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2017 Volume 45 Issue 1
2017, 45(1): 1-6
doi: 10.11895/j.issn.0253-3820.160290
Abstract:
Oligo-adenine sequence (OAS) containing DNA probes (DNAprobe) was immobilized on gold nanoparticles (AuNPs) with various surface densities via the strong interaction between OAS sequence and gold surface, and the influences of different conditions (e.g., length of OAS, size of AuNPs, concentration of NaCl, etc.) on the immobilization of DNAprobe and hybridization performance of the resulting nanoparticle probe (Au-probe) were investigated. Transmission electron microscopy (TEM), ultraviolet-visible absorption spectroscopy (UV-Vis) and nanoparticle size analyzer were utilized to characterize the morphology and size of AuNPs and Au-probe, as well as the DNAprobe immobilization on AuNPs surface and their hybridization with DNA target(DNAtarget). The results showed that, when the number of adenine in an OAS sequence increased from 10, to 30 and 50, the amount of the immobilized DNAprobe decreased as expected. The optimal NaCl concentrations for the hybridization were 300 mmol/L for 10.2-nm AuNPs, and 25 mmol/L for 24.3-nm AuNPs, respectively. With increasing size of AuNPs, the amount of both immobilized DNAprobe and hybridized DNAtarget decreased.
Oligo-adenine sequence (OAS) containing DNA probes (DNAprobe) was immobilized on gold nanoparticles (AuNPs) with various surface densities via the strong interaction between OAS sequence and gold surface, and the influences of different conditions (e.g., length of OAS, size of AuNPs, concentration of NaCl, etc.) on the immobilization of DNAprobe and hybridization performance of the resulting nanoparticle probe (Au-probe) were investigated. Transmission electron microscopy (TEM), ultraviolet-visible absorption spectroscopy (UV-Vis) and nanoparticle size analyzer were utilized to characterize the morphology and size of AuNPs and Au-probe, as well as the DNAprobe immobilization on AuNPs surface and their hybridization with DNA target(DNAtarget). The results showed that, when the number of adenine in an OAS sequence increased from 10, to 30 and 50, the amount of the immobilized DNAprobe decreased as expected. The optimal NaCl concentrations for the hybridization were 300 mmol/L for 10.2-nm AuNPs, and 25 mmol/L for 24.3-nm AuNPs, respectively. With increasing size of AuNPs, the amount of both immobilized DNAprobe and hybridized DNAtarget decreased.
2017, 45(1): 7-13
doi: 10.11895/j.issn.0253-3820.160288
Abstract:
The concept of flow-field shaped (FFS) electrode was firstly put forward and the FFS three-electrode system was built. Combined with the 3D-printed thin-layer flow cell (TLFC), the flowing electrochemical detection system for detection of Cd by square wave stripping voltammetry (SWSV) was thus constructed. Several factors affecting the determination were investigated, including the shape of the electrode, measuring method, buffer medium, flow rate and deposition time. This detection system exhibited attractive properties, such as high sensitivity, good reproducibility and stability. Under optimized conditions, Cd concentration presented a good linear relationship with the stripping current in a range of 2-100 μg/L. The correlation coefficient was 0.997 and the detection limit was 0.5 μg/L. The proposed system was applied to determine trace Cd in environmental water and biological methane fermentation liquor. The detection results were consistent with the results obtained by ICP-AES and the recovery was 90%-106%.
The concept of flow-field shaped (FFS) electrode was firstly put forward and the FFS three-electrode system was built. Combined with the 3D-printed thin-layer flow cell (TLFC), the flowing electrochemical detection system for detection of Cd by square wave stripping voltammetry (SWSV) was thus constructed. Several factors affecting the determination were investigated, including the shape of the electrode, measuring method, buffer medium, flow rate and deposition time. This detection system exhibited attractive properties, such as high sensitivity, good reproducibility and stability. Under optimized conditions, Cd concentration presented a good linear relationship with the stripping current in a range of 2-100 μg/L. The correlation coefficient was 0.997 and the detection limit was 0.5 μg/L. The proposed system was applied to determine trace Cd in environmental water and biological methane fermentation liquor. The detection results were consistent with the results obtained by ICP-AES and the recovery was 90%-106%.
2017, 45(1): 14-22
doi: 10.11895/j.issn.0253-3820.160605
Abstract:
Pb isotope is an important geochemical tracer in the study of ore-forming material source, mineralization process and deposit formation mechanism. In this study, the matrix effect on Pb isotope determination by 193 nm excimer laser and multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) was investigated, and the results showed that it was of importance to select an appropriate matrix matching standard material for determination of Pb isotope composition in sulfide. By the simulation, it was found that the accurate determination of Tl and Hg fractionation factor could effectively correct the interference of 204Hg-204Pb in the range of 204Hg/204Pb<2. It was also found that the spot size (24-160 μm) and the pulse frequency (2-20 Hz) did not affect the Pb isotope analysis, so changing the laser ablation parameters could solve the problem of narrow detection range for MC-ICP-MS. To solve the lack of sulfide solid standard materials, the preparation of sulfide standard materials by pressing and rapid melting method was attempted. The pellet samples showed a good homogeneity of Pb isotope composition. For the rapid melting method, there was Pb isotope fractionation in different batches. But the homogeneous Pb isotopic composition was found in the single-batch molten samples. The results showed that these two methods were promising candidates for the preparation of sulfide standard samples, though the rapid melting method needed to be further modified. The Pb isotopic compositions in natural sulfide samples (pyrite and sphalerite) and synthetic sulfides were determined by the established method. The measured values were consistent with the solution values in the error range.
