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2016 Volume 44 Issue 12
2016, 44(12): 1801-1807
doi: 10.11895/j.issn.0253-3820.160344
Abstract:
A mycobacterium smegmatis porin A (MspA) protein nanopore was prepared by E.coil prokaryotic expression system. The extraction experiments of MspA nanopore using surfactants showed that an extraction agent concentration of 0.5%, a temperature of 90℃ and an extraction time of 30 min were the optimum extraction conditions. The interactions of MspA nanopore with a variety of cyclodextrins were examined at single-molecule level. The interaction between MspA and Per-6-amino-β-cyclodextrin (am7-β-CD) was stronger and consistent with blocking platform. Its retention time in the MspA nanopore decreased with the increasing voltage, whereas the blocking current was almost not affected by voltage. So the am7-β-CD was selected as a non-covalent adapter and lodged within single MspA nanopore to study the single-molecule host-guest chemistry. After adding am7-β-CD to form a first blocked platform, a small concentration of 50 μmol/L for the amantadine hydrochloride showed a second blocked platform and its residence time decreased with the increasing voltage. This new protein nanopore sensor can be used as a single-molecule detector and identifier for small organic molecules, which will greatly broaden the application range of MspA nanopore.
A mycobacterium smegmatis porin A (MspA) protein nanopore was prepared by E.coil prokaryotic expression system. The extraction experiments of MspA nanopore using surfactants showed that an extraction agent concentration of 0.5%, a temperature of 90℃ and an extraction time of 30 min were the optimum extraction conditions. The interactions of MspA nanopore with a variety of cyclodextrins were examined at single-molecule level. The interaction between MspA and Per-6-amino-β-cyclodextrin (am7-β-CD) was stronger and consistent with blocking platform. Its retention time in the MspA nanopore decreased with the increasing voltage, whereas the blocking current was almost not affected by voltage. So the am7-β-CD was selected as a non-covalent adapter and lodged within single MspA nanopore to study the single-molecule host-guest chemistry. After adding am7-β-CD to form a first blocked platform, a small concentration of 50 μmol/L for the amantadine hydrochloride showed a second blocked platform and its residence time decreased with the increasing voltage. This new protein nanopore sensor can be used as a single-molecule detector and identifier for small organic molecules, which will greatly broaden the application range of MspA nanopore.
2016, 44(12): 1808-1813
doi: 10.11895/j.issn.0253-3820.160294
Abstract:
Desalination of seawater is one of the potential solutions to the freshwater shortage nowadays. Large-scale infrastructures and high cost are required in present desalination technologies, which hinder the widely used desalted seawater. Developing new desalination techniques could be of substantial benefit. In this study, poly(dimethylsiloxane) based microfluidic chips were developed to desalt the salt water by ion concentration polarization (ICP). Effects of the bias voltages, the flow rates of salt water, the dimensions of the micro channels and the lengths of the nano channels filled with Nafion polymer were investigated to improve the desalination efficiency. An optimized structure was obtained where the depth-to-width ratio of the micro channel was 1:20 and the length of the nano channel was 450 μm. When a bias voltage of 25 V and a flow rate of 4 μL/min of the salt water were applied, a champion desalination efficiency of 99% was reached. The study has important guiding significance for development of energy-efficient desalination devices in the near future.
Desalination of seawater is one of the potential solutions to the freshwater shortage nowadays. Large-scale infrastructures and high cost are required in present desalination technologies, which hinder the widely used desalted seawater. Developing new desalination techniques could be of substantial benefit. In this study, poly(dimethylsiloxane) based microfluidic chips were developed to desalt the salt water by ion concentration polarization (ICP). Effects of the bias voltages, the flow rates of salt water, the dimensions of the micro channels and the lengths of the nano channels filled with Nafion polymer were investigated to improve the desalination efficiency. An optimized structure was obtained where the depth-to-width ratio of the micro channel was 1:20 and the length of the nano channel was 450 μm. When a bias voltage of 25 V and a flow rate of 4 μL/min of the salt water were applied, a champion desalination efficiency of 99% was reached. The study has important guiding significance for development of energy-efficient desalination devices in the near future.
2016, 44(12): 1814-1819
doi: 10.11895/j.issn.0253-3820.160496
Abstract:
Infrared spectrum, UV-visible absorption spectrum and differential expression of proteome between Spirulina platensis (SP) and selenium enriched SP (Se-SP) were investigated. The selenium containing proteins were separated from the total proteins in Se-SP by a proteomic approach of two-dimensional electrophoresis (2DE), identified by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and determined by inductively coupled plasma mass spectrometry (ICP-MS). Results showed that Se enrichment cultivation could significantly up-regulate the expression of pigment proteins such as α/β subunits of phycocyanin (PC) and allophycocyanin (APC) which involved in light harvest. The large subunits of Rbisco and superoxide dismutase were also increased obviously in Se-SP. In addition, it was found that Se was abundantly distributed in the range of pH 4-7 and MW of 14.4-43 kDa in the 2DE gel. Individuals of Se containing protein should be explored in Se-SP in further studies.
Infrared spectrum, UV-visible absorption spectrum and differential expression of proteome between Spirulina platensis (SP) and selenium enriched SP (Se-SP) were investigated. The selenium containing proteins were separated from the total proteins in Se-SP by a proteomic approach of two-dimensional electrophoresis (2DE), identified by matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS), and determined by inductively coupled plasma mass spectrometry (ICP-MS). Results showed that Se enrichment cultivation could significantly up-regulate the expression of pigment proteins such as α/β subunits of phycocyanin (PC) and allophycocyanin (APC) which involved in light harvest. The large subunits of Rbisco and superoxide dismutase were also increased obviously in Se-SP. In addition, it was found that Se was abundantly distributed in the range of pH 4-7 and MW of 14.4-43 kDa in the 2DE gel. Individuals of Se containing protein should be explored in Se-SP in further studies.
