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2020 Volume 48 Issue 10
2020, 48(10): 1279-1287
doi: 10.19756/j.issn.0253-3820.201259
Abstract:
The new coronavirus SARS-CoV-2 has spread to the whole world, seriously threatening human life and disrupting people's lives. SARS-CoV-2 is a highly infectious virus with a long incubation period, encompassing asymptomatic infections. Therefore, accurate detection of SARS-CoV-2 is essential for the prevention and control of the epidemic. Currently, nucleic acid detection has played an important role in the prevention and control of SARS-CoV-2. A variety of nucleic acid detection technologies for SARS-CoV-2 have been developed, and some technologies have been converted into available kits for clinical detection. However, these technologies have different principles and detection platforms. How to choose the appropriate nucleic acid detection technology for SARS-CoV-2 perplexes epidemic prevention and control. Based on the latest research progress of nucleic acid technologies for SARS-CoV-2, this paper introduced the principles and technology platforms of these detection technologies, thoroughly compared the advantages and disadvantages of each technology and clarified the scope of applications, a reference was provided for selecting the appropriate nucleic acid detection technology for SARS-CoV-2. Furthermore, this paper provided a prospect for developing the technologies of detecting pathogens similar to SARS-CoV-2.
The new coronavirus SARS-CoV-2 has spread to the whole world, seriously threatening human life and disrupting people's lives. SARS-CoV-2 is a highly infectious virus with a long incubation period, encompassing asymptomatic infections. Therefore, accurate detection of SARS-CoV-2 is essential for the prevention and control of the epidemic. Currently, nucleic acid detection has played an important role in the prevention and control of SARS-CoV-2. A variety of nucleic acid detection technologies for SARS-CoV-2 have been developed, and some technologies have been converted into available kits for clinical detection. However, these technologies have different principles and detection platforms. How to choose the appropriate nucleic acid detection technology for SARS-CoV-2 perplexes epidemic prevention and control. Based on the latest research progress of nucleic acid technologies for SARS-CoV-2, this paper introduced the principles and technology platforms of these detection technologies, thoroughly compared the advantages and disadvantages of each technology and clarified the scope of applications, a reference was provided for selecting the appropriate nucleic acid detection technology for SARS-CoV-2. Furthermore, this paper provided a prospect for developing the technologies of detecting pathogens similar to SARS-CoV-2.
2020, 48(10): 1288-1295
doi: 10.19756/j.issn.0253-3820.201005
Abstract:
As a novel class of luminescent nanomaterials, carbon quantum dots (CQDs) have attracted considerable interest in the field of food safety due to their high bright luminescence, low toxicity and good biocompatibility. This paper introduced the fluorescence detection mechanism of CQDs, including internal filter effect, photoinduced electron transfer effect, fluorescence resonance energy transfer effect, and so on. And their applications in food analysis were reviewed systematically, such as heavy metal ions detection, food additives detection, foodborne pathogenic bacteria detection, pesticide residue detection, veterinary drug residue detection, food nutrients detection and other molecular detection. The challenges and perspectives of CQDs in food safety field were also discussed.
As a novel class of luminescent nanomaterials, carbon quantum dots (CQDs) have attracted considerable interest in the field of food safety due to their high bright luminescence, low toxicity and good biocompatibility. This paper introduced the fluorescence detection mechanism of CQDs, including internal filter effect, photoinduced electron transfer effect, fluorescence resonance energy transfer effect, and so on. And their applications in food analysis were reviewed systematically, such as heavy metal ions detection, food additives detection, foodborne pathogenic bacteria detection, pesticide residue detection, veterinary drug residue detection, food nutrients detection and other molecular detection. The challenges and perspectives of CQDs in food safety field were also discussed.
A Novel Laser Ablation Chamber for Microwave Plasma Atomic Emission Spectrometry and Its Application
2020, 48(10): 1296-1304
doi: 10.19756/j.issn.0253-3820.201238
Abstract:
Microwave plasma torch atomic emission spectrometry (MPT-AES) is a widely used element detection method. However, MPT-AES requires complex digestion and desolvation treatment when detecting solid samples. After many improvements, a new Z-shaped laser ablation chamber and constructing laser ablation microwave plasma torch atomic emission spectroscopy (LA-MPT-AES) was developed. This method eliminated the complex processing of solid samples. The ablation chamber was sealed with a flat surface of solid sample (>3 mm×2 mm), which did not limit the size of the solid sample. The chamber internal volume was 0.04 cm3, the cleaning time was as low as 0.5 s, and the relative standard deviation (RSD) of the signal when analyzing pure Cu samples was 1.2% (n=11). Under the optimal experimental conditions, 12 elements (Si, Mg, Fe, Al, Mn, Ca, Ba, Sr, Na, Li, K, Rb) in the rock-polyethylene tablet were detected, and the detection limit was 0.00002-362 μg/g, with relative standard deviations of 3.7%-9.1% (n=11). The 10 elements in the 3 igneous rock samples were analyzed, showing good uniformity with the theoretical values, with a relative error of 0.04%-14.32%. The LA-MPT-AES had good stability, and its sensitivity was comparable to laser ablation inductively coupled plasma-atomic emission spectrometry (LA-ICP-AES), and even better for some elements. Otherwise, the cost of using this method was much lower than that of the LA-ICP-AES.
Microwave plasma torch atomic emission spectrometry (MPT-AES) is a widely used element detection method. However, MPT-AES requires complex digestion and desolvation treatment when detecting solid samples. After many improvements, a new Z-shaped laser ablation chamber and constructing laser ablation microwave plasma torch atomic emission spectroscopy (LA-MPT-AES) was developed. This method eliminated the complex processing of solid samples. The ablation chamber was sealed with a flat surface of solid sample (>3 mm×2 mm), which did not limit the size of the solid sample. The chamber internal volume was 0.04 cm3, the cleaning time was as low as 0.5 s, and the relative standard deviation (RSD) of the signal when analyzing pure Cu samples was 1.2% (n=11). Under the optimal experimental conditions, 12 elements (Si, Mg, Fe, Al, Mn, Ca, Ba, Sr, Na, Li, K, Rb) in the rock-polyethylene tablet were detected, and the detection limit was 0.00002-362 μg/g, with relative standard deviations of 3.7%-9.1% (n=11). The 10 elements in the 3 igneous rock samples were analyzed, showing good uniformity with the theoretical values, with a relative error of 0.04%-14.32%. The LA-MPT-AES had good stability, and its sensitivity was comparable to laser ablation inductively coupled plasma-atomic emission spectrometry (LA-ICP-AES), and even better for some elements. Otherwise, the cost of using this method was much lower than that of the LA-ICP-AES.