Pb isotope is an important geochemical tracer in the study of ore-forming material source, mineralization process and deposit formation mechanism. In this study, the matrix effect on Pb isotope determination by 193 nm excimer laser and multiple collector inductively coupled plasma mass spectrometry (MC-ICP-MS) was investigated, and the results showed that it was of importance to select an appropriate matrix matching standard material for determination of Pb isotope composition in sulfide. By the simulation, it was found that the accurate determination of Tl and Hg fractionation factor could effectively correct the interference of 204Hg-204Pb in the range of 204Hg/204Pb<2. It was also found that the spot size (24-160 μm) and the pulse frequency (2-20 Hz) did not affect the Pb isotope analysis, so changing the laser ablation parameters could solve the problem of narrow detection range for MC-ICP-MS. To solve the lack of sulfide solid standard materials, the preparation of sulfide standard materials by pressing and rapid melting method was attempted. The pellet samples showed a good homogeneity of Pb isotope composition. For the rapid melting method, there was Pb isotope fractionation in different batches. But the homogeneous Pb isotopic composition was found in the single-batch molten samples. The results showed that these two methods were promising candidates for the preparation of sulfide standard samples, though the rapid melting method needed to be further modified. The Pb isotopic compositions in natural sulfide samples (pyrite and sphalerite) and synthetic sulfides were determined by the established method. The measured values were consistent with the solution values in the error range.
2017, 45(1): 23-27
doi: 10.11895/j.issn.0253-3820.160596
Abstract:
A turn-on fluorescence analysis method was established for detection of Pb2+ based on aggregation-induced emission. Glutathione-protected non-noble metal copper nanoclusters (CuNCs@GSH) exhibited nearly no fluorescence. However, the fluorescence intensity of CuNCs@GSH was remarkably improved in the presence of Pb2+and showed bright orange fluorescence. A fluorescencent method for detection of Pb2+ was established based on this principle. The fluorescence change of the CuNCs@GSH solution showed a linear relationship with Pb2+ concentration within the range of 200-700 μmol/L. The limit of detection was 106 μmol/L (S/N=3). This method is simple, rapid and highly selective, and can be used for the visual qualitative detection of Pb2+ under ultraviolet (UV) lamp.
A turn-on fluorescence analysis method was established for detection of Pb2+ based on aggregation-induced emission. Glutathione-protected non-noble metal copper nanoclusters (CuNCs@GSH) exhibited nearly no fluorescence. However, the fluorescence intensity of CuNCs@GSH was remarkably improved in the presence of Pb2+and showed bright orange fluorescence. A fluorescencent method for detection of Pb2+ was established based on this principle. The fluorescence change of the CuNCs@GSH solution showed a linear relationship with Pb2+ concentration within the range of 200-700 μmol/L. The limit of detection was 106 μmol/L (S/N=3). This method is simple, rapid and highly selective, and can be used for the visual qualitative detection of Pb2+ under ultraviolet (UV) lamp.
2017, 45(1): 28-34
doi: 10.11895/j.issn.0253-3820.160606
Abstract:
A moderate and simple in situ growth approach was employed to load copper nanoparticles (CuNPs) noncovalently on graphene for preparation of CuNPs/poly acrylic acid/reduced graphene oxide (CuNPs/PAA/GR) nanocomposites for electro-catalysis of 4-nitrophenol (4-NP). The morphology of the material was observed by scanning electron microscopy (SEM). Tests with various scan rates and pH conditions indicated an adsorption-controlled electrode process occurred. The mechanism of the electrode reaction of 4-NP involved a two-electron process accompanied by a deprotonation step. Electrochemical parameters were calculated with the electron transfer number (n) as 2.3, the effective area (0.6275 cm2) of CuNPs/PAA/GR/GCE electrode was 2.22 times as large as that of bare electrode, the adsorption capacity Гs value was 1.6×10-11 mol/cm2, and the average value of the calculated kcat value was 1.15×104 L/(mol·s). Under the optimal conditions, the differential pulse voltammetric response of the electrode showed a linear relationship with 4-NP concentration in the range of 1-150 μmol/L. The regression equation was Ipa (μA)=-0.015C (μmol/L)-0.98 (R2=0.9951), and the detection limit was 0.23 μmol/L (S/N=3). The fabricated sensor exhibited high sensitivity, good stability and high reproducibility. This sensor was applied for detection of 4-NP in water samples with favorable recoveries of 88.6%-100.7% and relative standard deviation (RSD) of 2.6%-5.9%.
A moderate and simple in situ growth approach was employed to load copper nanoparticles (CuNPs) noncovalently on graphene for preparation of CuNPs/poly acrylic acid/reduced graphene oxide (CuNPs/PAA/GR) nanocomposites for electro-catalysis of 4-nitrophenol (4-NP). The morphology of the material was observed by scanning electron microscopy (SEM). Tests with various scan rates and pH conditions indicated an adsorption-controlled electrode process occurred. The mechanism of the electrode reaction of 4-NP involved a two-electron process accompanied by a deprotonation step. Electrochemical parameters were calculated with the electron transfer number (n) as 2.3, the effective area (0.6275 cm2) of CuNPs/PAA/GR/GCE electrode was 2.22 times as large as that of bare electrode, the adsorption capacity Гs value was 1.6×10-11 mol/cm2, and the average value of the calculated kcat value was 1.15×104 L/(mol·s). Under the optimal conditions, the differential pulse voltammetric response of the electrode showed a linear relationship with 4-NP concentration in the range of 1-150 μmol/L. The regression equation was Ipa (μA)=-0.015C (μmol/L)-0.98 (R2=0.9951), and the detection limit was 0.23 μmol/L (S/N=3). The fabricated sensor exhibited high sensitivity, good stability and high reproducibility. This sensor was applied for detection of 4-NP in water samples with favorable recoveries of 88.6%-100.7% and relative standard deviation (RSD) of 2.6%-5.9%.
