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2018 Volume 46 Issue 10
2018, 46(10): 1507-1517
doi: 10.11895/j.issn.0253-3820.181280
Abstract:
Protein drugs, represented by recombinant protein drugs and therapeutic antibodies, have become important components of biotech medicines. The efficacy and biosafety of protein drugs are superior to small molecule drugs in the treatment of serious diseases such as malignant tumor, autoimmune disease and virus infection. However, the stability of proteins is poor and they are prone to aggregate upon environmental stimulation or due to their own instability during the process of production, purification, transportation and storage. Protein aggregation may reduce therapeutic efficacy and thus induce immune responses. High-sensitivity, high-resolution, simple and practical techniques for protein aggregation detection are of great importance in the development and advancement of protein drugs. This paper intends to review the techniques used for protein aggregation analysis such as size-exclusion chromatography, gel-electrophoresis, analytical ultracentrifugation, field flow fractionation, turbidimetry/nephelometry, dynamic light scattering, nanoparticle tracking analysis, flow cytometry, and electron microscopy. The principle, strengths, limitations and applications of these techniques are discussed, and the direction in the future development is prospected.
Protein drugs, represented by recombinant protein drugs and therapeutic antibodies, have become important components of biotech medicines. The efficacy and biosafety of protein drugs are superior to small molecule drugs in the treatment of serious diseases such as malignant tumor, autoimmune disease and virus infection. However, the stability of proteins is poor and they are prone to aggregate upon environmental stimulation or due to their own instability during the process of production, purification, transportation and storage. Protein aggregation may reduce therapeutic efficacy and thus induce immune responses. High-sensitivity, high-resolution, simple and practical techniques for protein aggregation detection are of great importance in the development and advancement of protein drugs. This paper intends to review the techniques used for protein aggregation analysis such as size-exclusion chromatography, gel-electrophoresis, analytical ultracentrifugation, field flow fractionation, turbidimetry/nephelometry, dynamic light scattering, nanoparticle tracking analysis, flow cytometry, and electron microscopy. The principle, strengths, limitations and applications of these techniques are discussed, and the direction in the future development is prospected.
2018, 46(10): 1518-1527
doi: 10.11895/j.issn.0253-3820.181150
Abstract:
The technique of micro-laser-induced breakdown spectroscopy usually refers to analyzing the surface of the sample using a compact focused laser beam in the optical microscope range. Compared to macro-laser-induced breakdown spectroscopy, it can provide more abundant form, structure, and content information in a smaller, less sample condition. Hence, the application field is very wide. In this paper, the basic status of micro-laser-induced breakdown spectroscopy in the selection of laser source and the structure of optical path system were introduced, and its application in metal, semiconductor, animal and plant fields was reviewed. The existing issues and potential development direction were also pointed out.
The technique of micro-laser-induced breakdown spectroscopy usually refers to analyzing the surface of the sample using a compact focused laser beam in the optical microscope range. Compared to macro-laser-induced breakdown spectroscopy, it can provide more abundant form, structure, and content information in a smaller, less sample condition. Hence, the application field is very wide. In this paper, the basic status of micro-laser-induced breakdown spectroscopy in the selection of laser source and the structure of optical path system were introduced, and its application in metal, semiconductor, animal and plant fields was reviewed. The existing issues and potential development direction were also pointed out.
2018, 46(10): 1528-1538
doi: 10.11895/j.issn.0253-3820.171264
Abstract:
Brown carbon is one of the hotspots in the field of atmospheric carbonaceous aerosol research. It has significant influence on regional radiative forcing and climatic effects due to its apparent absorbance in the near ultraviolet-visible region. Brown carbon mainly originates from biomass or coal incomplete combustion, and it also comes from some secondary sources, such as a series of atmospheric photochemical reactions from volatile organic compounds (VOCs). Though the composition of the brown carbon is very complex, high resolution mass spectrometry technology provides effective methods for revealing the characteristic of organic components at the molecular level with its ultra-high mass resolution and precision. This paper introduced the application of high resolution mass spectrometry combined with traditional analytical methods in the study of brown carbon:the development of high resolution mass spectrometry for brown carbon separation was reviewed, as well as the composition analysis, source apportionment and formation mechanism of brown carbon based on high resolution data. In addition, the present situation, existing issues and prospects about the application of high resolution mass spectrometry on brown carbon were also discussed.
Brown carbon is one of the hotspots in the field of atmospheric carbonaceous aerosol research. It has significant influence on regional radiative forcing and climatic effects due to its apparent absorbance in the near ultraviolet-visible region. Brown carbon mainly originates from biomass or coal incomplete combustion, and it also comes from some secondary sources, such as a series of atmospheric photochemical reactions from volatile organic compounds (VOCs). Though the composition of the brown carbon is very complex, high resolution mass spectrometry technology provides effective methods for revealing the characteristic of organic components at the molecular level with its ultra-high mass resolution and precision. This paper introduced the application of high resolution mass spectrometry combined with traditional analytical methods in the study of brown carbon:the development of high resolution mass spectrometry for brown carbon separation was reviewed, as well as the composition analysis, source apportionment and formation mechanism of brown carbon based on high resolution data. In addition, the present situation, existing issues and prospects about the application of high resolution mass spectrometry on brown carbon were also discussed.
2018, 46(10): 1539-1544
doi: 10.11895/j.issn.0253-3820.181483
Abstract:
Polyethyleneglycol (PEG)-modified (PEGylated) nanoprobes have attracted a great deal of interest in the area of molecular imaging area along with the rapid development of modern medicine. These nanoprobes play an important role especially in the diagnosis and prognosis of gastric diseases. The transition metal oxides as gastric contrast agents based on PEGylated WO3-x nanoprobes (PEG-WO3-x) were designed and synthesized. The nanoprobes ewere synthesized via a high-temperature solvent thermal method, and then modified with PEG. These PEGylated nanoprobes exhibited excellent aqueous stability. Besides evaluating the characteristics of PEG-WO3-x, in vivo, toxicological studies were carried out with histopathology. Otherwise, as a contrast agent, MDCT imaging was illustrated via both in vitro and in vivo assessment. The experimental results indicated that the prepared PEG-WO3-x showed great potential for further MDCT imaging in detection of gastric diseases.
