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2021 Volume 49 Issue 3
2021, 49(3): 319-329
doi: 10.19756/j.issn.0253-3820.201664
Abstract:
Environmental pollutants are difficult to degrade and easy to accumulate, and thus pose a serious threat to human health and ecological environment. Therefore, it is very important to rapidly and sensitively detect pollutants. Metal nanoclusters (MNCs) have good application prospects in the field of chemical sensing due to their advantages such as small size, high stability, short preparation time and easy modification. As a new type of fluorescent nanomaterials, MNCs have attracted much attention in the field of pollutant detection. In this paper, the research progresses of MNCs in detecting heavy metal ions, sulfides, cyanides, polynitroaromatics, formaldehyde, organic pesticides, bacteria and viruses in recent years are summarized, and the development prospect of MNCs is discussed.
Environmental pollutants are difficult to degrade and easy to accumulate, and thus pose a serious threat to human health and ecological environment. Therefore, it is very important to rapidly and sensitively detect pollutants. Metal nanoclusters (MNCs) have good application prospects in the field of chemical sensing due to their advantages such as small size, high stability, short preparation time and easy modification. As a new type of fluorescent nanomaterials, MNCs have attracted much attention in the field of pollutant detection. In this paper, the research progresses of MNCs in detecting heavy metal ions, sulfides, cyanides, polynitroaromatics, formaldehyde, organic pesticides, bacteria and viruses in recent years are summarized, and the development prospect of MNCs is discussed.
2021, 49(3): 330-340
doi: 10.19756/j.issn.0253-3820.201352
Abstract:
Heavy metal ions are extremely harmful to human health and ecosystems. The establishment of fast, convenient, accurate and sensitive detection techniques for heavy metal ion has important theoretical and application significance for protecting human health and maintaining ecosystem balance. The electrochemical analytical method has many advantages such as high sensitivity, fast analysis speed, simple equipment, and portability in detecting heavy metal ions. The appropriate modification of the working electrode is an effective way to improve the detection sensitivity. A variety of organic and inorganic materials have been widely used to modify the working electrode for this purpose with great progresses. This article reviews recent progresses on electrochemical detection of heavy metal ions, focusing on the influence of the electrode modification of material (inorganic materials, organic materials and biological materials) on the ion detection range and sensitivity. The advantages, limitations and prospects of various modified materials are also briefly described.
Heavy metal ions are extremely harmful to human health and ecosystems. The establishment of fast, convenient, accurate and sensitive detection techniques for heavy metal ion has important theoretical and application significance for protecting human health and maintaining ecosystem balance. The electrochemical analytical method has many advantages such as high sensitivity, fast analysis speed, simple equipment, and portability in detecting heavy metal ions. The appropriate modification of the working electrode is an effective way to improve the detection sensitivity. A variety of organic and inorganic materials have been widely used to modify the working electrode for this purpose with great progresses. This article reviews recent progresses on electrochemical detection of heavy metal ions, focusing on the influence of the electrode modification of material (inorganic materials, organic materials and biological materials) on the ion detection range and sensitivity. The advantages, limitations and prospects of various modified materials are also briefly described.
2021, 49(3): 341-349
doi: 10.19756/j.issn.0253-3820.201134
Abstract:
In the past decades, the application of on-line high performance liquid chromatography coupled with gas chromatography (HPLC-GC) has rapidly developed in quantitative analysis of mineral oil hydrocarbons (MOH). MOH are derived from petroleum and synthetic fuels and cover a large range of boiling points, mainly consisting of mineral oil saturated hydrocarbons (MOSH) and aromatic hydrocarbons (MOAH). Usually, MOH are migrated from variety of sources to various foods, thus existing in foods widely, which have been an adverse impact on human health. However, the analysis of MOH is challenging due to the limited selectivity and sensitivity of hydrogen flame ionization detector (FID). The on-line HPLC-GC combines high separation efficiency of HPLC and equal-carbon-response detection of GC-FID, which solves the problem of selectivity and sensitivity of MOH analysis. The innovation of retention gap, Y-piece interface and solvent vapor exit equipped in HPLC-GC employ large volume injection into GC-FID. Since the elution fractions from HPLC are completely transferred to GC, the analytical sensitivity of MOH is enhanced by more than two orders of magnitude and the contaminants introduced are minimized during the analytical procedure, ensuring reproducibility and accuracy of the MOH analysis. In this paper, the research history of interfaces used in on-line HPLC-GC and the matching conditions of HPLC and GC were described in detail and the sample preparation methods of interference removal and MOH enrichment based on HPLC-GC were reviewed. The limitations of HPLC-GC were summarized and the future application of the technology and the development trend in MOH analysis were prospected in the end.
In the past decades, the application of on-line high performance liquid chromatography coupled with gas chromatography (HPLC-GC) has rapidly developed in quantitative analysis of mineral oil hydrocarbons (MOH). MOH are derived from petroleum and synthetic fuels and cover a large range of boiling points, mainly consisting of mineral oil saturated hydrocarbons (MOSH) and aromatic hydrocarbons (MOAH). Usually, MOH are migrated from variety of sources to various foods, thus existing in foods widely, which have been an adverse impact on human health. However, the analysis of MOH is challenging due to the limited selectivity and sensitivity of hydrogen flame ionization detector (FID). The on-line HPLC-GC combines high separation efficiency of HPLC and equal-carbon-response detection of GC-FID, which solves the problem of selectivity and sensitivity of MOH analysis. The innovation of retention gap, Y-piece interface and solvent vapor exit equipped in HPLC-GC employ large volume injection into GC-FID. Since the elution fractions from HPLC are completely transferred to GC, the analytical sensitivity of MOH is enhanced by more than two orders of magnitude and the contaminants introduced are minimized during the analytical procedure, ensuring reproducibility and accuracy of the MOH analysis. In this paper, the research history of interfaces used in on-line HPLC-GC and the matching conditions of HPLC and GC were described in detail and the sample preparation methods of interference removal and MOH enrichment based on HPLC-GC were reviewed. The limitations of HPLC-GC were summarized and the future application of the technology and the development trend in MOH analysis were prospected in the end.
