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2019 Volume 47 Issue 12
2019, 47(12): 1871-1877
doi: 10.19756/j.issn.0253-3820.191280
Abstract:
Membrane fusion plays an important regulatory role in the life activities of organisms. Membrane fusion in cells plays a role in promoting the operation of molecules in cells throughout the life cycle of an organism, and the fusion of viruses and cell membranes may sometimes mark the end of an organism's life. However, due to the complexity of living cells, the interpretation of biological research results is often ambiguous, so only a few protein structures on the membrane such as SNARE (soluble N-ethyl maleimide sensitive factor attachment protein receptors) protein family and its role in promoting membrane fusion have been gradually explored. At the same time, to better study the mechanism of membrane fusion, a simple artificial model system was established to simulate the biofilm fusion, for example, the biological model of membrane fusion was established by using liposomes modified by DNA strand and liposomes modified by coiled coil peptide. The mechanism of SNARE promoting membrane fusion and the establishment of DNA and curling helical mediated membrane fusion were reviewed in this paper.
Membrane fusion plays an important regulatory role in the life activities of organisms. Membrane fusion in cells plays a role in promoting the operation of molecules in cells throughout the life cycle of an organism, and the fusion of viruses and cell membranes may sometimes mark the end of an organism's life. However, due to the complexity of living cells, the interpretation of biological research results is often ambiguous, so only a few protein structures on the membrane such as SNARE (soluble N-ethyl maleimide sensitive factor attachment protein receptors) protein family and its role in promoting membrane fusion have been gradually explored. At the same time, to better study the mechanism of membrane fusion, a simple artificial model system was established to simulate the biofilm fusion, for example, the biological model of membrane fusion was established by using liposomes modified by DNA strand and liposomes modified by coiled coil peptide. The mechanism of SNARE promoting membrane fusion and the establishment of DNA and curling helical mediated membrane fusion were reviewed in this paper.
2019, 47(12): 1878-1886
doi: 10.19756/j.issn.0253-3820.191251
Abstract:
Sample pretreatment is a key link in the whole process of analysis and detection. For samples whose original concentration is lower than the detection limit of analytical method, pre concentration technology is necessary, which is beneficial to improve the accuracy of the analytical method and expand the application range. However, conventional sample pre concentration technology is often cumbersome and depends on expensive equipment, resulting in the increased inspection time and cost. The paper-based microfluidic sample pre concentration technology is favored by domestic and foreign scholars for its easy preparation, low cost and high efficiency. This technology simplifies the operation process and reduces the detection cost. This paper focuses on the research and application progress of paper-based microfluidic sample preconcentration in recent years, including enrichment principle, paper-based material selection and device structure design, and the application of this technology. Finally, the development trend of this technology is prospected.
Sample pretreatment is a key link in the whole process of analysis and detection. For samples whose original concentration is lower than the detection limit of analytical method, pre concentration technology is necessary, which is beneficial to improve the accuracy of the analytical method and expand the application range. However, conventional sample pre concentration technology is often cumbersome and depends on expensive equipment, resulting in the increased inspection time and cost. The paper-based microfluidic sample pre concentration technology is favored by domestic and foreign scholars for its easy preparation, low cost and high efficiency. This technology simplifies the operation process and reduces the detection cost. This paper focuses on the research and application progress of paper-based microfluidic sample preconcentration in recent years, including enrichment principle, paper-based material selection and device structure design, and the application of this technology. Finally, the development trend of this technology is prospected.
2019, 47(12): 1887-1892
doi: 10.19756/j.issn.0253-3820.191449
Abstract:
Electrode-electrolyte interface, where the electrochemical reaction happens, plays an important role in the investigation of electrochemical mechanism. The traditional electrochemical techniques pay more attention on the charge transfer process happened on the electrode. However, they cannot provide information of the electrode-electrolyte interface at molecular level. How to realize the in-situ electrochemical monitoring of the intermediates on the electrode-electrolyte interface during redox reaction is of great significance to the study of electrochemical mechanism. In this work, electrochemical reaction of coenzyme Q0 (CoQ0) on the gold electrode was studied by time-of-flight secondary ion mass spectrometry (ToF-SIMS). A high vacuum compatible microfluidic electrochemical cell was fabricated for the electrochemical study of CoQ0. Then, a micro-hole with diameter of 2 μm was fabricated on the electrochemical cell by the primary ion beam of ToF-SIMS for the subsequent analysis. To evaluate the feasibility of ToF-SIMS for liquid sample measurement, the chemical distribution of CoQ0 and the SiN- around the micro-hole were measured. The stable distribution of CoQ0 and the SiN- during the ToF-SIMS measurement indicated that the microfluidic electrochemical cell was compatible for the in-situ detection of the electrode-electrolyte interface in high vacuum environment (1×10-5 Pa). Electrochemical behavior of CoQ0 in the electrochemical cell was further studied. The variations of CoQ0, CoQ0H2 and related intermediate at different potentials agreed well with the electrochemical reaction of CoQ0 in aqueous solution, which showed that the direct molecular evidence of the electrode-electrolyte interface was obtained. The direct monitoring of electrode-electrolyte interface by ToF-SIMS revealed the electrochemical evolution on the electrode at molecular level, which was of great potential for the detailed understanding of the electrochemical reaction mechanism.
