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2017 Volume 45 Issue 10
2017, 45(10): 1421-1426
doi: 10.11895/j.issn.0253-3820.170268
Abstract:
A switch thrombin aptamer sensor was constructed based on the host-guest competition mode of β-cyclodextrin (β-CD). The aptamer that modified with ferrocene (Fc) at its terminal was fixed on the surface of the gold electrode via the host-guest recognization with β-CD. When thrombin was present, the configuration of aptamer transformed from vertical linear to "G-quadruplex" and far away from the electrode surface, which resulted in a decrease in the redox current of the aptamer probe and produce "Signal-off" effect. On the basis of this, a high sensitive detection of thrombin was made. The detection result indicated that the thrombin concentration had a consideration linear response to the signal of aptasensor between 5.0×10-13-5.0×10-9 mol/L, and as low as 2.0×10-13 mol/L thrombin had been detected. This method for thrombin detection showed a higher specificity compared to other protein molecules. Besides, the sensor was constructed easily and possessed excellent regeneration, which provided a significant platform for highly efficient real-time detection of thrombin in biological serum samples.
A switch thrombin aptamer sensor was constructed based on the host-guest competition mode of β-cyclodextrin (β-CD). The aptamer that modified with ferrocene (Fc) at its terminal was fixed on the surface of the gold electrode via the host-guest recognization with β-CD. When thrombin was present, the configuration of aptamer transformed from vertical linear to "G-quadruplex" and far away from the electrode surface, which resulted in a decrease in the redox current of the aptamer probe and produce "Signal-off" effect. On the basis of this, a high sensitive detection of thrombin was made. The detection result indicated that the thrombin concentration had a consideration linear response to the signal of aptasensor between 5.0×10-13-5.0×10-9 mol/L, and as low as 2.0×10-13 mol/L thrombin had been detected. This method for thrombin detection showed a higher specificity compared to other protein molecules. Besides, the sensor was constructed easily and possessed excellent regeneration, which provided a significant platform for highly efficient real-time detection of thrombin in biological serum samples.
2017, 45(10): 1427-1433
doi: 10.11895/j.issn.0253-3820.170280
Abstract:
The tumor targeted fluorescent magnetic IR780-Fe3O4 nanoparticles were prepared for separation and detection of circulating tumor cells (CTCs). These IR780-Fe3O4 nanoparticles were characterized by electron microscopy, fluorescence spectrometer, and superconducting quantum interferometer. The targeting effect of IR780-Fe3O4 nanoparticles was analyzed on the tumor and normal cells by confocal microscope and flow cytometry, and the confocal microscope was used to target the location of IR780-Fe3O4 nanoparticles in MCF-7 cells. The standard curve was drawn and evaluated accorded to the IR780-Fe3O4 nanoparticles fluorescence intensity of tumor cells after incubation. The results showed that IR780-Fe3O4 nanoparticles could target a variety of CTCs. Furthermore, cellular localization experiment proved that IR780-Fe3O4 nanoparticles could target the mitochondria of tumor cells. With the method of coupling magnetic Fe3O4 nanoparticles, IR780 could well distinguish the tumor and normal cells, which could be used for separating and detecting the CTCs in simulated blood.
The tumor targeted fluorescent magnetic IR780-Fe3O4 nanoparticles were prepared for separation and detection of circulating tumor cells (CTCs). These IR780-Fe3O4 nanoparticles were characterized by electron microscopy, fluorescence spectrometer, and superconducting quantum interferometer. The targeting effect of IR780-Fe3O4 nanoparticles was analyzed on the tumor and normal cells by confocal microscope and flow cytometry, and the confocal microscope was used to target the location of IR780-Fe3O4 nanoparticles in MCF-7 cells. The standard curve was drawn and evaluated accorded to the IR780-Fe3O4 nanoparticles fluorescence intensity of tumor cells after incubation. The results showed that IR780-Fe3O4 nanoparticles could target a variety of CTCs. Furthermore, cellular localization experiment proved that IR780-Fe3O4 nanoparticles could target the mitochondria of tumor cells. With the method of coupling magnetic Fe3O4 nanoparticles, IR780 could well distinguish the tumor and normal cells, which could be used for separating and detecting the CTCs in simulated blood.
2017, 45(10): 1434-1440
doi: 10.11895/j.issn.0253-3820.170139
Abstract:
Protein tyrosine phosphorylation is an important post-translational modification and has become one of the most active areas in proteome research in recent years. Protein tyrosine phosphorylation plays a key regulatory role in the numerous signal transduction processes and in the occurrence & development of tumor. The study of tyrosine phosphorylation and activity of it corresponding tyrosine kinases is of great significance for the research of drug targets for cancer treatment. However, tyrosine phosphorylation only represents less than 0.1% of the total cellular protein phosphorylation. Therefore, there is a great challenge to identify tyrosine phosphorylation in real complex samples. In this work, a new centrifugal device by combining application of titanium dioxide (TiO2) and C18 reversed phase packing materials for phosphopeptide enrichment and separation was developed, which led to simplified procedure, reduced sample loss and minimized interference. This new centrifugal device was made of pipette tips, adapters and Eppendorf tubes. Sample loading, phosphopeptides enrichment, washing, eluting and separation were combined into this device and could be achieved by simple centrifugation. This device was capable of paralleled sample processing with improved analysis throughput. Tandem enrichment by anti-phosphotyrosine antibody resulted in efficient enrichment and large scale identification of phosphotyrosine peptides by mass spectrometry. As a result, 967 phosphotyrosine sites corresponding to 545 proteins were successfully identified from 5 mg of mouse liver proteins, demonstrating the robustness and potential of this new strategy.