2021, 49(3): 350-358
doi: 10.19756/j.issn.0253-3820.201470
Abstract:
Based on wet chemical sampling and long path absorption photometry, an instrument for on-line monitoring atmospheric nitrogen dioxide was developed. The instrument contained three parts, including external sampling unit, transfer unit, and detection unit. The external sampling unit was composed of three spiral coils connected in series, in which NO2 was selectively absorbed. It was protected with thermal insulation and light shielding, and no inlet line was used. The transfer unit used a diaphragm pump and a peristaltic pump to control gas sampling and solution delivery through a pipeline system. The detection unit included a LEDs light source, a long path flow cell, and a spectrometer to quantify the azo dye generated by NO2. By optimizing the measurement wavelength, the accuracy and stability of the instrument were improved, and the absorption liquid formula was changed to reduce the maintenance requirement. The instrument had a high absorption efficiency (>99.5%), a low detection limit (40 ng/m3) at a response time of 4 min, and a measurement uncertainty of ±10%. With a wide measurement range from 40 ng/m3 to 410 μg/m3, it could be used to monitor the background environment atmosphere and the pollution source. The interference test showed that the main interference species in the atmosphere had negligible influences on the instrument. Compared with the commercial nitrogen oxide analyzer (Thermo 42i), the coefficient of determination R2 reached 0.98, and the difference between the two measurement results was only 3%, showing high accuracy and reliability.
Based on wet chemical sampling and long path absorption photometry, an instrument for on-line monitoring atmospheric nitrogen dioxide was developed. The instrument contained three parts, including external sampling unit, transfer unit, and detection unit. The external sampling unit was composed of three spiral coils connected in series, in which NO2 was selectively absorbed. It was protected with thermal insulation and light shielding, and no inlet line was used. The transfer unit used a diaphragm pump and a peristaltic pump to control gas sampling and solution delivery through a pipeline system. The detection unit included a LEDs light source, a long path flow cell, and a spectrometer to quantify the azo dye generated by NO2. By optimizing the measurement wavelength, the accuracy and stability of the instrument were improved, and the absorption liquid formula was changed to reduce the maintenance requirement. The instrument had a high absorption efficiency (>99.5%), a low detection limit (40 ng/m3) at a response time of 4 min, and a measurement uncertainty of ±10%. With a wide measurement range from 40 ng/m3 to 410 μg/m3, it could be used to monitor the background environment atmosphere and the pollution source. The interference test showed that the main interference species in the atmosphere had negligible influences on the instrument. Compared with the commercial nitrogen oxide analyzer (Thermo 42i), the coefficient of determination R2 reached 0.98, and the difference between the two measurement results was only 3%, showing high accuracy and reliability.
2021, 49(3): 359-365
doi: 10.19756/j.issn.0253-3820.201519
Abstract:
Radio frequency quadrupole ion guide (RF-QIG) is widely used in various mass spectrometry systems because of its simple structure and high transmission efficiency. In this study, the self-developed RF-QIG was successfully integrated into the proton transfer reaction time-of-flight mass spectrometry (PTR-TOF MS). Through the adjustment of variable radio frequency electric field, the transmission characteristics of the device in ions with different mass-charge ratio (m/z) at different operating frequencies and voltage amplitudes were investigated. The results showed that when the frequency was less than 1 MHz, the RF-QIG reported here couldn't transport ions with m/z less than 40, while H3O+ (m/z 19) and H2O·H3O+ (m/z 37) could obtain strong MS signals at 2.48 MHz and 3.43 MHz. In addition, for the ions with higher m/z, such as[C3H6O+H]+ (m/z 59),[C6H6+H]+ (m/z 79) and[C7H8+H]+ (m/z 93), the strongest signals were all obtained at 2.48 MHz. The results of MATLAB's numerical solution of the effective potential showed that when the voltage amplitude was constant, the higher the frequency was given, the lower the effective potential was obtained. Finally, the successful detection of the background air in the laboratory showed that RF-QIG could be used in the ion transportation of PTR-TOF MS system.
Radio frequency quadrupole ion guide (RF-QIG) is widely used in various mass spectrometry systems because of its simple structure and high transmission efficiency. In this study, the self-developed RF-QIG was successfully integrated into the proton transfer reaction time-of-flight mass spectrometry (PTR-TOF MS). Through the adjustment of variable radio frequency electric field, the transmission characteristics of the device in ions with different mass-charge ratio (m/z) at different operating frequencies and voltage amplitudes were investigated. The results showed that when the frequency was less than 1 MHz, the RF-QIG reported here couldn't transport ions with m/z less than 40, while H3O+ (m/z 19) and H2O·H3O+ (m/z 37) could obtain strong MS signals at 2.48 MHz and 3.43 MHz. In addition, for the ions with higher m/z, such as[C3H6O+H]+ (m/z 59),[C6H6+H]+ (m/z 79) and[C7H8+H]+ (m/z 93), the strongest signals were all obtained at 2.48 MHz. The results of MATLAB's numerical solution of the effective potential showed that when the voltage amplitude was constant, the higher the frequency was given, the lower the effective potential was obtained. Finally, the successful detection of the background air in the laboratory showed that RF-QIG could be used in the ion transportation of PTR-TOF MS system.