2017, 45(1): 35-41
doi: 10.11895/j.issn.0253-3820.160610
Abstract:
The upconversion nanoparticles (UCNPs) NaYF4∶Yb,Er were synthesized by the solvent thermal method. Fluorescence probe was prepared by coupling the anti-diethylstilbestrol (DES) monoclonal antibody with UCNPs. The DES-labeled bovine serum albumin (BSA) conjugates and goat anti-mouse antibodies were sprayed onto the nitrocellulose membrane as the test line and the control line, respectively. The resultant fluorescence probes were introduced into the immunochromatographic strip for rapid determination of DES. The UCNPs-based immunochromatographic strips for determination of DES exhibited a good linear range from 25 ng/mL to 10000 ng/mL (y=0.43927x-0.57647, R2=0.996), with a limit of detection of 20.84 ng/mL. The detection time of the proposed UCNPs based immunochromatographic strips for each sample was only 15 min. The RSDs of the intra and inter assay were less than 10%. The strip showed excellent specificity to structural and functional analogues, and the average RSD of detection value after storage at 37℃ for 7 days was about 15%. The recovery experiment showed that the average recoveries of DES at 5 spiked concentration levels were 90.1%-115.2%, and the RSDs were below 5%. These results were consistent with that of HPLC.
The upconversion nanoparticles (UCNPs) NaYF4∶Yb,Er were synthesized by the solvent thermal method. Fluorescence probe was prepared by coupling the anti-diethylstilbestrol (DES) monoclonal antibody with UCNPs. The DES-labeled bovine serum albumin (BSA) conjugates and goat anti-mouse antibodies were sprayed onto the nitrocellulose membrane as the test line and the control line, respectively. The resultant fluorescence probes were introduced into the immunochromatographic strip for rapid determination of DES. The UCNPs-based immunochromatographic strips for determination of DES exhibited a good linear range from 25 ng/mL to 10000 ng/mL (y=0.43927x-0.57647, R2=0.996), with a limit of detection of 20.84 ng/mL. The detection time of the proposed UCNPs based immunochromatographic strips for each sample was only 15 min. The RSDs of the intra and inter assay were less than 10%. The strip showed excellent specificity to structural and functional analogues, and the average RSD of detection value after storage at 37℃ for 7 days was about 15%. The recovery experiment showed that the average recoveries of DES at 5 spiked concentration levels were 90.1%-115.2%, and the RSDs were below 5%. These results were consistent with that of HPLC.
2017, 45(1): 42-47
doi: 10.11895/j.issn.0253-3820.160629
Abstract:
A cantilever array sensor platform has been developed based on the optical lever method, the cantilever array chip is also fabricated to introduce its applications on biochemical detection. Optical fibers coupled to lasers are used as the scanning light source. This sensor system has good stability, and the noise of the detection signal is about 2 nm. Meanwhile, the cantilevers of the fabricated chip have good straightness and are consistent to temperature response, and the deviations of response sensitivity of cantilevers caused by temperature change are no more than 5.0%. This sensing system is used to detect Hg2+ in aqueous solution with a concentration range of 1-200 ng/mL. The deflections of one array chip are close in the same concentration, and the average deviation is less than 15%. Samples at the concentration levels of 1 ng/mL and 0.2 ng/mL are detected separately by the fabricated chip and a foreign commercial chip on the sensor platform. The result shows that it's difficult for the fabricated chip to achieve a higher detection sensitivity and necessary to improve the cantilever array production process.
A cantilever array sensor platform has been developed based on the optical lever method, the cantilever array chip is also fabricated to introduce its applications on biochemical detection. Optical fibers coupled to lasers are used as the scanning light source. This sensor system has good stability, and the noise of the detection signal is about 2 nm. Meanwhile, the cantilevers of the fabricated chip have good straightness and are consistent to temperature response, and the deviations of response sensitivity of cantilevers caused by temperature change are no more than 5.0%. This sensing system is used to detect Hg2+ in aqueous solution with a concentration range of 1-200 ng/mL. The deflections of one array chip are close in the same concentration, and the average deviation is less than 15%. Samples at the concentration levels of 1 ng/mL and 0.2 ng/mL are detected separately by the fabricated chip and a foreign commercial chip on the sensor platform. The result shows that it's difficult for the fabricated chip to achieve a higher detection sensitivity and necessary to improve the cantilever array production process.
2017, 45(1): 48-55
doi: 10.11895/j.issn.0253-3820.160611
Abstract:
A novel and simple electrochemical immunoassay for carcino-embryonic antigen (CEA) was developed using Au nanoparticles loaded-metal-organic frameworks (AuNPs/Cu-TPA) as signal unit and electrochemical reduction of graphene oxide on the surface of electrode to capture CEA antibody (Ab1). MOFs contain large amounts of Cu2+ ions, which can be used as stable electrochemical signals to achieve the detection of CEA. This new class of signal probe differs from traditional probe because it does not require pre-treatment and acid treatment, and easy to load noble metal for the immobilization of antibody, which will greatly simplify the detection steps and reduce the detection time. This immunosensor has good sensitivity and ease to operate. Under the optimized experimental conditions, the proposed sensing strategy provides a linear dynamic range from 0.1 ng/mL to 80 ng/mL with a detection limit of 0.03 ng/mL and linear correlation coefficient of 0.9887. The developed CEA immunosensor can be used to detect CEA in real sample.
A novel and simple electrochemical immunoassay for carcino-embryonic antigen (CEA) was developed using Au nanoparticles loaded-metal-organic frameworks (AuNPs/Cu-TPA) as signal unit and electrochemical reduction of graphene oxide on the surface of electrode to capture CEA antibody (Ab1). MOFs contain large amounts of Cu2+ ions, which can be used as stable electrochemical signals to achieve the detection of CEA. This new class of signal probe differs from traditional probe because it does not require pre-treatment and acid treatment, and easy to load noble metal for the immobilization of antibody, which will greatly simplify the detection steps and reduce the detection time. This immunosensor has good sensitivity and ease to operate. Under the optimized experimental conditions, the proposed sensing strategy provides a linear dynamic range from 0.1 ng/mL to 80 ng/mL with a detection limit of 0.03 ng/mL and linear correlation coefficient of 0.9887. The developed CEA immunosensor can be used to detect CEA in real sample.