2020, 48(10): 1305-1314
doi: 10.19756/j.issn.0253-3820.201443
Abstract:
Urinary extracellular vesicles (uEVs) are a rising star in liquid biopsies and have shown great potential in disease diagnosis and treatment monitoring. However, knowledge about the size distribution, particle concentration and biochemical phenotype of uEVs remains poorly understood owing to the limited characterization methods. The large heterogeneity and diversity of EVs call for the development of a high-throughout, multi-parameter technique that can analyze EVs at the single-particle level. Employing strategies for single molecule fluorescence detection in a sheathed flow, our laboratory has successfully developed nano-flow cytometer (nFCM) that enables detection of single EVs as small as 40 nm. Here, using nFCM, the characterization of uEVs isolated via differential ultracentrifugation was reported. The purity, particle concentration, size distribution, DNA, RNA, and protein expression were reported. The results indicated that the purity of isolated uEVs was about 92%. For uEVs isolated from 10 healthy donors, the concentrations were 3.0×109-8.9×1010 particles/mL and the particle sizes fell in the range of 40-120 nm. In addition, DNA and RNA were mainly encapsulated inside the lumen of relatively large-size uEVs and there were no nucleic acids adhered to the surface of uEVs. The percentages of CD9, CD63, CD81 or CD24 positive uEVs were also measured. It was demonstrated that nFCM provided an important tool for studying the biochemical properties of uEVs along with their clinical applications.
Urinary extracellular vesicles (uEVs) are a rising star in liquid biopsies and have shown great potential in disease diagnosis and treatment monitoring. However, knowledge about the size distribution, particle concentration and biochemical phenotype of uEVs remains poorly understood owing to the limited characterization methods. The large heterogeneity and diversity of EVs call for the development of a high-throughout, multi-parameter technique that can analyze EVs at the single-particle level. Employing strategies for single molecule fluorescence detection in a sheathed flow, our laboratory has successfully developed nano-flow cytometer (nFCM) that enables detection of single EVs as small as 40 nm. Here, using nFCM, the characterization of uEVs isolated via differential ultracentrifugation was reported. The purity, particle concentration, size distribution, DNA, RNA, and protein expression were reported. The results indicated that the purity of isolated uEVs was about 92%. For uEVs isolated from 10 healthy donors, the concentrations were 3.0×109-8.9×1010 particles/mL and the particle sizes fell in the range of 40-120 nm. In addition, DNA and RNA were mainly encapsulated inside the lumen of relatively large-size uEVs and there were no nucleic acids adhered to the surface of uEVs. The percentages of CD9, CD63, CD81 or CD24 positive uEVs were also measured. It was demonstrated that nFCM provided an important tool for studying the biochemical properties of uEVs along with their clinical applications.
2020, 48(10): 1315-1324
doi: 10.19756/j.issn.0253-3820.201263
Abstract:
A custom membrane extraction electrospray ionization mass spectrometry (MEESI-MS) method was developed to detect the representative bacteric metabolites and classify four kinds of bacteria including Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa. The chemical fingerprints of each bacterium were obtained using this MEESI-MS method. Principal component analysis (PCA) was then applied to analyze the information from the obtained fingerprint spectra and classify the samples. The results showed that MEESI-MS method was capable of rapidly obtaining metabolic fingerprints of blood samples and direct identifying the representative metabolites from each bacterium via employing both accurate mass measurements and structural information from tandem mass spectra. The overall analysis time was less than 65 min (including a culture time of about 60 min). This method was featured by the simplicity in sample pretreatment, ionization activation and data analysis and was promising in rapid identification of bacterial species in clinical bacteremia and septicemia.
A custom membrane extraction electrospray ionization mass spectrometry (MEESI-MS) method was developed to detect the representative bacteric metabolites and classify four kinds of bacteria including Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae and Pseudomonas aeruginosa. The chemical fingerprints of each bacterium were obtained using this MEESI-MS method. Principal component analysis (PCA) was then applied to analyze the information from the obtained fingerprint spectra and classify the samples. The results showed that MEESI-MS method was capable of rapidly obtaining metabolic fingerprints of blood samples and direct identifying the representative metabolites from each bacterium via employing both accurate mass measurements and structural information from tandem mass spectra. The overall analysis time was less than 65 min (including a culture time of about 60 min). This method was featured by the simplicity in sample pretreatment, ionization activation and data analysis and was promising in rapid identification of bacterial species in clinical bacteremia and septicemia.
2020, 48(10): 1325-1333
doi: 10.19756/j.issn.0253-3820.201295
Abstract:
A highly sensitive and label-free fluorescence carcinoembryonic antigen (CEA) biosensor was developed via target-triggered enzymatic recycling amplification reaction. In this strategy, aggregation induced emission fluorogen (AIEgen) TPE-M was chosen as a signal reporter to enhance the detection efficiency, as well as L-cysteine (L-cys) was utilized as a reactant to control over the fluorescence intensity due to its distinct capability of reacting with TPE-M and hemin/G-quadruplex. CEA triggered the in-situ generation of abundant hemin/G-quadruplex through polymerase/nicking enzyme-assisted recycling amplification, and the in-situ generated hemin/G-quadruplex catalyzed the destruction of L-cys. With L-cys consuming, a significantly decreased fluorescence was observed, demonstrating that the fluorescence intensity was relied on CEA amount. As a consequence, a facile, precise and sensitive strategy for CEA assay was readily realized. Furthermore, the detection limit was 0.033 fmol/L (S/N=3). The developed AIEgen-based biosensor provided a new method for sensitive and reliable detection of CEA in biological liquids, displaying a significant promise for CEA-related disease diagnosis.
