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2020 Volume 48 Issue 7
2020, 48(7): 817-826
doi: 10.19756/j.issn.0253-3820.201090
Abstract:
Host-guest interaction is the process in which the host selectively combines the guest to form a supramolecular with specific function through non-covalent bonding according to the principles of structural complementarity and energy matching. The identification of biomolecules through antigen-antibody, DNA-protein, enzyme-substrate interactions in biological systems is based on the recognition of non-covalent interactions. The host-guest interaction possesses distinct characteristics of mild reaction conditions and dynamic reversible reaction process, and it not only can efficiently overcome the limitations of covalent bonding, but also can simulate the biological functions at the molecular level. This review summarizes the advance in the applications of host-guest interaction in biochemical analysis including the detection of proteins, nucleic acids, small biological molecules, metal ions and isomers. In addition, the challenges and trends in the development of biosensors based on host-guest interaction are highlighted.
Host-guest interaction is the process in which the host selectively combines the guest to form a supramolecular with specific function through non-covalent bonding according to the principles of structural complementarity and energy matching. The identification of biomolecules through antigen-antibody, DNA-protein, enzyme-substrate interactions in biological systems is based on the recognition of non-covalent interactions. The host-guest interaction possesses distinct characteristics of mild reaction conditions and dynamic reversible reaction process, and it not only can efficiently overcome the limitations of covalent bonding, but also can simulate the biological functions at the molecular level. This review summarizes the advance in the applications of host-guest interaction in biochemical analysis including the detection of proteins, nucleic acids, small biological molecules, metal ions and isomers. In addition, the challenges and trends in the development of biosensors based on host-guest interaction are highlighted.
2020, 48(7): 827-837
doi: 10.19756/j.issn.0253-3820.191704
Abstract:
Tissue samples contain abundant biological molecular information, which is widely used for the study of metabolomics, lipidomics and proteomics. Ambient mass spectrometry (AMS) has the ability to directly obtain the information of tissue samples, including the kind and content of biomolecules. Moreover, it has many advantages such as high sensitivity, high throughput, and low consumption, etc. Recently, AMS has been increasingly applied in analyzing various tissue samples. In this paper, the applications of AMS in plant, animal and postoperative tissue samples in recent years were reviewed. Furthermore, the challenges and prospects of analyzing tissue samples by ambient mass spectrometry imaging were briefly discussed.
Tissue samples contain abundant biological molecular information, which is widely used for the study of metabolomics, lipidomics and proteomics. Ambient mass spectrometry (AMS) has the ability to directly obtain the information of tissue samples, including the kind and content of biomolecules. Moreover, it has many advantages such as high sensitivity, high throughput, and low consumption, etc. Recently, AMS has been increasingly applied in analyzing various tissue samples. In this paper, the applications of AMS in plant, animal and postoperative tissue samples in recent years were reviewed. Furthermore, the challenges and prospects of analyzing tissue samples by ambient mass spectrometry imaging were briefly discussed.
2020, 48(7): 838-846
doi: 10.19756/j.issn.0253-3820.201227
Abstract:
Nanoparticles (NPs) are playing increasingly important roles in the fields of biomedicine, biochemical analysis, and energy materials. Because NPs are intrinsically heterogeneous, rapid and high resolution size distribution measurement of NPs is a challenging task. Compared with traditional approaches for the analysis of NPs, such as electron microscopy, atomic force microscopy, dynamic light scattering, and nanoparticle tracking analysis, flow cytometry is a well-established technique for high-throughput, quantitative, and multi-parameter analysis of individual cells and microscopic particles. However, it has been extremely difficult for conventional flow cytometry to detect polystyrene NPs smaller than 200 nm in diameter via light scattering. Employing strategies for single molecule fluorescence detection in a sheathed flow, we have recently developed Nano-flow cytometer (nFCM) that enables light scattering detection of single silica nanoparticles (SiO2 NPs) as small as 24 nm in diameter. However, the dynamic range of the nFCM is limited by the maximum photon count of the single photon counting avalanche photodiode (APD) detector. Owing to the exponential dependence of scattered light intensity on particle size, there is an urgent need to enhance the dynamic range of the nFCM for the analysis of samples with wide size distributions. Adopting strategies of beam shaping with binary optical element, background reduction upon the combined usage of an iris-diaphragm and a rectangular aperture, and signal enhancement using high quantum efficiency PMT, here we reported the development of a highly sensitive and wide dynamic range nFCM. Sensitive light-scattering detection of single SiO2 NPs as small as 59 nm in diameter was achieved with a signal-to-noise ratio of 119. Baseline separation of seven different sizes of SiO2 NPs ranging from 59 to 222 nm was obtained. The as-developed nFCM was successfully applied to the size distribution analysis of outer membrane vesicles derived from Salmonella Typhimurium.
Nanoparticles (NPs) are playing increasingly important roles in the fields of biomedicine, biochemical analysis, and energy materials. Because NPs are intrinsically heterogeneous, rapid and high resolution size distribution measurement of NPs is a challenging task. Compared with traditional approaches for the analysis of NPs, such as electron microscopy, atomic force microscopy, dynamic light scattering, and nanoparticle tracking analysis, flow cytometry is a well-established technique for high-throughput, quantitative, and multi-parameter analysis of individual cells and microscopic particles. However, it has been extremely difficult for conventional flow cytometry to detect polystyrene NPs smaller than 200 nm in diameter via light scattering. Employing strategies for single molecule fluorescence detection in a sheathed flow, we have recently developed Nano-flow cytometer (nFCM) that enables light scattering detection of single silica nanoparticles (SiO2 NPs) as small as 24 nm in diameter. However, the dynamic range of the nFCM is limited by the maximum photon count of the single photon counting avalanche photodiode (APD) detector. Owing to the exponential dependence of scattered light intensity on particle size, there is an urgent need to enhance the dynamic range of the nFCM for the analysis of samples with wide size distributions. Adopting strategies of beam shaping with binary optical element, background reduction upon the combined usage of an iris-diaphragm and a rectangular aperture, and signal enhancement using high quantum efficiency PMT, here we reported the development of a highly sensitive and wide dynamic range nFCM. Sensitive light-scattering detection of single SiO2 NPs as small as 59 nm in diameter was achieved with a signal-to-noise ratio of 119. Baseline separation of seven different sizes of SiO2 NPs ranging from 59 to 222 nm was obtained. The as-developed nFCM was successfully applied to the size distribution analysis of outer membrane vesicles derived from Salmonella Typhimurium.