2017, 45(1): 56-60
doi: 10.11895/j.issn.0253-3820.160520
Abstract:
A C18-sulfonic group dual modification chromatographic stationary phase was prepared by one-pot reaction to modify the surface of silica with two modifier of octadecyltrichlorosilane (OTS) and trimethoxysilylpropanethiol (MPS) and oxidize the thiol group. Under the optimized reaction conditions, the stationary phase with a mole ratio of 3∶7 between C18 and sulfonic group was obtained. The morphology and feature of the stationary phase were characterized by scanning electronic microscopy, elemental analysis and infrared spectra. The chromatographic properties of the prepared stationary phase were systematically investigated in different separation modes. Five alkyl benzenes and three nucleosides were separated successfully in reversed phase chromatography and hydrophilic interaction chromatography respectively. The bovine serum albumin digests could also be separated well on the stationary phase. The results indicated that the prepared mixed-mode stationary phase could provide multiple separation mechanism and had potential advantages in separating complex samples and adjusting the selectivity.
A C18-sulfonic group dual modification chromatographic stationary phase was prepared by one-pot reaction to modify the surface of silica with two modifier of octadecyltrichlorosilane (OTS) and trimethoxysilylpropanethiol (MPS) and oxidize the thiol group. Under the optimized reaction conditions, the stationary phase with a mole ratio of 3∶7 between C18 and sulfonic group was obtained. The morphology and feature of the stationary phase were characterized by scanning electronic microscopy, elemental analysis and infrared spectra. The chromatographic properties of the prepared stationary phase were systematically investigated in different separation modes. Five alkyl benzenes and three nucleosides were separated successfully in reversed phase chromatography and hydrophilic interaction chromatography respectively. The bovine serum albumin digests could also be separated well on the stationary phase. The results indicated that the prepared mixed-mode stationary phase could provide multiple separation mechanism and had potential advantages in separating complex samples and adjusting the selectivity.
2017, 45(1): 61-68
doi: 10.11895/j.issn.0253-3820.160415
Abstract:
Selective enrichment before mass spectrometric analysis is very important for detection and identification of phosphopeptides. In this work, a novel method based on the reversed phase/strong anion exchange material (C18/SAX) was established and applied in phosphopeptide enrichment. The influence of mobile phase composition (acetonitrile content, formic acid content, salt concentration) on the phosphopeptide enrichment selectivity was carried out by taking α-casein digests as model sample. It was found that the retention of phosphopeptides on C18/SAX was ascribed to both the hydrophobic and strong anion exchange interactions. Mono-phosphopeptides were eluted earlier than multi-phosphopeptides. The retention of phosphopeptides on C18/SAX was reduced along with the increase of formic acid content and the increase of salt content. After optimization, an enrichment method was developed with 20% ACN/20 mmol/L NH4Ac as loading buffer, 20% ACN/0.1% FA and 50% ACN/100 mmol/L NH4Ac/2% FA as two steps elution phase to fractionate mono-and multi-phosphopeptides. By using the developed method, 4 mono-phosphopeptides and 14 multi-phosphopeptides were isolated from the mixture of α-Casein and HSA at a molar ratio of 1∶20. The application of the developed method to bovine milk digests resulted in the separation and identification of 4 mono-phosphopeptide and 8 multi-phosphopeptides. These results indicated that the methods had great potential for practical application.
Selective enrichment before mass spectrometric analysis is very important for detection and identification of phosphopeptides. In this work, a novel method based on the reversed phase/strong anion exchange material (C18/SAX) was established and applied in phosphopeptide enrichment. The influence of mobile phase composition (acetonitrile content, formic acid content, salt concentration) on the phosphopeptide enrichment selectivity was carried out by taking α-casein digests as model sample. It was found that the retention of phosphopeptides on C18/SAX was ascribed to both the hydrophobic and strong anion exchange interactions. Mono-phosphopeptides were eluted earlier than multi-phosphopeptides. The retention of phosphopeptides on C18/SAX was reduced along with the increase of formic acid content and the increase of salt content. After optimization, an enrichment method was developed with 20% ACN/20 mmol/L NH4Ac as loading buffer, 20% ACN/0.1% FA and 50% ACN/100 mmol/L NH4Ac/2% FA as two steps elution phase to fractionate mono-and multi-phosphopeptides. By using the developed method, 4 mono-phosphopeptides and 14 multi-phosphopeptides were isolated from the mixture of α-Casein and HSA at a molar ratio of 1∶20. The application of the developed method to bovine milk digests resulted in the separation and identification of 4 mono-phosphopeptide and 8 multi-phosphopeptides. These results indicated that the methods had great potential for practical application.
2017, 45(1): 69-74
doi: 10.11895/j.issn.0253-3820.160503
Abstract:
A mathematical model of sandwich-type lateral flow immunoassay (LFIA) is established to describe the dynamic process of LFIA according to the biochemical principle of LFIA together with the convection-diffusion equations and the hydromagnetic equations. Based on the established model, the COMSOL software is utilized to simulate the dynamic process of LFIA. The simulation results not only demonstrate the relationships between the concentration of the sandwiched substance and the position or the time, but also analyze the influences of the initial concentrations of all substances and the structure on the performance of LFIA system when the target analyte A is from 0 to 20 mol/L, reporter particle P is from 1×10-2 mol/L to 1×103 mol/L and the porosity is from 0 to 1. Especially, within a certain concentration range, the increasing concentration of target analyte A and reporter particle P will enhance the quantitative performance of LFIA, and the porosity affects the result by controlling the flow rate of the test mixture and the material contact in the mixture.
