does not quantify. Fluorescence emission is a powerful technique to detect and qualify organic dissolved compounds but fails in quantitative aspects. In this work, we propose an in situ method for direct determination of DOC using synchronous fluorescence spectra with independent component analysis (ICA). Well known standard solutions were used for method development and validation. In this work, we show that it is possible to predict the number of independent contributions using an unsupervised method based on iterative Principal Component Analysis and Independent Component Analysis (PCA-ICA) approach over combined matrix results. Within these results it’s also possible to see that with a very small amount of independent components it is possible to describe environmental samples of HA, FA and primary productivity (PP).展开更多
In acid medium, sparfloxacin is oxidized by nitrous acid, then reacts with hydrobromic acid to form a new fluorescence substance, which can emit the strong fluorescence. which is 151 fold more than that of sparfloxaci...In acid medium, sparfloxacin is oxidized by nitrous acid, then reacts with hydrobromic acid to form a new fluorescence substance, which can emit the strong fluorescence. which is 151 fold more than that of sparfloxacin itself. By this, a new sensitive method for the determination of sparfloxacin in human urine by derivative-synchronous fluorescence is presented with good results.展开更多
A sensitive analytical method, constant-energy synchronous fluorimetry, has been used to determine benzo[a]pyrene （BaP） selectively in airborne particulates （AP）. A constant-energy difference of 1 400 cm^-1 was se...A sensitive analytical method, constant-energy synchronous fluorimetry, has been used to determine benzo[a]pyrene （BaP） selectively in airborne particulates （AP）. A constant-energy difference of 1 400 cm^-1 was selected for obtaining single spectral peak. The method could easily identify BaP in an 18-component polycylic aromatic hydrocarbons（PAHs） mixtures. Calibration plots in methanol solution and in sodium dodecylsulfate （SDS） micellar media show a good linearity （R〉0.999） in the BaP concentration range generally fotund in the environment. The method gives a detection limit of 0.40 nmol/L in SDS micellar medium and 1.34 nmol/L in methanol solution.展开更多
Interaction of the synthetic chalcones (1b,1c) and their cyclic analogues (2b,2c) with bovine (BSA) and human serum albumin (HSA) as well as with rat liver mitochondria (RLM) was studied by fluorescence spectroscopy. ...Interaction of the synthetic chalcones (1b,1c) and their cyclic analogues (2b,2c) with bovine (BSA) and human serum albumin (HSA) as well as with rat liver mitochondria (RLM) was studied by fluorescence spectroscopy. The maxima of emission fluorescence spectra were changed only in the case of 2b and 2c during interaction with BSA, HSA as well as mitochondrial outer membrane showing a slight hypsochromic shift and decrease of fluorescence. Interaction of the methoxy-(1b,2b) and the dimethylamino-substituted (1c,2c) compounds with outer mitochondrial membrane were studied by fluorescence polarization. Fluorescence polarization of 1b in the presence of the two proteins and mitochondria was found to be unchanged. Under similar conditions (2b,1c,2c) showed continuously increasing fluorescence polarization signal during the 30 minute period of investigations. Since fluorescence polarization supposes that as a result of binding these substances to proteins and lipids. Compound 2c displayed a continuous increase of fluorescence polarization signal in the presence of proteins (BSA, HSA), yeast cytoplasm (YC) and mitochondria (YM and RLM). This compound displayed a significant cytotoxic effect. This pattern of interaction with proteins might be one of the contributing vectors of the observed cytotoxicity against several human carcinoma cell lines.展开更多
Anaerobic digestion of biomasses originates different products, the most abundant of which are methane and carbon dioxide. During this process, a 60-70% organic matter reduction occurs and the final product, the diges...Anaerobic digestion of biomasses originates different products, the most abundant of which are methane and carbon dioxide. During this process, a 60-70% organic matter reduction occurs and the final product, the digestate, is charac- terized by high biological stability and high contents of recalcitrant organic molecules and nutrients. In the present work digestates obtained by different mixture of biomasses in a full-scale co-digestion plant operating in Italy were characterized as whole samples without any pre-treatment or