2020, 48(7): 847-854
doi: 10.19756/j.issn.0253-3820.201109
Abstract:
Insight into the exocytosis process of diagnostical nanomaterials is critical for their clinical transformation. However, it is unclear whether nanomaterials will be eliminated during cell migration. Herein, gold nanoparticles (AuNPs) were utilized as plasmonic imaging probes and dark field microscopy was applied to examine the movement as well as exocytosis of gold nanoparticles during cell migration. The results showed that the internalized AuNPs could localize into the retraction fibers. The mobility of nanoparticles reduced with the increased distance from the cell body. When the retraction fibers disconnected from the cell body, AuNPs were left outside the cell. This study demonstrated the migracytosis of nanomaterials, which could benefit the future design of safer and more efficient nanomaterials for diagnostics.
Insight into the exocytosis process of diagnostical nanomaterials is critical for their clinical transformation. However, it is unclear whether nanomaterials will be eliminated during cell migration. Herein, gold nanoparticles (AuNPs) were utilized as plasmonic imaging probes and dark field microscopy was applied to examine the movement as well as exocytosis of gold nanoparticles during cell migration. The results showed that the internalized AuNPs could localize into the retraction fibers. The mobility of nanoparticles reduced with the increased distance from the cell body. When the retraction fibers disconnected from the cell body, AuNPs were left outside the cell. This study demonstrated the migracytosis of nanomaterials, which could benefit the future design of safer and more efficient nanomaterials for diagnostics.
2020, 48(7): 855-862
doi: 10.19756/j.issn.0253-3820.201022
Abstract:
Currently available bacterium quantitation assays majorly depend on specialized facilities and associate with long turnaround time. To overcome these limitations, a droplet digital microfluidic assay was developed for rapid bacterium quantitation. The microfluidic assay featured by syringe vacuum activated droplet generation, by which stochastic single cell confinement in monodisperse picoliter volumes in parallel modules was achieved. The presence of live bacteria in droplets was indicated by the change of fluorescence intensity due to the chromogenic reaction caused by live bacteria. Bacteria density in the original sample was calculated by fitting the proportion of positives (p) to the Poisson distribution algorithm. The total analytical process for bacteria quantitation was completed in 3.5 h. The dynamic detection range was 105-108 CFU/mL, with relative standard deviation <5%. With advantages of simple operation and short analysis time, the developed microfluidic assay was expected to be adapted for rapid bacterium quantitation.
Currently available bacterium quantitation assays majorly depend on specialized facilities and associate with long turnaround time. To overcome these limitations, a droplet digital microfluidic assay was developed for rapid bacterium quantitation. The microfluidic assay featured by syringe vacuum activated droplet generation, by which stochastic single cell confinement in monodisperse picoliter volumes in parallel modules was achieved. The presence of live bacteria in droplets was indicated by the change of fluorescence intensity due to the chromogenic reaction caused by live bacteria. Bacteria density in the original sample was calculated by fitting the proportion of positives (p) to the Poisson distribution algorithm. The total analytical process for bacteria quantitation was completed in 3.5 h. The dynamic detection range was 105-108 CFU/mL, with relative standard deviation <5%. With advantages of simple operation and short analysis time, the developed microfluidic assay was expected to be adapted for rapid bacterium quantitation.
2020, 48(7): 863-870
doi: 10.19756/j.issn.0253-3820.191325
Abstract:
A label-free colorimetric sensor based on DNA-gold nanoparticles (DNA-AuNPs) was constructed for discrimination of multiple heavy metal ions. Different lengths of ssDNA strands (15A, 30A and 45AT) were used as non-specific receptors, which were combined with AuNPs to form 15A DNA-AuNPs, 30A DNA-AuNPs and 45AT DNA-AuNPs complex and acted as three sensing elements of this colorimetric sensor. It was found that different metal ions could trigger the DNA-protected AuNPs and showed different aggregation behaviors along with various color changes in the presence of high concentrations salt. The different absorption of AuNPs was used as the response signal of the sensor, which was then analyzed by principal component analysis (PCA) and linear discriminant analysis (LDA). The experimental results showed that 11 kinds of heavy metal ions (Ag+, Pb2+, Zn2+, Cu2+, Cd2+, Mn2+, Ni2+, Co2+, Hg2+, Bi3+ and Cr3+) could be well distinguished by LDA at the level of 0.5 μmol/L.
A label-free colorimetric sensor based on DNA-gold nanoparticles (DNA-AuNPs) was constructed for discrimination of multiple heavy metal ions. Different lengths of ssDNA strands (15A, 30A and 45AT) were used as non-specific receptors, which were combined with AuNPs to form 15A DNA-AuNPs, 30A DNA-AuNPs and 45AT DNA-AuNPs complex and acted as three sensing elements of this colorimetric sensor. It was found that different metal ions could trigger the DNA-protected AuNPs and showed different aggregation behaviors along with various color changes in the presence of high concentrations salt. The different absorption of AuNPs was used as the response signal of the sensor, which was then analyzed by principal component analysis (PCA) and linear discriminant analysis (LDA). The experimental results showed that 11 kinds of heavy metal ions (Ag+, Pb2+, Zn2+, Cu2+, Cd2+, Mn2+, Ni2+, Co2+, Hg2+, Bi3+ and Cr3+) could be well distinguished by LDA at the level of 0.5 μmol/L.