2021, 49(3): 366-376
doi: 10.19756/j.issn.0253-3820.201627
Abstract:
Peptide de novo sequencing is of great significance for the functional study of active peptides, discovery of disease-related protein mutants and the quality control of monoclonal antibodies. The peptide de novo sequencing method determines the types of amino acid residues based on the mass differences of ions in the mass spectrum, and then derives the amino acid sequence of the peptide. Due to the presence of noise and interfering ions in mass spectrum, the accuracy of sequencing by current sequencing algorithms is low. In this study, a de novo sequencing method based on pseudo-isobaric peptide termini labeling (PIPTL) was developed. The peptides were divided equally into two parts. For the first part, the N-termini of the peptide was dimethylated with formaldehyde, and the 16O of the C-terminal carboxyl group was replaced with 18O.For the other part, the N-termini was dimethylated with deuterated formaldehyde. The two labeled peptide samples were mixed in equal. Different labeled peptides of the same sequence differ in precursor mass by only 0.016 Da. These pseudo isobaric peptides could be fragmented at the same time in the mass spectrum to produce paired fragment ions. The developed sequencing algorithm simplified the spectra and effectively extracted and distinguished b/y ions and sequence peptides. This strategy had an accuracy of 95.51% for sequencing tryptic digested bovine serum albumin. The sequencing accuracy was significantly higher than the commercial sequencing software PEAKS. In addtion, the monoclonal antibody Herceptin tryptic peptides were sequenced, and the sequencing accuracy was 93.60%. This method could be applied to the field of characterization of monoclonal antibody sequences.
Peptide de novo sequencing is of great significance for the functional study of active peptides, discovery of disease-related protein mutants and the quality control of monoclonal antibodies. The peptide de novo sequencing method determines the types of amino acid residues based on the mass differences of ions in the mass spectrum, and then derives the amino acid sequence of the peptide. Due to the presence of noise and interfering ions in mass spectrum, the accuracy of sequencing by current sequencing algorithms is low. In this study, a de novo sequencing method based on pseudo-isobaric peptide termini labeling (PIPTL) was developed. The peptides were divided equally into two parts. For the first part, the N-termini of the peptide was dimethylated with formaldehyde, and the 16O of the C-terminal carboxyl group was replaced with 18O.For the other part, the N-termini was dimethylated with deuterated formaldehyde. The two labeled peptide samples were mixed in equal. Different labeled peptides of the same sequence differ in precursor mass by only 0.016 Da. These pseudo isobaric peptides could be fragmented at the same time in the mass spectrum to produce paired fragment ions. The developed sequencing algorithm simplified the spectra and effectively extracted and distinguished b/y ions and sequence peptides. This strategy had an accuracy of 95.51% for sequencing tryptic digested bovine serum albumin. The sequencing accuracy was significantly higher than the commercial sequencing software PEAKS. In addtion, the monoclonal antibody Herceptin tryptic peptides were sequenced, and the sequencing accuracy was 93.60%. This method could be applied to the field of characterization of monoclonal antibody sequences.
2021, 49(3): 377-386
doi: 10.19756/j.issn.0253-3820.201744
Abstract:
Foodborne illnesses caused by pathogenic bacteria are prominent issues in food safety. Fast and sensitive detection of pathogenic bacteria is significantly essential for food safety. In this work, an aptasensor based on aldehyde magnetic beads, rolling circle amplification (RCA) and DNA hydrogel was developed for visualized, simple and rapid detection of Escherichia Coli O157:H7 (E.coli O157:H7). The Mbs@dsDNA complexes were first prepared. In the presence of target, the aptamer combined with E.coli O157:H7, which released E.coliaptamer-initiator. The supernatant collected by magnetic separation and the released primers were hybridized with circular sequence to form padlock probe. Then, the RCA reaction was initiated by adding T4 DNA ligase, phi29 DNA polymerase and dNTPs, while the RCA could not be triggered in the absence of target. Those two circular sequences were designed to contain partially complementary bases. Thus, when those two circular sequences generated two long single-stranded DNA (ssDNA) products respectively after RCA reaction, two ssDNA products hybridized with each other and formed naked-eye visible DNA hydrogel. The aptasensor was successfully used for visualized detection of E.coli O157:H7 with a detection limit of 4×103 CFU/mL, and the detection could be finished within 30 min. The aptasensor had many advantages such as high specificity and specificity, easy operation, efficient amplification, and rapid and visualized readout, showing potential in applications of food safety detection.