Polyethyleneglycol (PEG)-modified (PEGylated) nanoprobes have attracted a great deal of interest in the area of molecular imaging area along with the rapid development of modern medicine. These nanoprobes play an important role especially in the diagnosis and prognosis of gastric diseases. The transition metal oxides as gastric contrast agents based on PEGylated WO3-x nanoprobes (PEG-WO3-x) were designed and synthesized. The nanoprobes ewere synthesized via a high-temperature solvent thermal method, and then modified with PEG. These PEGylated nanoprobes exhibited excellent aqueous stability. Besides evaluating the characteristics of PEG-WO3-x, in vivo, toxicological studies were carried out with histopathology. Otherwise, as a contrast agent, MDCT imaging was illustrated via both in vitro and in vivo assessment. The experimental results indicated that the prepared PEG-WO3-x showed great potential for further MDCT imaging in detection of gastric diseases.
2018, 46(10): 1545-1551
doi: 10.11895/j.issn.0253-3820.181107
Abstract:
Gold nanoclusters-tungsten sulfide nanocomposites (Au-WS2 NCs) were synthesized through electrostatic self-assembly method. The synthesized Au-WS2 NCs could effectively catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 due to its excellent peroxidase-like catalytic activity. The effects of Au-WS2 NCs/TMB/H2O2 coloration conditions on peroxidase-like activity of Au-WS2 NCs were investigated and the steady-state kinetic analysis was carried out. The experimental results showed that the Au-WS2 NCs catalytic reaction using H2O2 and TMB as reaction substrates followed a typical Michaelis-Menten kinetic model. Based on the intrinsic peroxidase-like activity of Au-WS2 NCs and that glucose could be oxidized by glucose oxidase to produce H2O2, a colorimetric detection method for H2O2 and glucose was established and the detection limits were 6.0×10-7 mol/L and 3.1×10-6 mol/L, respectively. Thus, a new colorimetric method was developed, which provided a significant reference value for other types of peroxidase mimics.
Gold nanoclusters-tungsten sulfide nanocomposites (Au-WS2 NCs) were synthesized through electrostatic self-assembly method. The synthesized Au-WS2 NCs could effectively catalyze the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2 due to its excellent peroxidase-like catalytic activity. The effects of Au-WS2 NCs/TMB/H2O2 coloration conditions on peroxidase-like activity of Au-WS2 NCs were investigated and the steady-state kinetic analysis was carried out. The experimental results showed that the Au-WS2 NCs catalytic reaction using H2O2 and TMB as reaction substrates followed a typical Michaelis-Menten kinetic model. Based on the intrinsic peroxidase-like activity of Au-WS2 NCs and that glucose could be oxidized by glucose oxidase to produce H2O2, a colorimetric detection method for H2O2 and glucose was established and the detection limits were 6.0×10-7 mol/L and 3.1×10-6 mol/L, respectively. Thus, a new colorimetric method was developed, which provided a significant reference value for other types of peroxidase mimics.
2018, 46(10): 1552-1559
doi: 10.11895/j.issn.0253-3820.181117
Abstract:
Bone morphogenetic protein 3 (BMP3) gene methylation in stool DNA is an effective biomarker for non-invasive screening of colorectal cancer. However, the detection of BMP3 gene methylation in stool DNA requires a highly sensitive and specific method. Here, we developed a BMP3 gene methylation quantification method by combining real-time polymerase chain reaction (PCR) with invasive reaction using Beta-actin (ACTB) gene as a reference. After optimizing the concentration of detection probes, FEN1 enzyme and Taq polymerase, both amplification efficiencies of BMP3 and ACTB genes were close to 100%, and the accurate relative quantification of methylation of BMP3 gene was achieved with ΔCT algorithms. The method could detect as low as 10 copies of BMP3 fragment, and 0.01% methylated templates could be picked up from unmethylated templates, indicating that the method was highly sensitive and specific for the detection of BMP3 gene methylation. The method was successfully applied to detect BMP3 methylation in stool DNA samples from 16 colorectal cancer patients, 7 adenoma patients and 19 healthy volunteers. The result showed that methylation of BMP3 occurred in 5 cases of 16 cancer patients and 2 cases of 7 adenoma patients, but was not observed in 19 cases of healthy volunteers. Therefore, this method could be used to quantify the gene methylation in stool samples, providing an effective technique for non-invasive screening of colorectal cancer.
Bone morphogenetic protein 3 (BMP3) gene methylation in stool DNA is an effective biomarker for non-invasive screening of colorectal cancer. However, the detection of BMP3 gene methylation in stool DNA requires a highly sensitive and specific method. Here, we developed a BMP3 gene methylation quantification method by combining real-time polymerase chain reaction (PCR) with invasive reaction using Beta-actin (ACTB) gene as a reference. After optimizing the concentration of detection probes, FEN1 enzyme and Taq polymerase, both amplification efficiencies of BMP3 and ACTB genes were close to 100%, and the accurate relative quantification of methylation of BMP3 gene was achieved with ΔCT algorithms. The method could detect as low as 10 copies of BMP3 fragment, and 0.01% methylated templates could be picked up from unmethylated templates, indicating that the method was highly sensitive and specific for the detection of BMP3 gene methylation. The method was successfully applied to detect BMP3 methylation in stool DNA samples from 16 colorectal cancer patients, 7 adenoma patients and 19 healthy volunteers. The result showed that methylation of BMP3 occurred in 5 cases of 16 cancer patients and 2 cases of 7 adenoma patients, but was not observed in 19 cases of healthy volunteers. Therefore, this method could be used to quantify the gene methylation in stool samples, providing an effective technique for non-invasive screening of colorectal cancer.