2020, 48(7): 871-880
doi: 10.19756/j.issn.0253-3820.191453
Abstract:
Early diagnosis is very important for improving the quality of life and prolonging the survival time of lung cancer patients. In this work, glutamine-functionalized graphene quantum dot (Glu-GQD) was prepared by pyrolysis of the mixture of citric acid and glutamine at 180℃ for 3 h. The resulting Gln-GQD was reacted with HAuCl4 to produce Gln-GQD/Au hybrid. On one hand, the Gln-GQD as the reductant converted Au3+ into Au0, finally leading to the formation of Au nanocrystals. On the other hand, the Gln-GQD as the stabilizer was immobilized on the surface of Au nanocrystals to achieve the hybridization of Gln-GQD and Au nanoparticle. The results of scanning electron microscopy, transmission electron microscopy, X-ray diffraction and infrared spectroscopy analysis revealed that the Gln-GQD/Au offerred the crystal structure of cubic gold, in which the gold and nitrogen elements were uniformly distributed on the surface of spherical Au nanoparticles, with the average particle size of (31.2±0.15) nm and the rich of functional groups such as -OH, -NH- and -COOH. To obtain H2-Gln-GQD/Au-Thi redox probe, one hairpin DNA 2 (H2) was connected to the surface of Au nanoparticles via the Au-S bond, and then the condensation of -COOH in the Gln-GQD with -NH2 in the thionine (Thi) by EDC/NHS activation was achieved. Further, the redox probe was used to construct electrochemical sensing platform coupled with the nonenzymatic amplification strategy. In the presence of CYFRA21-1, the H2 in the redox probe was hybridized with the hairpin DNA 1 (H1) modified on the surface of gold electrode to release one CYFRA21-1, which could be directly used in the next target DNA cycle. By the target-induced DNA self-assembly reaction, one CYFRA21-1 molecule transferred multiple redox probes to the surface of gold electrodes, resulting in a significant electrochemical signal amplification. In the detection of CYFRA21-1, the hybridization of H2 with H1 achieved the specific response to target DNA. Thi underwent reversible redox reaction on the electrode surface and produced the electrochemical signal in the response to target DNA. The Gln-GQD/Au in situ catalytzed the oxidation-reduction reaction of Thi. This would further amplify the detection signal. When the concentrations of CYFRA21-1 were in the range of 2-100000 fmol/L, the differential pulse voltammetric peak current increased linearly with the increase of CYFRA21-1 concentration. The detection limit was found to be 0.67 fmol/L (S/N=3). The sensitivity was much better than that of reported electrochemical sensors for CYFRA21-1. This method was successfully applied to the electrochemical detection of CYFRA21-1 in human serum samples.
Early diagnosis is very important for improving the quality of life and prolonging the survival time of lung cancer patients. In this work, glutamine-functionalized graphene quantum dot (Glu-GQD) was prepared by pyrolysis of the mixture of citric acid and glutamine at 180℃ for 3 h. The resulting Gln-GQD was reacted with HAuCl4 to produce Gln-GQD/Au hybrid. On one hand, the Gln-GQD as the reductant converted Au3+ into Au0, finally leading to the formation of Au nanocrystals. On the other hand, the Gln-GQD as the stabilizer was immobilized on the surface of Au nanocrystals to achieve the hybridization of Gln-GQD and Au nanoparticle. The results of scanning electron microscopy, transmission electron microscopy, X-ray diffraction and infrared spectroscopy analysis revealed that the Gln-GQD/Au offerred the crystal structure of cubic gold, in which the gold and nitrogen elements were uniformly distributed on the surface of spherical Au nanoparticles, with the average particle size of (31.2±0.15) nm and the rich of functional groups such as -OH, -NH- and -COOH. To obtain H2-Gln-GQD/Au-Thi redox probe, one hairpin DNA 2 (H2) was connected to the surface of Au nanoparticles via the Au-S bond, and then the condensation of -COOH in the Gln-GQD with -NH2 in the thionine (Thi) by EDC/NHS activation was achieved. Further, the redox probe was used to construct electrochemical sensing platform coupled with the nonenzymatic amplification strategy. In the presence of CYFRA21-1, the H2 in the redox probe was hybridized with the hairpin DNA 1 (H1) modified on the surface of gold electrode to release one CYFRA21-1, which could be directly used in the next target DNA cycle. By the target-induced DNA self-assembly reaction, one CYFRA21-1 molecule transferred multiple redox probes to the surface of gold electrodes, resulting in a significant electrochemical signal amplification. In the detection of CYFRA21-1, the hybridization of H2 with H1 achieved the specific response to target DNA. Thi underwent reversible redox reaction on the electrode surface and produced the electrochemical signal in the response to target DNA. The Gln-GQD/Au in situ catalytzed the oxidation-reduction reaction of Thi. This would further amplify the detection signal. When the concentrations of CYFRA21-1 were in the range of 2-100000 fmol/L, the differential pulse voltammetric peak current increased linearly with the increase of CYFRA21-1 concentration. The detection limit was found to be 0.67 fmol/L (S/N=3). The sensitivity was much better than that of reported electrochemical sensors for CYFRA21-1. This method was successfully applied to the electrochemical detection of CYFRA21-1 in human serum samples.