Electrode-electrolyte interface, where the electrochemical reaction happens, plays an important role in the investigation of electrochemical mechanism. The traditional electrochemical techniques pay more attention on the charge transfer process happened on the electrode. However, they cannot provide information of the electrode-electrolyte interface at molecular level. How to realize the in-situ electrochemical monitoring of the intermediates on the electrode-electrolyte interface during redox reaction is of great significance to the study of electrochemical mechanism. In this work, electrochemical reaction of coenzyme Q0 (CoQ0) on the gold electrode was studied by time-of-flight secondary ion mass spectrometry (ToF-SIMS). A high vacuum compatible microfluidic electrochemical cell was fabricated for the electrochemical study of CoQ0. Then, a micro-hole with diameter of 2 μm was fabricated on the electrochemical cell by the primary ion beam of ToF-SIMS for the subsequent analysis. To evaluate the feasibility of ToF-SIMS for liquid sample measurement, the chemical distribution of CoQ0 and the SiN- around the micro-hole were measured. The stable distribution of CoQ0 and the SiN- during the ToF-SIMS measurement indicated that the microfluidic electrochemical cell was compatible for the in-situ detection of the electrode-electrolyte interface in high vacuum environment (1×10-5 Pa). Electrochemical behavior of CoQ0 in the electrochemical cell was further studied. The variations of CoQ0, CoQ0H2 and related intermediate at different potentials agreed well with the electrochemical reaction of CoQ0 in aqueous solution, which showed that the direct molecular evidence of the electrode-electrolyte interface was obtained. The direct monitoring of electrode-electrolyte interface by ToF-SIMS revealed the electrochemical evolution on the electrode at molecular level, which was of great potential for the detailed understanding of the electrochemical reaction mechanism.
2019, 47(12): 1893-1900
doi: 10.19756/j.issn.0253-3820.191444
Abstract:
To simulate the life-saving circulation of Pacific oysters, ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF) was used to analyze the changes of endogenous peptides of live Pacific oysters at different circulation stages. Chemometric method was used to screen the differential peptide markers at each stage of circulation to obtain a set of new indicators for evaluating the quality changes in the circulation of live Pacific oysters. According to the peptide histology technique, the endogenous peptide was extracted from samples at 7 key time points in the whole process of circulation of live Pacific oysters (cleaning, temporary purification and nourishing), and then separated and identified by UHPLC-Q-TOF to obtain the peptide group profile at each circulation stage. Multivariate statistical analysis such as principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used for data mining and screening for differential markers. The online amino acid sequence was used to identify the amino acid sequences of differential peptides. The results showed that 3, 10, and 8 potential peptide markers were screened in the cleaning, temporary purification, and water-free preservation phases, respectively. The potential marker peptide DYDPVDK was selected for synthesis and the multi-reaction monitoring (MRM) analysis method based on liquid chromatography-triple quadrupole mass spectrometry was used to verify the correctness of the differential marker peptide sequence and its applicability for routine liquid chromatography analysis. In this work, peptide analysis was used for the first time to characterize the endogenous peptides of live Pacific oysters at different circulation stages. The differential marker peptides in different circulation stages were selected to provide the basis for detection of circulation process of live shellfish.
To simulate the life-saving circulation of Pacific oysters, ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-Q-TOF) was used to analyze the changes of endogenous peptides of live Pacific oysters at different circulation stages. Chemometric method was used to screen the differential peptide markers at each stage of circulation to obtain a set of new indicators for evaluating the quality changes in the circulation of live Pacific oysters. According to the peptide histology technique, the endogenous peptide was extracted from samples at 7 key time points in the whole process of circulation of live Pacific oysters (cleaning, temporary purification and nourishing), and then separated and identified by UHPLC-Q-TOF to obtain the peptide group profile at each circulation stage. Multivariate statistical analysis such as principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) were used for data mining and screening for differential markers. The online amino acid sequence was used to identify the amino acid sequences of differential peptides. The results showed that 3, 10, and 8 potential peptide markers were screened in the cleaning, temporary purification, and water-free preservation phases, respectively. The potential marker peptide DYDPVDK was selected for synthesis and the multi-reaction monitoring (MRM) analysis method based on liquid chromatography-triple quadrupole mass spectrometry was used to verify the correctness of the differential marker peptide sequence and its applicability for routine liquid chromatography analysis. In this work, peptide analysis was used for the first time to characterize the endogenous peptides of live Pacific oysters at different circulation stages. The differential marker peptides in different circulation stages were selected to provide the basis for detection of circulation process of live shellfish.
2019, 47(12): 1901-1908
doi: 10.19756/j.issn.0253-3820.191538
Abstract:
Water-soluble green fluorescent carbon nanodots (CDs) were synthesized by one-step hydrothermal method with ascorbic acid (AA) as carbon source. The morphology and properties of CDs were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infra-Red (FTIR), ultraviolet-visible (UV-vis) spectroscopy and fluorescence spectroscopy. Based on the fluorescence enhancement phenomenon generated by the combination of CD and aluminum ions (Al3+), a fluorescence analysis method was established to detect Al3+ with a linear range of 50-500 nmol/L (R2=0.9988) and 500-2000 nmol/L (R2=0.9976), respectively. The limit of detection (LODs) was 10.23 nmol/L (S/N=3). Moreover, this method was successfully applied in detection of Al3+ in bottled drinking water samples with recoveries of 97.7%-105.7%.
Water-soluble green fluorescent carbon nanodots (CDs) were synthesized by one-step hydrothermal method with ascorbic acid (AA) as carbon source. The morphology and properties of CDs were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier Transform Infra-Red (FTIR), ultraviolet-visible (UV-vis) spectroscopy and fluorescence spectroscopy. Based on the fluorescence enhancement phenomenon generated by the combination of CD and aluminum ions (Al3+), a fluorescence analysis method was established to detect Al3+ with a linear range of 50-500 nmol/L (R2=0.9988) and 500-2000 nmol/L (R2=0.9976), respectively. The limit of detection (LODs) was 10.23 nmol/L (S/N=3). Moreover, this method was successfully applied in detection of Al3+ in bottled drinking water samples with recoveries of 97.7%-105.7%.