2018, 46(10): 1560-1569
doi: 10.11895/j.issn.0253-3820.171233
Abstract:
A gas chromatography-mass spectrometry (GC-MS) method was used for investigation of the fragmentation behavior of a series of trimethylsilyl (TMS) derivatives of aliphatic halides and aromatic halides under the environment of electron impact ion source (EI) in order to acquire it's fragmentation regularity, which, in return, provided guidance for the structure of organic halogenated compounds. The results of mass spectral indicated that the TMS derivatives of organic halides produced characteristic skeleton rearrangement product ions with elemental composition conforming to[(CH3)2XSi]+(X=F, Cl, Br, I) during the fragmentation reaction, namely m/z 77, m/z 93, m/z 137 and m/z 185. In addition, the change in the position of the halogen atom substitution also had significant effect on the intensity and type of the rearranged product ion peak. Through the study of this type of rearranged product ions, the positional isomers of the halogenated compounds could be identified quickly and efficiently, and the elemental composition of the organic molecules could be reversely analyzed. This analysis method not only provided a new idea for the analysis of the structure of organic halogenated compounds, but also expanded the application of silane derivatization reagents in the field of organic mass spectrometry.
A gas chromatography-mass spectrometry (GC-MS) method was used for investigation of the fragmentation behavior of a series of trimethylsilyl (TMS) derivatives of aliphatic halides and aromatic halides under the environment of electron impact ion source (EI) in order to acquire it's fragmentation regularity, which, in return, provided guidance for the structure of organic halogenated compounds. The results of mass spectral indicated that the TMS derivatives of organic halides produced characteristic skeleton rearrangement product ions with elemental composition conforming to[(CH3)2XSi]+(X=F, Cl, Br, I) during the fragmentation reaction, namely m/z 77, m/z 93, m/z 137 and m/z 185. In addition, the change in the position of the halogen atom substitution also had significant effect on the intensity and type of the rearranged product ion peak. Through the study of this type of rearranged product ions, the positional isomers of the halogenated compounds could be identified quickly and efficiently, and the elemental composition of the organic molecules could be reversely analyzed. This analysis method not only provided a new idea for the analysis of the structure of organic halogenated compounds, but also expanded the application of silane derivatization reagents in the field of organic mass spectrometry.
2018, 46(10): 1570-1580
doi: 10.11895/j.issn.0253-3820.181290
Abstract:
The conformation change of bovine serum albumin (BSA) absorbed on Fe3O4 nanoparticle surface was characterized by chemical cross-linking mass spectrometry (CXMS)-based proteomics approach. The effects of nanoparticle surface curvatures and initial protein concentrations on protein conformation change were investigated by the CXMS. The results revealed that the BSA adsorbed on the surface of Fe3O4 nanoparticle could undergo an altered conformational state in comparison to that of BSA in solution as the crosslinking frequency of some amino acid residues of the BSA varied significantly, with the assistant analysis of the attenuated total reflectance Fourier transfer infrared spectroscopy (ATR-FTIR). By virtue of the high-throughput, high accuracy and high sensitivity of mass spectrometry, the CXMS-based proteomic method could provide structural information of proteins adsorbed on nanoparticle surface by crosslinking restraints and would be promised to be applied to the analysis of nano-bio interaction for proteins in complex biological systems.
The conformation change of bovine serum albumin (BSA) absorbed on Fe3O4 nanoparticle surface was characterized by chemical cross-linking mass spectrometry (CXMS)-based proteomics approach. The effects of nanoparticle surface curvatures and initial protein concentrations on protein conformation change were investigated by the CXMS. The results revealed that the BSA adsorbed on the surface of Fe3O4 nanoparticle could undergo an altered conformational state in comparison to that of BSA in solution as the crosslinking frequency of some amino acid residues of the BSA varied significantly, with the assistant analysis of the attenuated total reflectance Fourier transfer infrared spectroscopy (ATR-FTIR). By virtue of the high-throughput, high accuracy and high sensitivity of mass spectrometry, the CXMS-based proteomic method could provide structural information of proteins adsorbed on nanoparticle surface by crosslinking restraints and would be promised to be applied to the analysis of nano-bio interaction for proteins in complex biological systems.
2018, 46(10): 1581-1587
doi: 10.11895/j.issn.0253-3820.181189
Abstract:
The rabbit anti-chloramphenicol (CAP) polyclonal antibodies were prepared by immunizing New Zealand rabbits by CAP antigen (CAP-HS-BSA), with antibody titer of 2×105. Then the indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and chemiluminescence immunoassay based on iPDMS for detection of CAP were established. The proposed ic-ELISA showed a half-inhibition concentration (IC50) of 12.9 ng/mL, with a linear detection range (IC20-IC80) of 0.8-250.0 ng/mL and limit of detection (LOD, IC10) of 0.1 ng/mL. The standard curve was B/B0=-0.2028lgCCAP+0.7281(R2=0.9926). The cross-reactivity of ic-ELISA towards structural analogues of CAP was less than 0.01%. When applied to detection of CAP in real milk sample, the average recoveries of ic-ELISA were from 81.8% to 97.9%, with relative standard deviation (RSD) of less than 10%. However, for the proposed chemiluminescence immunoassay, the IC50 was 263.0 ng/mL, the linear range (IC20-IC80) was 1-5000 ng/mL, and the LOD was 1 ng/mL. The standard curve was B/B0=-0.1781lgCCAP +0.9318(R2=0.9891). The average recoveries of iPDMS based chemiluminescence immunoassay were from 77.0% to 100.5%, with the RSD of less than 15% for spiked milk samples.
The rabbit anti-chloramphenicol (CAP) polyclonal antibodies were prepared by immunizing New Zealand rabbits by CAP antigen (CAP-HS-BSA), with antibody titer of 2×105. Then the indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) and chemiluminescence immunoassay based on iPDMS for detection of CAP were established. The proposed ic-ELISA showed a half-inhibition concentration (IC50) of 12.9 ng/mL, with a linear detection range (IC20-IC80) of 0.8-250.0 ng/mL and limit of detection (LOD, IC10) of 0.1 ng/mL. The standard curve was B/B0=-0.2028lgCCAP+0.7281(R2=0.9926). The cross-reactivity of ic-ELISA towards structural analogues of CAP was less than 0.01%. When applied to detection of CAP in real milk sample, the average recoveries of ic-ELISA were from 81.8% to 97.9%, with relative standard deviation (RSD) of less than 10%. However, for the proposed chemiluminescence immunoassay, the IC50 was 263.0 ng/mL, the linear range (IC20-IC80) was 1-5000 ng/mL, and the LOD was 1 ng/mL. The standard curve was B/B0=-0.1781lgCCAP +0.9318(R2=0.9891). The average recoveries of iPDMS based chemiluminescence immunoassay were from 77.0% to 100.5%, with the RSD of less than 15% for spiked milk samples.