extraction by means of Fourier transform infrared spec- troscopy and fluorescence spectroscopy in the synchronous-scan mode and results were compared to those obtained on the single fresh substrates. Biomasses considered were: beef cattle slurry, maize or sorghum silage, agro-industrial residues, olive residues and olive mill wastewater. These substrates exhibited typical spectra related to their different chemical composition. Results obtained on digestates provided evidence of distinctive characteristic of the final product as a function of the different composition of the biomasses loaded into the digestion plant. We concluded that FTIR and fluorescence spectra of digestates produced in a real co-digestion plant “inherit” the main spectroscopic features of the organic wastes from which they are produced. Spectroscopic techniques used in this work succeeded in qualitatively characterizing and differentiating digestates obtained from biomasses of different chemical composition.展开更多
We have developed a multiplexed DNA detection method based on graphene oxide （GO） and molecular beacons （MBs） by synchronous fluorescence analysis, demonstrated it by an oligonucleotide sequence of wild-type HBV ...We have developed a multiplexed DNA detection method based on graphene oxide （GO） and molecular beacons （MBs） by synchronous fluorescence analysis, demonstrated it by an oligonucleotide sequence of wild-type HBV （T1） and a re- verse-transcription oligonucleotide sequence of the RNA fragment of HIV （T2） as a model system. In the absence of targets DNA, FAM-tagged free MB probes （PHBv） and ROX-tagged free MB probes （PHIv） are adsorbed on GO via π-π interactions between DNA nucleobases and nucleosides, and the π-rich GO brings the fluorophores of MB and GO into close proximity. And then, the fluorescence of fluorophores is quenched by GO. But in the presence of targets DNA, PHBV and PHW hybridize with their targets DNA resulting in the formation of double-stranded DNA （dsDNA）, causing the separation of PHBV and PHW from the surface of GO and the recovery of the fluorescence of fluorophores （FAM and ROX） simultaneously. The simultane- ous detection of T1 and T2 can be realized by measuring fluorescence signals of FAM and ROX, respectively. Under the op- timum conditions, the fluorescence intensities of two dyes all exhibit good linear dependence on their target DNA concentra- tion in the range of 5×10-11-5×10 9 M. The detection limit of T1 is 3×10-11 M （3σ）, and that of T2 is 2×10-11 M. Compared with other methods for DNA detection based on GO, the proposed method has some advantages including higher selectivity and shorter analytical time.展开更多
The changes of the synchronous fluorescence spectra and the electrochemical behaviour of cytochrome c with the urea concentration are studied. It has been found that with the increase of urea concentration, there occu...The changes of the synchronous fluorescence spectra and the electrochemical behaviour of cytochrome c with the urea concentration are studied. It has been found that with the increase of urea concentration, there occur sequentially the deaggregation of cytochrome c molecules, the increase of exposure extent of the heme group to the solvent, the disruption of Fe-S bond of the heme group and the change in the electrochemical behaviour of cytochrome c. It is suggested that the reason why the electrochemical reaction of cytochrome c is irreversible is that cytochrome c molecules exist in the concentrated solution as oligomers which are electrochemically inactive.展开更多
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.
文摘Interaction of procainamide hydrochloride（PAH） with human serum albumin（HSA） is of great significance in understanding the pharmacokinetic and pharmacodynamic mechanisms of the drug. Multi-spectroscopic techniques were used to investigate the binding mode of PAH to HSA and results revealed the presence of static type of quenching mechanism. The number of binding sites, binding constants and thermodynamic parameters were calculated. The results showed a spontaneous binding of PAH to HSA and hydrophobic interactions played a major role. In addition, the distance between PAH and the Trp–214 was estimated employing the F？rster＇s theory. Site marker competitive experiments indicated that the binding of PAH to HSA primarily took place in subdomain IIA（Sudlow＇s site I）. The influence of interference of some common metal ions on the binding of PAH to HSA was studied. Synchronous fluorescence spectra（SFS）, 3D fluorescence spectra and circular dichroism（CD） results indicated the conformational changes in the structure of HSA.
