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2020 Volume 48 Issue 3
2020, 48(3): 307-315
doi: 10.19756/j.issn.0253-3820.191548
Abstract:
The human brain consists of billions of neurons, and the communication between neurons mainly relies on various neurotransmitters which are released at chemical synapses. Therefore, it is important to monitor neurotransmitter release with high temporal and spatial resolution to understand the functions of nervous system and in turn provide insights into psychiatric disease mechanisms. In this review, we summarize different categories of methods for monitoring neurotransmitters dynamics developed in recent decades in terms of principles, applications and limitations. We focus on the G protein-coupled receptor (GPCR) activation Based sensors, GRAB, which shows high temporal-spatial resolution, high sensitivity and high molecular specificity. GRAB sensors also perform well in multiple organisms, including zebrafish, drosophila and mice. In addition, the principle of GRAB sensors can be applied in general to develop sensors for detecting different neurotransmitters whose receptors share the conserved conformational changes when activated by corresponding ligands. In summary, these tools are useful for deciphering the dynamic regulation of a plethora of neurotransmitters in various neural circuits, and may enhance the understanding of the complex neuromodulation in both physiological and pathological processes.
The human brain consists of billions of neurons, and the communication between neurons mainly relies on various neurotransmitters which are released at chemical synapses. Therefore, it is important to monitor neurotransmitter release with high temporal and spatial resolution to understand the functions of nervous system and in turn provide insights into psychiatric disease mechanisms. In this review, we summarize different categories of methods for monitoring neurotransmitters dynamics developed in recent decades in terms of principles, applications and limitations. We focus on the G protein-coupled receptor (GPCR) activation Based sensors, GRAB, which shows high temporal-spatial resolution, high sensitivity and high molecular specificity. GRAB sensors also perform well in multiple organisms, including zebrafish, drosophila and mice. In addition, the principle of GRAB sensors can be applied in general to develop sensors for detecting different neurotransmitters whose receptors share the conserved conformational changes when activated by corresponding ligands. In summary, these tools are useful for deciphering the dynamic regulation of a plethora of neurotransmitters in various neural circuits, and may enhance the understanding of the complex neuromodulation in both physiological and pathological processes.
2020, 48(3): 316-322
doi: 10.19756/j.issn.0253-3820.191714
Abstract:
A system based on electrochemical microsensor was developed for total nitrogen (TN) determination in freshwaters. A new method combined alkaline potassium persulfate digestion with electrochemical sensor was used to detect TN concentration. After the digestion pretreatment for water samples, a customized electrochemical sensor, rather than the expensive spectrophotometer, was employed to detect the nitrate concentration in the digested solution, and then the TN concentration was calculated by a portable meter. Copper was electrodeposited onto the working-electrode of the sensor as the electrocatalyst material and performed high sensitivity in nitrate detection. The calibration in digested samples showed that the system had a sensitivity of 7.31 μA·L/mg for TN in the concentration range of 0.2-2.0 mg/L. The concentrations of TN in 3 standard samples and 6 real samples from lakes and rivers were detected by the portable electrochemical system, and the results were in good agreement with the data obtained by standard TN measurement method with the maximal relative deviation of 26.9%.
A system based on electrochemical microsensor was developed for total nitrogen (TN) determination in freshwaters. A new method combined alkaline potassium persulfate digestion with electrochemical sensor was used to detect TN concentration. After the digestion pretreatment for water samples, a customized electrochemical sensor, rather than the expensive spectrophotometer, was employed to detect the nitrate concentration in the digested solution, and then the TN concentration was calculated by a portable meter. Copper was electrodeposited onto the working-electrode of the sensor as the electrocatalyst material and performed high sensitivity in nitrate detection. The calibration in digested samples showed that the system had a sensitivity of 7.31 μA·L/mg for TN in the concentration range of 0.2-2.0 mg/L. The concentrations of TN in 3 standard samples and 6 real samples from lakes and rivers were detected by the portable electrochemical system, and the results were in good agreement with the data obtained by standard TN measurement method with the maximal relative deviation of 26.9%.