Foodborne illnesses caused by pathogenic bacteria are prominent issues in food safety. Fast and sensitive detection of pathogenic bacteria is significantly essential for food safety. In this work, an aptasensor based on aldehyde magnetic beads, rolling circle amplification (RCA) and DNA hydrogel was developed for visualized, simple and rapid detection of Escherichia Coli O157:H7 (E.coli O157:H7). The Mbs@dsDNA complexes were first prepared. In the presence of target, the aptamer combined with E.coli O157:H7, which released E.coliaptamer-initiator. The supernatant collected by magnetic separation and the released primers were hybridized with circular sequence to form padlock probe. Then, the RCA reaction was initiated by adding T4 DNA ligase, phi29 DNA polymerase and dNTPs, while the RCA could not be triggered in the absence of target. Those two circular sequences were designed to contain partially complementary bases. Thus, when those two circular sequences generated two long single-stranded DNA (ssDNA) products respectively after RCA reaction, two ssDNA products hybridized with each other and formed naked-eye visible DNA hydrogel. The aptasensor was successfully used for visualized detection of E.coli O157:H7 with a detection limit of 4×103 CFU/mL, and the detection could be finished within 30 min. The aptasensor had many advantages such as high specificity and specificity, easy operation, efficient amplification, and rapid and visualized readout, showing potential in applications of food safety detection.
2021, 49(3): 387-396
doi: 10.19756/j.issn.0253-3820.201594
Abstract:
A novel nonenzymatic glucose sensor based on solution-gated graphene transistor (SGGT) was constructed by combining the good electrocatalytic activity of metal organic framework (MOF) materials with the signal amplification of SGGT in sensing. With trimesic acid (BTC) as the organic ligands, copper-based MOF materials (Cu-BTC) were synthesized by solvothermal method and fixed on the glassy carbon electrode with Nafion film as the gate of the device. Monolayer graphene acted as the channel of transistor. The sensing mechanism was attributed to the change of effective gate voltage applied to SGGT induced by the electrochemical reactions of glucose at the Cu-BTC modified gate electrode, thus changing the channel carrier concentration and the channel current. Due to the good electrocatalytic activity of Cu-BTC for glucose and the high sensitivity of SGGT, the SGGT sensor modified with Cu-BTC exhibited excellent sensing performance for glucose with detection limit of as low as 1 nmol/L and linear range from 1 nmol/L to 40 mmol/L, which was superior to most of the traditional glucose detection methods. Moreover, the device exhibited a good anti-interference to the main components in sweat and blood, and showed good time stability in long-term repetitive experiments. Finally, the device was successfully applied to detection of glucose in human sweat. The SGGT sensor modified with Cu-BTC was expected to be applied to non-enzyme and non-invasive detection of glucose in the realm of diabetes treatment and monitoring.
A novel nonenzymatic glucose sensor based on solution-gated graphene transistor (SGGT) was constructed by combining the good electrocatalytic activity of metal organic framework (MOF) materials with the signal amplification of SGGT in sensing. With trimesic acid (BTC) as the organic ligands, copper-based MOF materials (Cu-BTC) were synthesized by solvothermal method and fixed on the glassy carbon electrode with Nafion film as the gate of the device. Monolayer graphene acted as the channel of transistor. The sensing mechanism was attributed to the change of effective gate voltage applied to SGGT induced by the electrochemical reactions of glucose at the Cu-BTC modified gate electrode, thus changing the channel carrier concentration and the channel current. Due to the good electrocatalytic activity of Cu-BTC for glucose and the high sensitivity of SGGT, the SGGT sensor modified with Cu-BTC exhibited excellent sensing performance for glucose with detection limit of as low as 1 nmol/L and linear range from 1 nmol/L to 40 mmol/L, which was superior to most of the traditional glucose detection methods. Moreover, the device exhibited a good anti-interference to the main components in sweat and blood, and showed good time stability in long-term repetitive experiments. Finally, the device was successfully applied to detection of glucose in human sweat. The SGGT sensor modified with Cu-BTC was expected to be applied to non-enzyme and non-invasive detection of glucose in the realm of diabetes treatment and monitoring.
2021, 49(3): 397-406
doi: 10.19756/j.issn.0253-3820.201644
Abstract:
MoS2 nanosheets with peroxidase-like activity were prepared by one-step hydrothermal method. The obtained MoS2 nanosheets could catalyze H2O2-mediated oxidation of 3, 3', 5, 5'-tetramethylbenzidine (TMB) to produce corresponding blue oxidized product (ox-TMB). Thus, a simple method for detection of H2O2 was established. Under the optimized conditions such as pH 3.7, temperature of 35℃, 1.0 μg/mL MoS2 and incubation time of 40 min, the absorbance of ox-TMB increased with the increase of H2O2 concentration. Given the fact that H2O2 was one of the products of uric acid oxidase-catalyzed uric acid oxidation, a method for the indirect detection of uric acid based on MoS2 nanosheets-catalyzed and H2O2-mediated TMB oxidation was developed. The increase of ox-TMB absorbance enabled the sensitive determination of uric acid in the lineatrange of 2.5-40 μmol/L and 40-100 μmol/L, respectively, and the detection limit was 0.093 μmol/L (3σ/k). The method exhibited potential application in the detection of uric acid in urine and serum samples with recoveries of 92.6%-102.0%.