2018, 46(10): 1588-1594
doi: 10.11895/j.issn.0253-3820.181187
Abstract:
A biosensor for detecting lipase activity was constructed by using the Tween 40-curcumin complex micelle as a fluorescence probe, Hg2+ as a quenching agent and methyl thioglycolate as the substrate of lipase. Hg2+ combined with the β-diketone structure of curcumin, resulting in quenching of Tween 40-curcumin complex micelle fluorescence. However, upon the addition of lipase, lipase could catalyze the hydrolysis of methyl thioglycolate to produce mercaptoacetic acid which could capture Hg2+ released from the curcumin-Hg2+ complex, resulting in the recovery of fluorescence of the Tween 40-curcumin complex micelle. The intensity of fluorescence recovery was related to lipase activity. The fluorescence sensing strategy was applied to quantitatively detect lipase activity. Under optimal experimental conditions, the change of fluorescence intensity was linear with the concentration of lipase in the range of 2-80 U/mL, and the detection limit was 0.01 U/mL. This method was employed to detect the activity of four other kinds of commercial lipases. The results were in agreement with those determined by potentiometric titration. The results showed that the method had the advantages of low cost, simple operation, high sensitivity, good practicability, and could be used for high throughput detection of lipase activity.
A biosensor for detecting lipase activity was constructed by using the Tween 40-curcumin complex micelle as a fluorescence probe, Hg2+ as a quenching agent and methyl thioglycolate as the substrate of lipase. Hg2+ combined with the β-diketone structure of curcumin, resulting in quenching of Tween 40-curcumin complex micelle fluorescence. However, upon the addition of lipase, lipase could catalyze the hydrolysis of methyl thioglycolate to produce mercaptoacetic acid which could capture Hg2+ released from the curcumin-Hg2+ complex, resulting in the recovery of fluorescence of the Tween 40-curcumin complex micelle. The intensity of fluorescence recovery was related to lipase activity. The fluorescence sensing strategy was applied to quantitatively detect lipase activity. Under optimal experimental conditions, the change of fluorescence intensity was linear with the concentration of lipase in the range of 2-80 U/mL, and the detection limit was 0.01 U/mL. This method was employed to detect the activity of four other kinds of commercial lipases. The results were in agreement with those determined by potentiometric titration. The results showed that the method had the advantages of low cost, simple operation, high sensitivity, good practicability, and could be used for high throughput detection of lipase activity.
2018, 46(10): 1595-1603
doi: 10.11895/j.issn.0253-3820.181347
Abstract:
Capillary electrophoresis based systematic evolution of ligands via exponential enrichment (CE-SELEX) was reported as a homogeneous efficient method for high-affinity selection of aptamer, with several merits involving screening in free solution without nonspecific binding, capable of high-efficient separation, low-sample consumption, and saving money. There are few studies regarding the aptamer selection against small molecule using CE-SELEX, resulting from the aspects of less binding sites and the negligible variety of its complex with nucleic acid in the electrophoretic mobility. In this study, the aptamer selection was performed towards a small molecule target of clenbuterol hydrochloride (Cle) by CE-SELEX. In brief, incubated Cle and an 80 nt ssDNA library were firstly incubated, and CZE-UV approach was used to separate complex and random ssDNA. The complex was then collected into a vial followed by PCR amplification. Through three round selections, the third pool was selected to clone and ten sequences were finally obtained. The dissociation constants (Kd) of three potential candidates (Apt 4, Apt 7 and Apt 12) were determined by CE-LIF, and showed high affinities of 9.315×10-7 mol/L, 1.040×10-6 mol/L and 1.143×10-5 mol/L, respectively. The m-Fold software analysis showed that the above three sequences could form stem-loop structure, and Apt 4 gave the lowest free energy and the most stable structure. Using salbutamol as a control, three selected aptamers were verified with high specificity.
Capillary electrophoresis based systematic evolution of ligands via exponential enrichment (CE-SELEX) was reported as a homogeneous efficient method for high-affinity selection of aptamer, with several merits involving screening in free solution without nonspecific binding, capable of high-efficient separation, low-sample consumption, and saving money. There are few studies regarding the aptamer selection against small molecule using CE-SELEX, resulting from the aspects of less binding sites and the negligible variety of its complex with nucleic acid in the electrophoretic mobility. In this study, the aptamer selection was performed towards a small molecule target of clenbuterol hydrochloride (Cle) by CE-SELEX. In brief, incubated Cle and an 80 nt ssDNA library were firstly incubated, and CZE-UV approach was used to separate complex and random ssDNA. The complex was then collected into a vial followed by PCR amplification. Through three round selections, the third pool was selected to clone and ten sequences were finally obtained. The dissociation constants (Kd) of three potential candidates (Apt 4, Apt 7 and Apt 12) were determined by CE-LIF, and showed high affinities of 9.315×10-7 mol/L, 1.040×10-6 mol/L and 1.143×10-5 mol/L, respectively. The m-Fold software analysis showed that the above three sequences could form stem-loop structure, and Apt 4 gave the lowest free energy and the most stable structure. Using salbutamol as a control, three selected aptamers were verified with high specificity.
2018, 46(10): 1604-1609
doi: 10.11895/j.issn.0253-3820.181246
Abstract:
In this work, a solid phase extraction (SPE) coupled with gas chromatography-mass spectrometry (SPE-GC-MS) method was developed for determination of 6 kinds of typical Cl-PAHs in water. The targets in water sample were concentrated by poly-sery HLB SPE cartridge and passed through the cartridge with a bulk sampler at a flow rate of 2 mL/min, and then eluted by 6 mL of n-hexane/dichloromethane (4:1, V/V). The Cl-PAHs were qualified and quantified by GC-MS in selective ion scan monitoring method (SIM). Good linearity was observed in the range of 1 to 1000 ng/mL Cl-PAHs with correlation coefficients of 0.9952-0.9997. The limits of detection and limits of quantification ranged from 0.013 to 0.592 ng/L and 0.051 to 0.257 ng/L, respectively. Spiked recoveries in pure water ranged from 77.8% to 105.4%, with the rlative standard deviations of less than 10%, except 9-ClFlu, with the spiked recoveries ranging from 34.4% to 45.6%. The results indicated that the SPE-GC-MS analytical method established here was sensitive and accurate for determination of Cl-PAHs in surface water samples. Then the method was applied to analyze Cl-PAHs in water samples collected from Nanjing industrial Park and surrounding areas, and it was found that the total concentration of Cl-PAHs was ranging from 23.594 ng/L to 106.374 ng/L.