2019, 47(12): 1909-1914
doi: 10.19756/j.issn.0253-3820.191390
Abstract:
Fingerprint analysis is of great significance in forensic sciences. Compared with existing fingerprint analytical methods, mass spectrometry-based methods can not only identify trace chemical components in fingerprints, but also obtain fingerprint imaging. In this study, four kinds of fingerprints, including sweat, inkpad, sunscreen, and liquid foundation, were analyzed by air-flow assisted desorption electrospray ionization mass spectrometry imaging (AFADESI-MSI). AFADESI was employed with the air flow of 45 L/min and 5 μL/min acetonitrile was used as spray solvent at spray voltage 7000 V. Positive ion full scan mode (100-1000 Da) was chosen. The results showed that AFADESI-MSI technology could not only obtain chemical information of various endogenous and exogenous substances in fingerprints, but also obtain high resolution images of fingerprints. In addition, overlapped fingerprints could be distinguished according to the typical chemical information in fingerprints. As a new fingerprint analysis method, AFADESI-MSI will be widely used in forensic scientific research and practical applications.
Fingerprint analysis is of great significance in forensic sciences. Compared with existing fingerprint analytical methods, mass spectrometry-based methods can not only identify trace chemical components in fingerprints, but also obtain fingerprint imaging. In this study, four kinds of fingerprints, including sweat, inkpad, sunscreen, and liquid foundation, were analyzed by air-flow assisted desorption electrospray ionization mass spectrometry imaging (AFADESI-MSI). AFADESI was employed with the air flow of 45 L/min and 5 μL/min acetonitrile was used as spray solvent at spray voltage 7000 V. Positive ion full scan mode (100-1000 Da) was chosen. The results showed that AFADESI-MSI technology could not only obtain chemical information of various endogenous and exogenous substances in fingerprints, but also obtain high resolution images of fingerprints. In addition, overlapped fingerprints could be distinguished according to the typical chemical information in fingerprints. As a new fingerprint analysis method, AFADESI-MSI will be widely used in forensic scientific research and practical applications.
2019, 47(12): 1915-1921
doi: 10.19756/j.issn.0253-3820.191451
Abstract:
To detect the level of hydrogen sulfide (H2S) in the environment and living beings, a colorimetric and fluorescent turn-off probe based on selective thiolyling of NBD (7-nitro-1,2,3-benzoxadiazole) amino was prepared through one-step organic synthesis. The selectivity and sensitivity of the probe were investigated by using sodium sulfide as an H2S donor in PBS buffer. The fluorescent intensity of the probe exhibited good linear relationship with concentration of H2S in the concentration range of 5-50 μmol/L, and the detection limit was estimated to be 0.125 μmol/L. The color of the solution changed from light yellow to light violet. The cell survival rate was higher than 90% when the concentration of the probe was below 50 μmol/L. The results of cell imaging experiments showed that the probe could be used for imaging H2S in the lysosomes of the cells.
To detect the level of hydrogen sulfide (H2S) in the environment and living beings, a colorimetric and fluorescent turn-off probe based on selective thiolyling of NBD (7-nitro-1,2,3-benzoxadiazole) amino was prepared through one-step organic synthesis. The selectivity and sensitivity of the probe were investigated by using sodium sulfide as an H2S donor in PBS buffer. The fluorescent intensity of the probe exhibited good linear relationship with concentration of H2S in the concentration range of 5-50 μmol/L, and the detection limit was estimated to be 0.125 μmol/L. The color of the solution changed from light yellow to light violet. The cell survival rate was higher than 90% when the concentration of the probe was below 50 μmol/L. The results of cell imaging experiments showed that the probe could be used for imaging H2S in the lysosomes of the cells.
2019, 47(12): 1922-1930
doi: 10.19756/j.issn.0253-3820.191290
Abstract:
The cationic water-pillar[5]arene (CP5A) modified zeolite (NZ) was prepared for adsorption of anionic dye bromocresol purple (BCP). The CP5A/NZ was characterized by scanning electron microscopy (SEM), infrared absorption spectroscopy (IR) and X-ray powder diffraction (XRD). The effects of NZ particle size, concentration of CP5A during modification, adsorption time, initial BCP concentration and solution pH on the removal percentage of BCP were studied. In addition, the kinetics and adsorption isotherms of BCP adsorption by CP5A/NZ were also analyzed, and the adsorption mechanism was discussed. SEM showed that the scaly structure of the NZ disappeared after CP5A modification, showing an enlarged bulk structure. The vibration of CH3N+ and CH2N+ in CP5A appeared in the CP5A/NZ. XRD revealed that the zeolite had different crystal structure after CP5A modification, and all of the above phenomena indicated that CP5A was successfully loaded into the NZ. Adsorption studies showed that due to charge repulsion, NZ had no scavenging ability to BCP. However, when CP5A solution (10 g/L) was used to modify NZ in the range of 0.42-0.59 nm, the removal percentage of BCP was 93.98%, and the adsorption reached equilibrium in 300 min. CP5A/NZ had a high removal percentage when treated with low concentrations (< 100 mg/L) of BCP solution. The second-order kinetic equation and the Langmuir isotherm could better fit the adsorption process of CP5A/NZ to BCP. The adsorption mechanism of CP5A/NZ on BCP could be described as follows:after the cation exchange of CH2N+ with NZ in CP5A, CH2N+ bound to the negative potential point on the surface of NZ, which increased the positive charge activity adsorption site of NZ surface, and thus the anion dye BCP had good scavenging ability.