2020, 48(3): 323-331
doi: 10.19756/j.issn.0253-3820.191603
Abstract:
Some G-quadruplex (G4) forming sequences are able to form multimers under physiological conditions, which limits the structure-activity study of G4s. Here we reported an in-gel visual method to probe the conformational polymorphism of the derivatives of a parallel G4-forming sequence, c-Myc by flanking with different A/T bases and typical intermolecular G4-forming sequences. Fluorescence and circular dichroism (CD) spectra showed that the interaction of c-Myc derivatives with Thioflavin T (ThT) caused different fluorescence enhancements of ThT, and intermolecular parallel G4s caused higher fluorescence enhancement of ThT than that of intramolecular parallel and intermolecular antiparallel G4s. These DNA sequences were separated on native gels and stained by ThT for G4 and then by Stains-all (dye) for all DNA structures. Most of the sequences adopted parallel G4 multimers and intramolecular G4s in the presence of K+, meanwhile only a part of them formed G4 multimers and intramolecular structures in the presence of Na+. The optical density (OD) ratio of DNA bands stained by ThT and Stains-all were derived by ImageJ, and the ratios of G4 multimers were higher than 1.0, intramolecular parallel G4s were about 0.5, and non-G4s were near 0. Furthermore, the flanking nucleotides were favorable to the formation of multimers of c-Myc in K+ solutions, especially those flanking with T; while in Na+ solutions, only those sequences flanking with two or more A preferred to form G4 multimers. The results suggested the current strategy had the potential for the polymorphic study of G4s.
Some G-quadruplex (G4) forming sequences are able to form multimers under physiological conditions, which limits the structure-activity study of G4s. Here we reported an in-gel visual method to probe the conformational polymorphism of the derivatives of a parallel G4-forming sequence, c-Myc by flanking with different A/T bases and typical intermolecular G4-forming sequences. Fluorescence and circular dichroism (CD) spectra showed that the interaction of c-Myc derivatives with Thioflavin T (ThT) caused different fluorescence enhancements of ThT, and intermolecular parallel G4s caused higher fluorescence enhancement of ThT than that of intramolecular parallel and intermolecular antiparallel G4s. These DNA sequences were separated on native gels and stained by ThT for G4 and then by Stains-all (dye) for all DNA structures. Most of the sequences adopted parallel G4 multimers and intramolecular G4s in the presence of K+, meanwhile only a part of them formed G4 multimers and intramolecular structures in the presence of Na+. The optical density (OD) ratio of DNA bands stained by ThT and Stains-all were derived by ImageJ, and the ratios of G4 multimers were higher than 1.0, intramolecular parallel G4s were about 0.5, and non-G4s were near 0. Furthermore, the flanking nucleotides were favorable to the formation of multimers of c-Myc in K+ solutions, especially those flanking with T; while in Na+ solutions, only those sequences flanking with two or more A preferred to form G4 multimers. The results suggested the current strategy had the potential for the polymorphic study of G4s.
2020, 48(3): 332-338
doi: 10.19756/j.issn.0253-3820.191697
Abstract:
Solid state nanopores are widely used as sensing elements for protein and nucleic acid analysis. However, the extremely low capture rate and fast translocation speed limit the sensitivity and resolution of nanopore-based sensors. In this work, we prepared a polyaniline conductive polymer-modified solid nanopore and explored its application for studying the translocation behavior of ssDNA and dsDNA. The results demonstrated that the electrostatic interaction between the polyaniline and DNA significantly reduced the translocation rate of ssDNA to 48.2 μs/base; meanwhile, the capture efficiency of the polyaniline nanopore for ssDNA was significantly increased by using LiCl as the electrolyte solution. Additional experimental results revealed that polyaniline nanopores could distinguish ssDNA and dsDNA based on the difference in blockage amplitude and translocation time. The results showed that functional modification of solid state nanopore could regulate DNA translocation behavior effectively. In addition, the polyaniline nanopores were expected to be used as a single-molecule nanodevice for the analysis and detection of biomolecules.