A highly sensitive and label-free fluorescence carcinoembryonic antigen (CEA) biosensor was developed via target-triggered enzymatic recycling amplification reaction. In this strategy, aggregation induced emission fluorogen (AIEgen) TPE-M was chosen as a signal reporter to enhance the detection efficiency, as well as L-cysteine (L-cys) was utilized as a reactant to control over the fluorescence intensity due to its distinct capability of reacting with TPE-M and hemin/G-quadruplex. CEA triggered the in-situ generation of abundant hemin/G-quadruplex through polymerase/nicking enzyme-assisted recycling amplification, and the in-situ generated hemin/G-quadruplex catalyzed the destruction of L-cys. With L-cys consuming, a significantly decreased fluorescence was observed, demonstrating that the fluorescence intensity was relied on CEA amount. As a consequence, a facile, precise and sensitive strategy for CEA assay was readily realized. Furthermore, the detection limit was 0.033 fmol/L (S/N=3). The developed AIEgen-based biosensor provided a new method for sensitive and reliable detection of CEA in biological liquids, displaying a significant promise for CEA-related disease diagnosis.
2020, 48(10): 1334-1342
doi: 10.19756/j.issn.0253-3820.201220
Abstract:
Protein glycosylation of human urine exosome can reflect important biological information, which promotes a large-scale identification for the study of urine exosome glycoproteome. In this work, a two step enrichment method based on extracellular vesicles total recovery and purification (EVTRAP) and click maltose materials was developed for urine glycoproteome study. Based on the lipid bilayer of exosome, EVTRAP, a lipophilic magnetic beads, could effectively extract exosomes from human urine. After lysis and digestion of exosomes, based on the hydrophilic glycan chains of glycopeptides, glycopeptides were effectively enriched by click maltose hydrophilic materials. The exosomes proteins digestion and glycopeptides were analyzed by LC-MS-MS. Finally, 1925 nonredundant proteins and 14233 peptides were obtained at proteome level, which indicated that the urine exosomes were extracted with highly specificity. Meanwhile, 468 nonredundant intact glycopeptides from 88 glycoproteins corresponding to 95 various glycans on 135 glycosites were identified. Furthermore, the glycopeptides with high heterogeneity and different glycan structures were analyzed. This study provided an effective approach for investigation of urine exosome glycoproteome for disease biomarker discovery.
Protein glycosylation of human urine exosome can reflect important biological information, which promotes a large-scale identification for the study of urine exosome glycoproteome. In this work, a two step enrichment method based on extracellular vesicles total recovery and purification (EVTRAP) and click maltose materials was developed for urine glycoproteome study. Based on the lipid bilayer of exosome, EVTRAP, a lipophilic magnetic beads, could effectively extract exosomes from human urine. After lysis and digestion of exosomes, based on the hydrophilic glycan chains of glycopeptides, glycopeptides were effectively enriched by click maltose hydrophilic materials. The exosomes proteins digestion and glycopeptides were analyzed by LC-MS-MS. Finally, 1925 nonredundant proteins and 14233 peptides were obtained at proteome level, which indicated that the urine exosomes were extracted with highly specificity. Meanwhile, 468 nonredundant intact glycopeptides from 88 glycoproteins corresponding to 95 various glycans on 135 glycosites were identified. Furthermore, the glycopeptides with high heterogeneity and different glycan structures were analyzed. This study provided an effective approach for investigation of urine exosome glycoproteome for disease biomarker discovery.
2020, 48(10): 1343-1350
doi: 10.19756/j.issn.0253-3820.201137
Abstract:
A method for analysis of various biotoxins and biological modifiers based on electrospray ionization-ion mobility spectrometry (ESI-IMS) and Raman spectroscopy was established. A database of 26 kinds of white powders, including alkaloids such as aconitine and tetrodotoxin, biological modifiers such as bradykinin, substance P and their structural analogs, biotoxins such as conotoxins, α-bungarotoxin and ricin, and common white powder such as salt, flour and bovine serum albumin was constructed. Six pattern recognition algorithms, including linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), k-nearest neighbor (kNN), naive bayesian (NB), classification tree (CT) and support vector machine (SVM), were used to classify the single spectrum and the fusion data with this database. The results showed that the recognition accuracy of different methods was 76.0%-97.2%, and among which, the fusion recognition algorithm based on the support vector machine model achieved a high recognition accuracy of 97.2%. Meanwhile, the difference of recognition accuracy was analyzed in this study. This method could also distinguish multiple structural analogues of the two biological modifiers, which could be used in rapid distinguish of unknown white powder.
A method for analysis of various biotoxins and biological modifiers based on electrospray ionization-ion mobility spectrometry (ESI-IMS) and Raman spectroscopy was established. A database of 26 kinds of white powders, including alkaloids such as aconitine and tetrodotoxin, biological modifiers such as bradykinin, substance P and their structural analogs, biotoxins such as conotoxins, α-bungarotoxin and ricin, and common white powder such as salt, flour and bovine serum albumin was constructed. Six pattern recognition algorithms, including linear discriminant analysis (LDA), quadratic discriminant analysis (QDA), k-nearest neighbor (kNN), naive bayesian (NB), classification tree (CT) and support vector machine (SVM), were used to classify the single spectrum and the fusion data with this database. The results showed that the recognition accuracy of different methods was 76.0%-97.2%, and among which, the fusion recognition algorithm based on the support vector machine model achieved a high recognition accuracy of 97.2%. Meanwhile, the difference of recognition accuracy was analyzed in this study. This method could also distinguish multiple structural analogues of the two biological modifiers, which could be used in rapid distinguish of unknown white powder.
