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2018 Volume 46 Issue 6
2018, 46(6): 803-813
doi: 10.11895/j.issn.0253-3820.181136
Abstract:
Biomacromolecules participate in various kinds of vital processes. Observing and analyzing their structural dynamic and the dynamic processes of intermolecular interaction at molecular level is important for understanding the action mechanism. Since its advent, single molecular fluorescence resonance energy transfer (SM-FRET) has demonstrated its great potential in studying the conformational change and interaction process of biomacromolecules, and a series of new mechanisms have been revealed. This review summarized recent progresses of SM-FRET in studying protein structural dynamic, nucleic acid structural dynamic, protein-protein and protein-nucleic acid interactions.
Biomacromolecules participate in various kinds of vital processes. Observing and analyzing their structural dynamic and the dynamic processes of intermolecular interaction at molecular level is important for understanding the action mechanism. Since its advent, single molecular fluorescence resonance energy transfer (SM-FRET) has demonstrated its great potential in studying the conformational change and interaction process of biomacromolecules, and a series of new mechanisms have been revealed. This review summarized recent progresses of SM-FRET in studying protein structural dynamic, nucleic acid structural dynamic, protein-protein and protein-nucleic acid interactions.
2018, 46(6): 814-825
doi: 10.11895/j.issn.0253-3820.181256
Abstract:
Nanopore/nanochannel sensing technique drawing more attention in analytical chemistry due to its unique advantages and the fabricated electrochemical sensors and electrochemical responsive gates have been widely used for more target detection, including single molecule protein and DNA sequencing. Nanopore/nanochannel that used for fabricating electrochemical detection system is mainly divided into biological nanopore and solid state nanopore, and among them, solid state nanopore/nanochannel has a wide range of application due to its inherent properties, such as easy for modification, good mechanical property and stability. Resistive pulse sensing and current-voltage curves (ion current rectification) are two main methods of nanopore/nanochannel sensing technique used for target analysis, so in this review, we introduced the fundamentals and applications of nanopore sensing technique based on the above two methods. In addition, we concluded the application and development of single state nanopore/nanochannel in recent years, and also gave a brief look at the future challenges and prospects in the development of this field.
Nanopore/nanochannel sensing technique drawing more attention in analytical chemistry due to its unique advantages and the fabricated electrochemical sensors and electrochemical responsive gates have been widely used for more target detection, including single molecule protein and DNA sequencing. Nanopore/nanochannel that used for fabricating electrochemical detection system is mainly divided into biological nanopore and solid state nanopore, and among them, solid state nanopore/nanochannel has a wide range of application due to its inherent properties, such as easy for modification, good mechanical property and stability. Resistive pulse sensing and current-voltage curves (ion current rectification) are two main methods of nanopore/nanochannel sensing technique used for target analysis, so in this review, we introduced the fundamentals and applications of nanopore sensing technique based on the above two methods. In addition, we concluded the application and development of single state nanopore/nanochannel in recent years, and also gave a brief look at the future challenges and prospects in the development of this field.
2018, 46(6): 826-835
doi: 10.11895/j.issn.0253-3820.181200
Abstract:
As a novel analytical method, nanopore sensing is widely applied in many fields such as nucleic acids sequencing, protein/peptide analysis, detection of metal ions and biomacromolecules including virus, bacteria, etc. With the growing public concerns over dietary safety and public security, there has been a greater demand on the detection of toxic molecules. With its high sensitivity and selectivity, nanopore sensing is considered as a more powerful assay, which has been reported in many research articles. Accordingly, this paper surveys the application studies of nanopore sensing in detection of toxic molecules.
As a novel analytical method, nanopore sensing is widely applied in many fields such as nucleic acids sequencing, protein/peptide analysis, detection of metal ions and biomacromolecules including virus, bacteria, etc. With the growing public concerns over dietary safety and public security, there has been a greater demand on the detection of toxic molecules. With its high sensitivity and selectivity, nanopore sensing is considered as a more powerful assay, which has been reported in many research articles. Accordingly, this paper surveys the application studies of nanopore sensing in detection of toxic molecules.
2018, 46(6): 836-842
doi: 10.11895/j.issn.0253-3820.181217
Abstract:
Nanopore technique is a low-cost tool for single-molecule level analysis without the need of label or amplification. The solid nanopores have been widely used in many fields such as chemistry and life sciences due to their advantages such as high stability, good tolerability, controllable size, and easy for modification. The solid nanopores commonly used in recent years are fabricated using two types of materials:membrane and tube. The membrane materials include silicon nitride, two-dimensional materials, aluminium oxide, and polymer membranes. The tube materials mainly include glass capillary and carbon nanotube. This review summarizes and prospects the research progress of different solid nanopores.
Nanopore technique is a low-cost tool for single-molecule level analysis without the need of label or amplification. The solid nanopores have been widely used in many fields such as chemistry and life sciences due to their advantages such as high stability, good tolerability, controllable size, and easy for modification. The solid nanopores commonly used in recent years are fabricated using two types of materials:membrane and tube. The membrane materials include silicon nitride, two-dimensional materials, aluminium oxide, and polymer membranes. The tube materials mainly include glass capillary and carbon nanotube. This review summarizes and prospects the research progress of different solid nanopores.
2018, 46(6): 843-850
doi: 10.11895/j.issn.0253-3820.171476
Abstract:
To achieve fast and accurate analysis of weak current signal of nanopore-based single molecule detection, we designed a real-time adaptive threshold data processing algorithm with data buffering technique and finite impulse response filtering. The system, which is designed based on the data processing algorithm, could realize real-time recognition and analysis of nanopore events during the data recording process. In order to verify the performance of the system, the ideal signals with different noise level (20-100 pA) and recording bandwidth (3-100 kHz) was generated. The results showed that the system was stable to analyze the generated signals even at high noise. In addition, the system was also suitable for the data recording conditions of low bandwidth and high sampling rate (250 kHz). The proposed nanopore data processing system was further applied in the Aerolysin nanopore experiment for the detection of poly(dA)4 molecules. The results showed that the data processing system could be applied in real nanopore recording system with high accuracy and speed.