文摘A spectrometric setup to perform total internal reflection fluorescence (TIRF) and synchronous TIRF measurements at solid/liquid interfaces is presented. The combination of TIRF and synchronous fluorescence was proposed to analyze simultaneously different components at interfaces. The TIRF excitation, emission and synchronous spectra of a watersoluble porphyrin were obtained from water/glass interface using this setup without the existence of a surfactant.
文摘[ Objective] This study aimed to establish a simultaneous detection method of shrimp viruses by real-time fluorescence quantitative RT-PCR, to improve the efficiency of inspection and quarantine. [ Method] A novel real-time fluorescence quantitative RT-PCR assay was established and optimized for simultaneously detecting DNA/RNA of four shrimp viruses （WSSV, IHHNV, TSV and YHV ）. [ Result] The optimized real-time fluorescence quantitative RT-PCR system gener- ated typical amplification curves with high amplification efficiencies （E = 1.06, 1.07, 0.92 and 0.92, respectively）, good hnear relationship （ r = 1 ）, uniform repeatability （ standard deviation = 0.05 - 0.46 ; variation coefficient = 0.26% - 1.62% ） and high sensitivity, exhibiting no significant differences compared with re- al-time fluorescence quantitative PCR （average error of Ct value = 0.04 -0.40; T = 0.53 -2.50; P 〉 0.05 ）. The total detection time was about 1 h. [ Conclusion] The optimized real-time fluorescence quantitative RT-PCR system can be used for rapid detection of WSSV, IHHNV, TSV and YHV.
文摘<div style="text-align:justify;"> Peanut oil oxidation was to monitor and quantify combining synchronous fluorescence spectroscopy and chemometrics. Peanut oil was subjected to an accelerated oxidation testing. The spectral and related chemical indicators were caught during oxidation induce testing. Fluorescence spectra were gained for each sample with simultaneous excitation from 200 to 800 nm and the offsets (Δλ) of 10 to 180 nm during the oxidation process. The results showed the induce period (IP) of the peanut oil was 16.45 h. Parallel factor analysis (PARAFAC) was performed to select the best Δλ interval of 70 nm, which spectral data was the most suitable for interval partial least square (iPLS) and synergy interval PLS (siPLS) modeling and forecast. The study presented all interval selection methods had the better results than the global spectrum modelling. iPLS reached the best into 10 intervals with a ratio of prediction to deviation (RPD) of 2.10. siPLS that separated the whole spectrum into 15 intervals and combined the third intervals (282 to 320 nm, 362 to 400 nm, and 761 to 800 nm) had a ratio of RPD of 2.26. The results showed the optimal siPLS model performed a little better than iPLS. The established model lying on interval selection could improve the prediction accuracy. It could provide a quick, accurate method to monitor oil oxidation process. </div>
文摘The synchronous fluorescence spectroscopy of three polymiclear aromatic hydrocarbons was studied. It was shown that the specific Δλ of the spectra were 10nm for benzo(k) fluoranthene, 25 nm for benzo(a) pyrene, and 40 nm for pyrene. The peaks of the spectra were at 407, 404, and 373 nm for the three chemicals, respectively. Benzo(k) fluoranthene, benzo(a) pyrene, and pyrene in the urine samples from smokers were identified by high pressure liquid chromatography combined with the synchronous fluorescence spectroscopy.