Protein tyrosine phosphorylation is an important post-translational modification and has become one of the most active areas in proteome research in recent years. Protein tyrosine phosphorylation plays a key regulatory role in the numerous signal transduction processes and in the occurrence & development of tumor. The study of tyrosine phosphorylation and activity of it corresponding tyrosine kinases is of great significance for the research of drug targets for cancer treatment. However, tyrosine phosphorylation only represents less than 0.1% of the total cellular protein phosphorylation. Therefore, there is a great challenge to identify tyrosine phosphorylation in real complex samples. In this work, a new centrifugal device by combining application of titanium dioxide (TiO2) and C18 reversed phase packing materials for phosphopeptide enrichment and separation was developed, which led to simplified procedure, reduced sample loss and minimized interference. This new centrifugal device was made of pipette tips, adapters and Eppendorf tubes. Sample loading, phosphopeptides enrichment, washing, eluting and separation were combined into this device and could be achieved by simple centrifugation. This device was capable of paralleled sample processing with improved analysis throughput. Tandem enrichment by anti-phosphotyrosine antibody resulted in efficient enrichment and large scale identification of phosphotyrosine peptides by mass spectrometry. As a result, 967 phosphotyrosine sites corresponding to 545 proteins were successfully identified from 5 mg of mouse liver proteins, demonstrating the robustness and potential of this new strategy.
2017, 45(10): 1441-1447
doi: 10.11895/j.issn.0253-3820.170250
Abstract:
Isobaric peptide termini labeling (IPTL) is a technology which uses light and heavy isotopes to label C-terminus and N-terminus of peptides. As the masses of labeled peptides are equivalent, the complexity of sample is low when analyzing MS data produced by this technology. Besides, paired b and y ions are helpful while analyzing MS/MS data in this kind of experiments. On the basis of this, a novel scoring algorithm, all ions scoring algorithm (AISA), has been designed for IPTL experiments. The information of quantification and qualification can be acquired at the same time using AISA. On Q-Exactive HeLa 2D RPLC dataset, peptide spectrum matches (PSMs), distinct peptides and protein groups identified by AISA are 15%, 26% and 22% higher than Morpheus. On human-HCC-HL dataset, PSMs, distinct peptides and protein groups identified by AISA are 24%, 39% and 27% higher than Morpheus. Quantification ratio on Q-Exactive HeLa and human-HCC-HL datasets are 1.18 and 0.90, respectively, which are very close to 1. Besides, quantification ratios between 0.5 and 2.0 are 91% and 94%, respectively.
Isobaric peptide termini labeling (IPTL) is a technology which uses light and heavy isotopes to label C-terminus and N-terminus of peptides. As the masses of labeled peptides are equivalent, the complexity of sample is low when analyzing MS data produced by this technology. Besides, paired b and y ions are helpful while analyzing MS/MS data in this kind of experiments. On the basis of this, a novel scoring algorithm, all ions scoring algorithm (AISA), has been designed for IPTL experiments. The information of quantification and qualification can be acquired at the same time using AISA. On Q-Exactive HeLa 2D RPLC dataset, peptide spectrum matches (PSMs), distinct peptides and protein groups identified by AISA are 15%, 26% and 22% higher than Morpheus. On human-HCC-HL dataset, PSMs, distinct peptides and protein groups identified by AISA are 24%, 39% and 27% higher than Morpheus. Quantification ratio on Q-Exactive HeLa and human-HCC-HL datasets are 1.18 and 0.90, respectively, which are very close to 1. Besides, quantification ratios between 0.5 and 2.0 are 91% and 94%, respectively.
2017, 45(10): 1448-1454
doi: 10.11895/j.issn.0253-3820.170332
Abstract:
By detecting SRY gene of cell-free fetal DNA (cffDNA) in maternal peripheral blood, the sex of fetuses was determined, the risks of sex-linked genetic disorders were assessed and the birth rate of sick fetuses was decreased. A method of real-time polymerase chain reaction (PCR) coupled with invader assay was established to detect SRY gene. This method possessed the advantages such as high sensitivity, high specificity and non-contaminated with closed tube detection. Under the optimized reaction conditions such as 250 nmol/L detection probes, 7.5 U FEN1 enzyme, 0.5 U Taq polymerase and 67℃ of annealing temperature in pre-amplification, the simulated samples as low as 4‰ (4 copies/μL) were detected and two clinical samples with the gestation age of 9 weeks and 10 weeks were successfully detected. The detection results showed that this method could be used to detect SRY gene of cffDNA in maternal peripheral blood, providing an effective technique for clinical non-invasive prenatal diagnosis based on SRY gene.
By detecting SRY gene of cell-free fetal DNA (cffDNA) in maternal peripheral blood, the sex of fetuses was determined, the risks of sex-linked genetic disorders were assessed and the birth rate of sick fetuses was decreased. A method of real-time polymerase chain reaction (PCR) coupled with invader assay was established to detect SRY gene. This method possessed the advantages such as high sensitivity, high specificity and non-contaminated with closed tube detection. Under the optimized reaction conditions such as 250 nmol/L detection probes, 7.5 U FEN1 enzyme, 0.5 U Taq polymerase and 67℃ of annealing temperature in pre-amplification, the simulated samples as low as 4‰ (4 copies/μL) were detected and two clinical samples with the gestation age of 9 weeks and 10 weeks were successfully detected. The detection results showed that this method could be used to detect SRY gene of cffDNA in maternal peripheral blood, providing an effective technique for clinical non-invasive prenatal diagnosis based on SRY gene.
2017, 45(10): 1455-1461
doi: 10.11895/j.issn.0253-3820.170066
Abstract:
Based on the electrochemiluminescence and magnetic suspension immunoassay strategy, a new magnetic graphene and paper-based screen-printed electrode (SPE) electrochemiluminescence sandwich immunoassay was developed by combination of the unique physical and chemical properties of magnetic graphene and the advantages such as low cost and low-volume sample consumption of paper-based SPE. Taking human IgG as the model analyte, EDC/NHS method was used to couple capture antibody (Ab1) and magnetic graphene, and direct labeling method was used to label signal antibody (Ab2) with Ru NHS ester. Nonspecific adsorption was highly reduced by the magnetic suspension sandwich immunoassay strategy, and the concentration information of the analyte was obtained by paper-electrochemiluminescence detection. Experimental study of immobilization and labeling effect of Ab1 and Ab2 showed that the magnetic graphene not only improved the load of immune substances, but also promoted the electron transfer. The developed magnetic suspension and paper-based electrochemiluminescence immunoassay could realize the quantitative detection of IgG and had certain application prospect in low cost and rapid immune detection field.