To achieve fast and accurate analysis of weak current signal of nanopore-based single molecule detection, we designed a real-time adaptive threshold data processing algorithm with data buffering technique and finite impulse response filtering. The system, which is designed based on the data processing algorithm, could realize real-time recognition and analysis of nanopore events during the data recording process. In order to verify the performance of the system, the ideal signals with different noise level (20-100 pA) and recording bandwidth (3-100 kHz) was generated. The results showed that the system was stable to analyze the generated signals even at high noise. In addition, the system was also suitable for the data recording conditions of low bandwidth and high sampling rate (250 kHz). The proposed nanopore data processing system was further applied in the Aerolysin nanopore experiment for the detection of poly(dA)4 molecules. The results showed that the data processing system could be applied in real nanopore recording system with high accuracy and speed.
2018, 46(6): 851-857
doi: 10.11895/j.issn.0253-3820.171416
Abstract:
Single nanopore current pulse method is a new, rapid and simple detection method, which is promising for single-molecule DNA sequencing and bio-sensing. Due to the short duration and the low current amplitude of the pulses caused by molecular translocation under normal conditions, pulse detection system with fast response and high sensitivity is required. In this work, based on a lab-established pulse detection system, the effect of protamine in the regulation of single-stranded (ssDNA) current pulses with α-hemolysin (α-HL) single nanopore interface was investigated. Experimental results showed that the pulses positive charged protamine and negative ssDNA probes were both well observed with the established system, and both the pulse amplitude and duration of ssDNA were increased as a result of interaction with protamine. This study provides a way to improve the resolving power of current pulses based on molecular interactions.
Single nanopore current pulse method is a new, rapid and simple detection method, which is promising for single-molecule DNA sequencing and bio-sensing. Due to the short duration and the low current amplitude of the pulses caused by molecular translocation under normal conditions, pulse detection system with fast response and high sensitivity is required. In this work, based on a lab-established pulse detection system, the effect of protamine in the regulation of single-stranded (ssDNA) current pulses with α-hemolysin (α-HL) single nanopore interface was investigated. Experimental results showed that the pulses positive charged protamine and negative ssDNA probes were both well observed with the established system, and both the pulse amplitude and duration of ssDNA were increased as a result of interaction with protamine. This study provides a way to improve the resolving power of current pulses based on molecular interactions.
2018, 46(6): 858-864
doi: 10.11895/j.issn.0253-3820.171404
Abstract:
Due to the difference in spatial configuration and charge of the bases in a DNA molecule, characteristic translocation current pulses through a single nanopore could be obtained. This could become the basis of DNA sequencing method. However, due to the fast translocation speed (sub-micro seconds) and the small current change (about pA), it is still a challenge to obtain the accurate molecular substructure with present electronic techniques. In this work, in order to control the translocation behavior of ssDNA, two kinds of ionic liquids with high viscosity and conductivity were introduced to establish a viscosity gradient with the α-hemolysin single nanopore interface and the acidity of the solution was optimized. The trans chamber contained pure BmimPF6 and the cis chamber contained 1 mol/L BmimCl and 10 mmol/L Tris-HCl (pH 5.5). Preliminary experiment results under this electrolyte configuration showed that poly(dC)15, poly(dC)15, poly(dC)30 and poly(dC)50 exhibited obvious long duration pulses with high current suppression ratio. The blocking depth reached more than 95% of long blocking events. The duration time of long blocking events prolonged to tens or hundreds of milliseconds. Meanwhile, the peak-peak of baseline noise was reduced by about 30%.
Due to the difference in spatial configuration and charge of the bases in a DNA molecule, characteristic translocation current pulses through a single nanopore could be obtained. This could become the basis of DNA sequencing method. However, due to the fast translocation speed (sub-micro seconds) and the small current change (about pA), it is still a challenge to obtain the accurate molecular substructure with present electronic techniques. In this work, in order to control the translocation behavior of ssDNA, two kinds of ionic liquids with high viscosity and conductivity were introduced to establish a viscosity gradient with the α-hemolysin single nanopore interface and the acidity of the solution was optimized. The trans chamber contained pure BmimPF6 and the cis chamber contained 1 mol/L BmimCl and 10 mmol/L Tris-HCl (pH 5.5). Preliminary experiment results under this electrolyte configuration showed that poly(dC)15, poly(dC)15, poly(dC)30 and poly(dC)50 exhibited obvious long duration pulses with high current suppression ratio. The blocking depth reached more than 95% of long blocking events. The duration time of long blocking events prolonged to tens or hundreds of milliseconds. Meanwhile, the peak-peak of baseline noise was reduced by about 30%.
2018, 46(6): 865-874
doi: 10.11895/j.issn.0253-3820.181056
Abstract:
Isothermal nucleic acid amplifications, as powerful as polymerase chain reaction but functioning at a constant temperature, are considered to be very promising technique in achieving point-of-care gene diagnostics. However, until now, their practical applications are still seriously lagged by the bad reliability resulting from the problems such as false positive amplification and low signal amplitude. In this work, a universal transduction method in which any sequence (including loop-mediated isothermal amplification products) could be transduced via a hairpin transducer into a catalyst of a well-engineered circuit (catalytic hairpin assembly, CHA) was established. Because CHA circuit could amplify tens to hundreds fold with especially high sequence specificity, it could provide both accuracy and high amplitude for sequence detection. And for a new targeting sequence, the only sequence needed to be changed was the hairpin transducer. Due to the importance of the transducer, we provided and verified a universal designing rule-set to guarantee the transducing efficiency (signal to background ratio) of the transducer. Transducers designed following this rule set were then proved to be very efficient in detecting pathogen gene targets. As less as near single molecule (20 copies) of pathogen genes could be detected with significant fluorescent and electrochemical signals.
