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2020 Volume 48 Issue 11
2020, 48(11): 1439-1447
doi: 10.19756/j.issn.0253-3820.201285
Abstract:
Oligonucleotide aptamers are an important kind of chemical antibody-like functional biomolecules. The aptamer-based mass spectrometric techniques can not only provide molecular mass and characteristic structures by mass spectrometry, but show high sensitivity and high affinity enrichment towards target molecules by aptamers. This review summarized the advances in the aptamer-based mass spectrometric applications, highlighted the progress of aptamer-target interaction characterization, as well as the applications of aptamer as off-line or on-line affinity materials in mass spectrometric techniques. It suggested that the combination of various new mass spectrometric techniques, the construction or combination of varied pretreatment or on-line signal amplification approaches, especially the applications of aptameric functional nanomaterials, should be focused in the aspects of interaction characterization, selective extraction and highly sensitive detection of trace target molecules. The future prospects of the development were also described.
Oligonucleotide aptamers are an important kind of chemical antibody-like functional biomolecules. The aptamer-based mass spectrometric techniques can not only provide molecular mass and characteristic structures by mass spectrometry, but show high sensitivity and high affinity enrichment towards target molecules by aptamers. This review summarized the advances in the aptamer-based mass spectrometric applications, highlighted the progress of aptamer-target interaction characterization, as well as the applications of aptamer as off-line or on-line affinity materials in mass spectrometric techniques. It suggested that the combination of various new mass spectrometric techniques, the construction or combination of varied pretreatment or on-line signal amplification approaches, especially the applications of aptameric functional nanomaterials, should be focused in the aspects of interaction characterization, selective extraction and highly sensitive detection of trace target molecules. The future prospects of the development were also described.
2020, 48(11): 1448-1457
doi: 10.19756/j.issn.0253-3820.201240
Abstract:
Paper-based colorimetric sensor array has attracted extensive attention due to its low-cost, easy-operation, powerful discrimination, good selectivity, rapid response and versatility. It combines the advantages of paper-based analytical devices and colorimetric sensor array, which extends its application fields in analytical chemistry. This review described the recent progress in paper-based colorimetric sensor array and summarized its applications in biomedicine, environmental and food safety. Moreover, the sensing materials, characteristics and performances of different paper-based colorimetric sensor arrays, as well as the prospects of future research for the paper-based colorimetric sensor array were discussed.
Paper-based colorimetric sensor array has attracted extensive attention due to its low-cost, easy-operation, powerful discrimination, good selectivity, rapid response and versatility. It combines the advantages of paper-based analytical devices and colorimetric sensor array, which extends its application fields in analytical chemistry. This review described the recent progress in paper-based colorimetric sensor array and summarized its applications in biomedicine, environmental and food safety. Moreover, the sensing materials, characteristics and performances of different paper-based colorimetric sensor arrays, as well as the prospects of future research for the paper-based colorimetric sensor array were discussed.
2020, 48(11): 1458-1466
doi: 10.19756/j.issn.0253-3820.201247
Abstract:
In biochemistry, exploring the conformation, response to external environment and interaction rules of biomacromolecules and small molecules is crucial to understanding the correlation of structures and properties among organic matters. However, it is a challenge for the traditional techniques to observe the conformation heterogeneity and interpret the interaction mechanism of the biomolecules in living cells. As the emerged third generation single-molecule gene sequencing technology, nanopore can monitor the conformation change of the molecules in situ and therefore demonstrates good applications in single-molecule sensing and nucleic acid and protein sequencing. To further improve the detection resolution and precision, the combined photoelectric detection can achieve higher accuracy via introducing optical-responsive molecules. In view of the extensive applications and development status of nanopore technique in single-molecule conformation resolution, this paper summarizes the research progress of the nanopore devices and the design and applications of some typical photo-responsive molecules in nanopore sensing, including azobenzenes and their derivatives, spiropyrane and diarylethene. Light regulation is a simple and effective approach for monitoring the molecular structures, and further integration with nanopore devices exhibits great potential in single-molecule detection meanwhile sheds light on the design and applications of multi-responsive nano-devices.
In biochemistry, exploring the conformation, response to external environment and interaction rules of biomacromolecules and small molecules is crucial to understanding the correlation of structures and properties among organic matters. However, it is a challenge for the traditional techniques to observe the conformation heterogeneity and interpret the interaction mechanism of the biomolecules in living cells. As the emerged third generation single-molecule gene sequencing technology, nanopore can monitor the conformation change of the molecules in situ and therefore demonstrates good applications in single-molecule sensing and nucleic acid and protein sequencing. To further improve the detection resolution and precision, the combined photoelectric detection can achieve higher accuracy via introducing optical-responsive molecules. In view of the extensive applications and development status of nanopore technique in single-molecule conformation resolution, this paper summarizes the research progress of the nanopore devices and the design and applications of some typical photo-responsive molecules in nanopore sensing, including azobenzenes and their derivatives, spiropyrane and diarylethene. Light regulation is a simple and effective approach for monitoring the molecular structures, and further integration with nanopore devices exhibits great potential in single-molecule detection meanwhile sheds light on the design and applications of multi-responsive nano-devices.