Based on the electrochemiluminescence and magnetic suspension immunoassay strategy, a new magnetic graphene and paper-based screen-printed electrode (SPE) electrochemiluminescence sandwich immunoassay was developed by combination of the unique physical and chemical properties of magnetic graphene and the advantages such as low cost and low-volume sample consumption of paper-based SPE. Taking human IgG as the model analyte, EDC/NHS method was used to couple capture antibody (Ab1) and magnetic graphene, and direct labeling method was used to label signal antibody (Ab2) with Ru NHS ester. Nonspecific adsorption was highly reduced by the magnetic suspension sandwich immunoassay strategy, and the concentration information of the analyte was obtained by paper-electrochemiluminescence detection. Experimental study of immobilization and labeling effect of Ab1 and Ab2 showed that the magnetic graphene not only improved the load of immune substances, but also promoted the electron transfer. The developed magnetic suspension and paper-based electrochemiluminescence immunoassay could realize the quantitative detection of IgG and had certain application prospect in low cost and rapid immune detection field.
2017, 45(10): 1462-1466
doi: 10.11895/j.issn.0253-3820.170162
Abstract:
A double quenching molecular beacon (MB) with simple structure was designed based on organic quencher and G bases, and a simple detection method for thrombin was developed using this MB. In this MB, FAM and BHQ-1 were selected as fluorophore and organic quencher, three continuous nucleotides with G base were connected with BHQ-1, and the loop of MB was designed as a nucleic acid aptamer of thrombin. In the absence of thrombin, the MB was in the stem-loop structure, the fluorophore FAM was close to BHQ-1 and G bases, the fluorescence of FAM was dual quenched by BHQ-1 and G bases, and the fluorescence signal of FAM was very weak. In the presence of thrombin, MB specifically bound thrombin and formed a G-quadruplex structure. The stem-loop structure of the MB was destroyed, and FAM was separated with BHQ-1 and G bases, leading to recovery of fluorescence of FAM. Under the optimal conditions, the fluorescence intensity of FAM exhibited a good linear relationship with concentration of thrombin in the range of 0.4-40.0 nmol/L, and regression equation was △I=24.63C (nmol/L)+ 13.06 (R2=0.9972) with the detection limit of 0.18 nmol/L (3σ, n=9). The average recoveries of this method in serum samples were 96.3%-98.7%, which indicated that the method had high accuracy.
A double quenching molecular beacon (MB) with simple structure was designed based on organic quencher and G bases, and a simple detection method for thrombin was developed using this MB. In this MB, FAM and BHQ-1 were selected as fluorophore and organic quencher, three continuous nucleotides with G base were connected with BHQ-1, and the loop of MB was designed as a nucleic acid aptamer of thrombin. In the absence of thrombin, the MB was in the stem-loop structure, the fluorophore FAM was close to BHQ-1 and G bases, the fluorescence of FAM was dual quenched by BHQ-1 and G bases, and the fluorescence signal of FAM was very weak. In the presence of thrombin, MB specifically bound thrombin and formed a G-quadruplex structure. The stem-loop structure of the MB was destroyed, and FAM was separated with BHQ-1 and G bases, leading to recovery of fluorescence of FAM. Under the optimal conditions, the fluorescence intensity of FAM exhibited a good linear relationship with concentration of thrombin in the range of 0.4-40.0 nmol/L, and regression equation was △I=24.63C (nmol/L)+ 13.06 (R2=0.9972) with the detection limit of 0.18 nmol/L (3σ, n=9). The average recoveries of this method in serum samples were 96.3%-98.7%, which indicated that the method had high accuracy.
2017, 45(10): 1467-1474
doi: 10.11895/j.issn.0253-3820.170015
Abstract:
As a kind of fluorescent nanoprobe, BHHCT-Eu3+@SiO2 fluorescent nanoparticles were synthesized using microwave irradiation. Transmission electron microscopy characterization showed that the nanoparticles were in spherical shape with particle size of about 36 nm. The BHHCT-Eu3+@SiO2 exhibited good fluorescence property, with a maximal excitation wavelength of 343 nm and an maximal emission wavelength of 615 nm. The fluorescence lateral flow immunoassay (LFIA) was established for rapid and quantitative detection of kanamycin (Kana) in milk after BHHCT-Eu3+@SiO2 fluorescent nanoparticles were conjugated with Kana antibody, with dextran as a linker. The limit of detection of Kana with the LFIA method was 0.85 ng/mL with IC50 of 12.76 ng/mL, and the detection range was from 3.0 ng/m to 76 ng/mL. The recoveries of Kana in milk were between 93.7% and 97.4% with RSD of 3.1%-4.6%, and cross-reactivity of the fluorescence immunoassay strip for Kana determination was < 1%. The detection results of kana in milk samples between the LFIA and traditional ELISA method showed good correlation.
As a kind of fluorescent nanoprobe, BHHCT-Eu3+@SiO2 fluorescent nanoparticles were synthesized using microwave irradiation. Transmission electron microscopy characterization showed that the nanoparticles were in spherical shape with particle size of about 36 nm. The BHHCT-Eu3+@SiO2 exhibited good fluorescence property, with a maximal excitation wavelength of 343 nm and an maximal emission wavelength of 615 nm. The fluorescence lateral flow immunoassay (LFIA) was established for rapid and quantitative detection of kanamycin (Kana) in milk after BHHCT-Eu3+@SiO2 fluorescent nanoparticles were conjugated with Kana antibody, with dextran as a linker. The limit of detection of Kana with the LFIA method was 0.85 ng/mL with IC50 of 12.76 ng/mL, and the detection range was from 3.0 ng/m to 76 ng/mL. The recoveries of Kana in milk were between 93.7% and 97.4% with RSD of 3.1%-4.6%, and cross-reactivity of the fluorescence immunoassay strip for Kana determination was < 1%. The detection results of kana in milk samples between the LFIA and traditional ELISA method showed good correlation.