Isothermal nucleic acid amplifications, as powerful as polymerase chain reaction but functioning at a constant temperature, are considered to be very promising technique in achieving point-of-care gene diagnostics. However, until now, their practical applications are still seriously lagged by the bad reliability resulting from the problems such as false positive amplification and low signal amplitude. In this work, a universal transduction method in which any sequence (including loop-mediated isothermal amplification products) could be transduced via a hairpin transducer into a catalyst of a well-engineered circuit (catalytic hairpin assembly, CHA) was established. Because CHA circuit could amplify tens to hundreds fold with especially high sequence specificity, it could provide both accuracy and high amplitude for sequence detection. And for a new targeting sequence, the only sequence needed to be changed was the hairpin transducer. Due to the importance of the transducer, we provided and verified a universal designing rule-set to guarantee the transducing efficiency (signal to background ratio) of the transducer. Transducers designed following this rule set were then proved to be very efficient in detecting pathogen gene targets. As less as near single molecule (20 copies) of pathogen genes could be detected with significant fluorescent and electrochemical signals.
2018, 46(6): 875-882,924
doi: 10.11895/j.issn.0253-3820.181178
Abstract:
Exopolysaccharides (EPSs), produced by lactic acid bacteria (LAB), have been used primarily to improve the quality and taste of food, also possess a variety of unique biological functions, such as immunoregulation and anti-tumor activities. The diversity of molecular structural characteristics of LAB-generated EPSs represents one of the main factors responsible for this plethora of functions. Accordingly, the structural analysis of the EPSs produced by LAB is both a prerequisite and basis for examining its functional and structure-activity relationships. In this article, we summarized the current progress of key methodologies involved in the structural analysis of LAB-generated EPSs, including their isolation, purification, primary structure and advances in structural research. A comprehensive discussion regarding the application of chemical analysis, instrument analysis and computer aided technology in the structure analysis of LAB-generated EPSs was provided. Further, the future development of the research on the structure of LAB-generated EPSs was presented.
Exopolysaccharides (EPSs), produced by lactic acid bacteria (LAB), have been used primarily to improve the quality and taste of food, also possess a variety of unique biological functions, such as immunoregulation and anti-tumor activities. The diversity of molecular structural characteristics of LAB-generated EPSs represents one of the main factors responsible for this plethora of functions. Accordingly, the structural analysis of the EPSs produced by LAB is both a prerequisite and basis for examining its functional and structure-activity relationships. In this article, we summarized the current progress of key methodologies involved in the structural analysis of LAB-generated EPSs, including their isolation, purification, primary structure and advances in structural research. A comprehensive discussion regarding the application of chemical analysis, instrument analysis and computer aided technology in the structure analysis of LAB-generated EPSs was provided. Further, the future development of the research on the structure of LAB-generated EPSs was presented.
2018, 46(6): 883-888
doi: 10.11895/j.issn.0253-3820.171525
Abstract:
The environmental organic pollutant of di-2-ethylhexy phthalate (DEHP) was analyzed by extractive electrospray ionization mass spectrometry (EESI-MS). Effect of some important experimental conditions were investigated systematically, including the electrospray voltage, temperature of ion-transport tube, sample injection rate and extractant composition. Under the optimal conditions, a method for rapid detection of DEHP in water sample was established. DEHP levels in different samples with complex matrixes were measured, including landfill leachate, urban sewage and lake water. The results showed that DEHP in water samples could be ionized by EESI source and obtained the molecule ion (m/z 391.28) at the positive detection mode, and then CID experiment were performed to obtain the secondary fragment ions m/z 279.26, 167.12 and 149.11. The intensity of characteristic peak m/z 149.11 possessed a good linearity with the concentration of DEHP in the range of 5-1000 μg/L with the correlation coefficient of R2=0.9991, and the detection limit (LOD) of 0.21 μg/L. The recoveries of DEHP at three spiked levels (8, 80, 400 μg/L) were 96.2%-111.2%, with RSDs of 5.6%-11.8%. With the developed EESI-MS method, the concentrations of DEHP in landfill leachate, urban sewage and Yan lake water were 556.5, 275.3 and 37.8 μg/L, respectively. The EESI-MS method possessed many advantages such as no requirement of sample pretreatment, fast analysis speed (about 3 min per sample), simple operation and high sensitivity, thus providing a new mass spectrometric method for rapid detection of phthalate esters.
The environmental organic pollutant of di-2-ethylhexy phthalate (DEHP) was analyzed by extractive electrospray ionization mass spectrometry (EESI-MS). Effect of some important experimental conditions were investigated systematically, including the electrospray voltage, temperature of ion-transport tube, sample injection rate and extractant composition. Under the optimal conditions, a method for rapid detection of DEHP in water sample was established. DEHP levels in different samples with complex matrixes were measured, including landfill leachate, urban sewage and lake water. The results showed that DEHP in water samples could be ionized by EESI source and obtained the molecule ion (m/z 391.28) at the positive detection mode, and then CID experiment were performed to obtain the secondary fragment ions m/z 279.26, 167.12 and 149.11. The intensity of characteristic peak m/z 149.11 possessed a good linearity with the concentration of DEHP in the range of 5-1000 μg/L with the correlation coefficient of R2=0.9991, and the detection limit (LOD) of 0.21 μg/L. The recoveries of DEHP at three spiked levels (8, 80, 400 μg/L) were 96.2%-111.2%, with RSDs of 5.6%-11.8%. With the developed EESI-MS method, the concentrations of DEHP in landfill leachate, urban sewage and Yan lake water were 556.5, 275.3 and 37.8 μg/L, respectively. The EESI-MS method possessed many advantages such as no requirement of sample pretreatment, fast analysis speed (about 3 min per sample), simple operation and high sensitivity, thus providing a new mass spectrometric method for rapid detection of phthalate esters.