The cationic water-pillar[5]arene (CP5A) modified zeolite (NZ) was prepared for adsorption of anionic dye bromocresol purple (BCP). The CP5A/NZ was characterized by scanning electron microscopy (SEM), infrared absorption spectroscopy (IR) and X-ray powder diffraction (XRD). The effects of NZ particle size, concentration of CP5A during modification, adsorption time, initial BCP concentration and solution pH on the removal percentage of BCP were studied. In addition, the kinetics and adsorption isotherms of BCP adsorption by CP5A/NZ were also analyzed, and the adsorption mechanism was discussed. SEM showed that the scaly structure of the NZ disappeared after CP5A modification, showing an enlarged bulk structure. The vibration of CH3N+ and CH2N+ in CP5A appeared in the CP5A/NZ. XRD revealed that the zeolite had different crystal structure after CP5A modification, and all of the above phenomena indicated that CP5A was successfully loaded into the NZ. Adsorption studies showed that due to charge repulsion, NZ had no scavenging ability to BCP. However, when CP5A solution (10 g/L) was used to modify NZ in the range of 0.42-0.59 nm, the removal percentage of BCP was 93.98%, and the adsorption reached equilibrium in 300 min. CP5A/NZ had a high removal percentage when treated with low concentrations (< 100 mg/L) of BCP solution. The second-order kinetic equation and the Langmuir isotherm could better fit the adsorption process of CP5A/NZ to BCP. The adsorption mechanism of CP5A/NZ on BCP could be described as follows:after the cation exchange of CH2N+ with NZ in CP5A, CH2N+ bound to the negative potential point on the surface of NZ, which increased the positive charge activity adsorption site of NZ surface, and thus the anion dye BCP had good scavenging ability.
2019, 47(12): 1931-1937
doi: 10.19756/j.issn.0253-3820.191384
Abstract:
The accurate quantification of β-amyloid peptides was achieved by the accurate measurement of sulfur elements in β-amyloid peptides based on high performance liquid chromatography isotope dilution inductively coupled plasmon mass spectrometry (HPLC-ID-ICPMS). Aβ42 in β-amyloid peptide was separated from impurities by optimizing liquid chromatography conditions, and then the eluent was mixed online with enriched 34S diluent. In view of the influence of enriched 34S diluent on 32S/34S signal strength and sensitivity, the flow rate of 34S diluent was optimized. According to the formula of isotope dilution method and the number of S elements in Aβ42, the content of Aβ42 in β amyloid peptide was (0.763±0.0044) g/g. The linear correlation coefficient was 0.999 within the range of 5-60 μg/g, the detection limit was 140 pg/g, and the quantitative limit was 467 pg/g. The recovery of the Aβ42 was between 98% and 105%, and the relative standard deviation was less than 6%. The measurement result of this sample by amino acid hydrolysis method was (0.768±0.0091) g/g, which was in good consistency with the result by this method.
The accurate quantification of β-amyloid peptides was achieved by the accurate measurement of sulfur elements in β-amyloid peptides based on high performance liquid chromatography isotope dilution inductively coupled plasmon mass spectrometry (HPLC-ID-ICPMS). Aβ42 in β-amyloid peptide was separated from impurities by optimizing liquid chromatography conditions, and then the eluent was mixed online with enriched 34S diluent. In view of the influence of enriched 34S diluent on 32S/34S signal strength and sensitivity, the flow rate of 34S diluent was optimized. According to the formula of isotope dilution method and the number of S elements in Aβ42, the content of Aβ42 in β amyloid peptide was (0.763±0.0044) g/g. The linear correlation coefficient was 0.999 within the range of 5-60 μg/g, the detection limit was 140 pg/g, and the quantitative limit was 467 pg/g. The recovery of the Aβ42 was between 98% and 105%, and the relative standard deviation was less than 6%. The measurement result of this sample by amino acid hydrolysis method was (0.768±0.0091) g/g, which was in good consistency with the result by this method.
2019, 47(12): 1938-1945
doi: 10.19756/j.issn.0253-3820.191243
Abstract:
A three-dimensional reduced graphene oxide (3D GR)-Prussian blue (PB)-based electrochemical enzyme sensor was constructed for sensitive detection of uric acid. The graphene oxide was thermally reduced by one-step hydrothermal method, and then 3D GR was formed by self-assembly. PB was electrodeposited onto 3D GR to synthesize 3D GR-PB composite. Due to its large specific surface area and porous nature, 3D GR provided more active sites for the reaction. Electrochemical tests showed that the enzyme sensor based on 3D GR-PB had a wide linear range (3.75×10-9-3.75×10-4 mol/L) and a low detection limit (4.21×10-10 mol/L). Because of the high specificity of uricase to catalyze uric acid, this sensor had high selectivity and provided a feasible solution for sensitive detection of uric acid.
A three-dimensional reduced graphene oxide (3D GR)-Prussian blue (PB)-based electrochemical enzyme sensor was constructed for sensitive detection of uric acid. The graphene oxide was thermally reduced by one-step hydrothermal method, and then 3D GR was formed by self-assembly. PB was electrodeposited onto 3D GR to synthesize 3D GR-PB composite. Due to its large specific surface area and porous nature, 3D GR provided more active sites for the reaction. Electrochemical tests showed that the enzyme sensor based on 3D GR-PB had a wide linear range (3.75×10-9-3.75×10-4 mol/L) and a low detection limit (4.21×10-10 mol/L). Because of the high specificity of uricase to catalyze uric acid, this sensor had high selectivity and provided a feasible solution for sensitive detection of uric acid.
2019, 47(12): 1946-1950
doi: 10.19756/j.issn.0253-3820.191263
Abstract:
SiO2/rosin-cardanol core-shell high performance liquid chromatography column was prepared with cardanol, rosin and spherical silica as main raw materials for purification of gastrodin. In the method, cardanol was esterified to prepare cardanol-ester as monomer, modified rosin and azodiisobutyronitrile (AIBN) were used as crosslinker and initiator, respectively. They were mixed and evenly coated on the surface of the silanized silica gels and polymerized in situ. The stationary phases were characterized by Fourier transform infrared sepctroscopy, scanning electron microscopy and transmission electron microscopy, and were packed in stainless steel hollow column by wet process. Phenyl-β-D-glucopyranoside and 4-methoxyphenyl-β-D-glucopyranoside were selected as competitors of gastrodin, acetonitrile-0.05% phosphoric acid aqueous solution (3:97, V/V) was used as mobile phase, the detection wavelength was set at 220 nm, the flow rate was 0.3 mL/min, and the separation performance about gastrodin of the core-shell stationary phase was explored at room temperature. The results showed that the particle size of the stationary phases was about 5 μm, the size distribution was uniform, and the thickness of shell (membrane) was about 75 nm. The resolution (Rs) of gastrodin/phenyl-β-D-glucopyranoside and gastrodin/4-methoxyphenyl-β-D-glucopyranoside was 7.43 and 12.35 respectively, which showed that the stationary phase had a higher selectivity to gastrodin. The method was simple and efficient, and provided a new way for separation of gastrodin.