MoS2 nanosheets with peroxidase-like activity were prepared by one-step hydrothermal method. The obtained MoS2 nanosheets could catalyze H2O2-mediated oxidation of 3, 3', 5, 5'-tetramethylbenzidine (TMB) to produce corresponding blue oxidized product (ox-TMB). Thus, a simple method for detection of H2O2 was established. Under the optimized conditions such as pH 3.7, temperature of 35℃, 1.0 μg/mL MoS2 and incubation time of 40 min, the absorbance of ox-TMB increased with the increase of H2O2 concentration. Given the fact that H2O2 was one of the products of uric acid oxidase-catalyzed uric acid oxidation, a method for the indirect detection of uric acid based on MoS2 nanosheets-catalyzed and H2O2-mediated TMB oxidation was developed. The increase of ox-TMB absorbance enabled the sensitive determination of uric acid in the lineatrange of 2.5-40 μmol/L and 40-100 μmol/L, respectively, and the detection limit was 0.093 μmol/L (3σ/k). The method exhibited potential application in the detection of uric acid in urine and serum samples with recoveries of 92.6%-102.0%.
2021, 49(3): 407-414
doi: 10.19756/j.issn.0253-3820.201547
Abstract:
ZnO, SnO2-ZnO, Pd@ZnO and Pd@SnO2-ZnO composite nanofibers were synthesized by electrospinning method. On the basis of this, a new film-type volatile organic compounds (VOCs) sensor was designed by transferring the composite nanofibers above onto silicon substrate with platinum-inter digital electrodes by dip-coating method. Multiple characterizations were employed to investigate the crystal structure, composition, morphology, and bonding states of the composite nanofibers. The characteristic tests of Pd@SnO2-ZnO sensor were carried out in gas sensor test system. The obtained results clearly demonstrated that Pd@SnO2-ZnO nanofibers exhibited significantly enhanced volatile organic compounds sensing performance compared with other nanofibers. When the operating temperature was 200℃ and the target gas concentration was 30 μg/m3, the responses of Pd@SnO2-ZnO sensor toward different volatile organic components including toluene, formaldehyde, acetone and ethanol were 70.1, 56, 34.9 and 13.8, respectively. Dynamic response time and recover time of Pd@SnO2-ZnO sensor were 4.9/9.6, 13.8/12.2, 20.2/17.6 and 29.6/39.6 s respectively, which was much higher than that of ZnO nanofibers. The enhanced VOC sensing properties of Pd@SnO2-ZnO composite nanofibers could be attributed to the electronic and chemical sensitizations of Pd and the junction formation at the interface of SnO2 and ZnO.
ZnO, SnO2-ZnO, Pd@ZnO and Pd@SnO2-ZnO composite nanofibers were synthesized by electrospinning method. On the basis of this, a new film-type volatile organic compounds (VOCs) sensor was designed by transferring the composite nanofibers above onto silicon substrate with platinum-inter digital electrodes by dip-coating method. Multiple characterizations were employed to investigate the crystal structure, composition, morphology, and bonding states of the composite nanofibers. The characteristic tests of Pd@SnO2-ZnO sensor were carried out in gas sensor test system. The obtained results clearly demonstrated that Pd@SnO2-ZnO nanofibers exhibited significantly enhanced volatile organic compounds sensing performance compared with other nanofibers. When the operating temperature was 200℃ and the target gas concentration was 30 μg/m3, the responses of Pd@SnO2-ZnO sensor toward different volatile organic components including toluene, formaldehyde, acetone and ethanol were 70.1, 56, 34.9 and 13.8, respectively. Dynamic response time and recover time of Pd@SnO2-ZnO sensor were 4.9/9.6, 13.8/12.2, 20.2/17.6 and 29.6/39.6 s respectively, which was much higher than that of ZnO nanofibers. The enhanced VOC sensing properties of Pd@SnO2-ZnO composite nanofibers could be attributed to the electronic and chemical sensitizations of Pd and the junction formation at the interface of SnO2 and ZnO.
2021, 49(3): 415-423
doi: 10.19756/j.issn.0253-3820.201465
Abstract:
An electrochemical aptasensor for detection of bisphenol A (BPA) was developed in this work. Disposable gold-film working electrode was modified with gold-coated multi-walled carbon nanotubes to form a sandwich structure, which could greatly enhance the surface area of the working electrode and electronic transport. TMB (3,3',5,5'-tetramethylbenzidine), acting as signal molecule, was intercalated into the immobilized aptamer to form a ssDNA-TMB complex. In the presence of BPA, the immobilized aptamer would have a conformational change, leading the intercalated TMB to be released from the complex. As a result, the electrochemical signal of the intercalated TMB was decreased. The change of peak current measured using differential pulse voltammetry was linearly correlated with the natural logarithm of concentration of BPA from 0.05 nmol/L to 500 nmol/L. The limit of detection was 43 pmol/L. The recoveries in real samples at different spiked levels were in the range of 88.9%-110.2%, and the relative standard deviations (RSDs) were 2.7%-9.0%. The proposed aptasensor here was simple, efficient and suitable for field testing, showing good potential for the supervision of consumer products safety.
An electrochemical aptasensor for detection of bisphenol A (BPA) was developed in this work. Disposable gold-film working electrode was modified with gold-coated multi-walled carbon nanotubes to form a sandwich structure, which could greatly enhance the surface area of the working electrode and electronic transport. TMB (3,3',5,5'-tetramethylbenzidine), acting as signal molecule, was intercalated into the immobilized aptamer to form a ssDNA-TMB complex. In the presence of BPA, the immobilized aptamer would have a conformational change, leading the intercalated TMB to be released from the complex. As a result, the electrochemical signal of the intercalated TMB was decreased. The change of peak current measured using differential pulse voltammetry was linearly correlated with the natural logarithm of concentration of BPA from 0.05 nmol/L to 500 nmol/L. The limit of detection was 43 pmol/L. The recoveries in real samples at different spiked levels were in the range of 88.9%-110.2%, and the relative standard deviations (RSDs) were 2.7%-9.0%. The proposed aptasensor here was simple, efficient and suitable for field testing, showing good potential for the supervision of consumer products safety.