2018, 46(6): 889-895
doi: 10.11895/j.issn.0253-3820.181035
Abstract:
p-Hydroxybenzoic acid can be oxidized by hydroxyl radicals (·OH) to produce electroactive 3,4-dihydroxybenzoic acid (3,4-DHBA). Therefore, it can be used as a probe to detect ·OH. In this work, 3,4-DHBA/PPy/TiO2 molecularly imprinted polymer film was prepared for indirect determination of ·OH based on its recognition ability for 3,4-DHBA. The sensor was constructed by using pyrrole as the functional monomer and 3,4-DHBA as the template molecule. The sensor was characterized by scanning electron microscope and different electrochemical methods. The preparation and determination conditions, such as the electropolymerization cycle number, pH value in the electropolymerization process, and elution time, were optimized. Under the optimal conditions, a linear range of 1.0×10-8-1.0×10-6 mol/L was obtained for 3,4-DHBA and the detection limit was down to 4.2×10-9 mol/L (S/N=3). This new approach was of low cost and convenience, and was successfully applied to measure the concentration of ·OH in the atmosphere.
p-Hydroxybenzoic acid can be oxidized by hydroxyl radicals (·OH) to produce electroactive 3,4-dihydroxybenzoic acid (3,4-DHBA). Therefore, it can be used as a probe to detect ·OH. In this work, 3,4-DHBA/PPy/TiO2 molecularly imprinted polymer film was prepared for indirect determination of ·OH based on its recognition ability for 3,4-DHBA. The sensor was constructed by using pyrrole as the functional monomer and 3,4-DHBA as the template molecule. The sensor was characterized by scanning electron microscope and different electrochemical methods. The preparation and determination conditions, such as the electropolymerization cycle number, pH value in the electropolymerization process, and elution time, were optimized. Under the optimal conditions, a linear range of 1.0×10-8-1.0×10-6 mol/L was obtained for 3,4-DHBA and the detection limit was down to 4.2×10-9 mol/L (S/N=3). This new approach was of low cost and convenience, and was successfully applied to measure the concentration of ·OH in the atmosphere.
2018, 46(6): 896-901
doi: 10.11895/j.issn.0253-3820.181017
Abstract:
Fourier transform infrared spectroscopic imaging (FTIRSI) technology can simultaneously obtain microstructure information and infrared spectral information of the samples. The method of FTIRSI combined with chemometric algorithms can be used for quantitative analysis of sample spectral information and tissue discrimination research. Based on this, FTIRSI and support vector machine classification (SVC) for the first time were used in this work to discriminate healthy and degenerated articular cartilage, with high accuracies of 100% and 95.4%, respectively, and sum accuracy of 97.7%. The support vector regression (SVR) model was used to quantitatively study the contents and distribution of two biomacromolecules, collagen and proteoglycan, in articular cartilage. The proteoglycan loss occurred in the degenerated articular cartilage, especially in the superficial area. This study indicates that the combination of FTIRSI and support vector machine (SVM) is expected to become a new diagnostic tool for osteoarthritis, which is of great significance for the early diagnosis and research of osteoarthritis.
Fourier transform infrared spectroscopic imaging (FTIRSI) technology can simultaneously obtain microstructure information and infrared spectral information of the samples. The method of FTIRSI combined with chemometric algorithms can be used for quantitative analysis of sample spectral information and tissue discrimination research. Based on this, FTIRSI and support vector machine classification (SVC) for the first time were used in this work to discriminate healthy and degenerated articular cartilage, with high accuracies of 100% and 95.4%, respectively, and sum accuracy of 97.7%. The support vector regression (SVR) model was used to quantitatively study the contents and distribution of two biomacromolecules, collagen and proteoglycan, in articular cartilage. The proteoglycan loss occurred in the degenerated articular cartilage, especially in the superficial area. This study indicates that the combination of FTIRSI and support vector machine (SVM) is expected to become a new diagnostic tool for osteoarthritis, which is of great significance for the early diagnosis and research of osteoarthritis.
2018, 46(6): 902-909
doi: 10.11895/j.issn.0253-3820.171227
Abstract:
In this study, a method for rapid identification of three kinds of honey and four kinds of syrup by microwave plasma torch mass spectrometry (MPT-MS) without sample pretreatment was established. Under the positive ion mode, honey and syrup were ionized by MPT-MS and analyzed by quadrupole mass spectrometry (QMS). The MS data were analyzed with chemometrics methods. Consequently, principal component analysis (PCA) showed that PC1, PC2 and PC3 had a total contribution rate of 91.2%, and cluster analysis (CA) indicated when the critical value was 7, this method could distinguish honey and syrup in addition to clover honey and inulin syrup. Partial least squares-discriminant analysis (PLS-DA) also manifested that honey and syrup could be effectively distinguished. Discriminant analysis (DA) demonstrated that the discriminant accuracy of honey and syrup was 100%. Accordingly, all the results showed that the method of MPT-MS combined with chemometrics could identify honey and syrup rapidly. In brief, this method has the advantages such as fast analysis speed, accurate information extraction, high recognition accuracy and without sample pretreatment, and can be used for the identification of honey and main adulterated syrup.
In this study, a method for rapid identification of three kinds of honey and four kinds of syrup by microwave plasma torch mass spectrometry (MPT-MS) without sample pretreatment was established. Under the positive ion mode, honey and syrup were ionized by MPT-MS and analyzed by quadrupole mass spectrometry (QMS). The MS data were analyzed with chemometrics methods. Consequently, principal component analysis (PCA) showed that PC1, PC2 and PC3 had a total contribution rate of 91.2%, and cluster analysis (CA) indicated when the critical value was 7, this method could distinguish honey and syrup in addition to clover honey and inulin syrup. Partial least squares-discriminant analysis (PLS-DA) also manifested that honey and syrup could be effectively distinguished. Discriminant analysis (DA) demonstrated that the discriminant accuracy of honey and syrup was 100%. Accordingly, all the results showed that the method of MPT-MS combined with chemometrics could identify honey and syrup rapidly. In brief, this method has the advantages such as fast analysis speed, accurate information extraction, high recognition accuracy and without sample pretreatment, and can be used for the identification of honey and main adulterated syrup.