2020, 48(7): 881-888
doi: 10.19756/j.issn.0253-3820.201066
Abstract:
Mass spectrometry signals were obtained from the mixtures of five matrixes and three standard product combinations. The five matrixes were 2,5-dihydroxybenzoic acid (DHB), α-cyano-4-hydroxycinnamic acid (CHCA), graphene (GR), graphene oxide (GO) and carbon nanotubes (CNT), while the three standard products were ginsenoside Rg1, ginsenoside Rb1 and notoginsenoside R1. DHB was utilized as a suitable matrix. After vacuum drying the 20 μm thick frozen sections of Panax notoginseng rhizome for 40 min, DHB was evenly coated on the section surface over 60 cycles, with a spray strength of 30%, a spray time of 1 s, an incubation time of 40 s and a drying time of 60 s. The data acquisition quality range was m/z 0-1500. PEG-600 was used for mass/charge ratio calibration and matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) was performed in 1000 Hz positive ion reflection mode. The spatial distribution of ten saponins in the cork layer, phloem, xylem and pith of Panax notoginseng rhizome was obtained. The t-distributed stochastic neighbor embedding (t-SNE) algorithm was used to analyze the data. A distinction between 2-year and 3-year panax notoginseng rhizomes was realized. This study provided an in-situ and visual method for the characterization of metabolites in the rhizome of Panax notoginseng and also provided valuable information for obtaining information on the specificity of Panax notoginseng.
Mass spectrometry signals were obtained from the mixtures of five matrixes and three standard product combinations. The five matrixes were 2,5-dihydroxybenzoic acid (DHB), α-cyano-4-hydroxycinnamic acid (CHCA), graphene (GR), graphene oxide (GO) and carbon nanotubes (CNT), while the three standard products were ginsenoside Rg1, ginsenoside Rb1 and notoginsenoside R1. DHB was utilized as a suitable matrix. After vacuum drying the 20 μm thick frozen sections of Panax notoginseng rhizome for 40 min, DHB was evenly coated on the section surface over 60 cycles, with a spray strength of 30%, a spray time of 1 s, an incubation time of 40 s and a drying time of 60 s. The data acquisition quality range was m/z 0-1500. PEG-600 was used for mass/charge ratio calibration and matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) was performed in 1000 Hz positive ion reflection mode. The spatial distribution of ten saponins in the cork layer, phloem, xylem and pith of Panax notoginseng rhizome was obtained. The t-distributed stochastic neighbor embedding (t-SNE) algorithm was used to analyze the data. A distinction between 2-year and 3-year panax notoginseng rhizomes was realized. This study provided an in-situ and visual method for the characterization of metabolites in the rhizome of Panax notoginseng and also provided valuable information for obtaining information on the specificity of Panax notoginseng.
2020, 48(7): 889-895
doi: 10.19756/j.issn.0253-3820.201051
Abstract:
A simple, sensitive and label-free colorimetric sensor for cyanide (CN-) was developed based on analyte-induced shielding of peroxidase-like activity of cysteamine-capped gold nanoparticles (cyst-AuNPs). The cyst-AuNPs could catalyze the H2O2-mediated oxidation of 3,3',5,5'-tetramethylbenzidine (TMB), producing blue oxidized TMB (oxTMB) with a maximum absorption at 652 nm. With the addition of cyanide, AuNPs could be efficiently oxidized by the dissolved oxygen under alkaline conditions to form soluble and colorless complex, Au(CN)2-, which reduced the catalytic ability of AuNPs, thus producing less oxTMB. On the basis of this, both color and absorption at 652 nm decreased corresponding to the concentration of CN-. Due to the signal amplification effect of the catalytic reaction, a detection limit as low as 0.33 μmol/L was obtained, which was much lower than the maximum level (1.9 μmol/L) of CN- in drinking water permitted by the World Health Organization. Furthermore, the as-proposed sensor required neither surface modification of nanoparticles nor complex operations. These advantages make this sensor a powerful protocol for the quantitative detection of cyanide in water samples with satisfactory results.
A simple, sensitive and label-free colorimetric sensor for cyanide (CN-) was developed based on analyte-induced shielding of peroxidase-like activity of cysteamine-capped gold nanoparticles (cyst-AuNPs). The cyst-AuNPs could catalyze the H2O2-mediated oxidation of 3,3',5,5'-tetramethylbenzidine (TMB), producing blue oxidized TMB (oxTMB) with a maximum absorption at 652 nm. With the addition of cyanide, AuNPs could be efficiently oxidized by the dissolved oxygen under alkaline conditions to form soluble and colorless complex, Au(CN)2-, which reduced the catalytic ability of AuNPs, thus producing less oxTMB. On the basis of this, both color and absorption at 652 nm decreased corresponding to the concentration of CN-. Due to the signal amplification effect of the catalytic reaction, a detection limit as low as 0.33 μmol/L was obtained, which was much lower than the maximum level (1.9 μmol/L) of CN- in drinking water permitted by the World Health Organization. Furthermore, the as-proposed sensor required neither surface modification of nanoparticles nor complex operations. These advantages make this sensor a powerful protocol for the quantitative detection of cyanide in water samples with satisfactory results.
2020, 48(7): 896-902
doi: 10.19756/j.issn.0253-3820.191620
Abstract:
For overall study of the soil aging influence on the common polychromy artworks proteinaceous binders, scanning electron microcopy, X-ray diffraction and infrared spectroscopy were applied to characterize the morphology, crystallinity, and proteins secondary structure contents of the common-used five binders (pig glue, whole egg, egg white, egg yolk and milk) in ancient China before and after soil aging. The results illustrated that the regular structures had deteriorated to the loosing states. The crystallinity all decreased, with milk declining the most. The binders still possessed the stair-stepped amide I, Ⅱ, Ⅲ FTIR absorbance while the helical structures had dissociated. Moreover, the content of α-helix declined while those at of β-sheet and random coils climbed, suggesting binders' structures had transformed to unordered states.