2020, 48(11): 1467-1476
doi: 10.19756/j.issn.0253-3820.201283
Abstract:
Based on the fluorescent characteristics of 3,5-difluoro-4-hydroxybenzylidene imidazolinone (DFHBI) and RNA aptamer complex, a novel biochemical sensor was designed for sensing carboxylesterase 2A (CES2A) activity via combination of virtual screening and experimental validation. Firstly, virtual screening was applied to predict the potential of a series of DFHBI derivatives as candidate substrates for CES2A. After then, the TOP3 candidate substrates were synthesized, while their chemical stability and specificity towards CES2A were assayed. The results showed that 3,5-difluoro-4-hydroxybenzylidene imidazolinone benzoate (Ph-DFHBI) displayed extremely high specificity and the best response to CES2A. Further investigations demonstrated that Ph-DFHBI could be selectively hydrolyzed by CES2A, while other abundant hydrolases (such as CES1A, BchE and AchE) in the human body were hardly catalyzing Ph-DFHBI hydrolysis. To quantitatively measure CES2A activity in real samples, the enzymatic kinetic behaviors of Ph-DFHBI hydrolysis in both recombinant CES2A and human liver preparations were further investigated. Under physiological conditions (pH 7.4 at 37℃), Ph-DFHBI exhibited extremely high affinity and relatively high turnover rate, with the Km value of 0.66 μmol/L, and the Vmax value of 18.92 nmol/(min·mg). Under the optimal conditions, the limit of detection of Ph-DFHBI for sensing CES2A was 14.5 ng/mL. On the basis of the above mentioned findings, this biochemical sensor was successfully utilized to rapidly measure the CES2A activities in complex biological systems (such as tissue preparations), as well as high-throughput screening of CES2A inhibitors. Collectively, this study developed a novel biochemical sensor for CES2A, which provided a powerful tool for exploring the biological functions of CES2A and for efficient discovery of CES2A modulators in complex biological systems.
Based on the fluorescent characteristics of 3,5-difluoro-4-hydroxybenzylidene imidazolinone (DFHBI) and RNA aptamer complex, a novel biochemical sensor was designed for sensing carboxylesterase 2A (CES2A) activity via combination of virtual screening and experimental validation. Firstly, virtual screening was applied to predict the potential of a series of DFHBI derivatives as candidate substrates for CES2A. After then, the TOP3 candidate substrates were synthesized, while their chemical stability and specificity towards CES2A were assayed. The results showed that 3,5-difluoro-4-hydroxybenzylidene imidazolinone benzoate (Ph-DFHBI) displayed extremely high specificity and the best response to CES2A. Further investigations demonstrated that Ph-DFHBI could be selectively hydrolyzed by CES2A, while other abundant hydrolases (such as CES1A, BchE and AchE) in the human body were hardly catalyzing Ph-DFHBI hydrolysis. To quantitatively measure CES2A activity in real samples, the enzymatic kinetic behaviors of Ph-DFHBI hydrolysis in both recombinant CES2A and human liver preparations were further investigated. Under physiological conditions (pH 7.4 at 37℃), Ph-DFHBI exhibited extremely high affinity and relatively high turnover rate, with the Km value of 0.66 μmol/L, and the Vmax value of 18.92 nmol/(min·mg). Under the optimal conditions, the limit of detection of Ph-DFHBI for sensing CES2A was 14.5 ng/mL. On the basis of the above mentioned findings, this biochemical sensor was successfully utilized to rapidly measure the CES2A activities in complex biological systems (such as tissue preparations), as well as high-throughput screening of CES2A inhibitors. Collectively, this study developed a novel biochemical sensor for CES2A, which provided a powerful tool for exploring the biological functions of CES2A and for efficient discovery of CES2A modulators in complex biological systems.
2020, 48(11): 1477-1485
doi: 10.19756/j.issn.0253-3820.201287
Abstract:
Taqman microfluidic chip technology was applied to the high-throughput identification and detection of 17 transgenic maize events on a real-time fluorescent PCR platform. In one PCR amplification process, 2 maize endogenous genes (hmgA gene, adh1 gene) and 1 loading control gene (18S gene) were used as internal reference, which could simultaneously complete totally 17 events of transgenic maize single-well single-plex amplification parallel detection, including TC1507, NK603, MON87640, MON863, MON810, MIR162, GA21, DAS40278, BT176, BT11, 98140, 59122, 3272, MON89034, MIR604, MON88017 and T25, and the limit of detection reached 10-20 copies. The method showed high specificity and sensitivity, and the detection result obtained by this method was completely consistent with that of the single real-time fluorescent PCR method of "gold standard". The method had the advantages of parallel detection of multiple samples and multiple targets, and provided an efficient and rapid approach for the identification of mixture of multiple events of genetically modified products. With this method, 9 batches of transgenic maize samples were detected from 16 batches of imported practical maize, containing 1-8 events. This method could be used for high-throughput detection of mixed transgenic multi-events in imported agricultural products at the port.
Taqman microfluidic chip technology was applied to the high-throughput identification and detection of 17 transgenic maize events on a real-time fluorescent PCR platform. In one PCR amplification process, 2 maize endogenous genes (hmgA gene, adh1 gene) and 1 loading control gene (18S gene) were used as internal reference, which could simultaneously complete totally 17 events of transgenic maize single-well single-plex amplification parallel detection, including TC1507, NK603, MON87640, MON863, MON810, MIR162, GA21, DAS40278, BT176, BT11, 98140, 59122, 3272, MON89034, MIR604, MON88017 and T25, and the limit of detection reached 10-20 copies. The method showed high specificity and sensitivity, and the detection result obtained by this method was completely consistent with that of the single real-time fluorescent PCR method of "gold standard". The method had the advantages of parallel detection of multiple samples and multiple targets, and provided an efficient and rapid approach for the identification of mixture of multiple events of genetically modified products. With this method, 9 batches of transgenic maize samples were detected from 16 batches of imported practical maize, containing 1-8 events. This method could be used for high-throughput detection of mixed transgenic multi-events in imported agricultural products at the port.