2018, 46(6): 910-916
doi: 10.11895/j.issn.0253-3820.181062
Abstract:
A green, rapid and efficient method was developed for the extraction of 4 kinds of hosenkosides from the seeds of Impatiens balsamina L. The hosenkosides were extracted by ionic liquid, and then enriched by solid phase extraction. The effects of the kinds and volume of ionic liquid, pH value, ultrasonic time, solid phase extractant and eluent on the extraction fields were investigated and optimized. Under the optimum conditions, the recoveries of 4 kinds of hosenkosides were between 92.1% and 108.2%, the correlation coefficients were 0.9945-0.9975, and the detection limits were 1.8-4.5 μg/mL. The RSD values were all less than 3.9%. The experimental results showed that this method was fast, efficient, environmental protection. This study provided a reference for the extraction and enrichment of trace components in Chinese medicinal herbs.
A green, rapid and efficient method was developed for the extraction of 4 kinds of hosenkosides from the seeds of Impatiens balsamina L. The hosenkosides were extracted by ionic liquid, and then enriched by solid phase extraction. The effects of the kinds and volume of ionic liquid, pH value, ultrasonic time, solid phase extractant and eluent on the extraction fields were investigated and optimized. Under the optimum conditions, the recoveries of 4 kinds of hosenkosides were between 92.1% and 108.2%, the correlation coefficients were 0.9945-0.9975, and the detection limits were 1.8-4.5 μg/mL. The RSD values were all less than 3.9%. The experimental results showed that this method was fast, efficient, environmental protection. This study provided a reference for the extraction and enrichment of trace components in Chinese medicinal herbs.
2018, 46(6): 917-924
doi: 10.11895/j.issn.0253-3820.171417
Abstract:
A novel fluorescent imprinted polymer (CDs@MIP) with selective recognition of hemoglobin was prepared by the sol-gel method using fluorescent carbon dots as the carrier material, 3-aminopropyltrieth-oxysilane as the functional monomer, tetraethoxysilane as the crosslinking agent and bovine hemoglobin as template molecule. The results of IR and scanning electron microscopy showed that the molecularly imprinted polymer was coated on the surface of fluorescent carbon dots. The CDs@MIP showed selective recognition properties for bovine hemoglobin with an imprinting factor of 4.60. Also the adsorption ability and specific recognition performance of CDs@MIP were investigated, and it was found that the CDs@MIP had high selectivity toward bovine hemoglobin, and the selection factors for ovalbumin, bovine serum albumin and human serum albumin were 4.38, 4.73 and 3.66, respectively. Under the optimal conditions, the linear range of CDs@MIP for bovine hemoglobin was 0.1-10.0 μmol/L and the detection limit was 23.0 nmol/L. The CDs@MIP was successfully used for the determination of bovine hemoglobin in bovine blood samples with recoveries of 99.0%-102.5%.
A novel fluorescent imprinted polymer (CDs@MIP) with selective recognition of hemoglobin was prepared by the sol-gel method using fluorescent carbon dots as the carrier material, 3-aminopropyltrieth-oxysilane as the functional monomer, tetraethoxysilane as the crosslinking agent and bovine hemoglobin as template molecule. The results of IR and scanning electron microscopy showed that the molecularly imprinted polymer was coated on the surface of fluorescent carbon dots. The CDs@MIP showed selective recognition properties for bovine hemoglobin with an imprinting factor of 4.60. Also the adsorption ability and specific recognition performance of CDs@MIP were investigated, and it was found that the CDs@MIP had high selectivity toward bovine hemoglobin, and the selection factors for ovalbumin, bovine serum albumin and human serum albumin were 4.38, 4.73 and 3.66, respectively. Under the optimal conditions, the linear range of CDs@MIP for bovine hemoglobin was 0.1-10.0 μmol/L and the detection limit was 23.0 nmol/L. The CDs@MIP was successfully used for the determination of bovine hemoglobin in bovine blood samples with recoveries of 99.0%-102.5%.
2018, 46(6): 925-930
doi: 10.11895/j.issn.0253-3820.181059
Abstract:
Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) is a new tool that can provide the element composition, size distribution, and number concentration of nanoparticles. Here we discussed the effects of dwell time and settling time on analysis of nanoparticles by SP-ICP-MS. We analyzed standard materials of gold nanoparticles (30, 40 and 60 nm AuNPs, from NIST and NCNST), showing that better signal-to-noise ratio and higher determination efficiency could be achived when using shorter dwell time and settling time. We utilized a nano mode for SP-ICP-MS, in which the dwell time was set as 0.05 ms and the settling time was 0. The size of NIST AuNP standard material determined here was in accord with the certified size using the developed method. The detection limits of size and number concentration of AuNPs were 8 nm and 1.1×105 particle/L, respectively.
Single particle inductively coupled plasma mass spectrometry (SP-ICP-MS) is a new tool that can provide the element composition, size distribution, and number concentration of nanoparticles. Here we discussed the effects of dwell time and settling time on analysis of nanoparticles by SP-ICP-MS. We analyzed standard materials of gold nanoparticles (30, 40 and 60 nm AuNPs, from NIST and NCNST), showing that better signal-to-noise ratio and higher determination efficiency could be achived when using shorter dwell time and settling time. We utilized a nano mode for SP-ICP-MS, in which the dwell time was set as 0.05 ms and the settling time was 0. The size of NIST AuNP standard material determined here was in accord with the certified size using the developed method. The detection limits of size and number concentration of AuNPs were 8 nm and 1.1×105 particle/L, respectively.