文摘Total internal reflection fluorescence spectroscopy (TIRF) and synchronous scanning technique were combined to study the adsorption behavior of the meso-tetrakis (4-sulfonatophenyl) porphyrin (TPPS) at the glass-water interface without any surfactant. The pH dependence of synchronous fluorescence signal at the interface was analyzed. Both unprotonated (TPPS4-) and diprotonated (H2TPPS2-) forms of TPPS were observed at the interface. But the interface favored the adsorption of. The apparent estimated pKa2 value shifted from 5.00 in the bulk solution to 2.7 at the interface. STIRF provides a good technique to study multi-component systems at the interface.
文摘A rapid method of determination of BaP in various environmental samples,using synchronous fluorescence spectroscopy scanning in defined range of dual-wavelengths(SFDW)is described in this paper.
基金The Project Supported by National Natural Science Foundation of China.
文摘Rapid simultaneous determination of chlorophyll a and chlorophyll b by reverse variable-angle synchronous spectrofluorimetry has been studied on a laboratory-constructed microcomputer-controlled versatile spectrofluorimeter.A method in estimation of scan parameters for the determination of two-component system by variable-angle synchronous spectrofluorimetry has been suggested
文摘Dissolved organic matter (DOM) can be originated from autochthonous or allochthonous sources, where allochthonous DOM can be from pedogenic sources (humic substances—HSs) or anthropogenicsources (wastewater). The analysis of fluorescence emission, excitation, synchronous or excitation-emission matrix (EEM) have been used to identify the main source or probable contribution of dissolved compounds, such as humic acids (HA), fulvic acids (FA) and dissolved organic carbon (DOC) from sewage, but does not quantify. Fluorescence emission is a powerful technique to detect and qualify organic dissolved compounds but fails in quantitative aspects. In this work, we propose an in situ method for direct determination of DOC using synchronous fluorescence spectra with independent component analysis (ICA). Well known standard solutions were used for method development and validation. In this work, we show that it is possible to predict the number of independent contributions using an unsupervised method based on iterative Principal Component Analysis and Independent Component Analysis (PCA-ICA) approach over combined matrix results. Within these results it’s also possible to see that with a very small amount of independent components it is possible to describe environmental samples of HA, FA and primary productivity (PP).
文摘In acid medium, sparfloxacin is oxidized by nitrous acid, then reacts with hydrobromic acid to form a new fluorescence substance, which can emit the strong fluorescence. which is 151 fold more than that of sparfloxacin itself. By this, a new sensitive method for the determination of sparfloxacin in human urine by derivative-synchronous fluorescence is presented with good results.
基金Supported by the Natural Science Foundation of Fujian Province (D0410027)
文摘A sensitive analytical method, constant-energy synchronous fluorimetry, has been used to determine benzo[a]pyrene （BaP） selectively in airborne particulates （AP）. A constant-energy difference of 1 400 cm^-1 was selected for obtaining single spectral peak. The method could easily identify BaP in an 18-component polycylic aromatic hydrocarbons（PAHs） mixtures. Calibration plots in methanol solution and in sodium dodecylsulfate （SDS） micellar media show a good linearity （R〉0.999） in the BaP concentration range generally fotund in the environment. The method gives a detection limit of 0.40 nmol/L in SDS micellar medium and 1.34 nmol/L in methanol solution.
基金supported by the Austrian Science and Research Liaison Office(ASO)grant,the VEGA 1/0999/11 grant；the Faculty of Medicine Research Fund(PTE AOK-KA-2013/20),(University of Pécs).