2016, 44(12): 1820-1827
doi: 10.11895/j.issn.0253-3820.160449
Abstract:
A colorimetric bionic aptasensor based on magnetic metal organic framework (MOF) compound-aptamer bionic probe was designed for detecting chloramphenicol (CAP). In this assay, the aptamer was labeled on the magnetic beads as capture probe and its complementary strand (cDNA) was immobilized on MOF as the nanotracer composite probe, and the ferromagnetic biomimetic composite probe was obtained by hybridizing the capture probe with the tracer. When the composite probe solution was incubated with CAP, the aptamer on the capture probes preferentially combines with CAP, and the signal tag was substituted into supernatant after magnetic separation. The supernatant containing numerous MOF could efficiently catalyze tetramethylbenzidine (TMB)-H2O2 solution for the color development quantified by ultraviolet-visible spectroscopy. Under the optimal reaction conditions, the experimental results showed the CAP detection owned a linear range of 0.001-10 ng/mL and limit of detection was 0.3 pg/mL (S/N=3). The recoveries of standard addition in the actual samples were 86.9%-93.5% with no interference of other antibiotics. Besides, the results of this method for CAP detection in the milk samples agreed well with the ELISA results. Compared with the enzyme labeled probe, the non-enzyme labeled bionic probe using the magnetic separation greatly simplifies the pre-processing step, and it has many advantages such as high catalytic activity and low cost, and can be applied to the field detection of CAP in food with rapidity, high specificity and high sensitivity.
A colorimetric bionic aptasensor based on magnetic metal organic framework (MOF) compound-aptamer bionic probe was designed for detecting chloramphenicol (CAP). In this assay, the aptamer was labeled on the magnetic beads as capture probe and its complementary strand (cDNA) was immobilized on MOF as the nanotracer composite probe, and the ferromagnetic biomimetic composite probe was obtained by hybridizing the capture probe with the tracer. When the composite probe solution was incubated with CAP, the aptamer on the capture probes preferentially combines with CAP, and the signal tag was substituted into supernatant after magnetic separation. The supernatant containing numerous MOF could efficiently catalyze tetramethylbenzidine (TMB)-H2O2 solution for the color development quantified by ultraviolet-visible spectroscopy. Under the optimal reaction conditions, the experimental results showed the CAP detection owned a linear range of 0.001-10 ng/mL and limit of detection was 0.3 pg/mL (S/N=3). The recoveries of standard addition in the actual samples were 86.9%-93.5% with no interference of other antibiotics. Besides, the results of this method for CAP detection in the milk samples agreed well with the ELISA results. Compared with the enzyme labeled probe, the non-enzyme labeled bionic probe using the magnetic separation greatly simplifies the pre-processing step, and it has many advantages such as high catalytic activity and low cost, and can be applied to the field detection of CAP in food with rapidity, high specificity and high sensitivity.
2016, 44(12): 1828-1833
doi: 10.11895/j.issn.0253-3820.160522
Abstract:
A molecularly imprinted photonic crystal hydrogel sensor was developed with 2,4,6-trichlorophenol (2,4,6-TCP) as imprinting molecule, methanol as solvent, methacrylic acid as monomers and ethylene glycol dimethylacrylate as cross-linkers. The three-dimension silica colloidal crystal template was removed by 1% HF (V/V) and molecularly imprinted template was removed by 0.015 mol/L NaOH. The results showed that the maximum absorption peak red-shifted 31 nm when the concentration of 2,4,6-TCP changed from 0 to 6×10-4 mol/L. Then, with further increasing 2,4,6-TCP concentration, the maximum absorption peak began to blue-shift. When the concentration of 2,4,6-TCP changed to 1×10-3 mol/L, the maximum absorption peak blue-shifted 56 nm and the response time was just 30 min. This molecularly imprinted photonic crystal hydrogel sensor showed high sensitivity, high selectivity and easy operation, and was applied for the naked-eye detection of 2,4,6-trichlorophenol.
A molecularly imprinted photonic crystal hydrogel sensor was developed with 2,4,6-trichlorophenol (2,4,6-TCP) as imprinting molecule, methanol as solvent, methacrylic acid as monomers and ethylene glycol dimethylacrylate as cross-linkers. The three-dimension silica colloidal crystal template was removed by 1% HF (V/V) and molecularly imprinted template was removed by 0.015 mol/L NaOH. The results showed that the maximum absorption peak red-shifted 31 nm when the concentration of 2,4,6-TCP changed from 0 to 6×10-4 mol/L. Then, with further increasing 2,4,6-TCP concentration, the maximum absorption peak began to blue-shift. When the concentration of 2,4,6-TCP changed to 1×10-3 mol/L, the maximum absorption peak blue-shifted 56 nm and the response time was just 30 min. This molecularly imprinted photonic crystal hydrogel sensor showed high sensitivity, high selectivity and easy operation, and was applied for the naked-eye detection of 2,4,6-trichlorophenol.
2016, 44(12): 1834-1839
doi: 10.11895/j.issn.0253-3820.160366
Abstract:
A sensitive electrochemical sensor for promecarb was prepared based on molecularly imprinted strategy by thermal polymerization. The molecularly imprinted polymers (MIP) were synthesized by using promecarb as template molecule, acrylamide (AM) as functional monomer, ethylene glycol acrylate, maleic rosin ester (EGMRA) as a cross-linking, homemaking 3D graphene as sensitizing materials to modify glassy carbon electrode surface, and synthesize the promecarb molecular imprinting electrochemical sensor. 3D graphene was characterized by scanning electron microscopy (SEM). The properties of the sensor were tested via cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The results showed that promecarb concentration in the range of 8.0×10-8-8.0×10-6 mol/L had a good linear relationship (linear correlation coefficient R=0.9954) with current, and the detection limit was 7.3×10-8 mol/L (S/N=3). The imprinted factor β of promecarb molecularly imprinted sensitive film was 3.88, the selection factor α was far greater than 1 compared to the three structural analogs. The imprinted sensor was successfully used to determine promecarb in lettuce samples with recoveries ranging from 96.7% to 98.7% by using standard addition method.