Solid state nanopores are widely used as sensing elements for protein and nucleic acid analysis. However, the extremely low capture rate and fast translocation speed limit the sensitivity and resolution of nanopore-based sensors. In this work, we prepared a polyaniline conductive polymer-modified solid nanopore and explored its application for studying the translocation behavior of ssDNA and dsDNA. The results demonstrated that the electrostatic interaction between the polyaniline and DNA significantly reduced the translocation rate of ssDNA to 48.2 μs/base; meanwhile, the capture efficiency of the polyaniline nanopore for ssDNA was significantly increased by using LiCl as the electrolyte solution. Additional experimental results revealed that polyaniline nanopores could distinguish ssDNA and dsDNA based on the difference in blockage amplitude and translocation time. The results showed that functional modification of solid state nanopore could regulate DNA translocation behavior effectively. In addition, the polyaniline nanopores were expected to be used as a single-molecule nanodevice for the analysis and detection of biomolecules.
2020, 48(3): 339-346
doi: 10.19756/j.issn.0253-3820.191493
Abstract:
As a short peptide containing active thiol group, glutathione participates in many intracellular reactions, so it is of great significance to detect glutathione in cells. In this work, amino-rich graphene quantum dots were synthesized, which could coordinate with copper ions and yield aggregation-induced fluorescence quenching. However, copper ions and glutathione have stronger coordination ability, so that glutathione can promote the dissociation of copper ions from graphene quantum dots, and then lead to the fluorescence recovery of graphene quantum dots. In BR buffer media at pH 6.8, glutathione can gradually recover the fluorescence of graphene quantum dots (1 μg/mL) that is quenched by Cu2+ (250 μmol/L), which can finish within 20 min. Additionally, recovery degree of fluorescence signal is linear to the concentration of glutathione in the range of 20-500 μmol/L, and the detection limit is 3.4 μmol/L. This method is applicable to the detection of glutathione in cell lysate by using the switch action of copper ion to improve the selectivity.
As a short peptide containing active thiol group, glutathione participates in many intracellular reactions, so it is of great significance to detect glutathione in cells. In this work, amino-rich graphene quantum dots were synthesized, which could coordinate with copper ions and yield aggregation-induced fluorescence quenching. However, copper ions and glutathione have stronger coordination ability, so that glutathione can promote the dissociation of copper ions from graphene quantum dots, and then lead to the fluorescence recovery of graphene quantum dots. In BR buffer media at pH 6.8, glutathione can gradually recover the fluorescence of graphene quantum dots (1 μg/mL) that is quenched by Cu2+ (250 μmol/L), which can finish within 20 min. Additionally, recovery degree of fluorescence signal is linear to the concentration of glutathione in the range of 20-500 μmol/L, and the detection limit is 3.4 μmol/L. This method is applicable to the detection of glutathione in cell lysate by using the switch action of copper ion to improve the selectivity.
2020, 48(3): 347-354
doi: 10.19756/j.issn.0253-3820.191609
Abstract:
Three new fluorescent probes (ISBD, ISPD and ISND) were designed and synthesized. The UV-visible absorption spectrum, fluorescence spectrum, and response to pH values of the probe were studied, and the HSO3-/pH dual detection fluorescent probe ISND with stronger fluorescence intensity (higher fluorescence quantum yield), longer emission wavelength and less interference was selected for the further study. The probe ISND could be used for the sensitive and specific detection of HSO3-, with a detection limit of 8.11×10-8 mol/L (λem=458 nm, response time <1 min). In addition, with different emission wavelength (λem=565 nm), the probe could accurately detect pH value. Furthermore, the probe ISND had many advantages such as low toxicity and good membrane permeability. It could achieve fluorescence imaging of HSO3- in living cell, and exhibited good application prospects in sensing, biological signal transduction and detection.
Three new fluorescent probes (ISBD, ISPD and ISND) were designed and synthesized. The UV-visible absorption spectrum, fluorescence spectrum, and response to pH values of the probe were studied, and the HSO3-/pH dual detection fluorescent probe ISND with stronger fluorescence intensity (higher fluorescence quantum yield), longer emission wavelength and less interference was selected for the further study. The probe ISND could be used for the sensitive and specific detection of HSO3-, with a detection limit of 8.11×10-8 mol/L (λem=458 nm, response time <1 min). In addition, with different emission wavelength (λem=565 nm), the probe could accurately detect pH value. Furthermore, the probe ISND had many advantages such as low toxicity and good membrane permeability. It could achieve fluorescence imaging of HSO3- in living cell, and exhibited good application prospects in sensing, biological signal transduction and detection.