2021, 49(3): 424-431
doi: 10.19756/j.issn.0253-3820.201662
Abstract:
Fritillaria is a kind of traditional Chinese medicine commonly used in China. Fritillaria has the effect of relieving cough and reducing phlegm, but its curative effect and price are quite different. In the market, the confusion and adulteration of Fritillaria medicinal materials are very common, the traditional character identification and microscopic identification cannot meet the actual needs, and the modern identification methods generally have the limitations of long analysis time, high instrument requirements, and high price. This work was based on the organic acids and nucleosides in Fritillaria, with the help of two color development principles, "indicator displacement" and "changes in pH", using commercial indicators with cross-response to build a 3×3 photochemical colorimetric sensor array for rapid identification of Fritillaria medicinal materials. The sensor array had different color change patterns in different fritillary herbs, which constituted the unique fingerprint of fritillary herbs. Partial least square discriminant analysis (PLS-DA) was used for distinguishing and identifying Chuanbeimu, Hubeibeimu, Pingbeimu, Yibeimu, Zhebeimu, fake Fritillaria, so as to realize the accurate and rapid distinguishing of Fritillaria. This work provided a simple and cost-effective method for the rapid identification and quality control of Fritillaria.
Fritillaria is a kind of traditional Chinese medicine commonly used in China. Fritillaria has the effect of relieving cough and reducing phlegm, but its curative effect and price are quite different. In the market, the confusion and adulteration of Fritillaria medicinal materials are very common, the traditional character identification and microscopic identification cannot meet the actual needs, and the modern identification methods generally have the limitations of long analysis time, high instrument requirements, and high price. This work was based on the organic acids and nucleosides in Fritillaria, with the help of two color development principles, "indicator displacement" and "changes in pH", using commercial indicators with cross-response to build a 3×3 photochemical colorimetric sensor array for rapid identification of Fritillaria medicinal materials. The sensor array had different color change patterns in different fritillary herbs, which constituted the unique fingerprint of fritillary herbs. Partial least square discriminant analysis (PLS-DA) was used for distinguishing and identifying Chuanbeimu, Hubeibeimu, Pingbeimu, Yibeimu, Zhebeimu, fake Fritillaria, so as to realize the accurate and rapid distinguishing of Fritillaria. This work provided a simple and cost-effective method for the rapid identification and quality control of Fritillaria.
2021, 49(3): 432-439
doi: 10.19756/j.issn.0253-3820.201514
Abstract:
Chromium plays an irreplaceable role in the life system. The exploration of chromium is beneficial to reveal its physiological or pathological processes. In this study, a new method was established for determination of chromium in gels by matrix-matched external standard method-laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The relative standard deviation of chromium signal intensity during ablation standard was less than 16% (n=300), the correlation coefficient (R2) of LA-ICP-MS quantitative calibration curve was 0.9805, and the detection limit of method was 2.22 μg/g. MCF-7 cells were used as an in vitro cell model, and two kinds of polyacrylamide gel electrophoresis (PAGE) methods were used to separate the protein extract after chromium incubation. And then, the electrophoresis bands obtained by two electrophoresis methods were ablated respectively by LA-ICP-MS with line scan mode, and the weak chromium-containing protein bands were obtained in electrophoresis band. Finally, the LA-ICP-MS was used to measure and image the chromium in individual cell, and it was found that cell element distribution map overlapped well with the cell contour map under the laser microscope.
Chromium plays an irreplaceable role in the life system. The exploration of chromium is beneficial to reveal its physiological or pathological processes. In this study, a new method was established for determination of chromium in gels by matrix-matched external standard method-laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The relative standard deviation of chromium signal intensity during ablation standard was less than 16% (n=300), the correlation coefficient (R2) of LA-ICP-MS quantitative calibration curve was 0.9805, and the detection limit of method was 2.22 μg/g. MCF-7 cells were used as an in vitro cell model, and two kinds of polyacrylamide gel electrophoresis (PAGE) methods were used to separate the protein extract after chromium incubation. And then, the electrophoresis bands obtained by two electrophoresis methods were ablated respectively by LA-ICP-MS with line scan mode, and the weak chromium-containing protein bands were obtained in electrophoresis band. Finally, the LA-ICP-MS was used to measure and image the chromium in individual cell, and it was found that cell element distribution map overlapped well with the cell contour map under the laser microscope.
2021, 49(3): 440-448
doi: 10.19756/j.issn.0253-3820.201658
Abstract:
Wilson's disease (WD) is an autosomal recessive inherited disease. It is characterized by liver cirrhosis and brain degeneration caused by copper (Cu) metabolic disorder, which is one of the few neurogenetic diseases that can be treated, but improper treatment will cause disability or even death. This research constructed a method for detecting Cu2+ based on surface-enhanced Raman spectroscopy (SERS). The gold nanorods (AuNRs) substrates modified with 4-mercaptopyridine (Mpy) with uniform morphology and dense hot spots were prepared. Due to the existence of lone pairs of electrons in the nitrogen atom (N) on the pyridine ring, Cu2+ could coordinate with it to change the Raman spectrum of Mpy and realized the detection of Cu2+ with high sensitivity and selectivity. Under the condition of 25℃ and reaction time of 2 min, the linear range of detection was 4.9×10-8-1×10-4 mol/L, with a detection limit of 49 nmol/L(S/N=3). This method was applied to the detection of Cu2+ in artificial urine, and the relative standard deviation (RSD) was less than 7.8%. The presented method here was simple, fast and accurate, and the detection process was nondestructive. And it had the potential to be applied to the early diagnosis and treatment of WD in the clinic.