2020, 48(10): 1351-1358
doi: 10.19756/j.issn.0253-3820.201373
Abstract:
Advanced renal cancer is not sensitive to chemotherapy or radiotherapy, and its effective treatment is very limited. At present, the recognition of specific and effective molecular targets for advanced renal cancer is far from enough. In this work, 2046 proteins were identified from the renal clear cell carcinoma and its adjacent normal tissues by using label-free quantitative proteomics approaches based on MS2 data. Two kinds of data processing methods, i.e. spectral counting and MS2 total ion current (MS2 TIC), were used to analyze the data derived from proteomics identification. The results showed that 144 differential proteins and 120 differential proteins were screened by MS2 TIC method and spectral counting method, respectively. A total of 147 differential proteins were screened by the two methods. Among them, there were 46 up-regulated proteins in tumor tissue, including annexin A4, laminin α-4 subunit, pyruvate kinase, ATP citrate synthetase and histone H1.5, carbonic anhydrase 9, etc.; there were 101 down-regulated proteins in tumor tissue, including beta subunit of electron transfer flavin, 3-ketoalkyl COA thiolase, villin-1, f subunit of V-type proton ATP synthetase, mitochondrial phosphate carrier protein, 8 subunit of cytochrome b-c1 complex, multidrug resistance protein 1, retinol dehydrogenase 2, uromodulin, etc. The results of some differential protein analyses were validated by using MS1-based quantitative method. The label-free quantification using MS2 data was used to analyze the proteome in renal clear cell carcinoma and its adjacent normal tissues. The differential proteins could be used as candidate biomarkers for diagnosis, treatment and prognosis of renal clear cell carcinoma, which could used to find the potential targets for effective treatment of advanced renal clear cell carcinoma.
Advanced renal cancer is not sensitive to chemotherapy or radiotherapy, and its effective treatment is very limited. At present, the recognition of specific and effective molecular targets for advanced renal cancer is far from enough. In this work, 2046 proteins were identified from the renal clear cell carcinoma and its adjacent normal tissues by using label-free quantitative proteomics approaches based on MS2 data. Two kinds of data processing methods, i.e. spectral counting and MS2 total ion current (MS2 TIC), were used to analyze the data derived from proteomics identification. The results showed that 144 differential proteins and 120 differential proteins were screened by MS2 TIC method and spectral counting method, respectively. A total of 147 differential proteins were screened by the two methods. Among them, there were 46 up-regulated proteins in tumor tissue, including annexin A4, laminin α-4 subunit, pyruvate kinase, ATP citrate synthetase and histone H1.5, carbonic anhydrase 9, etc.; there were 101 down-regulated proteins in tumor tissue, including beta subunit of electron transfer flavin, 3-ketoalkyl COA thiolase, villin-1, f subunit of V-type proton ATP synthetase, mitochondrial phosphate carrier protein, 8 subunit of cytochrome b-c1 complex, multidrug resistance protein 1, retinol dehydrogenase 2, uromodulin, etc. The results of some differential protein analyses were validated by using MS1-based quantitative method. The label-free quantification using MS2 data was used to analyze the proteome in renal clear cell carcinoma and its adjacent normal tissues. The differential proteins could be used as candidate biomarkers for diagnosis, treatment and prognosis of renal clear cell carcinoma, which could used to find the potential targets for effective treatment of advanced renal clear cell carcinoma.
2020, 48(10): 1359-1366
doi: 10.19756/j.issn.0253-3820.201270
Abstract:
A fluorescence imaging protocol was developed for the quantification analysis of intracellular glutathione-copper nanoparticles (GSH-CuNPs). After culturing MCF-7 cells with near infrared luminescent GSH-CuNPs, the fluorescence imaging of intracellular CuNPs was achieved at λex/λem=559/(600-700) nm. The cells were then subjected to lysis and ultrafiltration to collect the GSH-CuNPs. The copper content in the collected GSH-CuNPs was quantified by inductively coupled plasma-mass spectrometry (ICP-MS). Thereafter, the fluorescence density in the imaging was correlated with the analytical data by ICP-MS with SPSS statistics analysis to develop a linear calibration between the fluorescence intensity and the intracellular content of GSH-CuNPs. The developed protocol here was applied to the investigation of GSH-CuNPs metabolism/transformation in live MCF-7 cells, and it was found that with incubation time of 50 min, the content of GSH-CuNPs decreased from 172.74 fg/cell to 18.66 fg/cell and the majority of GSH-CuNPs were metabolized and transformed into soluble copper species.
A fluorescence imaging protocol was developed for the quantification analysis of intracellular glutathione-copper nanoparticles (GSH-CuNPs). After culturing MCF-7 cells with near infrared luminescent GSH-CuNPs, the fluorescence imaging of intracellular CuNPs was achieved at λex/λem=559/(600-700) nm. The cells were then subjected to lysis and ultrafiltration to collect the GSH-CuNPs. The copper content in the collected GSH-CuNPs was quantified by inductively coupled plasma-mass spectrometry (ICP-MS). Thereafter, the fluorescence density in the imaging was correlated with the analytical data by ICP-MS with SPSS statistics analysis to develop a linear calibration between the fluorescence intensity and the intracellular content of GSH-CuNPs. The developed protocol here was applied to the investigation of GSH-CuNPs metabolism/transformation in live MCF-7 cells, and it was found that with incubation time of 50 min, the content of GSH-CuNPs decreased from 172.74 fg/cell to 18.66 fg/cell and the majority of GSH-CuNPs were metabolized and transformed into soluble copper species.