SiO2/rosin-cardanol core-shell high performance liquid chromatography column was prepared with cardanol, rosin and spherical silica as main raw materials for purification of gastrodin. In the method, cardanol was esterified to prepare cardanol-ester as monomer, modified rosin and azodiisobutyronitrile (AIBN) were used as crosslinker and initiator, respectively. They were mixed and evenly coated on the surface of the silanized silica gels and polymerized in situ. The stationary phases were characterized by Fourier transform infrared sepctroscopy, scanning electron microscopy and transmission electron microscopy, and were packed in stainless steel hollow column by wet process. Phenyl-β-D-glucopyranoside and 4-methoxyphenyl-β-D-glucopyranoside were selected as competitors of gastrodin, acetonitrile-0.05% phosphoric acid aqueous solution (3:97, V/V) was used as mobile phase, the detection wavelength was set at 220 nm, the flow rate was 0.3 mL/min, and the separation performance about gastrodin of the core-shell stationary phase was explored at room temperature. The results showed that the particle size of the stationary phases was about 5 μm, the size distribution was uniform, and the thickness of shell (membrane) was about 75 nm. The resolution (Rs) of gastrodin/phenyl-β-D-glucopyranoside and gastrodin/4-methoxyphenyl-β-D-glucopyranoside was 7.43 and 12.35 respectively, which showed that the stationary phase had a higher selectivity to gastrodin. The method was simple and efficient, and provided a new way for separation of gastrodin.
2019, 47(12): 1951-1959
doi: 10.19756/j.issn.0253-3820.191259
Abstract:
In this study, metabolites of 2,2',4,5,5'-pentachlorodiphenyl (PCB101) in mice were identified. Kunming mice were exposed to PCB101 by intraperitoneal injection, and gas chromatography-tandem mass spectrometry (GC-MS/MS) was adopted for metabolites identification. It was confirmed that 5 kinds of compounds including 2 hydroxylated-PCB101, 2 methyl sulfonated-PCB101 and 1 methoxylated-PCB101 were metabolized. The hydroxylated metabolites were identified as 3-OH-PCB101 and 4-OH-PCB101 mainly in the stomach, intestines, gonads, liver and blood of mice. Hydroxylation might occur in the 2,5-dichlorinated ring, via formation of an 3,4-arene oxide that subsequently rearranged to a hydroxyl group by epoxide opening, or by direct insertion of a hydroxyl group in non-chlorinated substitution site. Methyl sulfonated metabolites were identified as 3-MeSO2-PCB101 and 4-MeSO2-PCB101 mainly in the stomach, intestines, kidneys, gonads, liver and lungs of mice, methyl sulfonation might also involve the formation of 3,4-epoxides, and then underwent the mercapturic acid pathway. Methoxylated metabolite was identified as 4-MeO-PCB101 mainly in the intestines, kidneys, lungs, muscles, spleen and brain of mice, simultaneously. In this study, it was basically confirmed that PCB101 could be biotransformed into three types of metabolites in mice at least, and methoxylated metabolite was confirmed in mice for the first time, which was of great scientific significance for further study on the persistence, toxicity effects and risk assessment of PCB metabolites in organisms.
In this study, metabolites of 2,2',4,5,5'-pentachlorodiphenyl (PCB101) in mice were identified. Kunming mice were exposed to PCB101 by intraperitoneal injection, and gas chromatography-tandem mass spectrometry (GC-MS/MS) was adopted for metabolites identification. It was confirmed that 5 kinds of compounds including 2 hydroxylated-PCB101, 2 methyl sulfonated-PCB101 and 1 methoxylated-PCB101 were metabolized. The hydroxylated metabolites were identified as 3-OH-PCB101 and 4-OH-PCB101 mainly in the stomach, intestines, gonads, liver and blood of mice. Hydroxylation might occur in the 2,5-dichlorinated ring, via formation of an 3,4-arene oxide that subsequently rearranged to a hydroxyl group by epoxide opening, or by direct insertion of a hydroxyl group in non-chlorinated substitution site. Methyl sulfonated metabolites were identified as 3-MeSO2-PCB101 and 4-MeSO2-PCB101 mainly in the stomach, intestines, kidneys, gonads, liver and lungs of mice, methyl sulfonation might also involve the formation of 3,4-epoxides, and then underwent the mercapturic acid pathway. Methoxylated metabolite was identified as 4-MeO-PCB101 mainly in the intestines, kidneys, lungs, muscles, spleen and brain of mice, simultaneously. In this study, it was basically confirmed that PCB101 could be biotransformed into three types of metabolites in mice at least, and methoxylated metabolite was confirmed in mice for the first time, which was of great scientific significance for further study on the persistence, toxicity effects and risk assessment of PCB metabolites in organisms.
2019, 47(12): 1960-1966
doi: 10.19756/j.issn.0253-3820.191323
Abstract:
As a conductive polymer, polypyrrole (PPy) has many advantages such as non-toxic monomer, low cost and high conductivity. The conductive polymer actuator has low driving voltage and can be operated in water and air, and is widely used in biomedical equipment, bionic robots, sensors and some other fields. In this work, electrochemical deposition was adopted to deposit PPy membrane on PVDF polymer to construct conductive polymer actuators. The process parameters such as temperature and current density on the surface of PPy and actuating performance were optimized. It was found that the PPy films were uniform, compact and conductive when the deposition temperature was controlled between -25 and -30℃, the polymerization time was 10 h and the current density was 0.1 mA/cm2. The displacement test platform of actuators was built by using micro laser sensor, data collector, electrochemical workstation and measuring microscope. Orthogonal experiments were carried out to investigate the actuating properties of PPy-based actuators, which showed that the tip displacement of actuators was proportional to their length and driving voltage; the wider actuators demonstrated increasing displacement. Furthermore, the process parameters were optimized from the angle of driving performance, which provided a complete parameter model for the optimal fabrication and practical application of PPy actuators. This study provides a theoretical basis for the application of PPy-based actuators in artificial muscles, sensors and actuators, and micro-nano manipulation systems.