Wilson's disease (WD) is an autosomal recessive inherited disease. It is characterized by liver cirrhosis and brain degeneration caused by copper (Cu) metabolic disorder, which is one of the few neurogenetic diseases that can be treated, but improper treatment will cause disability or even death. This research constructed a method for detecting Cu2+ based on surface-enhanced Raman spectroscopy (SERS). The gold nanorods (AuNRs) substrates modified with 4-mercaptopyridine (Mpy) with uniform morphology and dense hot spots were prepared. Due to the existence of lone pairs of electrons in the nitrogen atom (N) on the pyridine ring, Cu2+ could coordinate with it to change the Raman spectrum of Mpy and realized the detection of Cu2+ with high sensitivity and selectivity. Under the condition of 25℃ and reaction time of 2 min, the linear range of detection was 4.9×10-8-1×10-4 mol/L, with a detection limit of 49 nmol/L(S/N=3). This method was applied to the detection of Cu2+ in artificial urine, and the relative standard deviation (RSD) was less than 7.8%. The presented method here was simple, fast and accurate, and the detection process was nondestructive. And it had the potential to be applied to the early diagnosis and treatment of WD in the clinic.
2021, 49(3): 449-459
doi: 10.19756/j.issn.0253-3820.201629
Abstract:
Ten kinds of edible wild fruits from China, especially northeast China, were analyzed for their α-amylase and tyrosinase inhibitory activities. The extract of the fruit of dwarf apple had the highest α-amylase inhibitory activities and its IC50 value was close to that of acarbose, which indicated that the extract of the fruit of dwarf apple could be a good candidate for the treatment of non-insulin dependent diabetes. The antioxidant capacity was determined using DPPH method. The total phenolics and total anthocyanins were determined by Folin-Ciocalteu method and pH-differential method, respectively. The contents of seven phenolic acids were determined by high-performance liquid chromatography (HPLC). The tyrosinase inhibitory activity was found to be highly correlated with both total phenolic content and antioxidant capacity. The contents of total phenolics in the frozen wild fruits ranged from 617.3 to 7447.4 μg/g. Eight out of ten wild fruits showed high antioxidant capacity. A significant correlation between the antioxidant capacity of raw (fresh) and frozen fruits indicated that fast freezing fruit powder in liquid nitrogen followed by fast thawing did not damage the antioxidant properties of the wild fruits.
Ten kinds of edible wild fruits from China, especially northeast China, were analyzed for their α-amylase and tyrosinase inhibitory activities. The extract of the fruit of dwarf apple had the highest α-amylase inhibitory activities and its IC50 value was close to that of acarbose, which indicated that the extract of the fruit of dwarf apple could be a good candidate for the treatment of non-insulin dependent diabetes. The antioxidant capacity was determined using DPPH method. The total phenolics and total anthocyanins were determined by Folin-Ciocalteu method and pH-differential method, respectively. The contents of seven phenolic acids were determined by high-performance liquid chromatography (HPLC). The tyrosinase inhibitory activity was found to be highly correlated with both total phenolic content and antioxidant capacity. The contents of total phenolics in the frozen wild fruits ranged from 617.3 to 7447.4 μg/g. Eight out of ten wild fruits showed high antioxidant capacity. A significant correlation between the antioxidant capacity of raw (fresh) and frozen fruits indicated that fast freezing fruit powder in liquid nitrogen followed by fast thawing did not damage the antioxidant properties of the wild fruits.
2021, 49(3): 460-467
doi: 10.19756/j.issn.0253-3820.201531
Abstract:
A method for determination of tranquilizer and their metabolites residues in aquatic products by HPLC-MS/MS was developed. The samples were added with internal standard of diazepam-d5, methaqualone-d7 and chlorpromazine-d6, and then extracted by ethyl acetate under alkaline conditions. Then the extract was dried under nitrogen, and the residues were dissolved in 80% acetonitrile solution and cleaned up with PSA and C18. Isotope internal standard was used for quantification. The analytes were separated by a Capcell PAK C18 MGⅡ(100 mm×2.0 mm, 5 μm) column, and gradient eluted with a mixed solution of (2 mmol/L ammonium acetate+0.1% formic acid) and methanol. The mass spectrometric analysis was carried out under multiple reaction monitoring mode. Good linearity of the calibration curves was obtained in the concentration range of 0.5-20.0 μg/kg with the correlation coefficients (R2) of more than 0.999. The limit of detection for this method was 0.5 μg/kg and the quantitative limit was 1.0 μg/kg. The average recoveries at three fortified levels (1, 5 and 10 μg/kg) were 80.6%-119.4%, and the RSDs ranged from 0.05% to 14.5%. This method was simple, rapid with high accuracy and sensitivity, and was suitable for detection of tranquilizer residues in aquatic products.