2020, 48(3): 355-362
doi: 10.19756/j.issn.0253-3820.191668
Abstract:
The gold nanoclusters (AuNCs) with red fluorescence were synthesized using glutathione (GSH) as protectants and reductants, which displayed high selectivity to Cu2+ in water and rat serum. Due to the coordination of Cu2+ with the capping ligand of AuNCs, ligand-metal charge transfer (LMCT) or ligand-metal-metal charge transfer (LMMCT) was blocked, and the fluorescence of the gold cluster was quenched, so Cu2+ could be selectively detected. Moreover, the gold cluster displayed ultrahigh selectivity and excellent sensitivity to Cu2+, which could shield 16 other interfering substances, with a detection limit of 23 nmol/L(S/N=3). In addition, the reliability of AuNCs was also verified by detection of Cu2+ in water samples and rat serum with satisfactory recoveries. This study provides a simple, fast and reliable method to detect Cu2+. The method is expected to be extended to the diagnosis of diseases, biological imaging, biomarker, water quality analysis, etc.
The gold nanoclusters (AuNCs) with red fluorescence were synthesized using glutathione (GSH) as protectants and reductants, which displayed high selectivity to Cu2+ in water and rat serum. Due to the coordination of Cu2+ with the capping ligand of AuNCs, ligand-metal charge transfer (LMCT) or ligand-metal-metal charge transfer (LMMCT) was blocked, and the fluorescence of the gold cluster was quenched, so Cu2+ could be selectively detected. Moreover, the gold cluster displayed ultrahigh selectivity and excellent sensitivity to Cu2+, which could shield 16 other interfering substances, with a detection limit of 23 nmol/L(S/N=3). In addition, the reliability of AuNCs was also verified by detection of Cu2+ in water samples and rat serum with satisfactory recoveries. This study provides a simple, fast and reliable method to detect Cu2+. The method is expected to be extended to the diagnosis of diseases, biological imaging, biomarker, water quality analysis, etc.
2020, 48(3): 363-370
doi: 10.19756/j.issn.0253-3820.191672
Abstract:
Diabetes has become a prominent issue that threatens human's health. Minimally invasive blood glucose testing may cause inconvenience and pain to patients. Wearable non-invasive blood glucose testing is becoming a hot topic in the scientific and medical field. In this study, novel palladium-silver nanowires (Pd-AgNWs) flexible electrodes were prepared by electrochemical deposition of Pd nanoparticles on the electrode with polydimethylsiloxane (PDMS) as the substrate and AgNWs as the conductive layer. The nanoparticles were uniformly deposited on AgNWs and different Pd-AgNWs electrodes were made by changing Pd deposition cycles. By using them as the working electrodes, glucose was detected by cyclic voltammetry. It was found that the Pd-AgNWs electrode deposited with 25 cycles of palladium had the best results in the detection of glucose. The experimental conditions of glucose detection were optimized. The linear ranges of glucose were 0.02-0.5 mmol/L and 1-4 mmol/L when detecting glucose by current-time method. The detection limit was 1 μmol/L and the response sensitivity was 33.18 μA/(cm2(mmol/L)) (S/N=3). This electrode exhibited good reproducibility, stability, selectivity, as well as good response in detection of salivary glucose.
Diabetes has become a prominent issue that threatens human's health. Minimally invasive blood glucose testing may cause inconvenience and pain to patients. Wearable non-invasive blood glucose testing is becoming a hot topic in the scientific and medical field. In this study, novel palladium-silver nanowires (Pd-AgNWs) flexible electrodes were prepared by electrochemical deposition of Pd nanoparticles on the electrode with polydimethylsiloxane (PDMS) as the substrate and AgNWs as the conductive layer. The nanoparticles were uniformly deposited on AgNWs and different Pd-AgNWs electrodes were made by changing Pd deposition cycles. By using them as the working electrodes, glucose was detected by cyclic voltammetry. It was found that the Pd-AgNWs electrode deposited with 25 cycles of palladium had the best results in the detection of glucose. The experimental conditions of glucose detection were optimized. The linear ranges of glucose were 0.02-0.5 mmol/L and 1-4 mmol/L when detecting glucose by current-time method. The detection limit was 1 μmol/L and the response sensitivity was 33.18 μA/(cm2(mmol/L)) (S/N=3). This electrode exhibited good reproducibility, stability, selectivity, as well as good response in detection of salivary glucose.