For overall study of the soil aging influence on the common polychromy artworks proteinaceous binders, scanning electron microcopy, X-ray diffraction and infrared spectroscopy were applied to characterize the morphology, crystallinity, and proteins secondary structure contents of the common-used five binders (pig glue, whole egg, egg white, egg yolk and milk) in ancient China before and after soil aging. The results illustrated that the regular structures had deteriorated to the loosing states. The crystallinity all decreased, with milk declining the most. The binders still possessed the stair-stepped amide I, Ⅱ, Ⅲ FTIR absorbance while the helical structures had dissociated. Moreover, the content of α-helix declined while those at of β-sheet and random coils climbed, suggesting binders' structures had transformed to unordered states.
2020, 48(7): 903-911
doi: 10.19756/j.issn.0253-3820.191595
Abstract:
A method for analysis of lipid profile by ultra high performance liquid chromatography-triple time-of-flight tandem mass spectrometry (UPLC-Triple TOF-MS/MS) was established. The chromatographic column was selected, and the concentration of ammonium formate in mobile phase and the collision energy of mass spectrometry were optimized. The ACQUITY UPLC CSH C18 chromatographic column (150 mm×2.1 mm, 1.7 μm) was used. The mobile phase A was acetonitrile/water (65:35, V/V), the mobile phase B was isopropanol/acetonitrile (85:15, V/V), and both of which contained 5 mmol/L ammonium formate and 0.1% formic acid. IDA automatic secondary scanning mode was adopted for mass spectrometry. Through methodological verification, lipid standards maintained good linearity in certain concentration ranges. The correlation coefficients (R2) were all above 0.995, the limits of detection (LOD) were 0.001-0.25 μmol/L, the limits of quantification (LOQ) were 0.0025-0.2 μmol/L, and the relative standard deviations were less than 10%. Most of the recovery rates were more than 80%. The lipid of Pacific cod (Gadus macrocephalus) was extracted by chloroform-methanol (2:1, V/V). A total of 498 lipid molecular species were identified in Pacific cod, including 255 phospholipid molecular species, 52 sphingolipid molecular species and 191 glyceride molecular species, of which the main subclasses were phosphatidylethanolamine, sphingomyelin and diglyceride. The results showed that the method had high sensitivity, high resolution and high throughput, and could be applied to the analysis of lipid profile of Pacific cod, which laid a foundation for the application of lipidomics in the field of aquatic products.
A method for analysis of lipid profile by ultra high performance liquid chromatography-triple time-of-flight tandem mass spectrometry (UPLC-Triple TOF-MS/MS) was established. The chromatographic column was selected, and the concentration of ammonium formate in mobile phase and the collision energy of mass spectrometry were optimized. The ACQUITY UPLC CSH C18 chromatographic column (150 mm×2.1 mm, 1.7 μm) was used. The mobile phase A was acetonitrile/water (65:35, V/V), the mobile phase B was isopropanol/acetonitrile (85:15, V/V), and both of which contained 5 mmol/L ammonium formate and 0.1% formic acid. IDA automatic secondary scanning mode was adopted for mass spectrometry. Through methodological verification, lipid standards maintained good linearity in certain concentration ranges. The correlation coefficients (R2) were all above 0.995, the limits of detection (LOD) were 0.001-0.25 μmol/L, the limits of quantification (LOQ) were 0.0025-0.2 μmol/L, and the relative standard deviations were less than 10%. Most of the recovery rates were more than 80%. The lipid of Pacific cod (Gadus macrocephalus) was extracted by chloroform-methanol (2:1, V/V). A total of 498 lipid molecular species were identified in Pacific cod, including 255 phospholipid molecular species, 52 sphingolipid molecular species and 191 glyceride molecular species, of which the main subclasses were phosphatidylethanolamine, sphingomyelin and diglyceride. The results showed that the method had high sensitivity, high resolution and high throughput, and could be applied to the analysis of lipid profile of Pacific cod, which laid a foundation for the application of lipidomics in the field of aquatic products.
2020, 48(7): 912-920
doi: 10.19756/j.issn.0253-3820.191723
Abstract:
Magnetic nanocomposites Ag/AgCl@Fe3O4@GO were synthesized by solvothermal process. The structure and morphology of the products were characterized by transmission electron microscopy, scanning transmission electron microscopy, energy dispersive X-ray spectroscopy and nitrogen adsorption and desorption method. The adsorption properties of the materials for 2,4-dichlorophenol (2,4-DCP) in aqueous solution were studied. The results indicated that the nanocomposites were composed of Ag/AgCl@Fe3O4 spherical magnetic nanoparticles with mesoporous structure loaded on the folded surface of graphene oxide. The average pore size of the product was 13.98 nm, and the specific surface area and pore volume were 46.91 m2/g and 0.1791 cm3/g, respectively. The adsorption experiment of 2,4-DCP on Ag/AgCl@Fe3O4@GO composite showed that for 20 mg/L of 2,4-DCP solution, the adsorption equilibrium was basically reached in 20 min, and the adsorption capacity was 13.74 mg/g. The adsorption fitted well with pseudo second-order kinetic model, and the correlation coefficient was 0.99954. The Langmuir model was more suitable for describing the adsorption with the correlation coefficient range of 0.9841-0.9972, which showed that the adsorption was a monolayer adsorption. Adsorption thermodynamic parameters ΔG were -5.0462 kJ/mol (293 K), -4.4076 kJ/mol (303 K), -3.7522 kJ/mol (313 K), -3.4358 kJ/mol (323 K), ΔH and ΔS were -17.1653 kJ/mol and -42.2158 J/(mol·K), respectively. The adsorption process was a spontaneous exothermic process with entropy decreasing. In addition, the temperature was lower and the adsorption was better, which showed the characteristics of physical adsorption. This kind of functional composite not only had good adsorption activity, but also could be recycled by the way of external magnetic field.