2020, 48(10): 1367-1374
doi: 10.19756/j.issn.0253-3820.201148
Abstract:
The conformation of glutathione is of great significance for its biological function. In this study, the absorption spectra of reduced (GSH) and oxidized (GSSG) glutathione in the frequency range of 0.5-12 THz were obtained by the air plasma terahertz time-domain spectroscopy (THz-TDS). The results demonstrated that GSH had rich characteristic absorption peaks in the THz region, while GSSG presented a monotonous absorption spectrum without obvious peaks. Combined with powder X-ray diffraction (PXRD), GSH had a certain crystal structure and GSSG was amorphous, suggesting that the THz spectroscopy was sensitive to the molecular structure and crystal form. The density functional theory (DFT) calculation based on the GSH crystal structure was performed to simulate the THz absorption spectrum and analyze the vibrational property. The result showed that GSH molecule could form rich intra-and inter-molecular hydrogen bonds, which helped to constrain flexible peptide. Lattice vibration and hydrogen bonding of GSH can effectively resonate with THz waves. The different THz absorption peaks of GSH correspond to different collective or local molecular vibrations which were closely related to the hydrogen bonding interactions. The study may help to deepen the understanding of GSH molecular conformation and weak interactions.
The conformation of glutathione is of great significance for its biological function. In this study, the absorption spectra of reduced (GSH) and oxidized (GSSG) glutathione in the frequency range of 0.5-12 THz were obtained by the air plasma terahertz time-domain spectroscopy (THz-TDS). The results demonstrated that GSH had rich characteristic absorption peaks in the THz region, while GSSG presented a monotonous absorption spectrum without obvious peaks. Combined with powder X-ray diffraction (PXRD), GSH had a certain crystal structure and GSSG was amorphous, suggesting that the THz spectroscopy was sensitive to the molecular structure and crystal form. The density functional theory (DFT) calculation based on the GSH crystal structure was performed to simulate the THz absorption spectrum and analyze the vibrational property. The result showed that GSH molecule could form rich intra-and inter-molecular hydrogen bonds, which helped to constrain flexible peptide. Lattice vibration and hydrogen bonding of GSH can effectively resonate with THz waves. The different THz absorption peaks of GSH correspond to different collective or local molecular vibrations which were closely related to the hydrogen bonding interactions. The study may help to deepen the understanding of GSH molecular conformation and weak interactions.
2020, 48(10): 1375-1382
doi: 10.19756/j.issn.0253-3820.201317
Abstract:
The novel core-shell magnetic imprinted polymers (MIPs-E2) were prepared for selective adsorption of estradiol (E2) by template immobilization strategy, in which aniline (AN), ammonium persulfate (APS), E2 and carboxyl-modified Fe3O4 magnetic nanoparticles (Fe3O4-COOH) were employed as the functional monomer, initiator, template molecule, and carrier, respectively. The prepared nanomaterials were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The results showed that MIPs-E2 had uniform particle size, stable crystal structure and outstanding magnetism. In addition, the adsorption experiments displayed that MIPs-E2 had large adsorption capacity (21.34 mg/g), high selectivity (IF=2.65, SC>1.89), fast mass transfer rate (30 min) and excellent reusability (adsorption efficiency remained 93.4% after reusing for 6 cycles). This work provided a new approach for detection of the content of E2 in environmental water.
The novel core-shell magnetic imprinted polymers (MIPs-E2) were prepared for selective adsorption of estradiol (E2) by template immobilization strategy, in which aniline (AN), ammonium persulfate (APS), E2 and carboxyl-modified Fe3O4 magnetic nanoparticles (Fe3O4-COOH) were employed as the functional monomer, initiator, template molecule, and carrier, respectively. The prepared nanomaterials were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM). The results showed that MIPs-E2 had uniform particle size, stable crystal structure and outstanding magnetism. In addition, the adsorption experiments displayed that MIPs-E2 had large adsorption capacity (21.34 mg/g), high selectivity (IF=2.65, SC>1.89), fast mass transfer rate (30 min) and excellent reusability (adsorption efficiency remained 93.4% after reusing for 6 cycles). This work provided a new approach for detection of the content of E2 in environmental water.
2020, 48(10): 1383-1391
doi: 10.19756/j.issn.0253-3820.201281
Abstract:
Juglone (Jug) is one of the main active substances in the folk anti-cancer prescription walnut green husk and there are few reports on its interaction with protein and its mechanism of action. Here, the interaction mechanism between Jug and human serum albumin (HSA) was investigated by endogenous fluorescence spectrum, ultraviolet absorption spectrum, synchronous fluorescence spectrum, 3D fluorescence spectrum and molecular docking methods under the simulative physiological conditions. Fluorescence spectra results revealed that Jug could quench (static quenching) the intrinsic fluorescence of HSA. According to the Mineweaver-Burk equation, the binding constant (KA) was calculated to be 3.72×102 L/mol (310 K) and the number of binding sites (n) were approximately equal to 1. The thermodynamic parameters obtained by van't Hoff's law (ΔH=-142.07 kJ/mol, ΔS=-409.08 J/(mol·K)) revealed that the main forces between Jug and HSA were hydrogen bond and van der Waals. The binding distance (2.61 nm) between Jug and HSA was determined based on F rster's energy transformation law. The results of ultraviolet absorption spectroscopy, simultaneous fluorescence spectroscopy and 3D fluorescence spectroscopy indicated that Jug slightly affected the secondary structure of HSA and increased the hydrophobicity of the microenvironment around the tryosine residue. Molecular docking results further illustrated that Jug interacted with amino acid residues on subdomain Ⅲ A of HSA through van der Waals forces, hydrogen bonding and hydrophobic forces. This study was helpful to understand the storage and transportation process of Jug in human body and its effect on protein function at molecular level.