2018, 46(6): 931-937
doi: 10.11895/j.issn.0253-3820.181066
Abstract:
Line scanning quantitative analysis method on silicate with small laser beam (<15 μm) was developed using laser ablation sector field inductively coupled plasma mass spectrometry (LA-SF-ICP-MS). Differences on signal intensity and elemental fractionation induced by different laser sampling patterns were compared. While spot ablation with small laser beam, the elemental signal intensity decreased with time significantly, and the elemental fractionation was obvious. In contrast, the elemental signal intensity by line scanning was higher and more stable and line scanning was free of elemental fractionation. Therefore, identical ablation pattern and condition should be used for the standard and the unknown sample in LA-ICP-MS quantitative analysis. A single pulse experiment was carried out to investigate the washout time when coupled to two-volume ablation cell. The result indicated that the elemental intensity decayed to the background value needed 2-3 s. The optimal parameters on SF-ICP-MS were set to reduce the effect of signal overlapping. Homogeneous sample KL2-G and titanite grains with composition zoning were analyzed by this method. Accurate element contents and element ratios indicated that fast washout time and optimal instrument parameters made it feasible to perform line scanning quantitative analysis accurately. Comparing to traditional microanalysis, line scanning quantitative analysis could reduce the laser beam size (<15 μm) and improve the spatial resolution efficiently. The potential of the technique to unveil compositional complexities in greater detail would help to improve our understanding of geochemical processes in mineral scale.
Line scanning quantitative analysis method on silicate with small laser beam (<15 μm) was developed using laser ablation sector field inductively coupled plasma mass spectrometry (LA-SF-ICP-MS). Differences on signal intensity and elemental fractionation induced by different laser sampling patterns were compared. While spot ablation with small laser beam, the elemental signal intensity decreased with time significantly, and the elemental fractionation was obvious. In contrast, the elemental signal intensity by line scanning was higher and more stable and line scanning was free of elemental fractionation. Therefore, identical ablation pattern and condition should be used for the standard and the unknown sample in LA-ICP-MS quantitative analysis. A single pulse experiment was carried out to investigate the washout time when coupled to two-volume ablation cell. The result indicated that the elemental intensity decayed to the background value needed 2-3 s. The optimal parameters on SF-ICP-MS were set to reduce the effect of signal overlapping. Homogeneous sample KL2-G and titanite grains with composition zoning were analyzed by this method. Accurate element contents and element ratios indicated that fast washout time and optimal instrument parameters made it feasible to perform line scanning quantitative analysis accurately. Comparing to traditional microanalysis, line scanning quantitative analysis could reduce the laser beam size (<15 μm) and improve the spatial resolution efficiently. The potential of the technique to unveil compositional complexities in greater detail would help to improve our understanding of geochemical processes in mineral scale.
2018, 46(6): 938-946
doi: 10.11895/j.issn.0253-3820.171277
Abstract:
A novel immunochromatographic assay was developed, which could provide visual evidence of triazophos in agro products, and also could directly identify the safety status by setting visual cut-off limit of detection in maximal residual limit (MRL) value. Three test lines (T1, T2, T3) were applied to the nitrocellulose membrane with different concentrations of Triazophos-OVA, and one control line (C) was settled with goat anti mouse IgG antibody. Thereafter, by combining with conjugate pad which immobilized monoclonal antibody labeled with 20 nm Colloidal gold particles, absorbent pad and PVC plate, a chromatographic test strip was assembled. With optimization of sample extraction and solvents selection, the test strips were employed for the determination of triazophos in rice, cabbage and apple. The results revealed that the cut-off limit of detection could reach 0.005, 0.01 and 0.02 μg/mL represented by test line T3, T2 and T1, respectively. After modification, the cut-off limit of detection was resettled to 0.05, 0.1 and 0.2 μg/mL according to the MRL values which enforced by the national standard of GB2763. Using acetonitrile for the sample extraction, the extracts were diluted 10 times or solvent exchanged with equivalent volume by PBS solution, and then tested by strips descripted above mentioned. The two test strips could precisely identified the safety status of agro product with MRL as threshold within 8-12 min. Furthermore, the residues value of triazophos could be quantified by the multiple quantitative test lines. Parallel GC data indicated that the strip had no false negative. This MRL-based multiple quantitative triazophos detection strip would provide a simple, direct, accurate and the most intuitionistic performance for the evaluation of agro product safety.
A novel immunochromatographic assay was developed, which could provide visual evidence of triazophos in agro products, and also could directly identify the safety status by setting visual cut-off limit of detection in maximal residual limit (MRL) value. Three test lines (T1, T2, T3) were applied to the nitrocellulose membrane with different concentrations of Triazophos-OVA, and one control line (C) was settled with goat anti mouse IgG antibody. Thereafter, by combining with conjugate pad which immobilized monoclonal antibody labeled with 20 nm Colloidal gold particles, absorbent pad and PVC plate, a chromatographic test strip was assembled. With optimization of sample extraction and solvents selection, the test strips were employed for the determination of triazophos in rice, cabbage and apple. The results revealed that the cut-off limit of detection could reach 0.005, 0.01 and 0.02 μg/mL represented by test line T3, T2 and T1, respectively. After modification, the cut-off limit of detection was resettled to 0.05, 0.1 and 0.2 μg/mL according to the MRL values which enforced by the national standard of GB2763. Using acetonitrile for the sample extraction, the extracts were diluted 10 times or solvent exchanged with equivalent volume by PBS solution, and then tested by strips descripted above mentioned. The two test strips could precisely identified the safety status of agro product with MRL as threshold within 8-12 min. Furthermore, the residues value of triazophos could be quantified by the multiple quantitative test lines. Parallel GC data indicated that the strip had no false negative. This MRL-based multiple quantitative triazophos detection strip would provide a simple, direct, accurate and the most intuitionistic performance for the evaluation of agro product safety.