2020, 48(11): 1486-1492
doi: 10.19756/j.issn.0253-3820.201345
Abstract:
The bending actuator based on polypyrrole has many advantages such as large mechanical stress, large strain value, high recoverability and safety, which shows tremendous application potential in the fields of micro/nano operating systems, biomedical equipment and biosensors. However, the relationship between the bending behavior of the actuator and the driving voltage still needs to be explored. In this work, the electrochemical mechanical properties of the layered bending polypyrrole actuator were studied on the basis of the self-built test platform. According to the structural characteristics and working principle, the actuator was equivalent to a cantilever beam for modeling, and the force generated by the ion migration inside the actuator was equivalent to the load applied on the cantilever beam to build the bending model of the actuator. Three kinds of actuators with different lengths were selected to apply low voltage to them and measure their tip displacement at different voltages. Taking the measured data into the above bending model, the functional relationship between the voltage and the tip displacement, curvature radius, bending moment and strain of the actuator were obtained, and the accuracy of the model was verified based on the experimental results. The model fitted the basic parameters of the actuator, and accurately predicted the deformation behavior in practical application, so as to improve the efficiency of research. This study provided the experimental and theoretical basis for the preparation and system modeling of polypyrrole actuators in practical applications, and promoted the application of micro actuators in the fields of micro/nano manipulation, particle analysis in solution, biosensors and so on.
The bending actuator based on polypyrrole has many advantages such as large mechanical stress, large strain value, high recoverability and safety, which shows tremendous application potential in the fields of micro/nano operating systems, biomedical equipment and biosensors. However, the relationship between the bending behavior of the actuator and the driving voltage still needs to be explored. In this work, the electrochemical mechanical properties of the layered bending polypyrrole actuator were studied on the basis of the self-built test platform. According to the structural characteristics and working principle, the actuator was equivalent to a cantilever beam for modeling, and the force generated by the ion migration inside the actuator was equivalent to the load applied on the cantilever beam to build the bending model of the actuator. Three kinds of actuators with different lengths were selected to apply low voltage to them and measure their tip displacement at different voltages. Taking the measured data into the above bending model, the functional relationship between the voltage and the tip displacement, curvature radius, bending moment and strain of the actuator were obtained, and the accuracy of the model was verified based on the experimental results. The model fitted the basic parameters of the actuator, and accurately predicted the deformation behavior in practical application, so as to improve the efficiency of research. This study provided the experimental and theoretical basis for the preparation and system modeling of polypyrrole actuators in practical applications, and promoted the application of micro actuators in the fields of micro/nano manipulation, particle analysis in solution, biosensors and so on.
2020, 48(11): 1493-1501
doi: 10.19756/j.issn.0253-3820.201388
Abstract:
As one of the most typical perfluorinated compounds in the environment, perfluorooctane sulfonate (PFOS) has the characteristics of persistence, toxicity and accumulation in organisms. It is especially important to establish a rapid and highly sensitive method for detection of PFOS in environmental matrix. In this work, a mesoporous-structured molecularly imprinting fluorescent nanoprobe NH2-unconversion nanoparticles@molecularly imprinted polymers (NH2-UCNPs@MIPs) was fabricated with PFOS as template molecule and N,O-bis (trimethylsilyl) trifluoroacetamide as functional monomer. In the analytical process, PFOS could specifically bind amino groups and fluorine-containing groups on the surface of NH2-UCNPs@MIPs, resulting in the fluorescence quenching of NH2-UCNPs@MIPs. Based on this, a highly selective and sensitive detection of PFOS method was developed with linear range of 0.01-15 nmol/L. The nanoprobe was applied in PFOS detection in surface water and human serum matrix under both acidic and neutral conditions. This work provided a theoretical basis for the rapid and sensitive detection of trace PFOS in complex matrix.
As one of the most typical perfluorinated compounds in the environment, perfluorooctane sulfonate (PFOS) has the characteristics of persistence, toxicity and accumulation in organisms. It is especially important to establish a rapid and highly sensitive method for detection of PFOS in environmental matrix. In this work, a mesoporous-structured molecularly imprinting fluorescent nanoprobe NH2-unconversion nanoparticles@molecularly imprinted polymers (NH2-UCNPs@MIPs) was fabricated with PFOS as template molecule and N,O-bis (trimethylsilyl) trifluoroacetamide as functional monomer. In the analytical process, PFOS could specifically bind amino groups and fluorine-containing groups on the surface of NH2-UCNPs@MIPs, resulting in the fluorescence quenching of NH2-UCNPs@MIPs. Based on this, a highly selective and sensitive detection of PFOS method was developed with linear range of 0.01-15 nmol/L. The nanoprobe was applied in PFOS detection in surface water and human serum matrix under both acidic and neutral conditions. This work provided a theoretical basis for the rapid and sensitive detection of trace PFOS in complex matrix.
2020, 48(11): 1502-1510
doi: 10.19756/j.issn.0253-3820.201299
Abstract:
Peroxynitrite (ONOO-) is one of the important reactive oxygen species in biosystems, and its effective detection has been attracting numerous attention. A fluorescent probe for ONOO- detection was prepared via one-step reaction of 4-(diethylamino)salicylaldehyde and 6-methoxy tetralone. The optical response of the probe toward ONOO- was investigated through UV and fluorescence spectra. The results showed that the probe was superior with the merits of high selectivity, superb sensitivity (the detection limit is 15.5 nmol/L), rapid response (within seconds), large Stokes shift (42 nm) and good water solubility. The 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay indicated an excellent biocompatibility of the probe (the survival rate of the cells was higher than 95% when the concentration of the probe was 20 μmol/L). Finally, the probe was successfully utilized for the fluorescence imaging of exogenous and endogenous ONOO- in living cells.
Peroxynitrite (ONOO-) is one of the important reactive oxygen species in biosystems, and its effective detection has been attracting numerous attention. A fluorescent probe for ONOO- detection was prepared via one-step reaction of 4-(diethylamino)salicylaldehyde and 6-methoxy tetralone. The optical response of the probe toward ONOO- was investigated through UV and fluorescence spectra. The results showed that the probe was superior with the merits of high selectivity, superb sensitivity (the detection limit is 15.5 nmol/L), rapid response (within seconds), large Stokes shift (42 nm) and good water solubility. The 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay indicated an excellent biocompatibility of the probe (the survival rate of the cells was higher than 95% when the concentration of the probe was 20 μmol/L). Finally, the probe was successfully utilized for the fluorescence imaging of exogenous and endogenous ONOO- in living cells.