Juglone (Jug) is one of the main active substances in the folk anti-cancer prescription walnut green husk and there are few reports on its interaction with protein and its mechanism of action. Here, the interaction mechanism between Jug and human serum albumin (HSA) was investigated by endogenous fluorescence spectrum, ultraviolet absorption spectrum, synchronous fluorescence spectrum, 3D fluorescence spectrum and molecular docking methods under the simulative physiological conditions. Fluorescence spectra results revealed that Jug could quench (static quenching) the intrinsic fluorescence of HSA. According to the Mineweaver-Burk equation, the binding constant (KA) was calculated to be 3.72×102 L/mol (310 K) and the number of binding sites (n) were approximately equal to 1. The thermodynamic parameters obtained by van't Hoff's law (ΔH=-142.07 kJ/mol, ΔS=-409.08 J/(mol·K)) revealed that the main forces between Jug and HSA were hydrogen bond and van der Waals. The binding distance (2.61 nm) between Jug and HSA was determined based on F rster's energy transformation law. The results of ultraviolet absorption spectroscopy, simultaneous fluorescence spectroscopy and 3D fluorescence spectroscopy indicated that Jug slightly affected the secondary structure of HSA and increased the hydrophobicity of the microenvironment around the tryosine residue. Molecular docking results further illustrated that Jug interacted with amino acid residues on subdomain Ⅲ A of HSA through van der Waals forces, hydrogen bonding and hydrophobic forces. This study was helpful to understand the storage and transportation process of Jug in human body and its effect on protein function at molecular level.
2020, 48(10): 1392-1399
doi: 10.19756/j.issn.0253-3820.201359
Abstract:
The Fe3O4@COF with core-shell structures was synthesized and used as sorbent in magnetic solid-phase extraction (MSPE). This Fe3O4@COF-MSPE method coupled with high-performance liquid chromatography-ultraviolet detector (HPLC-UV) was employed for simultaneous analysis of thiamethoxam, imidacloprid, carbendazim and thiabendazole residues in citrus samples. The synthesized Fe3O4@COF was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, X-ray diffraction and magnetometry techniques. The operation conditions of MSPE were optimized. In each trial, 20.0 mg of Fe3O4@COF was dispersed into 10 mL of citrus sample and shaken for 20 min. Then, the Fe3O4@COF was separated by an external magnetic field. Next, the pesticide target compounds were eluted from Fe3O4@COF with 1 mL of methanol and shaken for 5 min. Under the optimized conditions, the method had an excellent linearity in the concentration range of 1-1000 μg/L for thiomethoxam, carbendazim and thiabendazle, and 5-1000 μg/L for imidacloprid. The limits of detection ranged from 0.27 μg/L to 1.22 μg/L. The recoveries ranged from 92.1% to 104.0%. The relative standard deviations (RSDs) ranged from 1.2% to 8.3%. The proposed Fe3O4@COF-MSPE-HPLC-UV method was demonstrated to be easy operation, low limit of detection and wide detection range, which was applicable to simultaneous determination of four pesticide residues in citrus samples.
The Fe3O4@COF with core-shell structures was synthesized and used as sorbent in magnetic solid-phase extraction (MSPE). This Fe3O4@COF-MSPE method coupled with high-performance liquid chromatography-ultraviolet detector (HPLC-UV) was employed for simultaneous analysis of thiamethoxam, imidacloprid, carbendazim and thiabendazole residues in citrus samples. The synthesized Fe3O4@COF was characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectra, X-ray diffraction and magnetometry techniques. The operation conditions of MSPE were optimized. In each trial, 20.0 mg of Fe3O4@COF was dispersed into 10 mL of citrus sample and shaken for 20 min. Then, the Fe3O4@COF was separated by an external magnetic field. Next, the pesticide target compounds were eluted from Fe3O4@COF with 1 mL of methanol and shaken for 5 min. Under the optimized conditions, the method had an excellent linearity in the concentration range of 1-1000 μg/L for thiomethoxam, carbendazim and thiabendazle, and 5-1000 μg/L for imidacloprid. The limits of detection ranged from 0.27 μg/L to 1.22 μg/L. The recoveries ranged from 92.1% to 104.0%. The relative standard deviations (RSDs) ranged from 1.2% to 8.3%. The proposed Fe3O4@COF-MSPE-HPLC-UV method was demonstrated to be easy operation, low limit of detection and wide detection range, which was applicable to simultaneous determination of four pesticide residues in citrus samples.
2020, 48(10): 1400-1408
doi: 10.19756/j.issn.0253-3820.191565
Abstract:
An efficient and rapid method for qualitative and quantitative determination of ferulic acid, gallic acid, p-coumaric acid, syringic acid and (+)-catechin hydrate in baijiu by solid phase extraction-high performance liquid chromatography (SPE-HPLC) was established. The pre-treatment conditions and chromatographic conditions were optimized. Under the optimal conditions including sample pH=2, methanol elution solution pH=4, and 6 mL of methanol elution solution, the contents of 5 phenolic active compounds in 17 different green barley base baijiu and 29 kinds of other type commercial baijiu were determined. This method showed a good linearity for the 5 phenolic active compounds and the linear correlation coefficients (R2) were 0.9945-0.9999. Besides, the limits of detection were 0.98-12.2 μg/L, and the recoveries were 84.1%-100.7%. Through chemometrics such as cluster analysis, combined with the content of 5 phenolic active compounds, different baijiu in different baijiu storage containers could be distinguished. The average content of 5 phenolic active compounds in green barley baijiu was higher than most of other light-aroma commercial baijiu. The total content of 5 phenolic active compounds in four kinds of aroma baijiu was sauce-aroma> light-aroma> sesame-aroma> strong-aroma. Among them, the content of p-coumaric acid and (+)-catechin hydrate in the sauce-aroma baijiu was the highest, and the content of ferulic acid in the sesame-aroma baijiu was the highest.
An efficient and rapid method for qualitative and quantitative determination of ferulic acid, gallic acid, p-coumaric acid, syringic acid and (+)-catechin hydrate in baijiu by solid phase extraction-high performance liquid chromatography (SPE-HPLC) was established. The pre-treatment conditions and chromatographic conditions were optimized. Under the optimal conditions including sample pH=2, methanol elution solution pH=4, and 6 mL of methanol elution solution, the contents of 5 phenolic active compounds in 17 different green barley base baijiu and 29 kinds of other type commercial baijiu were determined. This method showed a good linearity for the 5 phenolic active compounds and the linear correlation coefficients (R2) were 0.9945-0.9999. Besides, the limits of detection were 0.98-12.2 μg/L, and the recoveries were 84.1%-100.7%. Through chemometrics such as cluster analysis, combined with the content of 5 phenolic active compounds, different baijiu in different baijiu storage containers could be distinguished. The average content of 5 phenolic active compounds in green barley baijiu was higher than most of other light-aroma commercial baijiu. The total content of 5 phenolic active compounds in four kinds of aroma baijiu was sauce-aroma> light-aroma> sesame-aroma> strong-aroma. Among them, the content of p-coumaric acid and (+)-catechin hydrate in the sauce-aroma baijiu was the highest, and the content of ferulic acid in the sesame-aroma baijiu was the highest.
