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2020 Volume 37 Issue 2
2020, 37(2): 123-133
doi: 10.11944/j.issn.1000-0518.2020.02.190261
Abstract:
Due to their unique physical and chemical properties, one-dimensional (1D) hybrid nanomaterials have been widely used in electrical, optical, catalytic and other fields, and their preparation methods are critical to the regulation of performance. In recent years, template method has been widely used as a simple and general synthetic method for the synthesis of 1D nanostructures and nanoarrays. This paper discusses trends in the 1D hybrid nanomaterials prepared by anodic aluminum oxide(AAO) template method combined with other techniques, and their applications in stimuli-responsive devices, energy storage and conversion devices, catalysis, etc.
Due to their unique physical and chemical properties, one-dimensional (1D) hybrid nanomaterials have been widely used in electrical, optical, catalytic and other fields, and their preparation methods are critical to the regulation of performance. In recent years, template method has been widely used as a simple and general synthetic method for the synthesis of 1D nanostructures and nanoarrays. This paper discusses trends in the 1D hybrid nanomaterials prepared by anodic aluminum oxide(AAO) template method combined with other techniques, and their applications in stimuli-responsive devices, energy storage and conversion devices, catalysis, etc.
2020, 37(2): 134-143
doi: 10.11944/j.issn.1000-0518.2020.02.190206
Abstract:
Tuberculosis is a chronic respiratory infectious disease caused by Mycobacterium tuberculosis and a serious threat to the health of people around the world. In the previous work, we adopted the strategy of combinatorial chemistry, combining the group nitrofuran and phenyl-thiazole, to generate a series of new compounds with high antitubercular activity. In this work, a methylene-piperidine group was introduced and used to replace the original amide bridge moiety to produce new derivatives 2-(1-((5-nitrofuran-2-yl)methyl)piperidin-4-yl)thiazole (5) and 2-(1-((5-nitrofuran-2-yl)methyl) piperidin-4-yl)-4-phenylthiazole (6). In total, 19 compounds were synthesized and then the inhibition rate against Mycobacterium tuberculosis H37Ra was tested at the concentration of 1 μmol/L and 0.1 μmol/L. Based on the structure-activity relationship analysis, we found that the substitution on the benzene ring is beneficial to the activity improvement, furthermore, the para substitution is better than the meta and ortho substitution, and the electron-withdrawing group in the para position is better than the electron-donating group. In the para substitution of electron-withdrawing groups, -CF3 substituted compound 2-(1-((5-nitrofuran-2-yl)methyl)piperidin-4-yl)-4-(4-(trifluoromethyl)phenyl)thiazole (6f) had the highest antitubercular activity, and the inhibition rates reached 99.6% and 93.4% at the concentration of 1 μmol/L and 0.1 μmol/L, respectively. Due to the high antitubercular activity of compound 6f, it can be further developed as an antitubercular candidate compound.
Tuberculosis is a chronic respiratory infectious disease caused by Mycobacterium tuberculosis and a serious threat to the health of people around the world. In the previous work, we adopted the strategy of combinatorial chemistry, combining the group nitrofuran and phenyl-thiazole, to generate a series of new compounds with high antitubercular activity. In this work, a methylene-piperidine group was introduced and used to replace the original amide bridge moiety to produce new derivatives 2-(1-((5-nitrofuran-2-yl)methyl)piperidin-4-yl)thiazole (5) and 2-(1-((5-nitrofuran-2-yl)methyl) piperidin-4-yl)-4-phenylthiazole (6). In total, 19 compounds were synthesized and then the inhibition rate against Mycobacterium tuberculosis H37Ra was tested at the concentration of 1 μmol/L and 0.1 μmol/L. Based on the structure-activity relationship analysis, we found that the substitution on the benzene ring is beneficial to the activity improvement, furthermore, the para substitution is better than the meta and ortho substitution, and the electron-withdrawing group in the para position is better than the electron-donating group. In the para substitution of electron-withdrawing groups, -CF3 substituted compound 2-(1-((5-nitrofuran-2-yl)methyl)piperidin-4-yl)-4-(4-(trifluoromethyl)phenyl)thiazole (6f) had the highest antitubercular activity, and the inhibition rates reached 99.6% and 93.4% at the concentration of 1 μmol/L and 0.1 μmol/L, respectively. Due to the high antitubercular activity of compound 6f, it can be further developed as an antitubercular candidate compound.