A mathematical model of sandwich-type lateral flow immunoassay (LFIA) is established to describe the dynamic process of LFIA according to the biochemical principle of LFIA together with the convection-diffusion equations and the hydromagnetic equations. Based on the established model, the COMSOL software is utilized to simulate the dynamic process of LFIA. The simulation results not only demonstrate the relationships between the concentration of the sandwiched substance and the position or the time, but also analyze the influences of the initial concentrations of all substances and the structure on the performance of LFIA system when the target analyte A is from 0 to 20 mol/L, reporter particle P is from 1×10-2 mol/L to 1×103 mol/L and the porosity is from 0 to 1. Especially, within a certain concentration range, the increasing concentration of target analyte A and reporter particle P will enhance the quantitative performance of LFIA, and the porosity affects the result by controlling the flow rate of the test mixture and the material contact in the mixture.
2017, 45(1): 75-82
doi: 10.11895/j.issn.0253-3820.160533
Abstract:
The fundamental technique of surface enhanced Raman scattering (SERS) is to fabricate a sensitive SERS substrate. A rapid and sensitive detection of trace amounts of melamine in sample was developed, in which a SERS substrate based on ordered silver nanowires (AgNWs) was synthesized and assembled via polyol-fluid flow method. The characteristic Raman peak of melamine was obtained through the theoretical calculation and experimental investigation. And the detection conditions of melamine SERS on the ordered silver nanowire substrate were optimized. Under the optimum conditions including pH=8, water as solvent and 14 min of solvent evaporation time, a good linearity (R=0.997) between characteristic peak intensity and melamine concentration was obtained in the range of 0.05-1.00 mg/L with the detection limit of 0.05 mg/L. The recovery of melamine spiked in milk sample was from 89.7% to 109.2% and the relative standard deviation was below 6.8%. The method exhibited good sensitivity and stability for the detection of melamine, and could provide the technical support for the SERS detection of other small molecule compounds.
The fundamental technique of surface enhanced Raman scattering (SERS) is to fabricate a sensitive SERS substrate. A rapid and sensitive detection of trace amounts of melamine in sample was developed, in which a SERS substrate based on ordered silver nanowires (AgNWs) was synthesized and assembled via polyol-fluid flow method. The characteristic Raman peak of melamine was obtained through the theoretical calculation and experimental investigation. And the detection conditions of melamine SERS on the ordered silver nanowire substrate were optimized. Under the optimum conditions including pH=8, water as solvent and 14 min of solvent evaporation time, a good linearity (R=0.997) between characteristic peak intensity and melamine concentration was obtained in the range of 0.05-1.00 mg/L with the detection limit of 0.05 mg/L. The recovery of melamine spiked in milk sample was from 89.7% to 109.2% and the relative standard deviation was below 6.8%. The method exhibited good sensitivity and stability for the detection of melamine, and could provide the technical support for the SERS detection of other small molecule compounds.
2017, 45(1): 83-88
doi: 10.11895/j.issn.0253-3820.160417
Abstract:
A fused quartz capillary was taken as the carrier for the immunoassay of the tumor marker alpha fetal protein (AFP) as a model protein. The capture antibody of AFP was immobilized in capillary. Based on a sandwich immunoassay format, the antigen and corresponding horseradish peroxidase (HRP) labeled antibodies were introduced into the capillary for online incubation. After the injection of the chemiluminescence substrate, the chemiluminescence signals were captured by the CCD camera and changed into figures. The results could be read by gray level analysis of the figures. When the capture antibody was diluted 100 times, the enzyme labeled antibody was diluted 200 times, and the exposure time was 20 s, the detection range of AFP was 3.1-50 ng/mL and the critical concentrations of 20 ng/mL clinical applications were covered. The limit of detection was 2.7 ng/mL. Twenty clinical samples were tested with fine accuracy. The recoveries of the spiked samples were between 96.0% and 106.7%. In the assay, the sample consumption was low and the experimental material was simple and cheap. The method does not require large instruments, and is appropriate for clinical application
A fused quartz capillary was taken as the carrier for the immunoassay of the tumor marker alpha fetal protein (AFP) as a model protein. The capture antibody of AFP was immobilized in capillary. Based on a sandwich immunoassay format, the antigen and corresponding horseradish peroxidase (HRP) labeled antibodies were introduced into the capillary for online incubation. After the injection of the chemiluminescence substrate, the chemiluminescence signals were captured by the CCD camera and changed into figures. The results could be read by gray level analysis of the figures. When the capture antibody was diluted 100 times, the enzyme labeled antibody was diluted 200 times, and the exposure time was 20 s, the detection range of AFP was 3.1-50 ng/mL and the critical concentrations of 20 ng/mL clinical applications were covered. The limit of detection was 2.7 ng/mL. Twenty clinical samples were tested with fine accuracy. The recoveries of the spiked samples were between 96.0% and 106.7%. In the assay, the sample consumption was low and the experimental material was simple and cheap. The method does not require large instruments, and is appropriate for clinical application
2017, 45(1): 89-96
doi: 10.11895/j.issn.0253-3820.160569
Abstract:
Molecular imprinted polymer cores (MIPs) were prepared through distillation-precipitation polymerization with methacrylic acid (MAA) as the functional monomer and paracetamol (PR) as the template molecule. Then, the hydrophilic shells were grafted successfully by free radical polymerization with acrylamide (AM) as the hydrophilic monomer. The influences of different shell cross-linking agents such as ethylene glycol dimethacrylate (EGDMA), trimethylolpropane triacrylate (TRIM), and N,N'-Methylenebisacrylamide (MBA) on the hydrophilic property were investigated. The resulting MIPs were characterized by various tests, including ultraviolet spectrometry (UV), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM). The absorbing test and contact angle measurement were also carried out for the investigation of hydrophilic property of microspheres. The results showed that MBA was the best shell cross-linking agent of the microspheres, and the adsorption capacity and contact angle of this prepared microsphere could reach 120 μmol/g and 23.3°, respectively. Core-shell (CS)-MIPs provide a new thought for detection of PR in aqueous solution.