2020, 48(10): 1409-1415
doi: 10.19756/j.issn.0253-3820.201260
Abstract:
Ochratoxin A (OTA) is one kind of mycotoxin, which is toxic and widely distributed. To avoid the poison of OTA, it is necessary to develop a rapid, low-cost and highly sensitive detection method to evaluate the concentration of OTA in the food. Here, an aptamer biosensor was developed to detect OTA in wine using single labeled oligonucleotide with fluorescein (FAM) as probe and guanine in the aptamer as quencher. Guanine was a heterocyclic compound that had a high electron density and the lowest oxidation potential in nucleic acid bases. Guanine was easily to be oxidized. As an electron donor, the fluorophore could be quenched by guanine through the process of photoinduced electron transfer (PET). When the probe labeled with FAM hybridized with the OTA aptamer, the fluorescence of FAM was quenched by the guanine in OTA aptamer. In the presence of OTA, due to the specific interaction between OTA and aptamer, OTA induced aptamer folding to G-quadruplexes, which inhibited the binding of probe with aptamer, and thus led to the fluorescence intensity recovery. The concentration of OTA could be determined by the recovery ratio of FAM fluorescence intensity. The linear range for detection of OTA by this aptasenor was 0.67-7.80 nmol/L, the linear calibration equation was R(%)=-0.02+1.76COTA (nmol/L), and LOD was 0.67 nmol/L (0.27 g/kg, S/N=3).The recoveries of OTA in red wine sample were in the range of 92.4%-100.9%. Compared with sensing strategies based on gold nanoparticles, single-walled nanotubes and graphene oxide, this method had many advantages such as low cost, good selectivity and high sensitivity.
Ochratoxin A (OTA) is one kind of mycotoxin, which is toxic and widely distributed. To avoid the poison of OTA, it is necessary to develop a rapid, low-cost and highly sensitive detection method to evaluate the concentration of OTA in the food. Here, an aptamer biosensor was developed to detect OTA in wine using single labeled oligonucleotide with fluorescein (FAM) as probe and guanine in the aptamer as quencher. Guanine was a heterocyclic compound that had a high electron density and the lowest oxidation potential in nucleic acid bases. Guanine was easily to be oxidized. As an electron donor, the fluorophore could be quenched by guanine through the process of photoinduced electron transfer (PET). When the probe labeled with FAM hybridized with the OTA aptamer, the fluorescence of FAM was quenched by the guanine in OTA aptamer. In the presence of OTA, due to the specific interaction between OTA and aptamer, OTA induced aptamer folding to G-quadruplexes, which inhibited the binding of probe with aptamer, and thus led to the fluorescence intensity recovery. The concentration of OTA could be determined by the recovery ratio of FAM fluorescence intensity. The linear range for detection of OTA by this aptasenor was 0.67-7.80 nmol/L, the linear calibration equation was R(%)=-0.02+1.76COTA (nmol/L), and LOD was 0.67 nmol/L (0.27 g/kg, S/N=3).The recoveries of OTA in red wine sample were in the range of 92.4%-100.9%. Compared with sensing strategies based on gold nanoparticles, single-walled nanotubes and graphene oxide, this method had many advantages such as low cost, good selectivity and high sensitivity.
2020, 48(10): 1416-1421
doi: 10.19756/j.issn.0253-3820.201146
Abstract:
The low temperature plasma (LTP) probe which can be used to quickly detect solid, liquid and gaseous samples has the characteristics of simple, fast and accurate, and easy to miniaturize. It has become a hot spot in the field of rapid detection of chemical warfare agents (CWAs). VX and HD have the characteristics of high toxicity, high boiling point and poor volatility. They are often dispersed on the surface of ground, equipment or clothing in the form of aerosols or droplets, which becomes a difficult problem for rapid detection on the spot. In this work, gold nanoparticles substrate-assisted low-temperature plasma-mass spectrometry was developed for rapidly detecting two CWA stimulants:malathion and 2-chloroethyl ethyl sulfide (CEES) in soil. Under the optimal conditions, the MS signal strength was improved by 7-9 times compared to the CWA simulants which were tested without the aid of gold nanoparticles. The experimental data of two simulants showed a good linear relationship between the signal and the concentration in the range of 5.0-1000 μg/g, with correlation coefficient (R2) of 0.9784 and 0.9915, and the limits of detection were 1.5 and 1.0 μg/g, respectively. The method could effectively improve the ionization efficiency of nonvolatile solid and liquid compounds through the interaction of gold nanoparticles and plasma. Also, the method was fast, accurate and sensitive, and had a good application prospect in the military field.
The low temperature plasma (LTP) probe which can be used to quickly detect solid, liquid and gaseous samples has the characteristics of simple, fast and accurate, and easy to miniaturize. It has become a hot spot in the field of rapid detection of chemical warfare agents (CWAs). VX and HD have the characteristics of high toxicity, high boiling point and poor volatility. They are often dispersed on the surface of ground, equipment or clothing in the form of aerosols or droplets, which becomes a difficult problem for rapid detection on the spot. In this work, gold nanoparticles substrate-assisted low-temperature plasma-mass spectrometry was developed for rapidly detecting two CWA stimulants:malathion and 2-chloroethyl ethyl sulfide (CEES) in soil. Under the optimal conditions, the MS signal strength was improved by 7-9 times compared to the CWA simulants which were tested without the aid of gold nanoparticles. The experimental data of two simulants showed a good linear relationship between the signal and the concentration in the range of 5.0-1000 μg/g, with correlation coefficient (R2) of 0.9784 and 0.9915, and the limits of detection were 1.5 and 1.0 μg/g, respectively. The method could effectively improve the ionization efficiency of nonvolatile solid and liquid compounds through the interaction of gold nanoparticles and plasma. Also, the method was fast, accurate and sensitive, and had a good application prospect in the military field.