2017, 45(10): 1475-1481
doi: 10.11895/j.issn.0253-3820.171080
Abstract:
As an extension of proteomics, peptidomics has been widely used in medical and biological researches. However, the effect of reproducibility of identification method on peptidomics is not yet clear. In this work, the urine sample of a healthy people was analyzed for seven times in parallel by nano-liquid chromatography-high-resolution tandem mass spectrometry. To illustrate the variability and stability among these experiments, the number of spectra, the utilization of total spectra, the number of identified peptides, the number of proteins, and the ionic strength and retention time of peptides were counted and compared. The average number of peptides was 208 and the standard deviation was 38.7. After all of data were combined, 426 peptides belonging to 114 proteins were obtained, while only 109 peptides coming from 35 proteins were identified in each experiment, indicating that there were both an randomness and a relative stability for LC-MS analysis. Increasing the number of parallel experiments would expand the data set of peptidomics, but the rate of increase would decrease over 3 or more measurements. Compared with peptides, the results of peptidomics were more stable at protein level, indicating that proteins were more robustly peptidomics biomarker than the peptides.
As an extension of proteomics, peptidomics has been widely used in medical and biological researches. However, the effect of reproducibility of identification method on peptidomics is not yet clear. In this work, the urine sample of a healthy people was analyzed for seven times in parallel by nano-liquid chromatography-high-resolution tandem mass spectrometry. To illustrate the variability and stability among these experiments, the number of spectra, the utilization of total spectra, the number of identified peptides, the number of proteins, and the ionic strength and retention time of peptides were counted and compared. The average number of peptides was 208 and the standard deviation was 38.7. After all of data were combined, 426 peptides belonging to 114 proteins were obtained, while only 109 peptides coming from 35 proteins were identified in each experiment, indicating that there were both an randomness and a relative stability for LC-MS analysis. Increasing the number of parallel experiments would expand the data set of peptidomics, but the rate of increase would decrease over 3 or more measurements. Compared with peptides, the results of peptidomics were more stable at protein level, indicating that proteins were more robustly peptidomics biomarker than the peptides.
2017, 45(10): 1482-1488
doi: 10.11895/j.issn.0253-3820.170357
Abstract:
The effects of cetyltrimethylammonium bromide (CTAB), ascorbic acid, NaBH4 and AgNO3, as well as the stirring time and reaction time on the preparation of gold nanorods synthesized with seedless growth method were studied. The optimum preparation conditions were obtained in the process of growth of gold nanorods. The gold nanorods prepared under different conditions were characterized by visible absorption spectroscopy and transmission electron microscopy (TEM). Under the optimum conditions such as room temperature, 0.1 mol/L CTAB, 96 μmol/L AgNO3, 0.97 mmol/L ascorbic acid, 1.5 μmol/L NaBH4 and stirring for 25 s, micro-sized gold nanorods with uniform morphology, good dispersibility, small shaft width and high aspect ratio were prepared within 6 h. The gold nanorods were expected to be applied to the detection of mercury ion in water environment.
The effects of cetyltrimethylammonium bromide (CTAB), ascorbic acid, NaBH4 and AgNO3, as well as the stirring time and reaction time on the preparation of gold nanorods synthesized with seedless growth method were studied. The optimum preparation conditions were obtained in the process of growth of gold nanorods. The gold nanorods prepared under different conditions were characterized by visible absorption spectroscopy and transmission electron microscopy (TEM). Under the optimum conditions such as room temperature, 0.1 mol/L CTAB, 96 μmol/L AgNO3, 0.97 mmol/L ascorbic acid, 1.5 μmol/L NaBH4 and stirring for 25 s, micro-sized gold nanorods with uniform morphology, good dispersibility, small shaft width and high aspect ratio were prepared within 6 h. The gold nanorods were expected to be applied to the detection of mercury ion in water environment.
2017, 45(10): 1489-1496
doi: 10.11895/j.issn.0253-3820.170222
Abstract:
One of the hot spots of nanomaterials research is the preparation of carbon-dots (C-dots) by simple steps with cheap raw materials and looking for its potential application. In this study, coal-based C-dots was prepared from coal mined of Wucaiwan in Xinjiang by mixed acids (H2SO4+HNO3)/ultrasound treatment, and at the same time of structural characterization, the coal-based C-dots were used as fluorescent probe to detect metal ions in water. It was found that the coal-based C-dots were polycyclic aromatic hydrocarbons with particle size of (8±4) nm linked with oxygen-containing groups such as nitro group, possessing the annulus wall of multilayer graphene fragment structures built up by sp2 carbons. This endowed the coal-based C-dots with good dispersity in water, high absorbance and strong fluorescence. The coal-based C-dots were used as viable probes in that their fluorescence was selectively quenching by Cu. The finding was exploited to design a fluorometric assay for Cu with a detection limit of 9.6 nmol/L.
One of the hot spots of nanomaterials research is the preparation of carbon-dots (C-dots) by simple steps with cheap raw materials and looking for its potential application. In this study, coal-based C-dots was prepared from coal mined of Wucaiwan in Xinjiang by mixed acids (H2SO4+HNO3)/ultrasound treatment, and at the same time of structural characterization, the coal-based C-dots were used as fluorescent probe to detect metal ions in water. It was found that the coal-based C-dots were polycyclic aromatic hydrocarbons with particle size of (8±4) nm linked with oxygen-containing groups such as nitro group, possessing the annulus wall of multilayer graphene fragment structures built up by sp2 carbons. This endowed the coal-based C-dots with good dispersity in water, high absorbance and strong fluorescence. The coal-based C-dots were used as viable probes in that their fluorescence was selectively quenching by Cu. The finding was exploited to design a fluorometric assay for Cu with a detection limit of 9.6 nmol/L.