2020, 48(3): 371-377
doi: 10.19756/j.issn.0253-3820.191658
Abstract:
A photoelectrochemical (PEC) method was constructed for detection of Co2+ based on a WO3/AuNPs/FTO electrode. Gold nanoparticles (AuNPs) were electrochemically deposited on the surface of FTO and then tungsten trioxide (WO3) with vertically aligned plate-like structure was hydrothermally grown on the surface of AuNPs/FTO. The WO3/AuNPs/FTO was characterized by scanning electron microscopy and X-ray diffraction (XRD) patterns. From the PEC results, Co2+ had a weak inhibition effect on the photocurrent of WO3/AuNPs/FTO. After addition of ethanol, the photocurrent decreased obviously. On this basis, a sensitive PEC platform was constructed for monitoring Co2+ in the range of 0.5-7.0 μmol/L with a detection limit of 0.3 μmol/L. The recovery was from 98.3% to 110.0%, indicating that this method had good accuracy and was expected to be applied to the detection of Co2+ in real samples.
A photoelectrochemical (PEC) method was constructed for detection of Co2+ based on a WO3/AuNPs/FTO electrode. Gold nanoparticles (AuNPs) were electrochemically deposited on the surface of FTO and then tungsten trioxide (WO3) with vertically aligned plate-like structure was hydrothermally grown on the surface of AuNPs/FTO. The WO3/AuNPs/FTO was characterized by scanning electron microscopy and X-ray diffraction (XRD) patterns. From the PEC results, Co2+ had a weak inhibition effect on the photocurrent of WO3/AuNPs/FTO. After addition of ethanol, the photocurrent decreased obviously. On this basis, a sensitive PEC platform was constructed for monitoring Co2+ in the range of 0.5-7.0 μmol/L with a detection limit of 0.3 μmol/L. The recovery was from 98.3% to 110.0%, indicating that this method had good accuracy and was expected to be applied to the detection of Co2+ in real samples.
2020, 48(3): 378-388
doi: 10.19756/j.issn.0253-3820.191628
Abstract:
A monolayer graphene electrochemical platform based on chemical vapor deposition grown graphene was constructed for electrochemical detection of nicotinamide adenine dinucleotide (NADH). Caffeic acid (CFA) was immobilized on the surface of the activated graphene platform electrode (GPE) via electrodeposition. The CFA-GPE was characterized by scanning electron microscopy, atomic force microscopy, energy dispersive spectrometer, X-ray photoelectron spectroscopy, Raman spectra, and Fourier transform infrared spectra. The electrochemical behaviors of NADH were investigated by cyclic voltammetry. With the synergetic effect of graphene and CFA, the overpotential of NADH oxidation peak decreased by 0.43 V and its peak current increased significantly. Hence, a novel electrochemical sensor for selective detection of NADH was created. The broad linear response was presented by chronoamperometry, which was 0.001 μmol/L to 1200 μmol/L with a detection limit of 0.52 nmol/L (S/N=3). The simultaneous determination of NADH, glutathione and folic acid was realized by differential pulse voltammetry technique at CFA-GPE. In addition, the as-obtained sensor delivered good stability as well as high resistance to interference, and was successfully utilized in real sample detection.
A monolayer graphene electrochemical platform based on chemical vapor deposition grown graphene was constructed for electrochemical detection of nicotinamide adenine dinucleotide (NADH). Caffeic acid (CFA) was immobilized on the surface of the activated graphene platform electrode (GPE) via electrodeposition. The CFA-GPE was characterized by scanning electron microscopy, atomic force microscopy, energy dispersive spectrometer, X-ray photoelectron spectroscopy, Raman spectra, and Fourier transform infrared spectra. The electrochemical behaviors of NADH were investigated by cyclic voltammetry. With the synergetic effect of graphene and CFA, the overpotential of NADH oxidation peak decreased by 0.43 V and its peak current increased significantly. Hence, a novel electrochemical sensor for selective detection of NADH was created. The broad linear response was presented by chronoamperometry, which was 0.001 μmol/L to 1200 μmol/L with a detection limit of 0.52 nmol/L (S/N=3). The simultaneous determination of NADH, glutathione and folic acid was realized by differential pulse voltammetry technique at CFA-GPE. In addition, the as-obtained sensor delivered good stability as well as high resistance to interference, and was successfully utilized in real sample detection.