A sensitive electrochemical sensor for promecarb was prepared based on molecularly imprinted strategy by thermal polymerization. The molecularly imprinted polymers (MIP) were synthesized by using promecarb as template molecule, acrylamide (AM) as functional monomer, ethylene glycol acrylate, maleic rosin ester (EGMRA) as a cross-linking, homemaking 3D graphene as sensitizing materials to modify glassy carbon electrode surface, and synthesize the promecarb molecular imprinting electrochemical sensor. 3D graphene was characterized by scanning electron microscopy (SEM). The properties of the sensor were tested via cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). The results showed that promecarb concentration in the range of 8.0×10-8-8.0×10-6 mol/L had a good linear relationship (linear correlation coefficient R=0.9954) with current, and the detection limit was 7.3×10-8 mol/L (S/N=3). The imprinted factor β of promecarb molecularly imprinted sensitive film was 3.88, the selection factor α was far greater than 1 compared to the three structural analogs. The imprinted sensor was successfully used to determine promecarb in lettuce samples with recoveries ranging from 96.7% to 98.7% by using standard addition method.
2016, 44(12): 1840-1845
doi: 10.11895/j.issn.0253-3820.160268
Abstract:
The low-toxic AgInS2 QDs were synthesized in aqueous phase and their absorption and photoluminescence spectra were characterized. The low-toxic AgInS2 QDs had a broad absorption spectra and the emission peak was around 700 nm. The composition elements were analyzed via ICP-OES. High resolution transmission electron microscopy (RTEM) was used to characterize the size and distribution of the synthesized low-toxic AgInS2 QDs. Then, the photostability and cytotoxicity of AgInS2 QDs were compared with the traditional CdTe QDs. The results showed that the AgInS2 QDs were much more stable than CdTe under the irradiation of a 405-nm laser. Without heavy metal elements, the cytotoxicity of AgInS2 QDs was much lower than CdTe QDs, which meant it was more likely to be applied in the biological field. Folic acid (FA) was known as an effective tumor targeting molecule. When AgInS2 QDs were combined with folic acid, the FA-AgInS2 QDs could be used to distinguish tumor cells between the normal cells and cancer cells. The results showed the AgInS2 QDs possessed great application prospects in the in vivo tumor detection.
The low-toxic AgInS2 QDs were synthesized in aqueous phase and their absorption and photoluminescence spectra were characterized. The low-toxic AgInS2 QDs had a broad absorption spectra and the emission peak was around 700 nm. The composition elements were analyzed via ICP-OES. High resolution transmission electron microscopy (RTEM) was used to characterize the size and distribution of the synthesized low-toxic AgInS2 QDs. Then, the photostability and cytotoxicity of AgInS2 QDs were compared with the traditional CdTe QDs. The results showed that the AgInS2 QDs were much more stable than CdTe under the irradiation of a 405-nm laser. Without heavy metal elements, the cytotoxicity of AgInS2 QDs was much lower than CdTe QDs, which meant it was more likely to be applied in the biological field. Folic acid (FA) was known as an effective tumor targeting molecule. When AgInS2 QDs were combined with folic acid, the FA-AgInS2 QDs could be used to distinguish tumor cells between the normal cells and cancer cells. The results showed the AgInS2 QDs possessed great application prospects in the in vivo tumor detection.
2016, 44(12): 1846-1851
doi: 10.11895/j.issn.0253-3820.160392
Abstract:
Two inevitable noise signals, baseline drifts and cosmic spikes in Raman spectral imaging data should be eliminated before data analysis. However, current denoising methods for a single spectrum often lead to unstable results with bad reproducible properties. In this study, a novel adaptive method for denoising Raman spectral imaging data was proposed to address this issue. Adaptive iteratively reweighted penalized least-squares (airPLS) and principal component analysis (PCA) based despiking algorithm were applied to correct drifting baselines and cosmic spikes, respectively. The method offers a variety of advantages such as less parameter to be set, no spectral distortion, fast computation speed, and stable results, etc. We utilized the method to eliminate the noise signals in Raman spectral imaging data of Miscanthus sinensis (involving 9010 spectra), and then employed PCA and cluster analysis (CA) to distinguish plant spectra from non-plant spectra. Theoretically, this method could be used to denoise other spectral imaging data and provide reliable foundation for achieving stable analysis results.
Two inevitable noise signals, baseline drifts and cosmic spikes in Raman spectral imaging data should be eliminated before data analysis. However, current denoising methods for a single spectrum often lead to unstable results with bad reproducible properties. In this study, a novel adaptive method for denoising Raman spectral imaging data was proposed to address this issue. Adaptive iteratively reweighted penalized least-squares (airPLS) and principal component analysis (PCA) based despiking algorithm were applied to correct drifting baselines and cosmic spikes, respectively. The method offers a variety of advantages such as less parameter to be set, no spectral distortion, fast computation speed, and stable results, etc. We utilized the method to eliminate the noise signals in Raman spectral imaging data of Miscanthus sinensis (involving 9010 spectra), and then employed PCA and cluster analysis (CA) to distinguish plant spectra from non-plant spectra. Theoretically, this method could be used to denoise other spectral imaging data and provide reliable foundation for achieving stable analysis results.
2016, 44(12): 1852-1858
doi: 10.11895/j.issn.0253-3820.160430
Abstract:
An extremely efficient, sensitive and facile fluorescent sensing approach for detection of 2,4,6-trinitrophenol (TNP) based on the graphite carbon nitride quantum dots (g-CNQDs) was reported. The g-CNQDs material, a novel nanometer sized semiconductor with distinct characteristics of good water-solubility, biocompatibility, environmental-friendly nontoxicity property, was successfully prepared by solid-state reaction strategy at an extremely low temperature, and we revealed that the fluorescence quenching of g-CNQDs ascribe to the molecular interactions (such as electrostatic, π-π, and hydrogen bonding interactions) between TNP and g-CNQDs. This fluorescence sensor presented high selectivity toward TNP with quick response. In the experiment, we found that g-CNQDs exhibited fine linear relationship in the concentration of 0.1-100 μmol/L and 0.1-100 μmol/L of TNP with a low detection limit (0.05 nmol/L, S/N=3). The proposed approach has a perfectly potential application prospect in fluorescence sensing field, and can be employed for determination of TNP in natural water samples and supervision of TNP in the natural water environment.