2017, 45(10): 1497-1503
doi: 10.11895/j.issn.0253-3820.170344
Abstract:
The photoluminescence properties of carbon quantum dots depend on their size and the properties of surface functional groups. The N-doped carbon dots (using small molecular ethylenediamine) with high quantum yield and excellent dispersibility were synthesized by one-step hydrothermal method with biomass tar that was generated in the reductive smelting process as a precursor. Rapid and accurate Fe3+ detection based on the selective fluorescence quenching effect of N-doped carbon quantum dots was achieved. The results showed that the as-synthesized N-doped carbon quantum dots were regular spherical, uniform in size with an average particle size of 2.64 nm with a quantum yield of 26.1%, and the crystal lattice spacing was 0.25 nm, corresponding to the (100) facet of graphitic carbon structure. The functional groups on the surface of N-doped carbon quantum dots could interact with Fe3+ to form complex compound by coordination, leading to the fluorescence quenching effect. Fluorescence emission ratios kept a linear relationship with the concentrations of Fe3+ in the range of 0.23-600 μmol/L with the detection limit of 230 nmol/L.
The photoluminescence properties of carbon quantum dots depend on their size and the properties of surface functional groups. The N-doped carbon dots (using small molecular ethylenediamine) with high quantum yield and excellent dispersibility were synthesized by one-step hydrothermal method with biomass tar that was generated in the reductive smelting process as a precursor. Rapid and accurate Fe3+ detection based on the selective fluorescence quenching effect of N-doped carbon quantum dots was achieved. The results showed that the as-synthesized N-doped carbon quantum dots were regular spherical, uniform in size with an average particle size of 2.64 nm with a quantum yield of 26.1%, and the crystal lattice spacing was 0.25 nm, corresponding to the (100) facet of graphitic carbon structure. The functional groups on the surface of N-doped carbon quantum dots could interact with Fe3+ to form complex compound by coordination, leading to the fluorescence quenching effect. Fluorescence emission ratios kept a linear relationship with the concentrations of Fe3+ in the range of 0.23-600 μmol/L with the detection limit of 230 nmol/L.
2017, 45(10): 1504-1510
doi: 10.11895/j.issn.0253-3820.170291
Abstract:
Volatile sulfur compounds (VSCs) in the marine environment has significant implications for global climate change. In the present study, a gas chromatographic analytical method was set up to determine the concentrations of VSCs in seawater and atmosphere, and the optimized experimental conditions were established. For the analysis of VSCs in atmosphere, multistage traps and gas chromatography-mass spectrometry (GC-MS) were used, with the precisions of 7.7%-15.1% and the detection limits of 0.23-4.7 ng. Moreover, for the analyses of VSCs in seawater, pre-concentration and gas chromatography coupled with flame photometric detector (GC-FPD) were utilized, with the precisions of 3.5%-5.3% and the detection limits of 2.5-3.5 ng. This method was applied to analyze the VSCs in Qingdao coastal seawater and atmosphere, and the average concentrations of carbonyl sulfide, dimethyl sulfide and carbon disulfide in the seawater were (268±58), (1264±278), (19±2) pmol/L, and (543±39), (29±9), (56±20) (×10-12, V/V) in the atmosphere, respectively.
Volatile sulfur compounds (VSCs) in the marine environment has significant implications for global climate change. In the present study, a gas chromatographic analytical method was set up to determine the concentrations of VSCs in seawater and atmosphere, and the optimized experimental conditions were established. For the analysis of VSCs in atmosphere, multistage traps and gas chromatography-mass spectrometry (GC-MS) were used, with the precisions of 7.7%-15.1% and the detection limits of 0.23-4.7 ng. Moreover, for the analyses of VSCs in seawater, pre-concentration and gas chromatography coupled with flame photometric detector (GC-FPD) were utilized, with the precisions of 3.5%-5.3% and the detection limits of 2.5-3.5 ng. This method was applied to analyze the VSCs in Qingdao coastal seawater and atmosphere, and the average concentrations of carbonyl sulfide, dimethyl sulfide and carbon disulfide in the seawater were (268±58), (1264±278), (19±2) pmol/L, and (543±39), (29±9), (56±20) (×10-12, V/V) in the atmosphere, respectively.
2017, 45(10): 1511-1516
doi: 10.11895/j.issn.0253-3820.170101
Abstract:
A sensitive electrochemical sensor for the detection of semicarbazide (SEM) based on the glassy carbon electrode modified with carboxylated multi-walled carbon nanotube (CMWCNTs) was constructed in this work. The modified materials were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and electrochemical impedance spectroscopy. The results showed that the CMWCNTs exhibited a certain degree of changes, such as the appearance of the characteristic peaks of carbon oxygen double bonds in carboxyl group, a decrease in diameter and length and a remarkable reduction of the impedance value. The electrochemical behavior of SEM on CMWCNTs/GCE was investigated by cyclic voltammetry and amperometric i-t curve in 1 mol/L HAc-NaAc buffer solution. An irreversible oxidation peak of SEM appeared at CMWCNTs/GCE. Compared to the bare electrode, the current of the oxidation peak was significantly increased. Under the optimal conditions such as HAc-NaAc solution (pH 7) and scan rate of 0.1 V/s, the obtained sensor presented linear response to SEM concentration in the range of 5.0×10-6 mol/L-1.09×10-3 mol/L, the linear regression equation was Ip(μA)=-0.472+0.0599C (μmol/L) with linear correlation coefficient of 0.997. The detection limit was 1.88×10-7 mol/L. At the same time, the recovery was from 92.8% to 98.0% in the test of pork liver samples.
A sensitive electrochemical sensor for the detection of semicarbazide (SEM) based on the glassy carbon electrode modified with carboxylated multi-walled carbon nanotube (CMWCNTs) was constructed in this work. The modified materials were characterized by Fourier transform infrared spectroscopy, transmission electron microscopy and electrochemical impedance spectroscopy. The results showed that the CMWCNTs exhibited a certain degree of changes, such as the appearance of the characteristic peaks of carbon oxygen double bonds in carboxyl group, a decrease in diameter and length and a remarkable reduction of the impedance value. The electrochemical behavior of SEM on CMWCNTs/GCE was investigated by cyclic voltammetry and amperometric i-t curve in 1 mol/L HAc-NaAc buffer solution. An irreversible oxidation peak of SEM appeared at CMWCNTs/GCE. Compared to the bare electrode, the current of the oxidation peak was significantly increased. Under the optimal conditions such as HAc-NaAc solution (pH 7) and scan rate of 0.1 V/s, the obtained sensor presented linear response to SEM concentration in the range of 5.0×10-6 mol/L-1.09×10-3 mol/L, the linear regression equation was Ip(μA)=-0.472+0.0599C (μmol/L) with linear correlation coefficient of 0.997. The detection limit was 1.88×10-7 mol/L. At the same time, the recovery was from 92.8% to 98.0% in the test of pork liver samples.