2018, 46(6): 947-951
doi: 10.11895/j.issn.0253-3820.171390
Abstract:
Excessive mercury ions have negative effects on individual health. So, it is of great significance to develop a method for rapid, sensitive and specific detection of Hg2+. In this study, the method for detection of Hg2+ was developed based on specific T-Hg-T mismatche and G-quadruplex. The template sequence mainly included the recognition region which could combine with Hg2+ specifically, the rich G region which could form G-quadruplex, and the speacer 18 partition zone. The target sequence mainly included 5' ends combining area and 3' end T-rich region. Templates and targets could be combined and the elongation was triggered only in the presence of Hg2+. Furthermore, the G-rich sequences were stripped off the templates and could form a single-stranded structure, because Spacer 18 had partition function. The G-quadruplex was formed with the K+ and hemin, and catalyzed H2O2-2,2-azinobis (3-ethylbenzothiozoline)-6-sulfonic acid(ABTS) reaction with color variations. The detection could be done within 35 min, and the Hg2+ concentration exhibited a linear correlation with absorbance at 414 nm within range of 20-500 nmol/L, with a detection limit of 16.5 nmol/L (3σ). The recoveries of Hg2+ spiked in tap water were 98.5%-103.5%. The method exhibited the advantages such as simple operation, low cost and short time, and operation value in emergency treatment and real-time environmental detection.
Excessive mercury ions have negative effects on individual health. So, it is of great significance to develop a method for rapid, sensitive and specific detection of Hg2+. In this study, the method for detection of Hg2+ was developed based on specific T-Hg-T mismatche and G-quadruplex. The template sequence mainly included the recognition region which could combine with Hg2+ specifically, the rich G region which could form G-quadruplex, and the speacer 18 partition zone. The target sequence mainly included 5' ends combining area and 3' end T-rich region. Templates and targets could be combined and the elongation was triggered only in the presence of Hg2+. Furthermore, the G-rich sequences were stripped off the templates and could form a single-stranded structure, because Spacer 18 had partition function. The G-quadruplex was formed with the K+ and hemin, and catalyzed H2O2-2,2-azinobis (3-ethylbenzothiozoline)-6-sulfonic acid(ABTS) reaction with color variations. The detection could be done within 35 min, and the Hg2+ concentration exhibited a linear correlation with absorbance at 414 nm within range of 20-500 nmol/L, with a detection limit of 16.5 nmol/L (3σ). The recoveries of Hg2+ spiked in tap water were 98.5%-103.5%. The method exhibited the advantages such as simple operation, low cost and short time, and operation value in emergency treatment and real-time environmental detection.
2018, 46(6): 952-959
doi: 10.11895/j.issn.0253-3820.171540
Abstract:
A colorimetric method was developed for detection of mercury based on the inhibition of oxidation of peroxidase substrates. The as-prepared gold nanoclusters (Au NCs), which has been stabilized and reduced by Glutathione (GSH), can effectively catalyze the H2O2-TMB to generate a blue color signal. It is interestingly that Hg2+ can inhibit the oxidation of peroxidase substrates, thus causing a color diminished. Taking advantage of the inhibitive effect of Hg2+, a novel Hg2+ sensor has been developed. In this system, sensing conditions, including pH of the buffer solution, substrate concentration and time, were optimized. Under the optimal conditions, the probe showed a linear range of 10-300 nmol/L (R2=0.997) with a detection limit of 6.26 nmol/L. In addition, this sensor exhibited good selectivity and sensitivity for Hg2+ against other common environmental mental ions, providing a new method for water analysis.
A colorimetric method was developed for detection of mercury based on the inhibition of oxidation of peroxidase substrates. The as-prepared gold nanoclusters (Au NCs), which has been stabilized and reduced by Glutathione (GSH), can effectively catalyze the H2O2-TMB to generate a blue color signal. It is interestingly that Hg2+ can inhibit the oxidation of peroxidase substrates, thus causing a color diminished. Taking advantage of the inhibitive effect of Hg2+, a novel Hg2+ sensor has been developed. In this system, sensing conditions, including pH of the buffer solution, substrate concentration and time, were optimized. Under the optimal conditions, the probe showed a linear range of 10-300 nmol/L (R2=0.997) with a detection limit of 6.26 nmol/L. In addition, this sensor exhibited good selectivity and sensitivity for Hg2+ against other common environmental mental ions, providing a new method for water analysis.
2018, 46(6): 960-968
doi: 10.11895/j.issn.0253-3820.181096
Abstract:
A novel method for rapid detection of arginine based on fluorescence resonance energy transfer effect (FRET) between carbon quantum dots (CQDs) and gold nanoparticles (AuNPs) was developed. Firstly, the CQDs with excellent fluorescence properties were synthesized by one-step microwave assisted method. The AuNPs/CQDs composites were characterized and their quenching mechanism was analyzed. Then the amount of AuNPs/CQDs, the pH value and the reaction time were optimal. Under the optimum conditions, the fluorescence system was used to detect the content of arginine, showing a good linear relationship (R2=0.993) between fluorescence intensity and concentration of arginine in the range of 0.1-10.0 μmol/L, and the detection limit was 5.8 nmol/L. Finally, the content of arginine in grape juice was determined by this method with recoveries of 105.4%-110.8%, which indicated that the proposed FRET system had the potential for practical detection of arginine in fruit juices
A novel method for rapid detection of arginine based on fluorescence resonance energy transfer effect (FRET) between carbon quantum dots (CQDs) and gold nanoparticles (AuNPs) was developed. Firstly, the CQDs with excellent fluorescence properties were synthesized by one-step microwave assisted method. The AuNPs/CQDs composites were characterized and their quenching mechanism was analyzed. Then the amount of AuNPs/CQDs, the pH value and the reaction time were optimal. Under the optimum conditions, the fluorescence system was used to detect the content of arginine, showing a good linear relationship (R2=0.993) between fluorescence intensity and concentration of arginine in the range of 0.1-10.0 μmol/L, and the detection limit was 5.8 nmol/L. Finally, the content of arginine in grape juice was determined by this method with recoveries of 105.4%-110.8%, which indicated that the proposed FRET system had the potential for practical detection of arginine in fruit juices
2018, 46(6): 969-974
doi: 10.11895/j.issn.0253-3820.171198
Abstract:
Exhaled breath condensate (EBC) was analyzed by gas chromatography-mass spectrometry (GC-MS/MS) in childhood asthma and healthy control, aiming to find the potential markers of EBC in children with asthma, and provide a scientific reference for its pathogenesis and early screening. EBC samples were collected from 21 asthmatic children (age (8.2±1.6) years) and 17 healthy children (age (8.1±1.3) years). GC-MS/MS was used to obtain the full scan data of chemical components. Cluster analysis was performed on the two groups of metabolites by principal component analysis (PCA), and potential biomarkers were found using Metaboanalyst 3.0 attributable metabolic pathways. The results showed that the EBC metabolic maps of asthmatic group and normal group were very different, and eight endogenous potential biomarkers were identified, suggesting that starch and sucrose metabolism, lysine degradation, aminoglycan nucleoside metabolism, phenylalanine metabolism may play important roles in the development of asthma in children.