An extremely efficient, sensitive and facile fluorescent sensing approach for detection of 2,4,6-trinitrophenol (TNP) based on the graphite carbon nitride quantum dots (g-CNQDs) was reported. The g-CNQDs material, a novel nanometer sized semiconductor with distinct characteristics of good water-solubility, biocompatibility, environmental-friendly nontoxicity property, was successfully prepared by solid-state reaction strategy at an extremely low temperature, and we revealed that the fluorescence quenching of g-CNQDs ascribe to the molecular interactions (such as electrostatic, π-π, and hydrogen bonding interactions) between TNP and g-CNQDs. This fluorescence sensor presented high selectivity toward TNP with quick response. In the experiment, we found that g-CNQDs exhibited fine linear relationship in the concentration of 0.1-100 μmol/L and 0.1-100 μmol/L of TNP with a low detection limit (0.05 nmol/L, S/N=3). The proposed approach has a perfectly potential application prospect in fluorescence sensing field, and can be employed for determination of TNP in natural water samples and supervision of TNP in the natural water environment.
2016, 44(12): 1859-1866
doi: 10.11895/j.issn.0253-3820.160451
Abstract:
A supersensitive molecular imprinting polymer (MIP) electrochemical sensor based on the structure of metal organic frameworks (MOFs) for detection of phenylethanolamine A (PEA) in swine urine samples was developed. In this sensor, PEA was used as template, p-aminothiophenol was selected as functional monomer and organic ligand, and Au nanoparticles were used as metal center to fabricate a composite membrane with molecular recognition property on gold electrode by in situ electrochemical polymerization. The characterizations of modified electrode were performed with electrochemical platform and scanning electronic microscope. The analytical conditions including scan rate, pH, elution time and incubation time and so on were optimized. Under the optimum conditions, the limit of the developed MOFs-MIP electrochemical sensor for the detection for PEA was as low as 1.0×10-13 mol/L and the linear rang was from 1.0×10-13 to 1.0×10-9 mol/L with correlation coefficient of 0.996. The recoveries of PEA were from 92.7% to 108.4% under different spiked levels of PEA in animal urine and the relative standard deviation (RSD) was below 8.0%. The developed method possessed many advantages such as high sensitivity, specificity and stability.
A supersensitive molecular imprinting polymer (MIP) electrochemical sensor based on the structure of metal organic frameworks (MOFs) for detection of phenylethanolamine A (PEA) in swine urine samples was developed. In this sensor, PEA was used as template, p-aminothiophenol was selected as functional monomer and organic ligand, and Au nanoparticles were used as metal center to fabricate a composite membrane with molecular recognition property on gold electrode by in situ electrochemical polymerization. The characterizations of modified electrode were performed with electrochemical platform and scanning electronic microscope. The analytical conditions including scan rate, pH, elution time and incubation time and so on were optimized. Under the optimum conditions, the limit of the developed MOFs-MIP electrochemical sensor for the detection for PEA was as low as 1.0×10-13 mol/L and the linear rang was from 1.0×10-13 to 1.0×10-9 mol/L with correlation coefficient of 0.996. The recoveries of PEA were from 92.7% to 108.4% under different spiked levels of PEA in animal urine and the relative standard deviation (RSD) was below 8.0%. The developed method possessed many advantages such as high sensitivity, specificity and stability.
2016, 44(12): 1867-1873
doi: 10.11895/j.issn.0253-3820.160432
Abstract:
16S rRNA gene high-throughput sequencing and nuclear magnetic resonance (NMR)-based metabolomics techniques were established to understand the composition of gut microbiota and metabolites of Portunus trituberculatus. Swimming crab gut samples were used for the extraction of bacterial genomic DNA, followed by the amplification of hypervariable domain V3-V4 of 16 S rRNA gene. The obtained PCR products were used for analysis on an Illumina MiSeq platform. The bacterial phylotypes were then clustered and assigned. The results showed that swimming crab gut was dominated by proteobacteria, bacteroidetes, fusobacteria, tenericutes, and acidobacteria at the phylum level. At the genus level, Photobacterium, Paludibacter, and Propionigenium were enriched in it. Crab intestinal samples were extracted with CH3OH/H2O (2:1, V/V) solution by shaking with a tissuelyser. After the removal of methanol, the resultant supernatants were lyophilized. Each of lyophilized extract was dissolved into Na+/K+ phosphate buffer and then centrifuged at high speed for NMR analysis. A standard noesypr1D was used to acquire 1H NMR spectra. The 90° pulse length was adjusted to approximately 10 μs. The recycle delay and mixing time were set to 2 s and 100 ms in sequence. The spectral width was set to 20 ppm. Sixty-four transients were collected into 32 k data points for each spectrum. A range of two-dimensional NMR spectra were acquired for the resonance assignment. The results showed that swimming crab gut metabolome comprised 30 metabolites including some amino acids, organic acids, and amines. In summary, this study provided a method for the systematic analysis of the compositions of gut bacterial community and metabolites of swimming crab.
16S rRNA gene high-throughput sequencing and nuclear magnetic resonance (NMR)-based metabolomics techniques were established to understand the composition of gut microbiota and metabolites of Portunus trituberculatus. Swimming crab gut samples were used for the extraction of bacterial genomic DNA, followed by the amplification of hypervariable domain V3-V4 of 16 S rRNA gene. The obtained PCR products were used for analysis on an Illumina MiSeq platform. The bacterial phylotypes were then clustered and assigned. The results showed that swimming crab gut was dominated by proteobacteria, bacteroidetes, fusobacteria, tenericutes, and acidobacteria at the phylum level. At the genus level, Photobacterium, Paludibacter, and Propionigenium were enriched in it. Crab intestinal samples were extracted with CH3OH/H2O (2:1, V/V) solution by shaking with a tissuelyser. After the removal of methanol, the resultant supernatants were lyophilized. Each of lyophilized extract was dissolved into Na+/K+ phosphate buffer and then centrifuged at high speed for NMR analysis. A standard noesypr1D was used to acquire 1H NMR spectra. The 90° pulse length was adjusted to approximately 10 μs. The recycle delay and mixing time were set to 2 s and 100 ms in sequence. The spectral width was set to 20 ppm. Sixty-four transients were collected into 32 k data points for each spectrum. A range of two-dimensional NMR spectra were acquired for the resonance assignment. The results showed that swimming crab gut metabolome comprised 30 metabolites including some amino acids, organic acids, and amines. In summary, this study provided a method for the systematic analysis of the compositions of gut bacterial community and metabolites of swimming crab.