In this work, a solid phase extraction (SPE) coupled with gas chromatography-mass spectrometry (SPE-GC-MS) method was developed for determination of 6 kinds of typical Cl-PAHs in water. The targets in water sample were concentrated by poly-sery HLB SPE cartridge and passed through the cartridge with a bulk sampler at a flow rate of 2 mL/min, and then eluted by 6 mL of n-hexane/dichloromethane (4:1, V/V). The Cl-PAHs were qualified and quantified by GC-MS in selective ion scan monitoring method (SIM). Good linearity was observed in the range of 1 to 1000 ng/mL Cl-PAHs with correlation coefficients of 0.9952-0.9997. The limits of detection and limits of quantification ranged from 0.013 to 0.592 ng/L and 0.051 to 0.257 ng/L, respectively. Spiked recoveries in pure water ranged from 77.8% to 105.4%, with the rlative standard deviations of less than 10%, except 9-ClFlu, with the spiked recoveries ranging from 34.4% to 45.6%. The results indicated that the SPE-GC-MS analytical method established here was sensitive and accurate for determination of Cl-PAHs in surface water samples. Then the method was applied to analyze Cl-PAHs in water samples collected from Nanjing industrial Park and surrounding areas, and it was found that the total concentration of Cl-PAHs was ranging from 23.594 ng/L to 106.374 ng/L.
2018, 46(10): 1610-1617
doi: 10.11895/j.issn.0253-3820.171446
Abstract:
Water dispersible fluorescent carbon nanodots (CDs) were prepared by a facile and eco-friendly hydrothermal process using Chinese wolfberry as precursor without any further surface modification. The obtained CDs were characterized by UV-visible absorption spectroscopy, fluorescence spectroscopy, high-resolution transmission electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. It showed emission spectrum of blue which located at 400 nm with excited wavelength of 320 nm. High quantum yield of 54%, long lifetime of 9.04 μs, and good biocompatibility were also observed. Importantly, the fluorescence intensity of CDs was selectively quenched within 2 min after addition of Fe3+. Based upon the phenomenon, a new fluorescent biosensor for detection of Fe3+ was proposed. No significant interference from other metal ions was observed. The linear range and detection limit for Fe3+ was 1-50 μmol/L and 232 nmol/L (3σ), respectively. These superior properties demonstrated that the synthesized CDs had promising applications in the fields of environmental and biomedical science.
Water dispersible fluorescent carbon nanodots (CDs) were prepared by a facile and eco-friendly hydrothermal process using Chinese wolfberry as precursor without any further surface modification. The obtained CDs were characterized by UV-visible absorption spectroscopy, fluorescence spectroscopy, high-resolution transmission electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. It showed emission spectrum of blue which located at 400 nm with excited wavelength of 320 nm. High quantum yield of 54%, long lifetime of 9.04 μs, and good biocompatibility were also observed. Importantly, the fluorescence intensity of CDs was selectively quenched within 2 min after addition of Fe3+. Based upon the phenomenon, a new fluorescent biosensor for detection of Fe3+ was proposed. No significant interference from other metal ions was observed. The linear range and detection limit for Fe3+ was 1-50 μmol/L and 232 nmol/L (3σ), respectively. These superior properties demonstrated that the synthesized CDs had promising applications in the fields of environmental and biomedical science.
2018, 46(10): 1618-1627
doi: 10.11895/j.issn.0253-3820.181431
Abstract:
A method for high-precision isotope measurement of Ti using multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) was developed. Ti separation for isotope measurement was achieved by ion exchange chromatography using Bio-Rad AG® 1-X8 anion exchange resin and DGA resin. For the basalt samples, two-column chemistry procedure was used. To get rid of large amounts of Fe and Mg in the peridotite samples, a three-column chemistry procedure was needed. The instrumental mass bias was corrected using 47Ti-49Ti Double Spiking and the Ti isotopes were relative to SRM 3162a. Alfa Ti (Ti standard solutions in house) was measured during three measurement sessions over 10 months with a reproducibility of 0.08‰ (in terms of δ49/46Ti, 2 sd), which was better than that of Standard-Sample Bracketing.
A method for high-precision isotope measurement of Ti using multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS) was developed. Ti separation for isotope measurement was achieved by ion exchange chromatography using Bio-Rad AG® 1-X8 anion exchange resin and DGA resin. For the basalt samples, two-column chemistry procedure was used. To get rid of large amounts of Fe and Mg in the peridotite samples, a three-column chemistry procedure was needed. The instrumental mass bias was corrected using 47Ti-49Ti Double Spiking and the Ti isotopes were relative to SRM 3162a. Alfa Ti (Ti standard solutions in house) was measured during three measurement sessions over 10 months with a reproducibility of 0.08‰ (in terms of δ49/46Ti, 2 sd), which was better than that of Standard-Sample Bracketing.