Molecular imprinted polymer cores (MIPs) were prepared through distillation-precipitation polymerization with methacrylic acid (MAA) as the functional monomer and paracetamol (PR) as the template molecule. Then, the hydrophilic shells were grafted successfully by free radical polymerization with acrylamide (AM) as the hydrophilic monomer. The influences of different shell cross-linking agents such as ethylene glycol dimethacrylate (EGDMA), trimethylolpropane triacrylate (TRIM), and N,N'-Methylenebisacrylamide (MBA) on the hydrophilic property were investigated. The resulting MIPs were characterized by various tests, including ultraviolet spectrometry (UV), Fourier transform infrared spectroscopy (FT-IR), and scanning electron microscope (SEM). The absorbing test and contact angle measurement were also carried out for the investigation of hydrophilic property of microspheres. The results showed that MBA was the best shell cross-linking agent of the microspheres, and the adsorption capacity and contact angle of this prepared microsphere could reach 120 μmol/g and 23.3°, respectively. Core-shell (CS)-MIPs provide a new thought for detection of PR in aqueous solution.
2017, 45(1): 97-103
doi: 10.11895/j.issn.0253-3820.160373
Abstract:
To avoid the inaccuracy measurement caused by the different temperature between calibration solution and test solution in actual use of enzyme injection glucose biosensor, a detection method was established for enzyme injection glucose biosensors based on temperature. Firstly, the concentration detection model of the enzyme injection glucose biosensor is established according to enzymatic reaction kinetics. Then, the relationship between the temperature and the unknown parameters in the dynamic model of concentration detection is built using Arrhenius equation, and this relationship is substituted into the original detection dynamics model to establish the new model based on temperature. In this model, the current initial slope of the enzymatic reaction and the temperature are the inputs, and the concentration of glucose is output. Based on this new model, a detection method which is derived by the temperature of the mixture and the slope of the initial current is proposed. The new detection method can not only reduce the impact of temperature difference to improve detection accuracy, but also avoid the removal procedure of sampling probe causing by the calibration before each measurement, and it is more conducive to online use. A comparison was made by detecting the glucose solution with a concentration of 1.5 mg/mL, 2.5 mg/mL at the temperature of 25, 30, and 42℃ using both the original detection method and the new detection method based on temperature. The result shows that the recovery rate of the new method is more than 95.0%, significantly better than that of the original detection method.
To avoid the inaccuracy measurement caused by the different temperature between calibration solution and test solution in actual use of enzyme injection glucose biosensor, a detection method was established for enzyme injection glucose biosensors based on temperature. Firstly, the concentration detection model of the enzyme injection glucose biosensor is established according to enzymatic reaction kinetics. Then, the relationship between the temperature and the unknown parameters in the dynamic model of concentration detection is built using Arrhenius equation, and this relationship is substituted into the original detection dynamics model to establish the new model based on temperature. In this model, the current initial slope of the enzymatic reaction and the temperature are the inputs, and the concentration of glucose is output. Based on this new model, a detection method which is derived by the temperature of the mixture and the slope of the initial current is proposed. The new detection method can not only reduce the impact of temperature difference to improve detection accuracy, but also avoid the removal procedure of sampling probe causing by the calibration before each measurement, and it is more conducive to online use. A comparison was made by detecting the glucose solution with a concentration of 1.5 mg/mL, 2.5 mg/mL at the temperature of 25, 30, and 42℃ using both the original detection method and the new detection method based on temperature. The result shows that the recovery rate of the new method is more than 95.0%, significantly better than that of the original detection method.
2017, 45(1): 104-110
doi: 10.11895/j.issn.0253-3820.160597
Abstract:
A peroxynitrite electrochemical sensor based on hemin/gold nanoparticles/poly(melamine)/multi-walled carbon nanotube composite modifying glassy carbon electrode was successfully constructed for the detection of peroxynitrite. The electrochemical behavior of peroxynitrite on the sensor was investigated by cyclic voltammetry and amperometric i-t curve, and the conditions for preparation of the sensor and detection of peroxynitrite were optimized. The results showed that the amperometric response of the sensor for peroxynitrite reached the maximum when the amount of carbon nanotubes was 5 μL, the deposition time of gold was 20 s, and the working potential was 0.8 V. Under the optimized experimental conditions, the sensor could detect peroxynitrite in a linear range from 1.0×10-5 mol/L to 3.5×10-4 mol/L and from 3.5×10-4 mol/L to 1.1×10-3 mol/L, with a sensitivity of 0.13 A/(mol/L) and a detection limit of 1.2×10-7 mol/L (S/N=3).
A peroxynitrite electrochemical sensor based on hemin/gold nanoparticles/poly(melamine)/multi-walled carbon nanotube composite modifying glassy carbon electrode was successfully constructed for the detection of peroxynitrite. The electrochemical behavior of peroxynitrite on the sensor was investigated by cyclic voltammetry and amperometric i-t curve, and the conditions for preparation of the sensor and detection of peroxynitrite were optimized. The results showed that the amperometric response of the sensor for peroxynitrite reached the maximum when the amount of carbon nanotubes was 5 μL, the deposition time of gold was 20 s, and the working potential was 0.8 V. Under the optimized experimental conditions, the sensor could detect peroxynitrite in a linear range from 1.0×10-5 mol/L to 3.5×10-4 mol/L and from 3.5×10-4 mol/L to 1.1×10-3 mol/L, with a sensitivity of 0.13 A/(mol/L) and a detection limit of 1.2×10-7 mol/L (S/N=3).