2017, 45(10): 1517-1522
doi: 10.11895/j.issn.0253-3820.170336
Abstract:
A terminal deoxynucleotidyl transferase (TdT) amplification based DNA-copper nanoclusters (CuNCs) sensor was developed for detection of L-histidine (L-His). Single strand DNA containing poly-thymine (T) sequences were synthesized by TdT in the presence of dTTP. In blank control, poly-T sequences worked as templates of CuNCs due to the affinity between thymine and copper ions(Ⅱ). Fluorescence intensity was enhanced when CuNCs formed with reducing agents. In the presence of L-His, the imidazolyl group of L-His worked as a chelating agent that formed L-His-Cu2+ chelated complex. Thus less copper ions were induced in poly-T sequences, and less CuNCs were obtained to produce week fluorescence signals. A good linear correlation was obtained between fluorescence change and the logarithm of the L-His concentration over the range of 5.0×10-9-5.0×10-4 mol/L. The detection limit was estimated as 3.4×10-9 mol/L. And the recoveries were 97.4%-104.6% for the actual urine samples. Compared with other methods of synthetic CuNCs, this method allowed to specifically determining L-histidine without template or labeling, which showed good potential in biomedical and clinical analysis.
A terminal deoxynucleotidyl transferase (TdT) amplification based DNA-copper nanoclusters (CuNCs) sensor was developed for detection of L-histidine (L-His). Single strand DNA containing poly-thymine (T) sequences were synthesized by TdT in the presence of dTTP. In blank control, poly-T sequences worked as templates of CuNCs due to the affinity between thymine and copper ions(Ⅱ). Fluorescence intensity was enhanced when CuNCs formed with reducing agents. In the presence of L-His, the imidazolyl group of L-His worked as a chelating agent that formed L-His-Cu2+ chelated complex. Thus less copper ions were induced in poly-T sequences, and less CuNCs were obtained to produce week fluorescence signals. A good linear correlation was obtained between fluorescence change and the logarithm of the L-His concentration over the range of 5.0×10-9-5.0×10-4 mol/L. The detection limit was estimated as 3.4×10-9 mol/L. And the recoveries were 97.4%-104.6% for the actual urine samples. Compared with other methods of synthetic CuNCs, this method allowed to specifically determining L-histidine without template or labeling, which showed good potential in biomedical and clinical analysis.
2017, 45(10): 1523-1528
doi: 10.11895/j.issn.0253-3820.170263
Abstract:
p-Nitroaniline (PNA) was one kind of highly toxic aromatic amine and becomes an environmental pollutant in recent years. Here we reported the construction of a fluorescent sensor based on an anionic pyrene, 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS), for the rapid and visual detection of PNA in aqueous media. The fluorescence quenching of HPTS caused by the presence of PNA was through non-covalent interactions. A good linear relationship between fluorescent intensity of HPTS at 512 nm was obtained in the range of 10-120 μmol/L. The detection limit (3σ) of this approach was 4.6 μmol/L. The results showed that the method was suitable for rapid detection of PNA in real samples with good sensitivity, selectivity, anti-interference, low cost and easy operation.
p-Nitroaniline (PNA) was one kind of highly toxic aromatic amine and becomes an environmental pollutant in recent years. Here we reported the construction of a fluorescent sensor based on an anionic pyrene, 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS), for the rapid and visual detection of PNA in aqueous media. The fluorescence quenching of HPTS caused by the presence of PNA was through non-covalent interactions. A good linear relationship between fluorescent intensity of HPTS at 512 nm was obtained in the range of 10-120 μmol/L. The detection limit (3σ) of this approach was 4.6 μmol/L. The results showed that the method was suitable for rapid detection of PNA in real samples with good sensitivity, selectivity, anti-interference, low cost and easy operation.
2017, 45(10): 1529-1534
doi: 10.11895/j.issn.0253-3820.170360
Abstract:
Currently, rapid detection of effective components in synthetic drugs and herbal medicine remains an important and difficult issue of medicine research. A novel ionization technique, called dielectric barrier discharge ionization (DBDI), has strong ionization ability, and is suitable for weak polar substances. Besides, this technique possesses many intrinsic advantages, such as simplicity, rapidity, no complicated sample pretreatment, etc. In this study, a new DBDI ion source, based on single electrode technique, was used to detect four weak polar synthetic drugs. The results showed that the protonated molecular ions[M+H]+ of four weak polar synthetic drugs were observed obviously. What's more, the DBDI ion source was also used for the rapid analysis of Radix Aconiti and Radix Aconiti Preparata pieces without any sample pretreatment. The result showed that the protonated molecular ions[M+H]+ and fragment ions[M+H-60]+of aconitine, hypaconitine, and mesaconitine were detected in Radix Aconiti. And only the fragment ions[M+H-60]+ were detected in Radix Aconiti Preparat. The researches indicated that diester aconitine and monoester aconitine were the main effective components of Radix Aconiti Radix and Aconiti Preparat, respectively. The new DBDI ion source provided a fast and reliable method to identify effective components of medicine, showing a broad application prospects in synthetic drugs and herbal medicine research.