2020, 48(3): 389-395
doi: 10.19756/j.issn.0253-3820.191684
Abstract:
The molecular imprinting technique and photonic crystal materials were combined to construct an array of sensors based on inverse-opal structure molecularly imprinted photonic crystal film (MIPPs) for the determination of trace amounts of bisphenol A (BPA) and dicandiamide (DCD) in environmental water samples. The polymerization system of molecularly imprinting and elution system were optimized. The best adsorptive property and the maximum diffraction peak of the prepared BPA and DCD molecularly imprinted photonic crystal film were achieved when the ratios of monomer and template molecules were 1:2 and 1:4, respectively. The performance of the MIPPs sensor array was investigated by adsorption kinetics and adsorption isotherm experiments. Experimental results showed that the response time of the prepared MIPPs for BPA and DCD were 2.5 and 4.0 min, respectively. In the concentration range of 0.1-5.0 μg/L and 0.1-10.0 μg/L, the diffraction peak displacement of MIPPs for BPA and DCD was obvious, the maximum displacement was 39 and 31 nm, and the limits of detection were 0.051 μg/L and 0.038 μg/L(S/N=3), respectively. However, the diffraction peak displacement of the non-imprinted photonic crystal film was not obvious, which indicated that the prepared MIPPs had selective specificity. The real sample test results showed that the development MIPPs had an obvious optical signal response to the target molecules, which could be used for the rapid, sensitive and selective detection of the residual BPA and DCD in environmental waters.
The molecular imprinting technique and photonic crystal materials were combined to construct an array of sensors based on inverse-opal structure molecularly imprinted photonic crystal film (MIPPs) for the determination of trace amounts of bisphenol A (BPA) and dicandiamide (DCD) in environmental water samples. The polymerization system of molecularly imprinting and elution system were optimized. The best adsorptive property and the maximum diffraction peak of the prepared BPA and DCD molecularly imprinted photonic crystal film were achieved when the ratios of monomer and template molecules were 1:2 and 1:4, respectively. The performance of the MIPPs sensor array was investigated by adsorption kinetics and adsorption isotherm experiments. Experimental results showed that the response time of the prepared MIPPs for BPA and DCD were 2.5 and 4.0 min, respectively. In the concentration range of 0.1-5.0 μg/L and 0.1-10.0 μg/L, the diffraction peak displacement of MIPPs for BPA and DCD was obvious, the maximum displacement was 39 and 31 nm, and the limits of detection were 0.051 μg/L and 0.038 μg/L(S/N=3), respectively. However, the diffraction peak displacement of the non-imprinted photonic crystal film was not obvious, which indicated that the prepared MIPPs had selective specificity. The real sample test results showed that the development MIPPs had an obvious optical signal response to the target molecules, which could be used for the rapid, sensitive and selective detection of the residual BPA and DCD in environmental waters.
2020, 48(3): 396-404
doi: 10.19756/j.issn.0253-3820.191608
Abstract:
A molecularly imprinted photoelectrochemical sensor based on AgBiS2/Bi2S3 was constructed for detection of insecticide propoxur. AgBiS2/Bi2S3 composites were synthesized on Ti substrate by solvothermal method. Using propoxur as a template molecule and o-phenylenediamine as a functional monomer, a molecularly imprinted polymer film was formed by electropolymerization on Ti modified with AgBiS2/Bi2S3 composite material, which could be used for the specifically recognition of propoxur. The specific binding of propoxur to the imprinted cavity hinders the electron donor from passing through the cavity to the surface of the electrode, resulting in a decrease in photocurrent, and based on this, the detection of propoxur was performed. The logarithm of the concentration of propoxur was linear with the photocurrent in the range of 1.0×10-12-5.0×10-10 mol/L, and the detection limit was 2.3×10-13 mol/L. The sensor was applied to the detection of propoxur residues in actual fruit sample, and the recoveries were 101.0%-103.1%.