2020, 48(11): 1511-1518
doi: 10.19756/j.issn.0253-3820.201350
Abstract:
The development of latent fingerprints on long-circulated RMB banknotes has been one of the difficulties in forensic science research. In this work, time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to perform chemical imaging of latent fingerprints on the surfaces of the substrates due to its advantages such as in-situ, quasi-nondestructive, high-throughput, simultaneous analysis of multi-components and high spatial resolution. The developing effect of TOF-SIMS was firstly compared with that of several traditional methods, and the reasons for the unique advantages of TOF-SIMS were discussed. Secondly, its applicability was further discussed from the perspective of universality, sensitivity and fingerprint three-level feature acquisition capability. Finally, exogenous substances in fingerprints were also analyzed by using this technique to detect the molecular ions (m/z 92.06) and fragment ion peaks (m/z 43.02) of glycerol in the moisture lotion and developed clear fingerprint images. Preliminary research results showed that TOF-SIMS technique could provide an effective method for the development of latent fingerprints on long-circulated RMB banknotes and was expected to be used for the detection of substances in fingerprints on the surface of the substrates.
The development of latent fingerprints on long-circulated RMB banknotes has been one of the difficulties in forensic science research. In this work, time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to perform chemical imaging of latent fingerprints on the surfaces of the substrates due to its advantages such as in-situ, quasi-nondestructive, high-throughput, simultaneous analysis of multi-components and high spatial resolution. The developing effect of TOF-SIMS was firstly compared with that of several traditional methods, and the reasons for the unique advantages of TOF-SIMS were discussed. Secondly, its applicability was further discussed from the perspective of universality, sensitivity and fingerprint three-level feature acquisition capability. Finally, exogenous substances in fingerprints were also analyzed by using this technique to detect the molecular ions (m/z 92.06) and fragment ion peaks (m/z 43.02) of glycerol in the moisture lotion and developed clear fingerprint images. Preliminary research results showed that TOF-SIMS technique could provide an effective method for the development of latent fingerprints on long-circulated RMB banknotes and was expected to be used for the detection of substances in fingerprints on the surface of the substrates.
2020, 48(11): 1519-1525
doi: 10.19756/j.issn.0253-3820.201452
Abstract:
The drawback of commercial Pt-based electrocatalysts, such as poor stability and high cost, is one of the major issues which limits the promotion of fuel cells and related green energy application. Therefore, developing the inexpensive alternative electrocatalysts for high-performance and stable oxygen reduction reaction (ORR) has become a research hotspot in the field of electrocatalysis. Herein, a series of heteroatom modified porous iron, cobalt-nitrogen-carbon based electrocatalysts were successfully fabricated by modifying the FeCo/NC by additional introduction of heteroatoms (B, P and F) in this work. The mechanism of ORR performance boosted by introduction of B, P and F was explored by combining well characterization of composition and morphology with rational electrochemical tests. The as-fabricated FeCo/NFC sample exhibited highly efficient ORR activity with the half-wave potential of 0.84 V, electron transfer number of 3.85 and HO2- yield of 7.61% at 0.5 V, which was comparable to those of commercial Pt/C. Meanwhile, the FeCo/NFC also displayed outstanding stability and methanol tolerance in alkaline electrolyte which demonstrated excellent application potential in the field of fuel cells as an alternative electrocatalyst for commercial Pt/C.
The drawback of commercial Pt-based electrocatalysts, such as poor stability and high cost, is one of the major issues which limits the promotion of fuel cells and related green energy application. Therefore, developing the inexpensive alternative electrocatalysts for high-performance and stable oxygen reduction reaction (ORR) has become a research hotspot in the field of electrocatalysis. Herein, a series of heteroatom modified porous iron, cobalt-nitrogen-carbon based electrocatalysts were successfully fabricated by modifying the FeCo/NC by additional introduction of heteroatoms (B, P and F) in this work. The mechanism of ORR performance boosted by introduction of B, P and F was explored by combining well characterization of composition and morphology with rational electrochemical tests. The as-fabricated FeCo/NFC sample exhibited highly efficient ORR activity with the half-wave potential of 0.84 V, electron transfer number of 3.85 and HO2- yield of 7.61% at 0.5 V, which was comparable to those of commercial Pt/C. Meanwhile, the FeCo/NFC also displayed outstanding stability and methanol tolerance in alkaline electrolyte which demonstrated excellent application potential in the field of fuel cells as an alternative electrocatalyst for commercial Pt/C.
2020, 48(11): 1526-1534
doi: 10.19756/j.issn.0253-3820.191630
Abstract:
Soil organic matter (SOM) is an important part of soil, which plays an important role in soil fertility, water content and other properties. In this work, soil samples were collected from seven oriental oak sites at different depths along a latitudinal gradient in eastern China. The chemical composition of SOM of 84 samples was analyzed qualitatively and semi-quantitatively by direct injection pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) and tetramethylammonium hydroxide derivatization pyrolysis gas chromatography/mass spectrometry (TMAH-Py-GC/MS), respectively. TMAH methanol solution (25%) was used for derivatization, and a DB-5ms (30 m×0.25 mm, 0.25 μm) column was selected for GC/MS analysis. A total of 261 and 117 biomarkers of SOM were identified by TMAH-Py-GC/MS and Py-GC/MS methods, respectively. The markers detected by the TMAH-Py-GC/MS method had more types and more diverse structures and included more numbers of lignin-derived and lipid-derived compounds. The contents of substances also varied with methods. The Py-GC/MS samples had higher proportions of polysaccharides (28%) and lipids (22%), while the TMAH-Py-GC/MS samples had higher contents of lipids (33%). The chromatographic retention times of alkanes, alkenes, and fatty acids all had good linear relationship with numbers of carbon atom (R2>0.95). The changes of contents of six groups with soil depth and latitude obtained by the two methods were compared.