2017, 45(1): 111-117
doi: 10.11895/j.issn.0253-3820.160678
Abstract:
The nanomaterial of n-HoPO4 was synthesized via hydrothermal method with Ho2O3 as raw material, and its morphology and component were characterized by SEM and EDS. The composite material of n-HoPO4 and hemoglobin (Hb) was dropped onto the surface of the glassy carbon electrode (GCE) so as to construct the biosensor for detection of hydrogen peroxide. The whole process was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicated that (Hb/n-HoPO4/GCE) possessed good electrochemical catalytic effect towards H2O2 reduction. The n-HoPO4 showed good electrical conductivity and could promote the direct electron transfer rate between Hb and GCE. The effect of different pH value and electrochemical scan rates on the response current of the modified electrode was studied. Under the optimal conditions, the biosensor exhibited a good linear detection range from 50 to 1000 μmol/L (correlation coefficient R=0.999) with the detection limit of 17 μmol/L (S/N=3). The biosensor showed wide detection range, good stability and reproducibility and strong anti-interference ability, and could be used for real sample detection.
The nanomaterial of n-HoPO4 was synthesized via hydrothermal method with Ho2O3 as raw material, and its morphology and component were characterized by SEM and EDS. The composite material of n-HoPO4 and hemoglobin (Hb) was dropped onto the surface of the glassy carbon electrode (GCE) so as to construct the biosensor for detection of hydrogen peroxide. The whole process was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results indicated that (Hb/n-HoPO4/GCE) possessed good electrochemical catalytic effect towards H2O2 reduction. The n-HoPO4 showed good electrical conductivity and could promote the direct electron transfer rate between Hb and GCE. The effect of different pH value and electrochemical scan rates on the response current of the modified electrode was studied. Under the optimal conditions, the biosensor exhibited a good linear detection range from 50 to 1000 μmol/L (correlation coefficient R=0.999) with the detection limit of 17 μmol/L (S/N=3). The biosensor showed wide detection range, good stability and reproducibility and strong anti-interference ability, and could be used for real sample detection.
2017, 45(1): 118-123
doi: 10.11895/j.issn.0253-3820.160342
Abstract:
A method for determination of tembotrione in vegetative foods using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. The sample was pretreated using modified QuEChERS (quick, easy, cheap, effective, rigged and safe) method in which the extraction and clean-up steps were completed in one procedure. The sample was extracted with acidic acetonitrile (containing 0.1% formic acid), and cleaned up by graphitized carbon black (GCB), and then the extracting solution was centrifuged and filtrated before detection. The HPLC-MS/MS method was performed on a C18 column with gradient elution of acetonitrile and 0.1% formic acid at a flow rate of 0.25 mL/min. The mass spectrometric analysis was carried out with electrospray positive ion source (ESI+), and multiple reaction monitoring mode (MRM). The matrix-matched external standard method was used for quantification. The results showed that the calibration curves were linear in the range of 0.5-100 ng/mL with the correlation coefficients larger than 0.996, the limits of quantification (LOQ, S/N≥10) were 1.0 μg/kg in ten different matrix (corn, rice, wheat, grape, apple, raisin, Chinese wolfberry, tomato, cucumber, cabbage). The mean recovery of tembotrione was 82.0%-111.8% and the relative deviation (RSD) was 3.0%-14.9% at 1.0, 2.0 and 10.0 μg/kg with three spiked levels. The method is highly effective and suitable for the monitoring of pesticide residue analysis.
A method for determination of tembotrione in vegetative foods using high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed. The sample was pretreated using modified QuEChERS (quick, easy, cheap, effective, rigged and safe) method in which the extraction and clean-up steps were completed in one procedure. The sample was extracted with acidic acetonitrile (containing 0.1% formic acid), and cleaned up by graphitized carbon black (GCB), and then the extracting solution was centrifuged and filtrated before detection. The HPLC-MS/MS method was performed on a C18 column with gradient elution of acetonitrile and 0.1% formic acid at a flow rate of 0.25 mL/min. The mass spectrometric analysis was carried out with electrospray positive ion source (ESI+), and multiple reaction monitoring mode (MRM). The matrix-matched external standard method was used for quantification. The results showed that the calibration curves were linear in the range of 0.5-100 ng/mL with the correlation coefficients larger than 0.996, the limits of quantification (LOQ, S/N≥10) were 1.0 μg/kg in ten different matrix (corn, rice, wheat, grape, apple, raisin, Chinese wolfberry, tomato, cucumber, cabbage). The mean recovery of tembotrione was 82.0%-111.8% and the relative deviation (RSD) was 3.0%-14.9% at 1.0, 2.0 and 10.0 μg/kg with three spiked levels. The method is highly effective and suitable for the monitoring of pesticide residue analysis.
2017, 45(1): 124-132
doi: 10.11895/j.issn.0253-3820.160530
Abstract:
An ultra-high performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) method for simultaneous determination of thirty different species of ‘lean meat agents’ (including clonidine, cyproheptadine, and other 28 β-agonists) residues in swine urine was developed. The parameters of separation conditions of liquid chromatography, MS/MS detection parameters and sample preparation procedure were optimized. After centrifuged at 5000 r/min for 5 min, the swine urine samples were performed directly by MCX column. Then the column was washed with 3 mL of water and 3 mL of methanol, respectively, and then the compounds were eluted with 5% ammonium hydroxide in methanol. The analytes were detected by UPLC-MS/MS after the elution was evaporated to dryness at 45℃ under a stream of nitrogen gas. Under the optimum conditions, thirty of analytes could be well separated in less than 5 min. The linear ranges were 0.1-10 μg/L for all analytes with the correlation coefficient (r2) higher than 0.992. Limits of detection (LOD) and limits of quantification (LOQ) of this method were less than 0.1 μg/L and 0.3 μg/L, respectively. The mean recoveries of three spiked concentration levels in blank sample varied from 67.6% to 103.2% with the intra-and inter-relative standard deviations of 2.8% to 16.8% and 2.6% to 15.8%, respectively. Overall, the proposed method is simple, quick, reliable, sensitivity, and can be applied in large scale supervision of illegal usage of 30 kinds of ‘lean meat agents’.