2016, 44(12): 1874-1879
doi: 10.11895/j.issn.0253-3820.160518
Abstract:
The mix-mode chromatography supports were prepared, including anion exchange and hydrophobic interaction chromatography. This matrix was based on the gigaporous polymer microspheres from copolymer of glycidyl methacrylate and ethylene glycol dimethacrylate. The microspheres were modified by poly (ethylene imine) and butyl glycidyl ether for mix-mode chromatography. The effects of ion capacity and hydrophobic ligand density on protein capacity and recovery were evaluated. The result indicated that the protein capacity and recovery increased with ion capacity of the supports in the range of 0.2-0.5 mmol/mL. The max capacity was 40 mg/mL and the protein recovery could reach more than 90%. The hydrophobic interaction chromatography occurred when hydrophobic ligand density was more than 0.03 mmol/mL. The back pressure on these supports was less than 2 MPa at 2000 cm/h. In the same time, the high resolution could be retained even at high flow rate of 2880 cm/h for purification of IgG from human serum. Therefore, this support showed a large potential in high through-put separation.
The mix-mode chromatography supports were prepared, including anion exchange and hydrophobic interaction chromatography. This matrix was based on the gigaporous polymer microspheres from copolymer of glycidyl methacrylate and ethylene glycol dimethacrylate. The microspheres were modified by poly (ethylene imine) and butyl glycidyl ether for mix-mode chromatography. The effects of ion capacity and hydrophobic ligand density on protein capacity and recovery were evaluated. The result indicated that the protein capacity and recovery increased with ion capacity of the supports in the range of 0.2-0.5 mmol/mL. The max capacity was 40 mg/mL and the protein recovery could reach more than 90%. The hydrophobic interaction chromatography occurred when hydrophobic ligand density was more than 0.03 mmol/mL. The back pressure on these supports was less than 2 MPa at 2000 cm/h. In the same time, the high resolution could be retained even at high flow rate of 2880 cm/h for purification of IgG from human serum. Therefore, this support showed a large potential in high through-put separation.
2016, 44(12): 1880-1886
doi: 10.11895/j.issn.0253-3820.160114
Abstract:
Fluorescent carbon nanodots were prepared by utilizing Maca as a carbon source via hydrothermal method. The carbon nanodots solution had a maximal fluorescent light emission at 425 nm and the excitation wavelength at 315 nm. Fluorescent light emission intensity of carbon nanodots solution could be effectively quenched by picric acid (PA) in 0.2 mol/L phosphate (pH 5.8) buffer conditions. Based on this, a novel method for the determination of picric acid was developed using carbon nanodots as fluorescent probe. This method had broad linear range from 0.4 μmol/L to 80 μmol/L with a correlation coefficient of 0.9978. The limit of detection (LOD, 3σ) was 0.11 μmol/L. Furthermore, it exhibited good selectivity and fast response time (within 2 min). The method was successfully applied in the detection of PA in real water samples with spiked recoveries ranging from 92.0% to 110.0%.
Fluorescent carbon nanodots were prepared by utilizing Maca as a carbon source via hydrothermal method. The carbon nanodots solution had a maximal fluorescent light emission at 425 nm and the excitation wavelength at 315 nm. Fluorescent light emission intensity of carbon nanodots solution could be effectively quenched by picric acid (PA) in 0.2 mol/L phosphate (pH 5.8) buffer conditions. Based on this, a novel method for the determination of picric acid was developed using carbon nanodots as fluorescent probe. This method had broad linear range from 0.4 μmol/L to 80 μmol/L with a correlation coefficient of 0.9978. The limit of detection (LOD, 3σ) was 0.11 μmol/L. Furthermore, it exhibited good selectivity and fast response time (within 2 min). The method was successfully applied in the detection of PA in real water samples with spiked recoveries ranging from 92.0% to 110.0%.
2016, 44(12): 1887-1891
doi: 10.11895/j.issn.0253-3820.160213
Abstract:
The salivary peptidomics provides a new method for study of disease biomarkers, but the effect of frozen storage conditions on analysis results is not very clear. In this study, we separated and enriched these peptides in human saliva by graphene-lanthanide phosphate composite nanomaterial (LaGM), then identified them by nano-liquid chromatography-high resolution tandem mass spectrometry. The salivary samples were analyzed after these samples were stored at -20℃ and -80℃ for six months respectively. We identified 429 peptides which belong to 33 proteins at -80℃ and 595 peptides corresponding to 31 proteins at -20℃. In comparison with the sample stored at -80℃, the "new" saliva peptides were mainly from the degradation of existing peptides. In addition, some salivary proteins also had a degree of degradation after stored at -20℃. In peptide sequence level, this study illustrated that frozen storage conditions had effects on salivary peptidome, suggesting that saliva sample should not be stored at -20℃ for long time when used to analyze peptidomics. This method can provide reference for relevant medical research.
The salivary peptidomics provides a new method for study of disease biomarkers, but the effect of frozen storage conditions on analysis results is not very clear. In this study, we separated and enriched these peptides in human saliva by graphene-lanthanide phosphate composite nanomaterial (LaGM), then identified them by nano-liquid chromatography-high resolution tandem mass spectrometry. The salivary samples were analyzed after these samples were stored at -20℃ and -80℃ for six months respectively. We identified 429 peptides which belong to 33 proteins at -80℃ and 595 peptides corresponding to 31 proteins at -20℃. In comparison with the sample stored at -80℃, the "new" saliva peptides were mainly from the degradation of existing peptides. In addition, some salivary proteins also had a degree of degradation after stored at -20℃. In peptide sequence level, this study illustrated that frozen storage conditions had effects on salivary peptidome, suggesting that saliva sample should not be stored at -20℃ for long time when used to analyze peptidomics. This method can provide reference for relevant medical research.