Currently, rapid detection of effective components in synthetic drugs and herbal medicine remains an important and difficult issue of medicine research. A novel ionization technique, called dielectric barrier discharge ionization (DBDI), has strong ionization ability, and is suitable for weak polar substances. Besides, this technique possesses many intrinsic advantages, such as simplicity, rapidity, no complicated sample pretreatment, etc. In this study, a new DBDI ion source, based on single electrode technique, was used to detect four weak polar synthetic drugs. The results showed that the protonated molecular ions[M+H]+ of four weak polar synthetic drugs were observed obviously. What's more, the DBDI ion source was also used for the rapid analysis of Radix Aconiti and Radix Aconiti Preparata pieces without any sample pretreatment. The result showed that the protonated molecular ions[M+H]+ and fragment ions[M+H-60]+of aconitine, hypaconitine, and mesaconitine were detected in Radix Aconiti. And only the fragment ions[M+H-60]+ were detected in Radix Aconiti Preparat. The researches indicated that diester aconitine and monoester aconitine were the main effective components of Radix Aconiti Radix and Aconiti Preparat, respectively. The new DBDI ion source provided a fast and reliable method to identify effective components of medicine, showing a broad application prospects in synthetic drugs and herbal medicine research.
2017, 45(10): 1535-1541
doi: 10.11895/j.issn.0253-3820.170215
Abstract:
An electrochemical sensor was fabricated for determination of cholesterol (ChO) based on the molecularly imprinting and signal amplification of graphene. The sensor was prepared by electropolymerizing phenol on the surface of graphene modified glassy carbon electrode with ChO as template. The structure, properties and molecular imprinting effect of the imprinted membrane were studied by SEM, CV and DPV. The results showed that the sensor had good selectivity and high sensitivity to cholesterol. The calibration graph for the determination of cholesterol was linear in the range of 8.0×10-8-2.0×10-4 mol/L, with the detection limit (S/N=3) of 5.6×10-8 mol/L. The sensor was applied to the determination of cholesterol in human serum samples with satisfactory results.
An electrochemical sensor was fabricated for determination of cholesterol (ChO) based on the molecularly imprinting and signal amplification of graphene. The sensor was prepared by electropolymerizing phenol on the surface of graphene modified glassy carbon electrode with ChO as template. The structure, properties and molecular imprinting effect of the imprinted membrane were studied by SEM, CV and DPV. The results showed that the sensor had good selectivity and high sensitivity to cholesterol. The calibration graph for the determination of cholesterol was linear in the range of 8.0×10-8-2.0×10-4 mol/L, with the detection limit (S/N=3) of 5.6×10-8 mol/L. The sensor was applied to the determination of cholesterol in human serum samples with satisfactory results.
2017, 45(10): 1542-1546
doi: 10.11895/j.issn.0253-3820.170209
Abstract:
Zeolite supported α-cyano-4-hydroxycinnamic acid (CHCA) as novel composite matrix was applied in matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis of substance P and small molecular compounds of fluoroquinolones. In the experiment, this new matrix was examined and compared with conventional organic matrix CHCA. The results indicated that the novel composite matrix was capable of suppressing the alkali metal related peaks and interference fragments, simplifying mass spectra in low-molecular-weight region, and promoting ionization efficiency. The influence of SiO2/Al2O3 ratio of ZSM-5 and porous diameter of ZSM-5 and Beta zeolites on performance of MALDI-TOF-MS analysis of substance P was also investigated under the same conditions. In contrast, it was regarded that the strong surface acidity and sufficient cavity for loading CHCA were beneficial for interference fragments suppression and peak intensity enhancement. Additionally, it was successfully applied in the detection of enrofloxacin and ciprofloxacin in complex samples.
Zeolite supported α-cyano-4-hydroxycinnamic acid (CHCA) as novel composite matrix was applied in matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) analysis of substance P and small molecular compounds of fluoroquinolones. In the experiment, this new matrix was examined and compared with conventional organic matrix CHCA. The results indicated that the novel composite matrix was capable of suppressing the alkali metal related peaks and interference fragments, simplifying mass spectra in low-molecular-weight region, and promoting ionization efficiency. The influence of SiO2/Al2O3 ratio of ZSM-5 and porous diameter of ZSM-5 and Beta zeolites on performance of MALDI-TOF-MS analysis of substance P was also investigated under the same conditions. In contrast, it was regarded that the strong surface acidity and sufficient cavity for loading CHCA were beneficial for interference fragments suppression and peak intensity enhancement. Additionally, it was successfully applied in the detection of enrofloxacin and ciprofloxacin in complex samples.
2017, 45(10): 1547-1555
doi: 10.11895/j.issn.0253-3820.170269
Abstract:
The inclusion complex of cordycepin (COR) with hydroxypropyl-β-cyclodextrin (HPβCD) was prepared by the method of saturated solution. The inclusion of HPβCD with COR in aqueous solution was studied by UV-vis spectroscopy, and the inclusion ratio of COR/HPβCD complex was determined with the Job plots. The COR/HPβCD complex was characterized and determined by means of 1H NMR and 2D NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The results showed that the COR/HPβCD complex ratio was 1:1 and the water solubility and stability of COR were obviously increased in the inclusion complex with HPβCD. The COR/HPβCD complex will be potentially useful for its medical application.
The inclusion complex of cordycepin (COR) with hydroxypropyl-β-cyclodextrin (HPβCD) was prepared by the method of saturated solution. The inclusion of HPβCD with COR in aqueous solution was studied by UV-vis spectroscopy, and the inclusion ratio of COR/HPβCD complex was determined with the Job plots. The COR/HPβCD complex was characterized and determined by means of 1H NMR and 2D NMR, differential scanning calorimetry (DSC), thermogravimetric analysis (TG), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The results showed that the COR/HPβCD complex ratio was 1:1 and the water solubility and stability of COR were obviously increased in the inclusion complex with HPβCD. The COR/HPβCD complex will be potentially useful for its medical application.
2017, 45(10): 1556-1563
doi: 10.11895/j.issn.0253-3820.170186
Abstract:
A method for simultaneous detection of multi-mycotoxins in ten kinds of common dried fruits was been exploited by using ultra performance liquid chromatography-tandem mass spectrometry. The edible part of dried fruits was ground up with certain quantity of water. The mash was extracted by 10 mmol/L citric acid-acetonitrile, purified by C18 column, and filtered using 0.22-μm organic filtration. All the sixteen mycotoxins were well separated in 8 min on ACQUITY UPLC BEH C18 column with acetonitrile as phase A and 10 mmol/L ammonium acetate solution containing 0.1% formic acid as mobile phase B. Result showed that the limits of detection (LODs) for the sixteen mycotoxins were 0.01-1.00 μg/L, with linearity range of 1-200 μg/L and correlation coefficients above 0.9981. The average recoveries of the sixteen mycotoxins in ten matrices were 70.48%-118.85%, and the relative standard deviation (RSD, n=6) was 0.3%-11.9%. This economical, fast, simple and efficient method could be used for simultaneous detection of multi-mycotoxins in different dried fruits matrixes.