A method for determination of tranquilizer and their metabolites residues in aquatic products by HPLC-MS/MS was developed. The samples were added with internal standard of diazepam-d5, methaqualone-d7 and chlorpromazine-d6, and then extracted by ethyl acetate under alkaline conditions. Then the extract was dried under nitrogen, and the residues were dissolved in 80% acetonitrile solution and cleaned up with PSA and C18. Isotope internal standard was used for quantification. The analytes were separated by a Capcell PAK C18 MGⅡ(100 mm×2.0 mm, 5 μm) column, and gradient eluted with a mixed solution of (2 mmol/L ammonium acetate+0.1% formic acid) and methanol. The mass spectrometric analysis was carried out under multiple reaction monitoring mode. Good linearity of the calibration curves was obtained in the concentration range of 0.5-20.0 μg/kg with the correlation coefficients (R2) of more than 0.999. The limit of detection for this method was 0.5 μg/kg and the quantitative limit was 1.0 μg/kg. The average recoveries at three fortified levels (1, 5 and 10 μg/kg) were 80.6%-119.4%, and the RSDs ranged from 0.05% to 14.5%. This method was simple, rapid with high accuracy and sensitivity, and was suitable for detection of tranquilizer residues in aquatic products.
2021, 49(3): 468-473
doi: 10.19756/j.issn.0253-3820.191378
Abstract:
To effectively analyze the infrared spectra characteristics of particulate organic carbon (POC) of primary saline-alkali soil fertilizing with different organic materials, the American AVATAR 360 Fourier transform infrared spectrometer (FTIR) was used to analyze the organic carbon infrared spectra of the POC in the range of 4000-500 cm-1. Principal components analysis (PCA) employing mean-clustering, dimensionality reduction and principal component load analysis was effectively used for analysis of infrared spectrum of POC. Meanwhile, the conventional method such semi-quantitative analysis was used to further analyze the infrared spectrum of POC for verification. The result of PCA analysis showed that the composition of POC after the different treatments was different, and the return of organic materials to the field was the main source of methylene fatty carbon and aromatic carbon in POC components. The semi-quantitative analysis also indicated that the soil POC functional group composition responded differently to the different organic material treatments. Moreover, returning organic materials increased the relative content of soil POC methylene fatty carbon and aromatic carbon, and reduced the content of soil POC carboxyl carbon, soil POC aliphatic functional groups and the aromaticity. The PCA analysis and semi-quantitative analysis results were similar. The results showed that PCA technology could be used as a preliminary technology to effectively analyze the infrared spectra characteristics of soil particles. Therefore PCA technology combined with semi-quantitative analysis could be used to comprehensively analyze the infrared spectra characteristics of soil particles.
To effectively analyze the infrared spectra characteristics of particulate organic carbon (POC) of primary saline-alkali soil fertilizing with different organic materials, the American AVATAR 360 Fourier transform infrared spectrometer (FTIR) was used to analyze the organic carbon infrared spectra of the POC in the range of 4000-500 cm-1. Principal components analysis (PCA) employing mean-clustering, dimensionality reduction and principal component load analysis was effectively used for analysis of infrared spectrum of POC. Meanwhile, the conventional method such semi-quantitative analysis was used to further analyze the infrared spectrum of POC for verification. The result of PCA analysis showed that the composition of POC after the different treatments was different, and the return of organic materials to the field was the main source of methylene fatty carbon and aromatic carbon in POC components. The semi-quantitative analysis also indicated that the soil POC functional group composition responded differently to the different organic material treatments. Moreover, returning organic materials increased the relative content of soil POC methylene fatty carbon and aromatic carbon, and reduced the content of soil POC carboxyl carbon, soil POC aliphatic functional groups and the aromaticity. The PCA analysis and semi-quantitative analysis results were similar. The results showed that PCA technology could be used as a preliminary technology to effectively analyze the infrared spectra characteristics of soil particles. Therefore PCA technology combined with semi-quantitative analysis could be used to comprehensively analyze the infrared spectra characteristics of soil particles.
2021, 49(3): 474-481
doi: 10.19756/j.issn.0253-3820.201615
Abstract:
The successful extraction of target spectra from the experimental data matrix by target factor analysis (TFA) without any preprocessing mainly depends on the concentration variance of the corresponding component. When the variance of ammonia concentrations is low and the baseline drift is serious, TFA may yield false negative results, so baseline correction is applied to improve TFA performance. In this study, six sets of data with different concentration variances and baseline drift were used to compare the baseline removal effects of standard normal variate (SNV), multiplicative scatter correction (MSC), linear fitting, wavelet transform (WT) and adaptive iterative reweighted penalty least squares (airPLS). The results showed that WT could effectively remove the baseline, so that more spectral information of ammonia and methane was allocated in the first eigenvectors of principal component analysis (PCA). The allocated information of ammonia and methane could be successfully extracted by TFA.
The successful extraction of target spectra from the experimental data matrix by target factor analysis (TFA) without any preprocessing mainly depends on the concentration variance of the corresponding component. When the variance of ammonia concentrations is low and the baseline drift is serious, TFA may yield false negative results, so baseline correction is applied to improve TFA performance. In this study, six sets of data with different concentration variances and baseline drift were used to compare the baseline removal effects of standard normal variate (SNV), multiplicative scatter correction (MSC), linear fitting, wavelet transform (WT) and adaptive iterative reweighted penalty least squares (airPLS). The results showed that WT could effectively remove the baseline, so that more spectral information of ammonia and methane was allocated in the first eigenvectors of principal component analysis (PCA). The allocated information of ammonia and methane could be successfully extracted by TFA.