Soil organic matter (SOM) is an important part of soil, which plays an important role in soil fertility, water content and other properties. In this work, soil samples were collected from seven oriental oak sites at different depths along a latitudinal gradient in eastern China. The chemical composition of SOM of 84 samples was analyzed qualitatively and semi-quantitatively by direct injection pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) and tetramethylammonium hydroxide derivatization pyrolysis gas chromatography/mass spectrometry (TMAH-Py-GC/MS), respectively. TMAH methanol solution (25%) was used for derivatization, and a DB-5ms (30 m×0.25 mm, 0.25 μm) column was selected for GC/MS analysis. A total of 261 and 117 biomarkers of SOM were identified by TMAH-Py-GC/MS and Py-GC/MS methods, respectively. The markers detected by the TMAH-Py-GC/MS method had more types and more diverse structures and included more numbers of lignin-derived and lipid-derived compounds. The contents of substances also varied with methods. The Py-GC/MS samples had higher proportions of polysaccharides (28%) and lipids (22%), while the TMAH-Py-GC/MS samples had higher contents of lipids (33%). The chromatographic retention times of alkanes, alkenes, and fatty acids all had good linear relationship with numbers of carbon atom (R2>0.95). The changes of contents of six groups with soil depth and latitude obtained by the two methods were compared.
Analysis of Facilitated Ion Transfer Across Liquid-Liquid Interfaces Using Collision Electrochemisty
2020, 48(11): 1535-1541
doi: 10.19756/j.issn.0253-3820.201252
Abstract:
An electrochemical method was developed to analyze the alkali metal ion transfer across the water/1,2-dichloroethane interfaces facilitated by dibenzo-18-crown-6 ether (DB18C6) by observing the collisions of single emulsion droplets on an ultramicroelectrode (UME). The water-in-oil emulsion droplets were stabilized by an ionic liquid of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides, in which a highly hydrophilic redox probe of K3Fe(CN)6/K4Fe(CN)6 was used. When the droplets collided with the UME that was biased at a potential to drive the oxidation reaction of 0.05 mol/L[Fe(CN)6]4-, the current spikes could be observed only with the addition of DB18C6. It was suggested that the DB18C6 as K+ ionophore facilitated the K+ transfer from the water to the oil to maintain charge balance during droplet electrolysis. As more K+ ionophores were added, the integrated charge of the current spikes showed a rising trend in general because of the ionophore to lower the Gibbs energy of ion transfer. Further collision experiments were conducted to investigate transfer of Na+ and K+ cations facilitated by the DB18C6. The order in which the ‘voltammetric’ oxidation waves appeared indicated that the ionophore of DB18C6 was more efficient in carrying K+ across the water/1,2-dichloroethane interface. Thereby, the collision electrochemistry is a convenient and effective mean to study the ion selectivity of ionophore.
An electrochemical method was developed to analyze the alkali metal ion transfer across the water/1,2-dichloroethane interfaces facilitated by dibenzo-18-crown-6 ether (DB18C6) by observing the collisions of single emulsion droplets on an ultramicroelectrode (UME). The water-in-oil emulsion droplets were stabilized by an ionic liquid of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imides, in which a highly hydrophilic redox probe of K3Fe(CN)6/K4Fe(CN)6 was used. When the droplets collided with the UME that was biased at a potential to drive the oxidation reaction of 0.05 mol/L[Fe(CN)6]4-, the current spikes could be observed only with the addition of DB18C6. It was suggested that the DB18C6 as K+ ionophore facilitated the K+ transfer from the water to the oil to maintain charge balance during droplet electrolysis. As more K+ ionophores were added, the integrated charge of the current spikes showed a rising trend in general because of the ionophore to lower the Gibbs energy of ion transfer. Further collision experiments were conducted to investigate transfer of Na+ and K+ cations facilitated by the DB18C6. The order in which the ‘voltammetric’ oxidation waves appeared indicated that the ionophore of DB18C6 was more efficient in carrying K+ across the water/1,2-dichloroethane interface. Thereby, the collision electrochemistry is a convenient and effective mean to study the ion selectivity of ionophore.
2020, 48(11): 1542-1549
doi: 10.19756/j.issn.0253-3820.191479
Abstract:
In conventional isotopic dilution method, when target isotope in a sample is influenced by the tracing material, it should be measured includes not only the isotope ratios of the mixture of dilution and sample, but also that of the original sample. In case that sample is insufficient, or measuring time is limited, the isotope dilute method meets its embarrassment. In this study, an efficient quantitative isotopic dilution method was provided, in which the measurement of the isotope ratios in the sample was unnecessary. This method had particularly advantage on reducing sample consumption, simplifying the measurement procedure and decreasing the influence of memory effect, which greatly improved the efficiency of the measurement. The six measurements showed that xenon standard gas was used to verify its applicability, which provided a bias of less than 1% to the nominal value and a relative standard deviation (RSD) of 0.4%. The measurement result was completely consistent with the value of conventional isotope dilution. In tracing experiment with 128Xe, despite of the interference of natural xenon, 128Xe of tracer was precisely determined. The diffusion curve which was drawn by 128Xe, also accorded with the rule of gas diffusion in the closed space. This method was suitable only for elements that with three or more isotopes.