A method for simultaneous detection of multi-mycotoxins in ten kinds of common dried fruits was been exploited by using ultra performance liquid chromatography-tandem mass spectrometry. The edible part of dried fruits was ground up with certain quantity of water. The mash was extracted by 10 mmol/L citric acid-acetonitrile, purified by C18 column, and filtered using 0.22-μm organic filtration. All the sixteen mycotoxins were well separated in 8 min on ACQUITY UPLC BEH C18 column with acetonitrile as phase A and 10 mmol/L ammonium acetate solution containing 0.1% formic acid as mobile phase B. Result showed that the limits of detection (LODs) for the sixteen mycotoxins were 0.01-1.00 μg/L, with linearity range of 1-200 μg/L and correlation coefficients above 0.9981. The average recoveries of the sixteen mycotoxins in ten matrices were 70.48%-118.85%, and the relative standard deviation (RSD, n=6) was 0.3%-11.9%. This economical, fast, simple and efficient method could be used for simultaneous detection of multi-mycotoxins in different dried fruits matrixes.
2017, 45(10): 1564-1570
doi: 10.11895/j.issn.0253-3820.170338
Abstract:
An analytical method based on ultra performance liquid chromatography-tandem mass spectrometry was developed for the determination of SIOC0426 residues in environment samples (soil, sediment and water). The fate of SIOC0426 in three kinds of soils was also evaluated. The target compound was extracted with acetonitrile, cleaned up by C18 cartridge, and analyzed by gradient ultra performance liquid chromatography-tandem mass spectrometry with electrospray ionization under positive mode (ESI+) using a UPLC BEH C18 column. The method was validated using fortified soil, sediment and water. Mean recoveries of SIOC0426 at three spiked levels (0.005, 0.05 and 2.0 mg/kg) ranged from 87% to 106% with relative standard deviations of 2.8%-8.0%. Limits of quantification (LOQs) of SIOC0426 in soil (sediment) and water were 0.2 μg/kg and 0.2 μg/L, respectively. Linear calibration functions with correlation coefficients R2>0.9999 were obtained in the concentration range of 0.5-20 μg/L. This method was applied to the analysis of SIOC0426 residues in soil degradation samples. The results showed that the half-life of SIOC0426 ranged from 1.72 days to 28.2 days in three kinds of soils under aerobiotic conditions. While, the half-life of SIOC0426 ranged from 2.93 days to 31.4 days in three kinds of soils under anaerobic conditions. The degradation speed of SIOC0426 under aerobiotic conditions was faster than that under anaerobic conditions in the same soil. And the degradation speed of SIOC0426 in soils may be connected with the pH value of soils, cation exchange capacity and soil texture.
An analytical method based on ultra performance liquid chromatography-tandem mass spectrometry was developed for the determination of SIOC0426 residues in environment samples (soil, sediment and water). The fate of SIOC0426 in three kinds of soils was also evaluated. The target compound was extracted with acetonitrile, cleaned up by C18 cartridge, and analyzed by gradient ultra performance liquid chromatography-tandem mass spectrometry with electrospray ionization under positive mode (ESI+) using a UPLC BEH C18 column. The method was validated using fortified soil, sediment and water. Mean recoveries of SIOC0426 at three spiked levels (0.005, 0.05 and 2.0 mg/kg) ranged from 87% to 106% with relative standard deviations of 2.8%-8.0%. Limits of quantification (LOQs) of SIOC0426 in soil (sediment) and water were 0.2 μg/kg and 0.2 μg/L, respectively. Linear calibration functions with correlation coefficients R2>0.9999 were obtained in the concentration range of 0.5-20 μg/L. This method was applied to the analysis of SIOC0426 residues in soil degradation samples. The results showed that the half-life of SIOC0426 ranged from 1.72 days to 28.2 days in three kinds of soils under aerobiotic conditions. While, the half-life of SIOC0426 ranged from 2.93 days to 31.4 days in three kinds of soils under anaerobic conditions. The degradation speed of SIOC0426 under aerobiotic conditions was faster than that under anaerobic conditions in the same soil. And the degradation speed of SIOC0426 in soils may be connected with the pH value of soils, cation exchange capacity and soil texture.
2017, 45(10): 1571-1581
doi: 10.11895/j.issn.0253-3820.170199
Abstract:
As the new popular fluorescent carbon nanomaterials, carbon dots have not only excellent optical properties and small size characteristics, but also have good biocompatibility, low toxicity and easy to achieve the surface functional characteristics, and can replace the traditional semi-quantum dots of the better choice. Based on the unique fluorescence characteristics and high sensitivity, carbon fluorescent probe has a good potential in food analysis and testing. In this experiment, the study of fluorescent carbon dots has been reviewed in recent years. The characteristics of carbon dots are briefly introduced and the preparation methods of carbon dots are summarized. The application of carbon dot fluorescent probes in food analysis and detection is introduced and the limitations and development of carbon point application are analyzed and forecasted.
As the new popular fluorescent carbon nanomaterials, carbon dots have not only excellent optical properties and small size characteristics, but also have good biocompatibility, low toxicity and easy to achieve the surface functional characteristics, and can replace the traditional semi-quantum dots of the better choice. Based on the unique fluorescence characteristics and high sensitivity, carbon fluorescent probe has a good potential in food analysis and testing. In this experiment, the study of fluorescent carbon dots has been reviewed in recent years. The characteristics of carbon dots are briefly introduced and the preparation methods of carbon dots are summarized. The application of carbon dot fluorescent probes in food analysis and detection is introduced and the limitations and development of carbon point application are analyzed and forecasted.