2018, 46(10): 1628-1636
doi: 10.11895/j.issn.0253-3820.181291
Abstract:
As the advantages of powerful data-handling capacity, excellent signal visualization and open source of calculation codes, Iolite package draw more attention in laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) community in recent years. In this study, the application of Iolite package was investigated for LA-ICP-MS elemental quantification, and a quantification code for bulk normalized as 100% (m/m) strategy was compiled. We found that the spline interpolation was better than linear interpolation for the correction of time-dependent instrument drift. BCR-2G as monitor material was used to evaluate the proposed code and the results revealed that the code was practical and reliable. The analytical results are affected by the used calibration materials. TiO2, MgO, K2O and rare earth elements in BCR-2G were slightly off (5%-10%) when NIST SRM 610 as the calibrator, while Cr and Mo were higher (10%-30%) than the recommended values when StHs6/80-G as the calibrator. Those phenomenon were attributed to the matrix effect or the inaccurate values of corresponding calibrators. Three main sources for the LA-ICP-MS combined uncertainty were recognized, which included the uncertainty of recommended values of analytes in calibration material, the uncertainty of measured intensity ratios in samples and the error in bulk normalized as 100% (m/m) strategy. 50 elements in CGSG glass reference materials were quantified based on the proposed Iolite code. Major elements (except MnO, CaO and P2O5) matched with the preliminary values in 5% and trace elements (except Cr, Ni, Zn, Ga, Mo and Sb) were agreement with the preliminary values in 10%. The dataset reported in this study was useful for the certification of CGSG reference materials. Overall, the proposed Iolite code broadened the application of Iolite package in the reduction of LA-ICP-MS transient signal.
As the advantages of powerful data-handling capacity, excellent signal visualization and open source of calculation codes, Iolite package draw more attention in laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS) community in recent years. In this study, the application of Iolite package was investigated for LA-ICP-MS elemental quantification, and a quantification code for bulk normalized as 100% (m/m) strategy was compiled. We found that the spline interpolation was better than linear interpolation for the correction of time-dependent instrument drift. BCR-2G as monitor material was used to evaluate the proposed code and the results revealed that the code was practical and reliable. The analytical results are affected by the used calibration materials. TiO2, MgO, K2O and rare earth elements in BCR-2G were slightly off (5%-10%) when NIST SRM 610 as the calibrator, while Cr and Mo were higher (10%-30%) than the recommended values when StHs6/80-G as the calibrator. Those phenomenon were attributed to the matrix effect or the inaccurate values of corresponding calibrators. Three main sources for the LA-ICP-MS combined uncertainty were recognized, which included the uncertainty of recommended values of analytes in calibration material, the uncertainty of measured intensity ratios in samples and the error in bulk normalized as 100% (m/m) strategy. 50 elements in CGSG glass reference materials were quantified based on the proposed Iolite code. Major elements (except MnO, CaO and P2O5) matched with the preliminary values in 5% and trace elements (except Cr, Ni, Zn, Ga, Mo and Sb) were agreement with the preliminary values in 10%. The dataset reported in this study was useful for the certification of CGSG reference materials. Overall, the proposed Iolite code broadened the application of Iolite package in the reduction of LA-ICP-MS transient signal.
2018, 46(10): 1637-1643
doi: 10.11895/j.issn.0253-3820.181166
Abstract:
An epoxy functionalized organic-silica hybrid monolith was successfully synthesized via one-step method with tetramethoxysilane (TMOS) and γ-glycidyloxypropyltrimethoxysilane (GPTMS) as precursors. The volume of reactive monomer was optimized and the capillary monolithic columns with good permeability and mechanical strength were obtained. Scanning electron microscope characterization demonstrated that a structure of continuous bed was formed. Then bovine serum albumin (BSA) was covalently immobilized on capillary monolith inner surface by Schiff base method. The preparation condition was studied and it was found that the appropriate concentration of BSA for preparation of BSA-modified hybrid monoliths was 8.0 g/L. Meanwhile, the influence factors on the sample separation were investigated, including running buffer pH (25 mmol/L Tris, pH 7.4), applied voltage (10 kV), capillary temperature (15℃) and sample condition (2 kV×3 s). The BSA-modified hybrid monolith exhibited good chiral separation ability to (±)-tryptophan and achieved satisfactory run-to-run, day-to-day and column-to-column repeatability. Compared with BSA-immobilized silica-based monolithic column, this work presented better chiral recognition ability and also simplified preparation procedures and shortened preparation period.
An epoxy functionalized organic-silica hybrid monolith was successfully synthesized via one-step method with tetramethoxysilane (TMOS) and γ-glycidyloxypropyltrimethoxysilane (GPTMS) as precursors. The volume of reactive monomer was optimized and the capillary monolithic columns with good permeability and mechanical strength were obtained. Scanning electron microscope characterization demonstrated that a structure of continuous bed was formed. Then bovine serum albumin (BSA) was covalently immobilized on capillary monolith inner surface by Schiff base method. The preparation condition was studied and it was found that the appropriate concentration of BSA for preparation of BSA-modified hybrid monoliths was 8.0 g/L. Meanwhile, the influence factors on the sample separation were investigated, including running buffer pH (25 mmol/L Tris, pH 7.4), applied voltage (10 kV), capillary temperature (15℃) and sample condition (2 kV×3 s). The BSA-modified hybrid monolith exhibited good chiral separation ability to (±)-tryptophan and achieved satisfactory run-to-run, day-to-day and column-to-column repeatability. Compared with BSA-immobilized silica-based monolithic column, this work presented better chiral recognition ability and also simplified preparation procedures and shortened preparation period.
2018, 46(10): 1644-1651
doi: 10.11895/j.issn.0253-3820.181346
Abstract:
Based on the tandem G-quadruplex-hemin DNAzymes for catalytic signal amplification and T-Hg2+-T structure for specific recognition, a highly sensitive "Turn-on" biosensor for detection of mercury ion (Hg2+) was developed on the polystyrene microbeads to achieve the detection of Hg2+ in urine samples. Through the specific binding of streptavidin and biotin, the T-rich biotinylated Hg2+ capture probe was immobilized on the surface of the microspheres. When Hg2+ was present in reaction system, the T-rich Hg2+ capture probe could capture the cyclic DNA containing G-quadruplex complementary fragments to the surface of beads by forming T-Hg2+-T structure. Through rolling circle amplification, a large number of tandem G-quadruplex forming sequences were amplified. When hemin was inserted into the G-quadruplex, a G-quadruplex-hemin DNAzyme with enhanced catalytic activity was formed, which could catalyze the oxidation of ABTS to ABTS·+ under the condition of H2O2. Finally, the absorbance difference at 420 nm was detected by UV-vis spectrophotometer. Under the optimal experimental conditions, the linear range for detection of Hg2+ was 0.4 pmol/L-100 pmol/L with the detection limit of 0.3 pmol/L, and the regression equation was ΔA420 nm=0.1+0.0019CHg2+ (pmol/L). This Hg2+ sensing system had excellent selectivity for Hg2+ against other possible competing ions. The fabricated sensor was applied to detection of Hg2+ in urine samples, the relative standard deviation and the recovery were 1.4%-2.6% and 94.0%-106.0%, respectively. The sensor had good selectivity, sensitivity, anti-interference ability and reliable detection capability for complex practical samples.