An ultra-high performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) method for simultaneous determination of thirty different species of ‘lean meat agents’ (including clonidine, cyproheptadine, and other 28 β-agonists) residues in swine urine was developed. The parameters of separation conditions of liquid chromatography, MS/MS detection parameters and sample preparation procedure were optimized. After centrifuged at 5000 r/min for 5 min, the swine urine samples were performed directly by MCX column. Then the column was washed with 3 mL of water and 3 mL of methanol, respectively, and then the compounds were eluted with 5% ammonium hydroxide in methanol. The analytes were detected by UPLC-MS/MS after the elution was evaporated to dryness at 45℃ under a stream of nitrogen gas. Under the optimum conditions, thirty of analytes could be well separated in less than 5 min. The linear ranges were 0.1-10 μg/L for all analytes with the correlation coefficient (r2) higher than 0.992. Limits of detection (LOD) and limits of quantification (LOQ) of this method were less than 0.1 μg/L and 0.3 μg/L, respectively. The mean recoveries of three spiked concentration levels in blank sample varied from 67.6% to 103.2% with the intra-and inter-relative standard deviations of 2.8% to 16.8% and 2.6% to 15.8%, respectively. Overall, the proposed method is simple, quick, reliable, sensitivity, and can be applied in large scale supervision of illegal usage of 30 kinds of ‘lean meat agents’.
2017, 45(1): 133-138
doi: 10.11895/j.issn.0253-3820.160309
Abstract:
Peptidomic has become a common method of screening biomarkers, but most researches focused on the mixture samples by analyzing and comparing the results of samples from patients and healthy controls. Unfortunately, there is little study about the individual differences among healthy person and the common features of them. Here, to obtain the general characteristics of serum peptidomics including molecular weight distribution, nanoliter liquid chromatography-high resolution tandem mass spectrometry was used to analyze the mixture samples of 20 healthy human serums. Next, six cases of individual samples were analyzed and compared, indicating that there were obvious individual difference and some common features among different samples. We found that the peptides within 7000 Da could be identified and the peptides from fibrinogen α-chain were detected with the highest frequency. Additionally, the distribution of serum peptidome at protein level was heterogeneous; namely, the top 10% protein accounted about 50% of the total peptides and only one peptide was detected for the last 40% proteins. In addition, 12 common peptides arising from 8 proteins were detected in all of the samples. Furthermore, the post-translational modification including N-terminal acetylation, oxidation, phosphorylation, deamination and dehydration, as well as the obvious sequence ladder phenomenon, were detected in all samples. In conclusion, the basic characteristics of peptidomics at the sequence level were explored and the individual difference of serum peptidome was proposed, which could provide a reference for the study of serum peptide biomarkers.
Peptidomic has become a common method of screening biomarkers, but most researches focused on the mixture samples by analyzing and comparing the results of samples from patients and healthy controls. Unfortunately, there is little study about the individual differences among healthy person and the common features of them. Here, to obtain the general characteristics of serum peptidomics including molecular weight distribution, nanoliter liquid chromatography-high resolution tandem mass spectrometry was used to analyze the mixture samples of 20 healthy human serums. Next, six cases of individual samples were analyzed and compared, indicating that there were obvious individual difference and some common features among different samples. We found that the peptides within 7000 Da could be identified and the peptides from fibrinogen α-chain were detected with the highest frequency. Additionally, the distribution of serum peptidome at protein level was heterogeneous; namely, the top 10% protein accounted about 50% of the total peptides and only one peptide was detected for the last 40% proteins. In addition, 12 common peptides arising from 8 proteins were detected in all of the samples. Furthermore, the post-translational modification including N-terminal acetylation, oxidation, phosphorylation, deamination and dehydration, as well as the obvious sequence ladder phenomenon, were detected in all samples. In conclusion, the basic characteristics of peptidomics at the sequence level were explored and the individual difference of serum peptidome was proposed, which could provide a reference for the study of serum peptide biomarkers.
2017, 45(1): 139-150
doi: 10.11895/j.issn.0253-3820.160295
Abstract:
Carbon dots (Cdots) become potential material for biosensing, drug delivery, and bioimaging because of their excellent optical properties, high biocompatibility, and low toxicity. The preparation, properties, and applications of Cdots have drawn great attention. In this review, we classify Cdots into two groups: graphene nanodots and carbon nanodots based on the difference in precursors and preparation methods. The synthetic methods of Cdots are summarized and their luminescence mechanism is analyzed. The applications of Cdots in biosensing, drug delivery, and bioimaging are also discussed. The issues and challenges of Cdots are analyzed for their further development.
Carbon dots (Cdots) become potential material for biosensing, drug delivery, and bioimaging because of their excellent optical properties, high biocompatibility, and low toxicity. The preparation, properties, and applications of Cdots have drawn great attention. In this review, we classify Cdots into two groups: graphene nanodots and carbon nanodots based on the difference in precursors and preparation methods. The synthetic methods of Cdots are summarized and their luminescence mechanism is analyzed. The applications of Cdots in biosensing, drug delivery, and bioimaging are also discussed. The issues and challenges of Cdots are analyzed for their further development.