As a conductive polymer, polypyrrole (PPy) has many advantages such as non-toxic monomer, low cost and high conductivity. The conductive polymer actuator has low driving voltage and can be operated in water and air, and is widely used in biomedical equipment, bionic robots, sensors and some other fields. In this work, electrochemical deposition was adopted to deposit PPy membrane on PVDF polymer to construct conductive polymer actuators. The process parameters such as temperature and current density on the surface of PPy and actuating performance were optimized. It was found that the PPy films were uniform, compact and conductive when the deposition temperature was controlled between -25 and -30℃, the polymerization time was 10 h and the current density was 0.1 mA/cm2. The displacement test platform of actuators was built by using micro laser sensor, data collector, electrochemical workstation and measuring microscope. Orthogonal experiments were carried out to investigate the actuating properties of PPy-based actuators, which showed that the tip displacement of actuators was proportional to their length and driving voltage; the wider actuators demonstrated increasing displacement. Furthermore, the process parameters were optimized from the angle of driving performance, which provided a complete parameter model for the optimal fabrication and practical application of PPy actuators. This study provides a theoretical basis for the application of PPy-based actuators in artificial muscles, sensors and actuators, and micro-nano manipulation systems.
2019, 47(12): 1967-1972
doi: 10.19756/j.issn.0253-3820.191342
Abstract:
A method was established for simultaneous determination of 15 kinds of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs) in soil sample using ultra performance liquid chromatography-tandem mass spectrometry coupled with solid phase extraction (SPE-UPLC-MS/MS). Firstly, 1 g of soil sample was ultraphonic extracted and then purified by SPE cartridge. The extracts were finally quantified by UPLC-MS/MS in negative electrospray ionization and multiple reaction monitoring (MRM) mode. The solvent volume and time of sonicated extraction, and the method of solid-phase extraction were optimized, and a satisfied pre-treatment effect was achieved when the sample was treated by ultraphonic extraction for 15 minutes in 2 mL of 1% ammonium hydroxide/methanol solution and eluted by methanol and 0.1% ammonium hydroxide/methanol successively on ENVI-Carb SPE cartridges. This method showed a good linear relationship in the concentration range of 0.01-5 ng/mL for the 15 kinds of PFCAs and PFSAs (R>0.998). The limits of detection (LOD) were in the range of 0.002-0.016 ng/g, while the limits of quantitation (LOQ) were in the range of 0.006-0.050 ng/g. The recoveries were 75.8%-113.0%, with relative standard deviations (RSDs) of less than 15%. Compared with the reported methods, comparable or even better quantification results were obtained by the method. The internationally accredited quality control sample NIST SRM 2586 was measured, and it was in the range of given concentration, which meant that this method was feasible for determination of PFAAs. Compared with the reported methods, this method consumed less solvent with shorter pretreatment time, and could be used for accurate analysis of PFAAs in soil.
A method was established for simultaneous determination of 15 kinds of perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs) in soil sample using ultra performance liquid chromatography-tandem mass spectrometry coupled with solid phase extraction (SPE-UPLC-MS/MS). Firstly, 1 g of soil sample was ultraphonic extracted and then purified by SPE cartridge. The extracts were finally quantified by UPLC-MS/MS in negative electrospray ionization and multiple reaction monitoring (MRM) mode. The solvent volume and time of sonicated extraction, and the method of solid-phase extraction were optimized, and a satisfied pre-treatment effect was achieved when the sample was treated by ultraphonic extraction for 15 minutes in 2 mL of 1% ammonium hydroxide/methanol solution and eluted by methanol and 0.1% ammonium hydroxide/methanol successively on ENVI-Carb SPE cartridges. This method showed a good linear relationship in the concentration range of 0.01-5 ng/mL for the 15 kinds of PFCAs and PFSAs (R>0.998). The limits of detection (LOD) were in the range of 0.002-0.016 ng/g, while the limits of quantitation (LOQ) were in the range of 0.006-0.050 ng/g. The recoveries were 75.8%-113.0%, with relative standard deviations (RSDs) of less than 15%. Compared with the reported methods, comparable or even better quantification results were obtained by the method. The internationally accredited quality control sample NIST SRM 2586 was measured, and it was in the range of given concentration, which meant that this method was feasible for determination of PFAAs. Compared with the reported methods, this method consumed less solvent with shorter pretreatment time, and could be used for accurate analysis of PFAAs in soil.
2019, 47(12): 1973-1980
doi: 10.19756/j.issn.0253-3820.191242
Abstract:
Immunomagnetic beads were prepared by coupling the functional magnetic beads modified by silanization and amination with Salmonella specific antibodies. The properties and biological activities of the beads were characterized by near infrared spectroscopy, fluorescence spectroscopy and absorption spectroscopy. Aminated magnetic beads, antibodies and quantum dots (QDs) were assembled in an orderly manner to construct a magnetic-bead-antibody-QDs composite fluorescent nanoprobe with magnetic collection and separation abilities for rapid detection of Salmonella. off-on fluorescence was realized through the fluorescence resonance energy transfer (FRET) effect between the QDs and gold nanoparticles (AuNPs), and an off-on fluorescent probe analytical method for rapidly detecting Salmonella was established. The results showed that the degree of fluorescence recovery of the composite fluorescent nanoprobe showed a good linear relationship with logarithm of bacterial concentration, and the linear regression equation was y=103.5x+121.4 (R2=0.9956). Moreover, the detection limit of the probe was 102 CFU/mL, and its detection time was less than 2 h. The proposed method features good specificity, low detection limit and high sensitivity,and can be used to rapidly detect Salmonella in food.