Magnetic nanocomposites Ag/AgCl@Fe3O4@GO were synthesized by solvothermal process. The structure and morphology of the products were characterized by transmission electron microscopy, scanning transmission electron microscopy, energy dispersive X-ray spectroscopy and nitrogen adsorption and desorption method. The adsorption properties of the materials for 2,4-dichlorophenol (2,4-DCP) in aqueous solution were studied. The results indicated that the nanocomposites were composed of Ag/AgCl@Fe3O4 spherical magnetic nanoparticles with mesoporous structure loaded on the folded surface of graphene oxide. The average pore size of the product was 13.98 nm, and the specific surface area and pore volume were 46.91 m2/g and 0.1791 cm3/g, respectively. The adsorption experiment of 2,4-DCP on Ag/AgCl@Fe3O4@GO composite showed that for 20 mg/L of 2,4-DCP solution, the adsorption equilibrium was basically reached in 20 min, and the adsorption capacity was 13.74 mg/g. The adsorption fitted well with pseudo second-order kinetic model, and the correlation coefficient was 0.99954. The Langmuir model was more suitable for describing the adsorption with the correlation coefficient range of 0.9841-0.9972, which showed that the adsorption was a monolayer adsorption. Adsorption thermodynamic parameters ΔG were -5.0462 kJ/mol (293 K), -4.4076 kJ/mol (303 K), -3.7522 kJ/mol (313 K), -3.4358 kJ/mol (323 K), ΔH and ΔS were -17.1653 kJ/mol and -42.2158 J/(mol·K), respectively. The adsorption process was a spontaneous exothermic process with entropy decreasing. In addition, the temperature was lower and the adsorption was better, which showed the characteristics of physical adsorption. This kind of functional composite not only had good adsorption activity, but also could be recycled by the way of external magnetic field.
2020, 48(7): 921-927
doi: 10.19756/j.issn.0253-3820.191703
Abstract:
Staphylococcus aureus is a typical food-borne pathogenic bacterium. The detection methods for Staphylococcus aureus still have some shortcomings, and it is necessary to develop new and fast detection methods. In this work, a new method for detecting food-borne pathogenic bacteria through the detection of their characteristic peptides by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. For the nine candidate characteristic peptides of Staphylococcus aureus reported in literature, it was necessary to investigate their targeted methods and compare their analysis performance. This study firstly investigated the untargeted method of nine candidate characteristic peptides, and then confirmed their targeted method based on multiple reaction monitoring model, after which their analysis performance were compared. The results indicated that I1 (AYLAVPAAPK), I2 (DYNSPTLIGWVK), I5 (AGYTVNNTPK) and I6 (SISSGYTSGR) were more suitable candidate characteristic peptides for Staphylococcus aureus. This work provided methodological basis for future application of detecting food-borne pathogenic bacteria through characteristic peptides.
Staphylococcus aureus is a typical food-borne pathogenic bacterium. The detection methods for Staphylococcus aureus still have some shortcomings, and it is necessary to develop new and fast detection methods. In this work, a new method for detecting food-borne pathogenic bacteria through the detection of their characteristic peptides by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. For the nine candidate characteristic peptides of Staphylococcus aureus reported in literature, it was necessary to investigate their targeted methods and compare their analysis performance. This study firstly investigated the untargeted method of nine candidate characteristic peptides, and then confirmed their targeted method based on multiple reaction monitoring model, after which their analysis performance were compared. The results indicated that I1 (AYLAVPAAPK), I2 (DYNSPTLIGWVK), I5 (AGYTVNNTPK) and I6 (SISSGYTSGR) were more suitable candidate characteristic peptides for Staphylococcus aureus. This work provided methodological basis for future application of detecting food-borne pathogenic bacteria through characteristic peptides.
2020, 48(7): 928-936
doi: 10.19756/j.issn.0253-3820.191644
Abstract:
A method for determination of multi-residues of seven target pesticides in sesame oil was established by dispersive solid-phase extraction of quick easy cheap effective rugged and safe method (QuEChERS) and HPLC-MS/MS. Seven kinds of pesticides often used in oil crops such as metalaxyl-M, butachlor, acetochlor, metolachlor, epoxiconazole, azoxystrobin and haloxyfop-P-methyl were determined. Due to the complexity of sesame oil matrix, the types of extraction solvent and cleaning agent in sesame oil matrix were selected and optimized. Finally, 10 mL of acetonitrile extraction, 60 mg of PSA and 20 mg of GCB were selected to effectively remove fat, pigment, organic acids and other interference impurities in sesame oil. In the concentration range of 0.001-10 mg/L, the standard solution concentration of seven target pesticides in sesame oil matrix showed a good linear relationship with the corresponding chromatographic response value, and the correlation coefficients were all greater than 0.99. The average recoveries of the three added concentrations in sesame oil were between 86.9% and 106.3%, and the RSDs were less than 5.2%. The accuracy, precision and sensitivity all met the requirements of pesticide residue analysis. This method was fast, simple and environmentally friendly and suitable for quantitative analysis of target pesticide residues in sesame oil.