Based on the tandem G-quadruplex-hemin DNAzymes for catalytic signal amplification and T-Hg2+-T structure for specific recognition, a highly sensitive "Turn-on" biosensor for detection of mercury ion (Hg2+) was developed on the polystyrene microbeads to achieve the detection of Hg2+ in urine samples. Through the specific binding of streptavidin and biotin, the T-rich biotinylated Hg2+ capture probe was immobilized on the surface of the microspheres. When Hg2+ was present in reaction system, the T-rich Hg2+ capture probe could capture the cyclic DNA containing G-quadruplex complementary fragments to the surface of beads by forming T-Hg2+-T structure. Through rolling circle amplification, a large number of tandem G-quadruplex forming sequences were amplified. When hemin was inserted into the G-quadruplex, a G-quadruplex-hemin DNAzyme with enhanced catalytic activity was formed, which could catalyze the oxidation of ABTS to ABTS·+ under the condition of H2O2. Finally, the absorbance difference at 420 nm was detected by UV-vis spectrophotometer. Under the optimal experimental conditions, the linear range for detection of Hg2+ was 0.4 pmol/L-100 pmol/L with the detection limit of 0.3 pmol/L, and the regression equation was ΔA420 nm=0.1+0.0019CHg2+ (pmol/L). This Hg2+ sensing system had excellent selectivity for Hg2+ against other possible competing ions. The fabricated sensor was applied to detection of Hg2+ in urine samples, the relative standard deviation and the recovery were 1.4%-2.6% and 94.0%-106.0%, respectively. The sensor had good selectivity, sensitivity, anti-interference ability and reliable detection capability for complex practical samples.
2018, 46(10): 1652-1659
doi: 10.11895/j.issn.0253-3820.181315
Abstract:
A novel two-photon fluorescent probe, NNTR, was synthesized by using 6-methylamino-2-acetyl-naphthalen as a two-photon fluorophore and 4-nitrobenzyl chloridocarbonate as a recognition domain for nitroreductase (NTR). The spectroscopic characteristics and fluorescent response towards NTR were investigated using one-and two-photon modes, respectively. In the presence of NADH, NNTR could react with nitroreductase completely within 5 min. NNTR showed a 350-fold fluorescence enhancement at 510 nm in one-photo model and a 500-fold fluorescence enhancement at 810 nm in two-photo model. The maximal two-photon action cross-section value was calculated to be 66 GM. NNTR presented quick response, high sensitivity and good photostability towards NTR with a detection limit of 22 ng/mL. Cell survival rate of HeLa cells incubating with NNTR probes with different concentrations was investigated. Two-photon microscopic imaging nitroreductase in HeLa Cells treated with 5 μmol/L NNTR was successfully performed.
A novel two-photon fluorescent probe, NNTR, was synthesized by using 6-methylamino-2-acetyl-naphthalen as a two-photon fluorophore and 4-nitrobenzyl chloridocarbonate as a recognition domain for nitroreductase (NTR). The spectroscopic characteristics and fluorescent response towards NTR were investigated using one-and two-photon modes, respectively. In the presence of NADH, NNTR could react with nitroreductase completely within 5 min. NNTR showed a 350-fold fluorescence enhancement at 510 nm in one-photo model and a 500-fold fluorescence enhancement at 810 nm in two-photo model. The maximal two-photon action cross-section value was calculated to be 66 GM. NNTR presented quick response, high sensitivity and good photostability towards NTR with a detection limit of 22 ng/mL. Cell survival rate of HeLa cells incubating with NNTR probes with different concentrations was investigated. Two-photon microscopic imaging nitroreductase in HeLa Cells treated with 5 μmol/L NNTR was successfully performed.
2018, 46(10): 1660-1668
doi: 10.11895/j.issn.0253-3820.181242
Abstract:
The change of measurement environment and spectral signals of spectroscopy instruments can lead to big error in the process of transferring the model of near infrared (NIR) spectra to slave instruments. Present work advanced a novel method of transferring NIR calibration models without standard samples basing on Screening stable and consistent wavelengths (SSCW). The method firstly eliminates the wavelengths at which the standard variation of difference spectra between master and slave instruments (SDDSI) is bigger than the standard variance of precision detection spectra (SDPDS) to screen the wavelengths at which the spectral signals of different instruments are consistent well. And then deletes the wavelengths at which the values of SDPDS are too high. Thus the spectral signals at the selected wavelengths are stable and consistent between instruments to build the NIR calibration models. Two datasets are applied to validate the method of SSCW:one is consisted of 72 radix scutellaria samples, whose NIR spectra are measured on two different types of NIR spectroscopy instruments, another one is consisted of 80 corn samples, whose NIR spectra measured on three NIR instruments are available online. The results show that the overall prediction effect of SSCW for salves' samples is much better than that of the full-wavelength PLS model. In most cases, the root mean square of error prediction (RMSEP) of salve samples of SSCW is lower than those given by the piecewise direct standardization (PDS) correction, and that of the other model transfer methods without standard samples. Therefore, the method of SSCW is of fewer parameters, robust and can maintain good prediction performance after transferring to salve instruments. It can be used to realize the sharing of PLS calibration model among spectroscopy instruments.