Immunomagnetic beads were prepared by coupling the functional magnetic beads modified by silanization and amination with Salmonella specific antibodies. The properties and biological activities of the beads were characterized by near infrared spectroscopy, fluorescence spectroscopy and absorption spectroscopy. Aminated magnetic beads, antibodies and quantum dots (QDs) were assembled in an orderly manner to construct a magnetic-bead-antibody-QDs composite fluorescent nanoprobe with magnetic collection and separation abilities for rapid detection of Salmonella. off-on fluorescence was realized through the fluorescence resonance energy transfer (FRET) effect between the QDs and gold nanoparticles (AuNPs), and an off-on fluorescent probe analytical method for rapidly detecting Salmonella was established. The results showed that the degree of fluorescence recovery of the composite fluorescent nanoprobe showed a good linear relationship with logarithm of bacterial concentration, and the linear regression equation was y=103.5x+121.4 (R2=0.9956). Moreover, the detection limit of the probe was 102 CFU/mL, and its detection time was less than 2 h. The proposed method features good specificity, low detection limit and high sensitivity,and can be used to rapidly detect Salmonella in food.
2019, 47(12): 1981-1986
doi: 10.19756/j.issn.0253-3820.191446
Abstract:
In situ infrared spectral detection can be fast and reliably achieved by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy technique. In this study, home-made hollow optical fiber (HOF-) ATR-FTIR technique was combined with principal component analysis (PCA) and Fisher discriminant (FDA) algorithm to identify in situ osteoarthritis (OA) canine samples at different pathological stages (health, lesions of 8 weeks, 3 months and 7months) in vitro. The initial samples were correctly recognized with 100% accuracy. And all of the prediction groups were 100% correctly identified when an independent sample was selected from each group for prediction, respectively. In cross-validation, the recognition rate was more than 95%. This method can objectively, quantitatively and accurately identify OA samples at different stages of OA, and can be used as a diagnostic basis at different OA stages. The HOF-ATR-FTIR technique has significant application prospect in in vivo and in situ clinical diagnosis when combined with subjective OA grading results, and is expected to provide more objective and accurate OA grading and staging.
In situ infrared spectral detection can be fast and reliably achieved by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy technique. In this study, home-made hollow optical fiber (HOF-) ATR-FTIR technique was combined with principal component analysis (PCA) and Fisher discriminant (FDA) algorithm to identify in situ osteoarthritis (OA) canine samples at different pathological stages (health, lesions of 8 weeks, 3 months and 7months) in vitro. The initial samples were correctly recognized with 100% accuracy. And all of the prediction groups were 100% correctly identified when an independent sample was selected from each group for prediction, respectively. In cross-validation, the recognition rate was more than 95%. This method can objectively, quantitatively and accurately identify OA samples at different stages of OA, and can be used as a diagnostic basis at different OA stages. The HOF-ATR-FTIR technique has significant application prospect in in vivo and in situ clinical diagnosis when combined with subjective OA grading results, and is expected to provide more objective and accurate OA grading and staging.
2019, 47(12): 1987-1994
doi: 10.19756/j.issn.0253-3820.191131
Abstract:
The near-infrared spectroscopy was used to predict the content of corn straw cellulose. According to the characteristics of high-dimensional and high correlation of near-infrared spectroscopy, the selection of characteristic wavelengths was discussed when using partial least squares (PLS) prediction model for corn straw cellulose. Firstly, the influence of interval partition number of synergy interval partial least squares (SIPLS) and backward interval partial least squares (BIPLS) on the algorithm effect was discussed. On the basis of SIPLS and BIPLS, genetic simulated annealing algorithm (GSAA) was used to filter the second characteristic wavelength, which could further improve the prediction accuracy and modeling efficiency of the model. The results showed that the three algorithms could improve the prediction accuracy of the model, but the effect of SIPLS and BIPLS was greatly affected by the partition number. Although the root mean square error of prediction (RMSEP) of BIPLS model was the smallest, the number of variables selected was up to 485, which affected the modeling efficiency of the model. On the basis of SIPLS and BIPLS, GSAA was used to filter the second characteristic wavelength. Compared with BIPLS, the RMSEP of BIPLS-GSAA model was slightly increased, but its input variables were reduced to 134, and the main component fraction of the model was also reduced from 11 to 10. Compared with SIPLS, the input variables of SIPLS-GSAA model were only 34, and the prediction accuracy was improved. Its RMSEP was next to that of BIPLS model. The experimental results showed that SIPLS-GSAA model had the best prediction effect. Therefore, the second screening of spectral data based on GSAA on SIPLS and BIPLS could not only simplify the input of the model, but also effectively improve the prediction ability of the model.
The near-infrared spectroscopy was used to predict the content of corn straw cellulose. According to the characteristics of high-dimensional and high correlation of near-infrared spectroscopy, the selection of characteristic wavelengths was discussed when using partial least squares (PLS) prediction model for corn straw cellulose. Firstly, the influence of interval partition number of synergy interval partial least squares (SIPLS) and backward interval partial least squares (BIPLS) on the algorithm effect was discussed. On the basis of SIPLS and BIPLS, genetic simulated annealing algorithm (GSAA) was used to filter the second characteristic wavelength, which could further improve the prediction accuracy and modeling efficiency of the model. The results showed that the three algorithms could improve the prediction accuracy of the model, but the effect of SIPLS and BIPLS was greatly affected by the partition number. Although the root mean square error of prediction (RMSEP) of BIPLS model was the smallest, the number of variables selected was up to 485, which affected the modeling efficiency of the model. On the basis of SIPLS and BIPLS, GSAA was used to filter the second characteristic wavelength. Compared with BIPLS, the RMSEP of BIPLS-GSAA model was slightly increased, but its input variables were reduced to 134, and the main component fraction of the model was also reduced from 11 to 10. Compared with SIPLS, the input variables of SIPLS-GSAA model were only 34, and the prediction accuracy was improved. Its RMSEP was next to that of BIPLS model. The experimental results showed that SIPLS-GSAA model had the best prediction effect. Therefore, the second screening of spectral data based on GSAA on SIPLS and BIPLS could not only simplify the input of the model, but also effectively improve the prediction ability of the model.