A molecularly imprinted photoelectrochemical sensor based on AgBiS2/Bi2S3 was constructed for detection of insecticide propoxur. AgBiS2/Bi2S3 composites were synthesized on Ti substrate by solvothermal method. Using propoxur as a template molecule and o-phenylenediamine as a functional monomer, a molecularly imprinted polymer film was formed by electropolymerization on Ti modified with AgBiS2/Bi2S3 composite material, which could be used for the specifically recognition of propoxur. The specific binding of propoxur to the imprinted cavity hinders the electron donor from passing through the cavity to the surface of the electrode, resulting in a decrease in photocurrent, and based on this, the detection of propoxur was performed. The logarithm of the concentration of propoxur was linear with the photocurrent in the range of 1.0×10-12-5.0×10-10 mol/L, and the detection limit was 2.3×10-13 mol/L. The sensor was applied to the detection of propoxur residues in actual fruit sample, and the recoveries were 101.0%-103.1%.
2020, 48(3): 405-412
doi: 10.19756/j.issn.0253-3820.191604
Abstract:
Five amanita peptide toxins, such as α-amanita, β-amanita, phalloidin, viroidin and ala-viroidin in human plasma and urine were determined by high-performance liquid chromatography coupled with triple quadrupole mass spectrometry under positive ion multiple reaction monitoring mode (MRM). The samples were enriched and purified by HLB solid phase extraction cartridge, and separated by CAPCELL CORE C18 column using 10 mmol/L aqueous ammonium acetate-methanol as mobile phase under a gradient elution. The results indicated that the five amanita peptide toxins in plasma or urine had good linear relationship in a wide range of concentration levels. The detection limits of the toxins were 0.2 and 0.5 μg/L (S/N=3), the average recoveries were 98.0%-114.6% and 90.1%-99.4% for spiked plasma and urine samples, respectively. Accuracy, precision and matrix effects could meet the methodological requirement for biological samples analysis. The established method had many advantages such as simple operation and high sensitivity, which provided an accurate and reliable technical support for the diagnosis and medical treatment of clinical amanita poisoned patients.
Five amanita peptide toxins, such as α-amanita, β-amanita, phalloidin, viroidin and ala-viroidin in human plasma and urine were determined by high-performance liquid chromatography coupled with triple quadrupole mass spectrometry under positive ion multiple reaction monitoring mode (MRM). The samples were enriched and purified by HLB solid phase extraction cartridge, and separated by CAPCELL CORE C18 column using 10 mmol/L aqueous ammonium acetate-methanol as mobile phase under a gradient elution. The results indicated that the five amanita peptide toxins in plasma or urine had good linear relationship in a wide range of concentration levels. The detection limits of the toxins were 0.2 and 0.5 μg/L (S/N=3), the average recoveries were 98.0%-114.6% and 90.1%-99.4% for spiked plasma and urine samples, respectively. Accuracy, precision and matrix effects could meet the methodological requirement for biological samples analysis. The established method had many advantages such as simple operation and high sensitivity, which provided an accurate and reliable technical support for the diagnosis and medical treatment of clinical amanita poisoned patients.
2020, 48(3): 413-422
doi: 10.19756/j.issn.0253-3820.191049
Abstract:
A high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF/MS) method for determination of seven kinds of alkylamines was established. Samples were amidated with 0.4% benzyl chloroformate (Cbz-Cl) in acetonitrile-sodium carbonate solution (50:50, V/V). The amidated conditions, including concentration of sodium carbonate solution (1.5%, m/V), benzyl chloroformate ratio and amount of sodium chloride (1.5 g), were optimized by response surface methodology. Under the optimized chromatographic and mass spectrometer conditions, the data were collected with electrospray ionization (ESI) sources under positive ion mode. The calibration curves of seven kinds of alkylamines showed good linearity in concentration range of 1.0-500 μg/L(R2>0.9957). The average recoveries were 82.0%-108.0%, the limits of detection and quantification were 0.5-1.0 μg/kg and 2.0-4.0 μg/kg, respectively, and the relative standard deviations (RSDs) were 3.5%-6.8%. This method is efficient and easy to be operated, and has good sensitivity, high precision and accuracy in the determination of seven alkylamines in food contact plastic materials.