Exhaled breath condensate (EBC) was analyzed by gas chromatography-mass spectrometry (GC-MS/MS) in childhood asthma and healthy control, aiming to find the potential markers of EBC in children with asthma, and provide a scientific reference for its pathogenesis and early screening. EBC samples were collected from 21 asthmatic children (age (8.2±1.6) years) and 17 healthy children (age (8.1±1.3) years). GC-MS/MS was used to obtain the full scan data of chemical components. Cluster analysis was performed on the two groups of metabolites by principal component analysis (PCA), and potential biomarkers were found using Metaboanalyst 3.0 attributable metabolic pathways. The results showed that the EBC metabolic maps of asthmatic group and normal group were very different, and eight endogenous potential biomarkers were identified, suggesting that starch and sucrose metabolism, lysine degradation, aminoglycan nucleoside metabolism, phenylalanine metabolism may play important roles in the development of asthma in children.
2018, 46(6): 975-984
doi: 10.11895/j.issn.0253-3820.171315
Abstract:
A fast, simple and cost-effective UPLC-MS/MS method was established for determination of 16 kinds of mycotoxins in vegetable oils with stable isotope dilution technique. Samples were extracted by acetonitrile-water-acetic acid 84:15:1(V/V) and then diluted using water without any further clean-up steps. The mycotoxins were fully separated on a pentafluorophenyl column. Matrix effects were efficiently compensated by the[13C]-labelled internal standards. The mean recoveries at three different concentration levels ranged from 74.2% to 105.6%, with RSD varied from 0.3% to 13.9%. Finally, the method was applied to analyze several kinds of vegetable oil samples. The method was simple, rapid, high sensitive and suitable for the determination of mycotoxins in vegetable oils.
A fast, simple and cost-effective UPLC-MS/MS method was established for determination of 16 kinds of mycotoxins in vegetable oils with stable isotope dilution technique. Samples were extracted by acetonitrile-water-acetic acid 84:15:1(V/V) and then diluted using water without any further clean-up steps. The mycotoxins were fully separated on a pentafluorophenyl column. Matrix effects were efficiently compensated by the[13C]-labelled internal standards. The mean recoveries at three different concentration levels ranged from 74.2% to 105.6%, with RSD varied from 0.3% to 13.9%. Finally, the method was applied to analyze several kinds of vegetable oil samples. The method was simple, rapid, high sensitive and suitable for the determination of mycotoxins in vegetable oils.
2018, 46(6): 985-992
doi: 10.11895/j.issn.0253-3820.171162
Abstract:
In view of the present situation that edible marine shellfishes are combinedly contaminated by different kinds of lipophilic toxins, common lipophilic shellfish toxins in marine shellfishes were simultaneously detected by liquid chromatography-tandem mass spectrometry, and the safety risk of commercial marine shellfish was evaluated using the risk assessment method based on combined contamination of various toxins. Under the optimum conditions, satisfactory recoveries (63.3%-88.8%), precision (relative standard deviations RSD ≤ 14.5%) and sensitivity (limit of detection in the range of 0.5-2.7 ng/g) of the method were achieved for all the analytes. Among the 105 commercially available shellfish samples, 42.86% of the samples had at least a kind of toxin. The highest average content was 47.6 μg/kg of DTX1, which was the most serious contaminant for marine shellfishes. The total Expose Risk Index (ΣERI) was calculated based on Tolerable Daily Intake (TDI) and Acute Reference Dose (ARfD) of each toxin to evaluate the safety risk of commercial marine shellfish. The results showed that the ratio of commercially available marine shellfish with safety risk was 19.05% and the food safety risk of scallop was the highest. In summary, a new method based on the combined contamination of lipophilic shellfish toxins was successfully developed for risk assessment of the commercial marine shellfish. The proposed method is more harsh compared with the European Food Safety Authority (EFSA) regulation and can make shellfish consumers better to avoid the risk of poisoning.
In view of the present situation that edible marine shellfishes are combinedly contaminated by different kinds of lipophilic toxins, common lipophilic shellfish toxins in marine shellfishes were simultaneously detected by liquid chromatography-tandem mass spectrometry, and the safety risk of commercial marine shellfish was evaluated using the risk assessment method based on combined contamination of various toxins. Under the optimum conditions, satisfactory recoveries (63.3%-88.8%), precision (relative standard deviations RSD ≤ 14.5%) and sensitivity (limit of detection in the range of 0.5-2.7 ng/g) of the method were achieved for all the analytes. Among the 105 commercially available shellfish samples, 42.86% of the samples had at least a kind of toxin. The highest average content was 47.6 μg/kg of DTX1, which was the most serious contaminant for marine shellfishes. The total Expose Risk Index (ΣERI) was calculated based on Tolerable Daily Intake (TDI) and Acute Reference Dose (ARfD) of each toxin to evaluate the safety risk of commercial marine shellfish. The results showed that the ratio of commercially available marine shellfish with safety risk was 19.05% and the food safety risk of scallop was the highest. In summary, a new method based on the combined contamination of lipophilic shellfish toxins was successfully developed for risk assessment of the commercial marine shellfish. The proposed method is more harsh compared with the European Food Safety Authority (EFSA) regulation and can make shellfish consumers better to avoid the risk of poisoning.