2019, 47(12): 1995-2003
doi: 10.19756/j.issn.0253-3820.191372
Abstract:
A rapid quantitative analysis method for detection of methanol content in methanol gasoline based on near infrared spectroscopy (NIR) coupled with wavelet transform-random forest algorithm(WT-RF) was developed. Firstly, spectra of 54 methanol gasoline samples were collected by Fourier transform infrared spectroscopy, and spectral analysis was also carried out. Secondly, the effects of different spectral pretreatment methods were explored, and an optimized spectral pretreatment method based on WT was obtained by using different wavelet basis functions and wavelet decomposition levels. Thirdly, an optimized input variable of RF calibration model was obtained by selecting different variable importance threshold values. Finally, an optimized WT-RF calibration model was constructed by using the optimized modeling parameters of wavelet basis function (db5), decomposition layers (4) and variable importance threshold value (0.0002). To further explore the predictive performance of WT-RF calibration model, the predictive results were compared with that of wavelet transform-partial least squares (WT-PLS) calibration models and wavelet transform-least square support vector machine (WT-LSSVM) calibration models. The WT-RF calibration model showed the best predictive performance, and its coefficient of determination of cross-validation (Rcv2) and root mean square error of cross-validation (RMSECV) were 0.9990 and 0.0044%, respectively. Coefficient of determination of prediction set (Rp2) and root mean square error of prediction set (RMSEP) were 0.9885 and 0.0191%, respectively. Therefore, NIR coupled with WT-RF algorithm was an effective method for the detection of methanol content in methanol gasoline.
A rapid quantitative analysis method for detection of methanol content in methanol gasoline based on near infrared spectroscopy (NIR) coupled with wavelet transform-random forest algorithm(WT-RF) was developed. Firstly, spectra of 54 methanol gasoline samples were collected by Fourier transform infrared spectroscopy, and spectral analysis was also carried out. Secondly, the effects of different spectral pretreatment methods were explored, and an optimized spectral pretreatment method based on WT was obtained by using different wavelet basis functions and wavelet decomposition levels. Thirdly, an optimized input variable of RF calibration model was obtained by selecting different variable importance threshold values. Finally, an optimized WT-RF calibration model was constructed by using the optimized modeling parameters of wavelet basis function (db5), decomposition layers (4) and variable importance threshold value (0.0002). To further explore the predictive performance of WT-RF calibration model, the predictive results were compared with that of wavelet transform-partial least squares (WT-PLS) calibration models and wavelet transform-least square support vector machine (WT-LSSVM) calibration models. The WT-RF calibration model showed the best predictive performance, and its coefficient of determination of cross-validation (Rcv2) and root mean square error of cross-validation (RMSECV) were 0.9990 and 0.0044%, respectively. Coefficient of determination of prediction set (Rp2) and root mean square error of prediction set (RMSEP) were 0.9885 and 0.0191%, respectively. Therefore, NIR coupled with WT-RF algorithm was an effective method for the detection of methanol content in methanol gasoline.
2019, 47(12): 2004-2011
doi: 10.19756/j.issn.0253-3820.181610
Abstract:
Seed aging affects the agricultural production and quality of food. Therefore, it is of great significance to distinguish the aging seed quickly for food security. In this work, Fourier transform infrared (FTIR) spectroscopy combined with curve-fitting analysis and hierarchical cluster analysis (HCA) was used to identify the legume seeds of different aging time. The results showed that the infrared spectroscopy of legume seeds were mainly composed of the absorption peaks of proteins and carbohydrates. The overall characteristics of the original spectra of seeds in different aging time were similar, but the absorption ratios of several peaks decreased with the increasing aging time. Amide I band (1700-1600 cm-1) and carbohydrate absorption band (1180-980 cm-1) in the original spectra were carried out for curve fitting. The results showed that the sub-bands position and area ratios of different aging seeds were obviously different. There were significant differences in beta-folding, disordered structure, alpha-helix and beta-corner components in the secondary structure of proteins and CO, CC and COH components in polysaccharides during aging. Hierarchical cluster analysis was performed using second derivative spectra in the range of 1800-800 cm-1, and the accuracy of clustering reached 100%. The results showed that FTIR combined with curve-fitting analysis and HCA could identify the natural aging legume seeds quickly and effectively.
Seed aging affects the agricultural production and quality of food. Therefore, it is of great significance to distinguish the aging seed quickly for food security. In this work, Fourier transform infrared (FTIR) spectroscopy combined with curve-fitting analysis and hierarchical cluster analysis (HCA) was used to identify the legume seeds of different aging time. The results showed that the infrared spectroscopy of legume seeds were mainly composed of the absorption peaks of proteins and carbohydrates. The overall characteristics of the original spectra of seeds in different aging time were similar, but the absorption ratios of several peaks decreased with the increasing aging time. Amide I band (1700-1600 cm-1) and carbohydrate absorption band (1180-980 cm-1) in the original spectra were carried out for curve fitting. The results showed that the sub-bands position and area ratios of different aging seeds were obviously different. There were significant differences in beta-folding, disordered structure, alpha-helix and beta-corner components in the secondary structure of proteins and CO, CC and COH components in polysaccharides during aging. Hierarchical cluster analysis was performed using second derivative spectra in the range of 1800-800 cm-1, and the accuracy of clustering reached 100%. The results showed that FTIR combined with curve-fitting analysis and HCA could identify the natural aging legume seeds quickly and effectively.