A high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF/MS) method for determination of seven kinds of alkylamines was established. Samples were amidated with 0.4% benzyl chloroformate (Cbz-Cl) in acetonitrile-sodium carbonate solution (50:50, V/V). The amidated conditions, including concentration of sodium carbonate solution (1.5%, m/V), benzyl chloroformate ratio and amount of sodium chloride (1.5 g), were optimized by response surface methodology. Under the optimized chromatographic and mass spectrometer conditions, the data were collected with electrospray ionization (ESI) sources under positive ion mode. The calibration curves of seven kinds of alkylamines showed good linearity in concentration range of 1.0-500 μg/L(R2>0.9957). The average recoveries were 82.0%-108.0%, the limits of detection and quantification were 0.5-1.0 μg/kg and 2.0-4.0 μg/kg, respectively, and the relative standard deviations (RSDs) were 3.5%-6.8%. This method is efficient and easy to be operated, and has good sensitivity, high precision and accuracy in the determination of seven alkylamines in food contact plastic materials.
2020, 48(3): 423-430
doi: 10.19756/j.issn.0253-3820.191503
Abstract:
A method for rapid and non-targeted screening of pesticide residues in green tea by Sin-QuEChERS combined with ultra performance liquid chromatography-Q-Exactive Orbitrap mass spectrometry was developed. The method was optimized using 38 pesticides and metabolites as quality control compounds. The samples were extracted with acetonitrile contained 0.1% formic acid, salted out, shaken, centrifuged, and single-step purified by a Sin-QuEChERS Nano purification column. The separation of sample was performed on a Thermo Accucore aQ (2.1 mm×150 mm, 2.6 μm) column. Methanol and 0.1% formic acid water solution (containing 5 mmol/L ammonium formate) were used as the mobile phase for gradient elution. The analysis was performed in Full MS/ddMS2 scan mode in positive ion mode. The exact molecular weight deviation of each substance was less than 3.8×10-6. The detection result showed that the 38 pesticides and metabolites had good linear relationships within their respective linear ranges (R>0.99). Except for ethiocarb and phosporine, at the spiked levels of 0.01, 0.02 and 0.05 mg/kg, the average recovery of each substance was 68%-115%, of which the RSDs were 0.4%-18.9%, and the limits of quantification (LOQs) were 0.005-0.020 mg/kg. This method was applied to non-target quickly screen residual pesticides in green tea samples and quantify the residual levels, and 10 pesticide residues were detected. The method was simple, fast, efficient and accurate, and could be used for the rapid screening of multi-pesticide residues and metabolites in green tea.
A method for rapid and non-targeted screening of pesticide residues in green tea by Sin-QuEChERS combined with ultra performance liquid chromatography-Q-Exactive Orbitrap mass spectrometry was developed. The method was optimized using 38 pesticides and metabolites as quality control compounds. The samples were extracted with acetonitrile contained 0.1% formic acid, salted out, shaken, centrifuged, and single-step purified by a Sin-QuEChERS Nano purification column. The separation of sample was performed on a Thermo Accucore aQ (2.1 mm×150 mm, 2.6 μm) column. Methanol and 0.1% formic acid water solution (containing 5 mmol/L ammonium formate) were used as the mobile phase for gradient elution. The analysis was performed in Full MS/ddMS2 scan mode in positive ion mode. The exact molecular weight deviation of each substance was less than 3.8×10-6. The detection result showed that the 38 pesticides and metabolites had good linear relationships within their respective linear ranges (R>0.99). Except for ethiocarb and phosporine, at the spiked levels of 0.01, 0.02 and 0.05 mg/kg, the average recovery of each substance was 68%-115%, of which the RSDs were 0.4%-18.9%, and the limits of quantification (LOQs) were 0.005-0.020 mg/kg. This method was applied to non-target quickly screen residual pesticides in green tea samples and quantify the residual levels, and 10 pesticide residues were detected. The method was simple, fast, efficient and accurate, and could be used for the rapid screening of multi-pesticide residues and metabolites in green tea.