In conventional isotopic dilution method, when target isotope in a sample is influenced by the tracing material, it should be measured includes not only the isotope ratios of the mixture of dilution and sample, but also that of the original sample. In case that sample is insufficient, or measuring time is limited, the isotope dilute method meets its embarrassment. In this study, an efficient quantitative isotopic dilution method was provided, in which the measurement of the isotope ratios in the sample was unnecessary. This method had particularly advantage on reducing sample consumption, simplifying the measurement procedure and decreasing the influence of memory effect, which greatly improved the efficiency of the measurement. The six measurements showed that xenon standard gas was used to verify its applicability, which provided a bias of less than 1% to the nominal value and a relative standard deviation (RSD) of 0.4%. The measurement result was completely consistent with the value of conventional isotope dilution. In tracing experiment with 128Xe, despite of the interference of natural xenon, 128Xe of tracer was precisely determined. The diffusion curve which was drawn by 128Xe, also accorded with the rule of gas diffusion in the closed space. This method was suitable only for elements that with three or more isotopes.
2020, 48(11): 1550-1555
doi: 10.19756/j.issn.0253-3820.201335
Abstract:
The investigation of the adhesion between red blood cells and vascular endothelial cells is of great significance to reveal the pathogenesis of cardiovascular disease. Under pathological conditions, the oxidative damage of red blood cells (RBCs) can cause down-regulating content of sialic acid combined with glycoprotein receptors on the cell membrane, and change the viscoelastic properties of the cells, lead to the enhancement of the adhesion of erythrocytes to vascular endothelial cells. In this work, a new method based on specific recognition of sialic acid and 3-aminophenylboronic acid integration with quartz crystal microbalance with dissipation (QCM-D) was developed for real-time monitoring the adhesion between damaged-erythrocytes and endothelial cells. Taking H2O2 oxidative damage to erythrocytes as a research model, the changes of the frequency and dissipation factor during cell adhesion process were monitored by QCM sensor, which was used to evaluate the degree of erythrocytes oxidative damage. The results showed that both the QCM frequency change and the dissipation factor decreased accordingly with the increase of H2O2 concentration. It revealed that the adhesion of erythrocytes was negatively correlated with the concentration of H2O2 and the degree of RBCs damage. Furthermore, endothelial cells were fixed on the sensing interface for simulating intravascular environment and their adhesion to red blood cells was monitored by QCM in real time. The results showed that the adhesion between cells increased with the increase of the degree of erythrocytes damage. Therefore, the strategy provided a simple, label free, highly sensitive and real-time method for the monitoring of cell adhesion and the evaluation of cells oxidative damage, which expended the application of QCM in the research of cell function in biological system.
The investigation of the adhesion between red blood cells and vascular endothelial cells is of great significance to reveal the pathogenesis of cardiovascular disease. Under pathological conditions, the oxidative damage of red blood cells (RBCs) can cause down-regulating content of sialic acid combined with glycoprotein receptors on the cell membrane, and change the viscoelastic properties of the cells, lead to the enhancement of the adhesion of erythrocytes to vascular endothelial cells. In this work, a new method based on specific recognition of sialic acid and 3-aminophenylboronic acid integration with quartz crystal microbalance with dissipation (QCM-D) was developed for real-time monitoring the adhesion between damaged-erythrocytes and endothelial cells. Taking H2O2 oxidative damage to erythrocytes as a research model, the changes of the frequency and dissipation factor during cell adhesion process were monitored by QCM sensor, which was used to evaluate the degree of erythrocytes oxidative damage. The results showed that both the QCM frequency change and the dissipation factor decreased accordingly with the increase of H2O2 concentration. It revealed that the adhesion of erythrocytes was negatively correlated with the concentration of H2O2 and the degree of RBCs damage. Furthermore, endothelial cells were fixed on the sensing interface for simulating intravascular environment and their adhesion to red blood cells was monitored by QCM in real time. The results showed that the adhesion between cells increased with the increase of the degree of erythrocytes damage. Therefore, the strategy provided a simple, label free, highly sensitive and real-time method for the monitoring of cell adhesion and the evaluation of cells oxidative damage, which expended the application of QCM in the research of cell function in biological system.
2020, 48(11): 1556-1563
doi: 10.19756/j.issn.0253-3820.201257
Abstract:
Metronidazole (MNZ) of nitroimidazole antibiotics is a kind of antibiotic commonly used in many fields. It is mostly used to treat the infection caused by anaerobic bacteria or as an additive in animal feed. However, when MNZ remains in the human body in excess, it will lead to teratogenic, carcinogenic and other serious side effects. In this work, a novel fluorescent probe based on polyethylenimine stabilized silver nanoclusters (AgNCs@PEI) was successfully synthesized by one-step microwave method. The as-prepared AgNCs@PEI showed good fluorescence stability in a wide ion concentration range or after long time of illumination (at 455 nm for 30 min). The hydrogen bonds between amino functional groups of PEI ligand and N atoms of the imidazole ring of MNZ resulted in formation of a stable non-radiative ground state complex that caused the decrease of fluorescence intensity of the AgNCs. The results showed that the probe had good selectivity for MNZ, with a linear range of 0.1-200 mol/L and a detection limit of 0.038 mol/L. The fluorescent probe was applied to determination of MNZ in human urine samples with recoveries of 95.8%-103.4%, and the relative standard deviations were less than 4.3%, indicating the new fluorescence probe had potential application value in drug detection.
Metronidazole (MNZ) of nitroimidazole antibiotics is a kind of antibiotic commonly used in many fields. It is mostly used to treat the infection caused by anaerobic bacteria or as an additive in animal feed. However, when MNZ remains in the human body in excess, it will lead to teratogenic, carcinogenic and other serious side effects. In this work, a novel fluorescent probe based on polyethylenimine stabilized silver nanoclusters (AgNCs@PEI) was successfully synthesized by one-step microwave method. The as-prepared AgNCs@PEI showed good fluorescence stability in a wide ion concentration range or after long time of illumination (at 455 nm for 30 min). The hydrogen bonds between amino functional groups of PEI ligand and N atoms of the imidazole ring of MNZ resulted in formation of a stable non-radiative ground state complex that caused the decrease of fluorescence intensity of the AgNCs. The results showed that the probe had good selectivity for MNZ, with a linear range of 0.1-200 mol/L and a detection limit of 0.038 mol/L. The fluorescent probe was applied to determination of MNZ in human urine samples with recoveries of 95.8%-103.4%, and the relative standard deviations were less than 4.3%, indicating the new fluorescence probe had potential application value in drug detection.