2020, 48(10): 1422-1427
doi: 10.19756/j.issn.0253-3820.201158
Abstract:
Analysis of big data is hot topic for exploring the contained values, however, the development of the analytical methods are still a challenging task due to the complexity in structure and variety. In this work, a method for pre-processing and modeling of the non-continuous industrial data was developed and applied in the analysis of a dataset for an industrial production during six years. Four quality parameters and five production parameters were included and the data were collected in batches and sampled in different time and frequency. Fourier transform was used to obtain the frequency composition of the parameters, and then reconstructed data for each parameter were calculated by the inverse transform using the same time schedule. Therefore, the data of all the parameters at the same time points could be obtained and the missing values in the raw data could be filled, making the reconstructed data suitable for building the model between the quality and production parameters. Furthermore, the smoothing effect could be observed in the reconstructed data. Four models were built for the four quality parameters, all of which had a reliable prediction with the mean bias less than 5%.
Analysis of big data is hot topic for exploring the contained values, however, the development of the analytical methods are still a challenging task due to the complexity in structure and variety. In this work, a method for pre-processing and modeling of the non-continuous industrial data was developed and applied in the analysis of a dataset for an industrial production during six years. Four quality parameters and five production parameters were included and the data were collected in batches and sampled in different time and frequency. Fourier transform was used to obtain the frequency composition of the parameters, and then reconstructed data for each parameter were calculated by the inverse transform using the same time schedule. Therefore, the data of all the parameters at the same time points could be obtained and the missing values in the raw data could be filled, making the reconstructed data suitable for building the model between the quality and production parameters. Furthermore, the smoothing effect could be observed in the reconstructed data. Four models were built for the four quality parameters, all of which had a reliable prediction with the mean bias less than 5%.
2020, 48(10): 1428-1433
doi: 10.19756/j.issn.0253-3820.201192
Abstract:
Regarding tandem mass spectrometry (MS/MS), the theory of the transition from precursor ion to product ion is actually chemical bond dissociation in gas phase resulted from the collision between ions and collision gas molecules with high energy. It is feasible to observe the generation and disappearance of ions via gradually varying the collision energy, which is the mechanism of online collision energy-resolved mass spectrometry (ER-MS). Afterwards, the assignment of fragmentation pathways to the ions-of-interest can be achieved through combining online ER-MS and structural calculation. In current study, the application of online ER-MS towards in-depth clarification of tandem mass spectrometric pattern was illustrated by employing kaempferide as a representative case. Under positive ionization mode, the precursor ion, actually the protonated molecular ion ([M+H]+), was generated at m/z 301.0712 in MS1 spectrum, which resulted in primary product ions, such as m/z 286.0518, 272.0454, 165.0155, 161.0573, 153.0192 and 139.0381 in MS2 spectrum. To clarify the generation of m/z 161.0573, a precursor>product ion transition was subsequently constructed as m/z 301>161. A set of pseudo-ion transitions (PITs) was afterwards derived, and assigned a batch of progressive collision energies. The peak areas of all PITs were acquired under multiple reaction monitoring mode on triple quadrupole mass spectrometer (QqQ-MS), and normalized within the PITs set to construct the breakdown graphs. Except for m/z 301>161, the breakdown graphs of the other ion transitions fitted for Gaussian curve. "M"-type breakdown graph consisting of two Gaussian curves was observed for m/z 301>161. Following structural calculation, the former Gaussian curve was primarily generated by C-ring hetero-ring fission (HRF) at 1,4-bond coupled with CH4 neutral loss, whereas the latter one corresponded to C-ring RDA fission at 0,4-bond coupled with CH3OH neutral loss. Above all, the combination of online ER-MS and structural calculation is able to provide meaningful information for the in-depth clarification of tandem mass spectrometric patterns of chemical compounds.
Regarding tandem mass spectrometry (MS/MS), the theory of the transition from precursor ion to product ion is actually chemical bond dissociation in gas phase resulted from the collision between ions and collision gas molecules with high energy. It is feasible to observe the generation and disappearance of ions via gradually varying the collision energy, which is the mechanism of online collision energy-resolved mass spectrometry (ER-MS). Afterwards, the assignment of fragmentation pathways to the ions-of-interest can be achieved through combining online ER-MS and structural calculation. In current study, the application of online ER-MS towards in-depth clarification of tandem mass spectrometric pattern was illustrated by employing kaempferide as a representative case. Under positive ionization mode, the precursor ion, actually the protonated molecular ion ([M+H]+), was generated at m/z 301.0712 in MS1 spectrum, which resulted in primary product ions, such as m/z 286.0518, 272.0454, 165.0155, 161.0573, 153.0192 and 139.0381 in MS2 spectrum. To clarify the generation of m/z 161.0573, a precursor>product ion transition was subsequently constructed as m/z 301>161. A set of pseudo-ion transitions (PITs) was afterwards derived, and assigned a batch of progressive collision energies. The peak areas of all PITs were acquired under multiple reaction monitoring mode on triple quadrupole mass spectrometer (QqQ-MS), and normalized within the PITs set to construct the breakdown graphs. Except for m/z 301>161, the breakdown graphs of the other ion transitions fitted for Gaussian curve. "M"-type breakdown graph consisting of two Gaussian curves was observed for m/z 301>161. Following structural calculation, the former Gaussian curve was primarily generated by C-ring hetero-ring fission (HRF) at 1,4-bond coupled with CH4 neutral loss, whereas the latter one corresponded to C-ring RDA fission at 0,4-bond coupled with CH3OH neutral loss. Above all, the combination of online ER-MS and structural calculation is able to provide meaningful information for the in-depth clarification of tandem mass spectrometric patterns of chemical compounds.