2016, 44(12): 1892-1899
doi: 10.11895/j.issn.0253-3820.160296
Abstract:
A new cation exchange resin was prepared based on surface-initiated atom transfer radical polymerization (SI-ATRP) of poly (sodium 4-styrene sulfonate) (PNASS) at 30℃ for 3 h from inactivated immobilized enzymes. The cation exchange resin was characterized by Fourier transform infrared spectrometry (FT-IR). Lysozyme was selected as a model protein to evaluate the adsorption performance of the as-prepared cation exchange resin. The effects of protein concentration, ionic strength, organic solvent, contacting time and temperature on protein adsorption were investigated. The results showed that the cation exchange resin exhibited very good performance for the adsorption of lysozyme with a high capacity (240 mg/g) at room temperature and fast speed (within 30 min), which were much better than those reported in previously reported works. The adsorption isotherms could be better fitted by Langmuir model than Freundlich model and the adsorption process followed the pseudo-second-order kinetic model.
A new cation exchange resin was prepared based on surface-initiated atom transfer radical polymerization (SI-ATRP) of poly (sodium 4-styrene sulfonate) (PNASS) at 30℃ for 3 h from inactivated immobilized enzymes. The cation exchange resin was characterized by Fourier transform infrared spectrometry (FT-IR). Lysozyme was selected as a model protein to evaluate the adsorption performance of the as-prepared cation exchange resin. The effects of protein concentration, ionic strength, organic solvent, contacting time and temperature on protein adsorption were investigated. The results showed that the cation exchange resin exhibited very good performance for the adsorption of lysozyme with a high capacity (240 mg/g) at room temperature and fast speed (within 30 min), which were much better than those reported in previously reported works. The adsorption isotherms could be better fitted by Langmuir model than Freundlich model and the adsorption process followed the pseudo-second-order kinetic model.
2016, 44(12): 1900-1906
doi: 10.11895/j.issn.0253-3820.160428
Abstract:
A monoclonal antibody based lateral flow immunoassay was developed for the simultaneous determination of four pyrethroid pesticides in vegetables and fruits, including fenpropathrin, cypermethrin, deltamethrin, and cyhalothrin. The colloidal gold particles (20-nm) were prepared by the method of sodium citrate reduction and conjugated with goat anti-mice IgG. Antigen and rabbit anti-goat IgG were immobilized on the nitrocellulose membrane as the test line (T line) and the control line (C line), separately. By sticking on PVC board, a gold immunochromatographic strip was assembled. About 10 g of samples was extracted by acetonitrile, and then diluted four times with PBS buffer. Anti-pyrethroid McAb was added in 100 μL of this extract solution for the antibody-antigen binding, thereafter, the mixture was ready for the strip testing. The results revealed that the test could be done within 10 min, and the cutoff values reached 0.5, 5.0, 5.0, 5.0 μg/mL for fenpropathrin, cypermethrin, deltamethrin, cyhalothrin, respectively. If the extraction going through QuEChERS method, the detection limit of method could be improved 16 times. Thereafter, the lateral flow immunoassay was employed for the verification test with 13 types of vegetables and fruits, except that the result of chillies presented the false positive result, the other results obtained higher consistency with the results of GC test. This new format of test strip using colloidal gold labeled goat anti-mice IgG as tracer, which could give more stable and repeatable results than classic test strip, would provide a new method for the simultaneous determination of four pyrethroid pesticides in vegetables and fruits.
A monoclonal antibody based lateral flow immunoassay was developed for the simultaneous determination of four pyrethroid pesticides in vegetables and fruits, including fenpropathrin, cypermethrin, deltamethrin, and cyhalothrin. The colloidal gold particles (20-nm) were prepared by the method of sodium citrate reduction and conjugated with goat anti-mice IgG. Antigen and rabbit anti-goat IgG were immobilized on the nitrocellulose membrane as the test line (T line) and the control line (C line), separately. By sticking on PVC board, a gold immunochromatographic strip was assembled. About 10 g of samples was extracted by acetonitrile, and then diluted four times with PBS buffer. Anti-pyrethroid McAb was added in 100 μL of this extract solution for the antibody-antigen binding, thereafter, the mixture was ready for the strip testing. The results revealed that the test could be done within 10 min, and the cutoff values reached 0.5, 5.0, 5.0, 5.0 μg/mL for fenpropathrin, cypermethrin, deltamethrin, cyhalothrin, respectively. If the extraction going through QuEChERS method, the detection limit of method could be improved 16 times. Thereafter, the lateral flow immunoassay was employed for the verification test with 13 types of vegetables and fruits, except that the result of chillies presented the false positive result, the other results obtained higher consistency with the results of GC test. This new format of test strip using colloidal gold labeled goat anti-mice IgG as tracer, which could give more stable and repeatable results than classic test strip, would provide a new method for the simultaneous determination of four pyrethroid pesticides in vegetables and fruits.
2016, 44(12): 1907-1911
doi: 10.11895/j.issn.0253-3820.160671
Abstract:
The water electrolysis for production of hydrogen in the Brönsted acid ionic liquid[HMIm]HSO4 aqueous solutions was investigated using glassy carbon (GC), platinum (Pt), and gold (Au) electrodes, respectively. It was found that the catalytic activity of the electrodes in the acid ionic liquid electrolytes ranked in sequence as Pt >Au >>GC. The optimal concentration of[HMIm]HSO4 in aqueous solutions was 30% (V/V), and the catalytic current density on Pt electrode for hydrogen evolution reaction (HER) at -0.5 V (Ag QRE) reached 110.52 mA/cm2. This was 15 and 650-fold larger than the current on the Au and GC electrode, respectively. The Arrhenius activation energy of the Pt electrode in the electrolyte solution was 5.68 kJ/mol. The high catalytic activity of the electrode was attributed to the[HMIm]HSO4 that would release protons enabling H2O molecules ionization, and facilitating the capture of electrons from the electrode.