2020, 48(11): 1564-1572
doi: 10.19756/j.issn.0253-3820.201127
Abstract:
The aim of this study was to determine the ions formed during the fragmentation of new generation cumyl-carboxamide synthetic cannabinoids using gas chromatography-mass spectrometry (GC-MS) and ultra performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UPLC-QTOF-MS) to identify ions characteristic for different parts of the molecules. Compounds were analyzed on Aglient DB-5MS column (30 m×0.25 mm×0.25 μm) with an initial temperature of 140℃ for gradient increased temperature by GC-MS and Acquity UPLC BEH C18 column (100 mm×2.1 mm i.d., 1.7 μm particle diameter) with 0.1% formic acid aqueous solution (A)-acetonitrile (B) as mobile phase for gradient elution by UPLC-QTOF-MS. The fragmentation behaviors, especially the MS fragmentation rules, were compared and summarized. According to the structure and the typical fragmentations, these compounds could be easily identified. The countless possibilities to create new synthetic cannabinoids by small changes in chemical structures posed a growing challenge to forensic analysts. The work was helpful to assist forensic laboratories in identifying these kinds of compounds or other substances with similar structure in their case work.
The aim of this study was to determine the ions formed during the fragmentation of new generation cumyl-carboxamide synthetic cannabinoids using gas chromatography-mass spectrometry (GC-MS) and ultra performance liquid chromatography-quadrupole time-of-flight-mass spectrometry (UPLC-QTOF-MS) to identify ions characteristic for different parts of the molecules. Compounds were analyzed on Aglient DB-5MS column (30 m×0.25 mm×0.25 μm) with an initial temperature of 140℃ for gradient increased temperature by GC-MS and Acquity UPLC BEH C18 column (100 mm×2.1 mm i.d., 1.7 μm particle diameter) with 0.1% formic acid aqueous solution (A)-acetonitrile (B) as mobile phase for gradient elution by UPLC-QTOF-MS. The fragmentation behaviors, especially the MS fragmentation rules, were compared and summarized. According to the structure and the typical fragmentations, these compounds could be easily identified. The countless possibilities to create new synthetic cannabinoids by small changes in chemical structures posed a growing challenge to forensic analysts. The work was helpful to assist forensic laboratories in identifying these kinds of compounds or other substances with similar structure in their case work.
2020, 48(11): 1573-1582
doi: 10.19756/j.issn.0253-3820.201104
Abstract:
Reversed phase-hydrophilic interaction chromatography-tailored multiple reaction monitoring (RPLC-HILIC-tailored MRM) was developed for simultaneous determination of 27 components with wide polarity and wide range of content in Cistanches herba. RPLC was directly coupled with HILIC to achieve comprehensive retention of numerous compounds regardless of the polarity. Acquity UPLC HSS T3 column (100 mm×2.1 mm, 1.8 μm) and Xbridge Amide column (150 mm×4.6 mm, 3.5 μm) were employed for reversed phase separation and HILIC mode, respectively. To overcome the obstacle of incompatible mobile phases, dilution pumps were involved between two columns via a mixer. Pump A and pump B were responsible for delivering 0.1% formic acid and acetonitrile, respectively, into the RPLC column with a flow rate of 0.15 mL/min by gradient elution. Pump C and pump D, served as dilution pumps, introduced the same mobile phase as pump A and pump B into the mixer at a flow rate of 1.0 mL/min, which contributed to retention of polar compounds on HILIC column. For mass detection, tailored MRM with optimal collision energy was carried out by online energy-resolved MS to suppress mass response of abundant constituents, and to advance mass response of trace compounds. A total of 27 components in thirty-six batches of Cistanches Herba, such as amino acids, organic acids, phenylethanoid glycosides, lignans, and iridoids, were determined by RPLC-HILIC-tailored MRM. Satisfactory correlation coefficients were observed for all calibration equations with greater than 0.9929 over their corresponding concentration ranges. The limits of detection (LODs) were 0.0032-160 μg/g and the limits of quantification (LOQs) were 0.032-320 μg/g. The average recoveries at three spiked levels were in the range of 74.7%-125.1% with relative standard deviations (RSDs) of 1.6%-13.7%. The developed method showed wide linear range, good accuracy and wide applicability, and had the potential for large-scale quantitative analysis of traditional Chinese medicine.
Reversed phase-hydrophilic interaction chromatography-tailored multiple reaction monitoring (RPLC-HILIC-tailored MRM) was developed for simultaneous determination of 27 components with wide polarity and wide range of content in Cistanches herba. RPLC was directly coupled with HILIC to achieve comprehensive retention of numerous compounds regardless of the polarity. Acquity UPLC HSS T3 column (100 mm×2.1 mm, 1.8 μm) and Xbridge Amide column (150 mm×4.6 mm, 3.5 μm) were employed for reversed phase separation and HILIC mode, respectively. To overcome the obstacle of incompatible mobile phases, dilution pumps were involved between two columns via a mixer. Pump A and pump B were responsible for delivering 0.1% formic acid and acetonitrile, respectively, into the RPLC column with a flow rate of 0.15 mL/min by gradient elution. Pump C and pump D, served as dilution pumps, introduced the same mobile phase as pump A and pump B into the mixer at a flow rate of 1.0 mL/min, which contributed to retention of polar compounds on HILIC column. For mass detection, tailored MRM with optimal collision energy was carried out by online energy-resolved MS to suppress mass response of abundant constituents, and to advance mass response of trace compounds. A total of 27 components in thirty-six batches of Cistanches Herba, such as amino acids, organic acids, phenylethanoid glycosides, lignans, and iridoids, were determined by RPLC-HILIC-tailored MRM. Satisfactory correlation coefficients were observed for all calibration equations with greater than 0.9929 over their corresponding concentration ranges. The limits of detection (LODs) were 0.0032-160 μg/g and the limits of quantification (LOQs) were 0.032-320 μg/g. The average recoveries at three spiked levels were in the range of 74.7%-125.1% with relative standard deviations (RSDs) of 1.6%-13.7%. The developed method showed wide linear range, good accuracy and wide applicability, and had the potential for large-scale quantitative analysis of traditional Chinese medicine.