The change of measurement environment and spectral signals of spectroscopy instruments can lead to big error in the process of transferring the model of near infrared (NIR) spectra to slave instruments. Present work advanced a novel method of transferring NIR calibration models without standard samples basing on Screening stable and consistent wavelengths (SSCW). The method firstly eliminates the wavelengths at which the standard variation of difference spectra between master and slave instruments (SDDSI) is bigger than the standard variance of precision detection spectra (SDPDS) to screen the wavelengths at which the spectral signals of different instruments are consistent well. And then deletes the wavelengths at which the values of SDPDS are too high. Thus the spectral signals at the selected wavelengths are stable and consistent between instruments to build the NIR calibration models. Two datasets are applied to validate the method of SSCW:one is consisted of 72 radix scutellaria samples, whose NIR spectra are measured on two different types of NIR spectroscopy instruments, another one is consisted of 80 corn samples, whose NIR spectra measured on three NIR instruments are available online. The results show that the overall prediction effect of SSCW for salves' samples is much better than that of the full-wavelength PLS model. In most cases, the root mean square of error prediction (RMSEP) of salve samples of SSCW is lower than those given by the piecewise direct standardization (PDS) correction, and that of the other model transfer methods without standard samples. Therefore, the method of SSCW is of fewer parameters, robust and can maintain good prediction performance after transferring to salve instruments. It can be used to realize the sharing of PLS calibration model among spectroscopy instruments.
2018, 46(10): 1669-1676
doi: 10.11895/j.issn.0253-3820.181198
Abstract:
Zinc is an essential trace element in human body, and the amount of zinc intake will affect human health. Therefore, it is necessary to detect the content of zinc in food, medicine and environmental sewage precisely. In this work, polypyrrole microcapsules containing ZnCl2 solution were coated between a glassy carbon electrode and zinc ion selective membrane as a solid-contact sensing layer to obtain an all-solid zinc ion selective membrane electrode (GC/PPy microcapsules/Zn2+-ISE). The electrode was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The results showed that the polypyrrole microcapsules, used as intermediate layer, could significantly improve the electrode capacitance, lower the electrode charge transfer impedance, and effectively convert the signal between electrons and ions. The linear response range of electrode potential was 1.0×10-5-1.0×10-1 mol/L, and the detection limit was 2.45×10-6 mol/L. In addition, the electrode using polypyrrole microcapsules as intermediate layer had good reproducibility and stability.
Zinc is an essential trace element in human body, and the amount of zinc intake will affect human health. Therefore, it is necessary to detect the content of zinc in food, medicine and environmental sewage precisely. In this work, polypyrrole microcapsules containing ZnCl2 solution were coated between a glassy carbon electrode and zinc ion selective membrane as a solid-contact sensing layer to obtain an all-solid zinc ion selective membrane electrode (GC/PPy microcapsules/Zn2+-ISE). The electrode was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The results showed that the polypyrrole microcapsules, used as intermediate layer, could significantly improve the electrode capacitance, lower the electrode charge transfer impedance, and effectively convert the signal between electrons and ions. The linear response range of electrode potential was 1.0×10-5-1.0×10-1 mol/L, and the detection limit was 2.45×10-6 mol/L. In addition, the electrode using polypyrrole microcapsules as intermediate layer had good reproducibility and stability.
2018, 46(10): 1677-1684
doi: 10.11895/j.issn.0253-3820.171520
Abstract:
A method for quantitative analysis of mineral oil saturated hydrocarbons (MOSH) and aromatic hydrocarbons (MOAH) in olive oils by solid phase extraction (SPE) combined with programmed temperature vaporizer-gas chromatography-flame ionization detection (PTV-GC-FID) was established. The samples were dissolved in hexane, purified by the means of epoxidation combined with self-made molecular sieve SPE column and 0.3% silver nitrate silica SPE column alternating purification mode, in which way the interfering substances of lipids, wax esters, olefins and natural alkenes were removed, and the MOSH and MOAH fractions were effectively separated. The fractions were then concentrated by nitrogen, analyzed by the GC with large volume injection, separated by the capillary columns of DB-1, determined by a flame ionization detector, and quantified by external standard method. In addition, the key experimental parameters were optimized, including the amount of epoxidation reagent (mCPBA), epoxidation reaction time and elution volume. Under the optimized experimental conditions, Gravex913 lubricating oil showed good linearity as a standard reference of mineral oil in the ranges of 2.0-500.0 mg/L, the limits of detection (LOD) of MOSH and MOAH fractions were 0.3 mg/kg and 1.0 mg/kg, the limits of quantification (LOQ) were 1.0 mg/kg and 3.0 mg/kg, respectively. The spiked recoveries of MOSH and MOAH fractions were in the range of 93.2%-103.7% and 78.5%-81.3% at three spiked levels with the relative standard deviations (RSDs) of 2.7%-5.0% and 2.9%-4.0% (n=6). The established method has many advantages such as good purification effect, low reagent consumption and low detection limit, and is suitable for the separation and quantification of MOSH and MOAH in olive oils.
A method for quantitative analysis of mineral oil saturated hydrocarbons (MOSH) and aromatic hydrocarbons (MOAH) in olive oils by solid phase extraction (SPE) combined with programmed temperature vaporizer-gas chromatography-flame ionization detection (PTV-GC-FID) was established. The samples were dissolved in hexane, purified by the means of epoxidation combined with self-made molecular sieve SPE column and 0.3% silver nitrate silica SPE column alternating purification mode, in which way the interfering substances of lipids, wax esters, olefins and natural alkenes were removed, and the MOSH and MOAH fractions were effectively separated. The fractions were then concentrated by nitrogen, analyzed by the GC with large volume injection, separated by the capillary columns of DB-1, determined by a flame ionization detector, and quantified by external standard method. In addition, the key experimental parameters were optimized, including the amount of epoxidation reagent (mCPBA), epoxidation reaction time and elution volume. Under the optimized experimental conditions, Gravex913 lubricating oil showed good linearity as a standard reference of mineral oil in the ranges of 2.0-500.0 mg/L, the limits of detection (LOD) of MOSH and MOAH fractions were 0.3 mg/kg and 1.0 mg/kg, the limits of quantification (LOQ) were 1.0 mg/kg and 3.0 mg/kg, respectively. The spiked recoveries of MOSH and MOAH fractions were in the range of 93.2%-103.7% and 78.5%-81.3% at three spiked levels with the relative standard deviations (RSDs) of 2.7%-5.0% and 2.9%-4.0% (n=6). The established method has many advantages such as good purification effect, low reagent consumption and low detection limit, and is suitable for the separation and quantification of MOSH and MOAH in olive oils.