A method for determination of multi-residues of seven target pesticides in sesame oil was established by dispersive solid-phase extraction of quick easy cheap effective rugged and safe method (QuEChERS) and HPLC-MS/MS. Seven kinds of pesticides often used in oil crops such as metalaxyl-M, butachlor, acetochlor, metolachlor, epoxiconazole, azoxystrobin and haloxyfop-P-methyl were determined. Due to the complexity of sesame oil matrix, the types of extraction solvent and cleaning agent in sesame oil matrix were selected and optimized. Finally, 10 mL of acetonitrile extraction, 60 mg of PSA and 20 mg of GCB were selected to effectively remove fat, pigment, organic acids and other interference impurities in sesame oil. In the concentration range of 0.001-10 mg/L, the standard solution concentration of seven target pesticides in sesame oil matrix showed a good linear relationship with the corresponding chromatographic response value, and the correlation coefficients were all greater than 0.99. The average recoveries of the three added concentrations in sesame oil were between 86.9% and 106.3%, and the RSDs were less than 5.2%. The accuracy, precision and sensitivity all met the requirements of pesticide residue analysis. This method was fast, simple and environmentally friendly and suitable for quantitative analysis of target pesticide residues in sesame oil.
2020, 48(7): 937-945
doi: 10.19756/j.issn.0253-3820.191506
Abstract:
An effective method was developed for the simultaneous determination of 4 kinds of antioxidants and 8 kinds of the ultraviolet absorbers in plastic packaging baked foods by QuEChERS enhanced matix removal-lipid (EMR-Lipid) combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were extracted by acetonitrile-acetone (1:1, V/V). The 12 targets were separated on a Waters BEH C18 column by gradient elution with methanol-10mmol/L ammonium acetate as mobile phase, ionized with positive and negative electrospray ionization (ESI+/-), detected under multiple reaction monitoring mode (MRM), and quantified with external standard method. The result showed that the 12 kinds of analytes presented favorable linearity in the respective linear range, with correlation coefficients (R2) of more than 0.9978. The method detection limits (S/N=3) were in the range of 5.0-10.0 μg/kg, except for the Antioxidant 2246 was 150.0 μg/kg. The average recoveries (n=6) ranged from 80.3% to 118.5%, with intra-day relative standard deviations (RSD, n=6) of 1.7%-9.8% and inter-day RSD (n=5) of 4.5%-9.9%. The developed method had simple pre-treatment procedure, satisfactory purification and sensitivity, and was suitable for the simultaneous determination of antioxidants and ultraviolet absorbers in plastic packaging baked foods.
An effective method was developed for the simultaneous determination of 4 kinds of antioxidants and 8 kinds of the ultraviolet absorbers in plastic packaging baked foods by QuEChERS enhanced matix removal-lipid (EMR-Lipid) combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The samples were extracted by acetonitrile-acetone (1:1, V/V). The 12 targets were separated on a Waters BEH C18 column by gradient elution with methanol-10mmol/L ammonium acetate as mobile phase, ionized with positive and negative electrospray ionization (ESI+/-), detected under multiple reaction monitoring mode (MRM), and quantified with external standard method. The result showed that the 12 kinds of analytes presented favorable linearity in the respective linear range, with correlation coefficients (R2) of more than 0.9978. The method detection limits (S/N=3) were in the range of 5.0-10.0 μg/kg, except for the Antioxidant 2246 was 150.0 μg/kg. The average recoveries (n=6) ranged from 80.3% to 118.5%, with intra-day relative standard deviations (RSD, n=6) of 1.7%-9.8% and inter-day RSD (n=5) of 4.5%-9.9%. The developed method had simple pre-treatment procedure, satisfactory purification and sensitivity, and was suitable for the simultaneous determination of antioxidants and ultraviolet absorbers in plastic packaging baked foods.
2020, 48(7): 946-954
doi: 10.19756/j.issn.0253-3820.191740
Abstract:
An accurate determination method for gold nanoparticle number concentration and size was developed based on single particle-inductively coupled plasma-mass spectrometry (SP-ICP-MS). Influence factors such as different calculation methods of transport efficiency, dwell time, dispersing agent and injection mode were investigated and optimized. The transport efficiency had a great impact on the accuracy of the measurement result, and it should be selected according to the measured target parameters. It was important to keep the stability of the transport efficiency and used the calibration standard calibrating during the measurement process. Dwell time directly affected the precision of result, and the data processing mode should be selected carefully according to the sample type, particle size and other properties. When the dwell time was 0.1 ms, for 30 nm and 60 nm gold nanoparticles, the linear ranges were 2-40 pg/g and 10-200 pg/g, respectively, the linear correlation coefficients were greater than 0.9998. The relative standard deviation of particle number concentration was less than 3.80%. The detection limits of particle number concentration and particle size were 110 NPs/g and 9 nm, respectively. Four kinds of synthesized gold nanoparticles and CCQM-P194 international pilot study sample were determined by the established method. The diviation of number concentration in pilot study from the reference values of the key comparison was less than 5%. The results were equivalent and the expanded uncertainty was less than 15% (k=2), which further verified the accuracy and applicability of the method.
An accurate determination method for gold nanoparticle number concentration and size was developed based on single particle-inductively coupled plasma-mass spectrometry (SP-ICP-MS). Influence factors such as different calculation methods of transport efficiency, dwell time, dispersing agent and injection mode were investigated and optimized. The transport efficiency had a great impact on the accuracy of the measurement result, and it should be selected according to the measured target parameters. It was important to keep the stability of the transport efficiency and used the calibration standard calibrating during the measurement process. Dwell time directly affected the precision of result, and the data processing mode should be selected carefully according to the sample type, particle size and other properties. When the dwell time was 0.1 ms, for 30 nm and 60 nm gold nanoparticles, the linear ranges were 2-40 pg/g and 10-200 pg/g, respectively, the linear correlation coefficients were greater than 0.9998. The relative standard deviation of particle number concentration was less than 3.80%. The detection limits of particle number concentration and particle size were 110 NPs/g and 9 nm, respectively. Four kinds of synthesized gold nanoparticles and CCQM-P194 international pilot study sample were determined by the established method. The diviation of number concentration in pilot study from the reference values of the key comparison was less than 5%. The results were equivalent and the expanded uncertainty was less than 15% (k=2), which further verified the accuracy and applicability of the method.