2020, 48(11): 1583-1589
doi: 10.19756/j.issn.0253-3820.201498
Abstract:
Phosphate anion (PO43-)-responsive controlled release pesticide based on hydrogel (PCRPH) was developed based on crosslinking effect between ferric ion (Fe3+) and sodium carboxymethylcellulose (CMC). In PCRPH, attapulgite (ATP) was served as carrier for loading imidacloprid (IM). The scanning electron microscope (SEM) and X-ray diffraction (XRD) results demonstrated that PCRPH in PO43- solution might swell and disaggregate, which could be enhanced as the PO43- contents in solution increase. As a result, the controlled-release of IM inside hydrogel could occur so that the utilization rate of pesticide was improved. According to the release kinetics analysis, the release mechanism of IM from PCRPH was consistent with the Fickian diffusion law. The release amount of IM from PCRPH remained stable against the coexisting Cl- and different pH, whereas temperature displayed positive relation with the release rate of IM.
Phosphate anion (PO43-)-responsive controlled release pesticide based on hydrogel (PCRPH) was developed based on crosslinking effect between ferric ion (Fe3+) and sodium carboxymethylcellulose (CMC). In PCRPH, attapulgite (ATP) was served as carrier for loading imidacloprid (IM). The scanning electron microscope (SEM) and X-ray diffraction (XRD) results demonstrated that PCRPH in PO43- solution might swell and disaggregate, which could be enhanced as the PO43- contents in solution increase. As a result, the controlled-release of IM inside hydrogel could occur so that the utilization rate of pesticide was improved. According to the release kinetics analysis, the release mechanism of IM from PCRPH was consistent with the Fickian diffusion law. The release amount of IM from PCRPH remained stable against the coexisting Cl- and different pH, whereas temperature displayed positive relation with the release rate of IM.
2020, 48(11): 1590-1596
doi: 10.19756/j.issn.0253-3820.191520
Abstract:
A new method for accurate detection of platium group metals in spent automobile exhaust catalysts samples by inductively coupled plasma spectrometry (ICP-OES) combined with fire assay enrichment through green metal bismuth was established. In this work, the ability of selective slag forming in bismuth fire assay was analyzed, the thermodynamic mechanism from the micro level of bismuth concentrate precious metals was revealed, the order of metal reduced in bismuth fire assay was discussed, and the main factors affecting the results of bismuth fire assay were investigated. The result showed that precious metal oxides were reduced prior to Bi2O3, Bi2O3 was reduced prior to TeO2, Cu2O, As2O3, PbO, NiO and other impurities, and Bi2O3 had a stronger ability to remove impurities such as Te, Cu, As and Ni. Precious metal elements dissolved in metallic bismuth phase could reduce the free energy of the system more than dissolved in slag phase. Each of the samples or above-mentioned powder were mixed with flux and collectors proportionately, such as 48.00 g of bismuth trioxide, 25.00 g of sodium carbonate anhydrous, 5.5 g of wheat flour, slag silicate degree of 1.1, and 1:1 mass ratio of silicon to boron. The mixture was transferred into fire-clay crucibles and fused at the temperature range from 900℃ to 1080℃ in 20 min, and maintained at 1080℃ for 25 min. The quality of bismuth button was 40 g. The average detection value of palladium was 2852 g/t, the extreme difference was 17 g/t with relative standard deviation of 0.21%. The bismuth fire assay for detection of platinum group metals had higher precision and recovery, and the detection error was less than the error range of national standard.
A new method for accurate detection of platium group metals in spent automobile exhaust catalysts samples by inductively coupled plasma spectrometry (ICP-OES) combined with fire assay enrichment through green metal bismuth was established. In this work, the ability of selective slag forming in bismuth fire assay was analyzed, the thermodynamic mechanism from the micro level of bismuth concentrate precious metals was revealed, the order of metal reduced in bismuth fire assay was discussed, and the main factors affecting the results of bismuth fire assay were investigated. The result showed that precious metal oxides were reduced prior to Bi2O3, Bi2O3 was reduced prior to TeO2, Cu2O, As2O3, PbO, NiO and other impurities, and Bi2O3 had a stronger ability to remove impurities such as Te, Cu, As and Ni. Precious metal elements dissolved in metallic bismuth phase could reduce the free energy of the system more than dissolved in slag phase. Each of the samples or above-mentioned powder were mixed with flux and collectors proportionately, such as 48.00 g of bismuth trioxide, 25.00 g of sodium carbonate anhydrous, 5.5 g of wheat flour, slag silicate degree of 1.1, and 1:1 mass ratio of silicon to boron. The mixture was transferred into fire-clay crucibles and fused at the temperature range from 900℃ to 1080℃ in 20 min, and maintained at 1080℃ for 25 min. The quality of bismuth button was 40 g. The average detection value of palladium was 2852 g/t, the extreme difference was 17 g/t with relative standard deviation of 0.21%. The bismuth fire assay for detection of platinum group metals had higher precision and recovery, and the detection error was less than the error range of national standard.