The water electrolysis for production of hydrogen in the Brönsted acid ionic liquid[HMIm]HSO4 aqueous solutions was investigated using glassy carbon (GC), platinum (Pt), and gold (Au) electrodes, respectively. It was found that the catalytic activity of the electrodes in the acid ionic liquid electrolytes ranked in sequence as Pt >Au >>GC. The optimal concentration of[HMIm]HSO4 in aqueous solutions was 30% (V/V), and the catalytic current density on Pt electrode for hydrogen evolution reaction (HER) at -0.5 V (Ag QRE) reached 110.52 mA/cm2. This was 15 and 650-fold larger than the current on the Au and GC electrode, respectively. The Arrhenius activation energy of the Pt electrode in the electrolyte solution was 5.68 kJ/mol. The high catalytic activity of the electrode was attributed to the[HMIm]HSO4 that would release protons enabling H2O molecules ionization, and facilitating the capture of electrons from the electrode.
2016, 44(12): 1912-1918
doi: 10.11895/j.issn.0253-3820.160476
Abstract:
A method for determination of four monosaccharides and disaccharides in honey was established by ultra performance convergence chromatography coupled with evaporative light scattering detector (ELSD). The monosaccharides are fructose and glucose, and the disaccharides are sucrose and maltose. The chromatographic separation was conducted on an ACQUITY UPC2 BEH column (100 mm×3.0 mm, 1.7 μm) using carbon dioxide and methanol (containing 0.2% ammonium hydroxide, V/V) as gradient elution. The flow rate was 1.0 mL/min with column temperature at 50℃. The drift tube temperature of the ELSD was set at 50℃ and the pressure of N2 was set at 260.7 kPa. It was found that the reasonable linearity was achieved for monosaccharides and disaccharides with correlation coefficients not less than 0.9983. The limits of detection (S/N≥3) of the four saccharides were 2.0-4.7 mg/L. The recoveries for the four monosaccharides and disaccharides at three spiked levels were 86.6%-103.8% with relative standard deviations of 1.8%-4.3%. This method can be regarded as an excellent method for the determination of monosaccharides and disaccharides in honey samples, with the advantages of simplicity, rapidness, good separability and low cost. The detection result was consistent with that of national standard method.
A method for determination of four monosaccharides and disaccharides in honey was established by ultra performance convergence chromatography coupled with evaporative light scattering detector (ELSD). The monosaccharides are fructose and glucose, and the disaccharides are sucrose and maltose. The chromatographic separation was conducted on an ACQUITY UPC2 BEH column (100 mm×3.0 mm, 1.7 μm) using carbon dioxide and methanol (containing 0.2% ammonium hydroxide, V/V) as gradient elution. The flow rate was 1.0 mL/min with column temperature at 50℃. The drift tube temperature of the ELSD was set at 50℃ and the pressure of N2 was set at 260.7 kPa. It was found that the reasonable linearity was achieved for monosaccharides and disaccharides with correlation coefficients not less than 0.9983. The limits of detection (S/N≥3) of the four saccharides were 2.0-4.7 mg/L. The recoveries for the four monosaccharides and disaccharides at three spiked levels were 86.6%-103.8% with relative standard deviations of 1.8%-4.3%. This method can be regarded as an excellent method for the determination of monosaccharides and disaccharides in honey samples, with the advantages of simplicity, rapidness, good separability and low cost. The detection result was consistent with that of national standard method.
2016, 44(12): 1919-1926
doi: 10.11895/j.issn.0253-3820.160514
Abstract:
The content of heavy metal chromium (Cr) in vegetable oil (soybean oil, peanut oil and corn oil) was quantitatively analyzed by collinear double pulse laser-induced breakdown spectroscopy (DP-LIBS). An Ava-Spec two-channel spectrometer was used to acquire LIBS spectra of samples, and then the CN molecular spectral line (421.49 nm), Ca atomic spectral line (422.64 nm) and three atomic lines of Cr (425.39 nm, 427.43nm and 428.87 nm) were determined by LIBS spectrum of samples. According to the above spectral lines, single variable calibration model and least squares support vector machine (LS-SVM) calibration model of Cr element were established, and they were verified by the validation samples. The results showed that the average prediction relative errors (PRE) of the validation samples by using single variable calibration method were 12.57%, 12.11% and 13.72%, respectively. When using LS-SVM method of three variables, the fitting degree (R2) between the true value and the predictive value of the calibration samples was 0.9785, 0.9792 and 0.9654, and the average PRE of the validation samples was 8.92%, 8.33% and 10.98%, respectively. While using LS-SVM method of five variables, the fitting degree (R2) between the true value and the predictive value of the calibration samples was 0.9895, 0.9901 and 0.9855, and the average PRE of the validation samples was 7.46%, 8.96% and 8.95%, respectively. Therefore, the LS-SVM calibration model has better performance than single variable calibration method. And the LS-SVM calibration model established with five variables has better performance than the one with three variables. The LS-SVM method and the introduction of suitable matrix elements (CN, Ca) can reduce the error of quantitative analysis effectively, and improve the accuracy of prediction for Cr content in vegetable oil by LIBS technique.