2020, 48(7): 955-961
doi: 10.19756/j.issn.0253-3820.191338
Abstract:
The ultra high preformance liquid chromatography-tandem high resolution mass spectrometry was used to find out the possible composition of quercetin and its bound glycosides in Rosa roxburghii. The quercetin and its glycosides of Rosa roxburghii were analyzed by standard chromatographic time control, relative molecular weight, second order mass spectrometry fragments, and so on. The results showed that one quercetin and nine nuclear structural substances containing quercetin were identified from Rosa roxburghii. The chemical composition of quercetin, quercetin-3-rhamnoside, quercetin-3-O-glucopyranoside, quercetin-3-O-rhamnoside, quercetin-3-O-rhamnoside, Quercetin-3-O-[6"-O-(3-hydroxy-3-methylglutaryl)-β-D-galactoside], quercetin-3-O-glucose-rhamnoside, Amongthem, quercetin-3-rhamnoside, quercetin-3-O-glucopyranoside, quercetin-3-O-[6"-O-(3-hydroxy-3-methylglutaryl)-β-D-galactoside] were found in Rosa roxburghii for the first time. According to the ion fragments, the pyrolysis pathway of quercetin glycosides was inferred, which enriched the basic research results of Rosa roxburghii resources, and provided a theoretical reference for the structure identification of quercetin and the subsequent rational development of the drug and food utilization value of quercetin glycosides of Rosa roxburghii.
The ultra high preformance liquid chromatography-tandem high resolution mass spectrometry was used to find out the possible composition of quercetin and its bound glycosides in Rosa roxburghii. The quercetin and its glycosides of Rosa roxburghii were analyzed by standard chromatographic time control, relative molecular weight, second order mass spectrometry fragments, and so on. The results showed that one quercetin and nine nuclear structural substances containing quercetin were identified from Rosa roxburghii. The chemical composition of quercetin, quercetin-3-rhamnoside, quercetin-3-O-glucopyranoside, quercetin-3-O-rhamnoside, quercetin-3-O-rhamnoside, Quercetin-3-O-[6"-O-(3-hydroxy-3-methylglutaryl)-β-D-galactoside], quercetin-3-O-glucose-rhamnoside, Amongthem, quercetin-3-rhamnoside, quercetin-3-O-glucopyranoside, quercetin-3-O-[6"-O-(3-hydroxy-3-methylglutaryl)-β-D-galactoside] were found in Rosa roxburghii for the first time. According to the ion fragments, the pyrolysis pathway of quercetin glycosides was inferred, which enriched the basic research results of Rosa roxburghii resources, and provided a theoretical reference for the structure identification of quercetin and the subsequent rational development of the drug and food utilization value of quercetin glycosides of Rosa roxburghii.
2020, 48(7): 962-968
doi: 10.19756/j.issn.0253-3820.191431
Abstract:
Lewisite as well as its hydrolysis products can react with cuprous ion and produce red cuprous acetylene under the alkaline condition. To overcome the issue that a change in the intensity leads to a change in all the three components based on the RGB (red, green, blue) model, the RGB chromaticity scheme derived from normalized RGB system instead of RGB scheme was utilized for the detection in this study. The type of solubilizers and reductants, the concentrations of reductants, copper chloride and sodium hydroxide, the dosage of acetic acid, the reaction temperature, and the reaction time were optimized. As a result, gelatin and hydroxylamine hydrochloride (0.32 mol/L) were respectively used as solubilizer and reductant, the concentrations of copper chloride, sodium hydroxide and 30 μL of acetic acid were 0.15 mol/L, 30% (m/m) and 36% (m/m), respectively, and the reaction was performed for 5 min at room temperature. Under the optimal conditions, the chromaticity value showed a linear correlation with Lewisite concentration in the range of 0.40-10.05 mg/L. The theoretical detection limits for R and B values were 0.389 mg/L and 0.391 mg/L, respectively, and the practical detection limit was 0.40 mg/L. The method was successfully applied to the determination of Lewisite in artificial water samples, with the recoveries of 96.9%-106.9%. The experimental results showed that the method had high selectivity, sensitivity and good repeatability.
Lewisite as well as its hydrolysis products can react with cuprous ion and produce red cuprous acetylene under the alkaline condition. To overcome the issue that a change in the intensity leads to a change in all the three components based on the RGB (red, green, blue) model, the RGB chromaticity scheme derived from normalized RGB system instead of RGB scheme was utilized for the detection in this study. The type of solubilizers and reductants, the concentrations of reductants, copper chloride and sodium hydroxide, the dosage of acetic acid, the reaction temperature, and the reaction time were optimized. As a result, gelatin and hydroxylamine hydrochloride (0.32 mol/L) were respectively used as solubilizer and reductant, the concentrations of copper chloride, sodium hydroxide and 30 μL of acetic acid were 0.15 mol/L, 30% (m/m) and 36% (m/m), respectively, and the reaction was performed for 5 min at room temperature. Under the optimal conditions, the chromaticity value showed a linear correlation with Lewisite concentration in the range of 0.40-10.05 mg/L. The theoretical detection limits for R and B values were 0.389 mg/L and 0.391 mg/L, respectively, and the practical detection limit was 0.40 mg/L. The method was successfully applied to the determination of Lewisite in artificial water samples, with the recoveries of 96.9%-106.9%. The experimental results showed that the method had high selectivity, sensitivity and good repeatability.