文摘Interaction of the synthetic chalcones (1b,1c) and their cyclic analogues (2b,2c) with bovine (BSA) and human serum albumin (HSA) as well as with rat liver mitochondria (RLM) was studied by fluorescence spectroscopy. The maxima of emission fluorescence spectra were changed only in the case of 2b and 2c during interaction with BSA, HSA as well as mitochondrial outer membrane showing a slight hypsochromic shift and decrease of fluorescence. Interaction of the methoxy-(1b,2b) and the dimethylamino-substituted (1c,2c) compounds with outer mitochondrial membrane were studied by fluorescence polarization. Fluorescence polarization of 1b in the presence of the two proteins and mitochondria was found to be unchanged. Under similar conditions (2b,1c,2c) showed continuously increasing fluorescence polarization signal during the 30 minute period of investigations. Since fluorescence polarization supposes that as a result of binding these substances to proteins and lipids. Compound 2c displayed a continuous increase of fluorescence polarization signal in the presence of proteins (BSA, HSA), yeast cytoplasm (YC) and mitochondria (YM and RLM). This compound displayed a significant cytotoxic effect. This pattern of interaction with proteins might be one of the contributing vectors of the observed cytotoxicity against several human carcinoma cell lines.
文摘Anaerobic digestion of biomasses originates different products, the most abundant of which are methane and carbon dioxide. During this process, a 60-70% organic matter reduction occurs and the final product, the digestate, is charac- terized by high biological stability and high contents of recalcitrant organic molecules and nutrients. In the present work digestates obtained by different mixture of biomasses in a full-scale co-digestion plant operating in Italy were characterized as whole samples without any pre-treatment or extraction by means of Fourier transform infrared spec- troscopy and fluorescence spectroscopy in the synchronous-scan mode and results were compared to those obtained on the single fresh substrates. Biomasses considered were: beef cattle slurry, maize or sorghum silage, agro-industrial residues, olive residues and olive mill wastewater. These substrates exhibited typical spectra related to their different chemical composition. Results obtained on digestates provided evidence of distinctive characteristic of the final product as a function of the different composition of the biomasses loaded into the digestion plant. We concluded that FTIR and fluorescence spectra of digestates produced in a real co-digestion plant “inherit” the main spectroscopic features of the organic wastes from which they are produced. Spectroscopic techniques used in this work succeeded in qualitatively characterizing and differentiating digestates obtained from biomasses of different chemical composition.
文摘We have developed a multiplexed DNA detection method based on graphene oxide （GO） and molecular beacons （MBs） by synchronous fluorescence analysis, demonstrated it by an oligonucleotide sequence of wild-type HBV （T1） and a re- verse-transcription oligonucleotide sequence of the RNA fragment of HIV （T2） as a model system. In the absence of targets DNA, FAM-tagged free MB probes （PHBv） and ROX-tagged free MB probes （PHIv） are adsorbed on GO via π-π interactions between DNA nucleobases and nucleosides, and the π-rich GO brings the fluorophores of MB and GO into close proximity. And then, the fluorescence of fluorophores is quenched by GO. But in the presence of targets DNA, PHBV and PHW hybridize with their targets DNA resulting in the formation of double-stranded DNA （dsDNA）, causing the separation of PHBV and PHW from the surface of GO and the recovery of the fluorescence of fluorophores （FAM and ROX） simultaneously. The simultane- ous detection of T1 and T2 can be realized by measuring fluorescence signals of FAM and ROX, respectively. Under the op- timum conditions, the fluorescence intensities of two dyes all exhibit good linear dependence on their target DNA concentra- tion in the range of 5×10-11-5×10 9 M. The detection limit of T1 is 3×10-11 M （3σ）, and that of T2 is 2×10-11 M. Compared with other methods for DNA detection based on GO, the proposed method has some advantages including higher selectivity and shorter analytical time.
基金Project supported by the National Natural Science Foundation of Chinathe National Institute of Health(GM 35108)
文摘The changes of the synchronous fluorescence spectra and the electrochemical behaviour of cytochrome c with the urea concentration are studied. It has been found that with the increase of urea concentration, there occur sequentially the deaggregation of cytochrome c molecules, the increase of exposure extent of the heme group to the solvent, the disruption of Fe-S bond of the heme group and the change in the electrochemical behaviour of cytochrome c. It is suggested that the reason why the electrochemical reaction of cytochrome c is irreversible is that cytochrome c molecules exist in the concentrated solution as oligomers which are electrochemically inactive.