The content of heavy metal chromium (Cr) in vegetable oil (soybean oil, peanut oil and corn oil) was quantitatively analyzed by collinear double pulse laser-induced breakdown spectroscopy (DP-LIBS). An Ava-Spec two-channel spectrometer was used to acquire LIBS spectra of samples, and then the CN molecular spectral line (421.49 nm), Ca atomic spectral line (422.64 nm) and three atomic lines of Cr (425.39 nm, 427.43nm and 428.87 nm) were determined by LIBS spectrum of samples. According to the above spectral lines, single variable calibration model and least squares support vector machine (LS-SVM) calibration model of Cr element were established, and they were verified by the validation samples. The results showed that the average prediction relative errors (PRE) of the validation samples by using single variable calibration method were 12.57%, 12.11% and 13.72%, respectively. When using LS-SVM method of three variables, the fitting degree (R2) between the true value and the predictive value of the calibration samples was 0.9785, 0.9792 and 0.9654, and the average PRE of the validation samples was 8.92%, 8.33% and 10.98%, respectively. While using LS-SVM method of five variables, the fitting degree (R2) between the true value and the predictive value of the calibration samples was 0.9895, 0.9901 and 0.9855, and the average PRE of the validation samples was 7.46%, 8.96% and 8.95%, respectively. Therefore, the LS-SVM calibration model has better performance than single variable calibration method. And the LS-SVM calibration model established with five variables has better performance than the one with three variables. The LS-SVM method and the introduction of suitable matrix elements (CN, Ca) can reduce the error of quantitative analysis effectively, and improve the accuracy of prediction for Cr content in vegetable oil by LIBS technique.
2016, 44(12): 1927-1933
doi: 10.11895/j.issn.0253-3820.160260
Abstract:
A sensitive electrochemical modified electrode (Cys/AuNPs/AuE) to Cu was fabricated by immobilizing gold nanoparticles (AuNPs) and L-cysteine (Cys) on the surface of gold electrode (AuE). Cephalexin was hydrolyzed in the presence of Cu, then the cephalexin concentration was obtained indirectly by using square wave voltammetry to detect the remaining Cu in hydrolysate. The modified conditions of AuE and hydrolytic conditions of cephalexin were optimized. When cephalexin was hydrolyzed in HAc-NaAc buffer solution (pH 4.5) with Cu at 100℃ for 25 min, the remaining Cu in hydrolysate showed good electrochemical response on Cys/AuNPs/AuE. The difference of reductive peak currents had good linear relationships with cephalexin concentration in the range of 0.0058-0.12 μmol/L and 0.12-2.9 μmol/L, respectively. The detection limit was 1.9 nmol/L based on the signal to noise ratio of 3. The proposed method was applied to detect cephalexin residue in chicken sample. The results showed that this method was simple, rapid, high sensitive, and suitable for the determination of cephalexin residue in chicken and other food samples.
A sensitive electrochemical modified electrode (Cys/AuNPs/AuE) to Cu was fabricated by immobilizing gold nanoparticles (AuNPs) and L-cysteine (Cys) on the surface of gold electrode (AuE). Cephalexin was hydrolyzed in the presence of Cu, then the cephalexin concentration was obtained indirectly by using square wave voltammetry to detect the remaining Cu in hydrolysate. The modified conditions of AuE and hydrolytic conditions of cephalexin were optimized. When cephalexin was hydrolyzed in HAc-NaAc buffer solution (pH 4.5) with Cu at 100℃ for 25 min, the remaining Cu in hydrolysate showed good electrochemical response on Cys/AuNPs/AuE. The difference of reductive peak currents had good linear relationships with cephalexin concentration in the range of 0.0058-0.12 μmol/L and 0.12-2.9 μmol/L, respectively. The detection limit was 1.9 nmol/L based on the signal to noise ratio of 3. The proposed method was applied to detect cephalexin residue in chicken sample. The results showed that this method was simple, rapid, high sensitive, and suitable for the determination of cephalexin residue in chicken and other food samples.
2016, 44(12): 1934-1941
doi: 10.11895/j.issn.0253-3820.160437
Abstract:
Chemiluminescence (CL) assay is able to measure the optical signal emitted from the CL reagents as a result of the transition from the excited state back to the ground state. CL assay has significant advantages such as no external light source, high sensitivity, convenient operation, rapid analysis and easy automation, and has wide applications in clinical test, drug analysis and environmental monitoring. Recently, the introduction of nanomaterials, biochip and microfluidic techniques promote the development of CL assay. In this review, we summarize the recent progress in CL assay with the integration of high performance liquid chromatography, capillary electrophoresis, quantum dots, microfluidic chips, microarrays, rolling circle amplification, isothermal exponential amplification, and two-stage isothermal amplification for the detection of DNA, small biological molecules, enzymes, proteins and metal ions. We also give a summary of its future directions and highlight its potential applications.
Chemiluminescence (CL) assay is able to measure the optical signal emitted from the CL reagents as a result of the transition from the excited state back to the ground state. CL assay has significant advantages such as no external light source, high sensitivity, convenient operation, rapid analysis and easy automation, and has wide applications in clinical test, drug analysis and environmental monitoring. Recently, the introduction of nanomaterials, biochip and microfluidic techniques promote the development of CL assay. In this review, we summarize the recent progress in CL assay with the integration of high performance liquid chromatography, capillary electrophoresis, quantum dots, microfluidic chips, microarrays, rolling circle amplification, isothermal exponential amplification, and two-stage isothermal amplification for the detection of DNA, small biological molecules, enzymes, proteins and metal ions. We also give a summary of its future directions and highlight its potential applications.
2016, 44(12): 1942-1949
doi: 10.11895/j.issn.0253-3820.160317
Abstract:
In comparison with with macro analysis system, microfluidic analysis system has many advantages such as small sample and reagent consumption, mass and heat transfer efficiently, good biocompatibility, high-throughput parallel analysis, functional unit integration, miniaturization, and automation control and so on. It has been applied in the analytical chemical, especially in life analytical chemistry. In this review, we mainly focused on the progress of cell analysis related microfluidic technologies during the past five years, such as material and fabrication, surface modification and droplet techniques. Then we briefly summarized the applications of microfluidic techniques on drug screening and cell analysis.
In comparison with with macro analysis system, microfluidic analysis system has many advantages such as small sample and reagent consumption, mass and heat transfer efficiently, good biocompatibility, high-throughput parallel analysis, functional unit integration, miniaturization, and automation control and so on. It has been applied in the analytical chemical, especially in life analytical chemistry. In this review, we mainly focused on the progress of cell analysis related microfluidic technologies during the past five years, such as material and fabrication, surface modification and droplet techniques. Then we briefly summarized the applications of microfluidic techniques on drug screening and cell analysis.