2020, 37(2): 144-154
doi: 10.11944/j.issn.1000-0518.2020.02.190213
Abstract:
Two novel phosphate-imine bifunctional flame-retardant compounds (FR:N1, N4-bis{[4-(5, 5-dimethyl-2-oxide-1, 3, 2-dioxaphosphinan-2-yl)oxy]benzylidene}benzene-1, 4-diamine(PNB); N1, N2-bis{[4-(5, 5-dimethyl-2-oxide-1, 3, 2-dioxaphosphinan-2-yl)oxy]benzylidene}ethane-1, 2-diamine(PNE)) were synthesized via aldehyde amine condensation reaction using 4-(5, 5-dimethyl-1, 3-dioxygen heterocyclic phosphoryl) benzaldehyde (PCHO), p-phenylene diamine and ethylenediamine as raw materials, respectively. FRs were applied on a bisphenol-A diglycidyl ether type epoxy resin (DGEBA) cured by 4, 4'-diaminodiphenylsulfone (DDS) and the flame retarded mechanism was studied. The results showed that the introduction of FR greatly improved the char residues (Rc) of DGEBA/DDS at 700℃ and enhanced the flame retardant properties of epoxy resin systems. PNE with ethylene diamine unit presented a better flame retardant performance than PNB with p-phenylene diamine unit. With 1.5% phosphorus content, PNE-1.5/DGEBA/DDS could obtain Rc of 35.1% in nitrogen atmosphere and 14.4% in air, respectively, and a limiting oxygen index(LOI) value of 33.2%, reaching UL-94 Ⅴ-0 grade. At the same time, PNE-1.5/DGEBA/DDS maintained the bending strength and more than 76% of the impact strength compared to DGEBA/DDS, which is significantly superior to PNB-1.5/DGEBA/DDS. Analysis of flame retardant results showed that FR presented a comprehensive mechanism of condensed phase, gas phase and phosphorus-nitrogen synergistic effect in DGEBA/DDS system. In conclusion, phosphate-imine bifunctional compounds FR have excellent flame retardancy for epoxy resin systems and have potential applications.
Two novel phosphate-imine bifunctional flame-retardant compounds (FR:N1, N4-bis{[4-(5, 5-dimethyl-2-oxide-1, 3, 2-dioxaphosphinan-2-yl)oxy]benzylidene}benzene-1, 4-diamine(PNB); N1, N2-bis{[4-(5, 5-dimethyl-2-oxide-1, 3, 2-dioxaphosphinan-2-yl)oxy]benzylidene}ethane-1, 2-diamine(PNE)) were synthesized via aldehyde amine condensation reaction using 4-(5, 5-dimethyl-1, 3-dioxygen heterocyclic phosphoryl) benzaldehyde (PCHO), p-phenylene diamine and ethylenediamine as raw materials, respectively. FRs were applied on a bisphenol-A diglycidyl ether type epoxy resin (DGEBA) cured by 4, 4'-diaminodiphenylsulfone (DDS) and the flame retarded mechanism was studied. The results showed that the introduction of FR greatly improved the char residues (Rc) of DGEBA/DDS at 700℃ and enhanced the flame retardant properties of epoxy resin systems. PNE with ethylene diamine unit presented a better flame retardant performance than PNB with p-phenylene diamine unit. With 1.5% phosphorus content, PNE-1.5/DGEBA/DDS could obtain Rc of 35.1% in nitrogen atmosphere and 14.4% in air, respectively, and a limiting oxygen index(LOI) value of 33.2%, reaching UL-94 Ⅴ-0 grade. At the same time, PNE-1.5/DGEBA/DDS maintained the bending strength and more than 76% of the impact strength compared to DGEBA/DDS, which is significantly superior to PNB-1.5/DGEBA/DDS. Analysis of flame retardant results showed that FR presented a comprehensive mechanism of condensed phase, gas phase and phosphorus-nitrogen synergistic effect in DGEBA/DDS system. In conclusion, phosphate-imine bifunctional compounds FR have excellent flame retardancy for epoxy resin systems and have potential applications.
2020, 37(2): 155-159
doi: 10.11944/j.issn.1000-0518.2020.02.190155
Abstract:
A simple and efficient synthesis of cyanuric acid by thermal polymerization and hydrothermal treatment was developed using melamine as the raw material. The product structure was characterized by X-ray single crystal diffraction, nuclear magnetic resonance (NMR), Fourier transform infrared spectrometry (FTIR), mass spectrometry and elemental analysis. Under the optimal hydrothermal reaction temperature of 140℃, the reaction was carried out for 2 h, and the total yield was up to 54%. The synthesis method is simple and has less pollution, providing a new reference method for industrial preparation of cyanuric acid.
A simple and efficient synthesis of cyanuric acid by thermal polymerization and hydrothermal treatment was developed using melamine as the raw material. The product structure was characterized by X-ray single crystal diffraction, nuclear magnetic resonance (NMR), Fourier transform infrared spectrometry (FTIR), mass spectrometry and elemental analysis. Under the optimal hydrothermal reaction temperature of 140℃, the reaction was carried out for 2 h, and the total yield was up to 54%. The synthesis method is simple and has less pollution, providing a new reference method for industrial preparation of cyanuric acid.
2020, 37(2): 160-167
doi: 10.11944/j.issn.1000-0518.2020.02.190211
Abstract:
Cu/ZrO2 catalysts with the Cu/Zr molar ratio of 1:1, 1:2, 1:4 and 1:8 were prepared by the sol-gel method. When n(Cu):n(Zr)=1:4, a high CO2 conversion (8.0%) with methanol selectivity of 59.5% was achieved. To increase CO2 conversion and CH3OH selectivity, Pd-Cu/ZrO2 catalyst with the Cu/Zr molar ratio of 1:4 and 1% mass fraction of Pd was synthesized by the impregnation method. The results showed that CO2 conversion and CH3OH yield over the Pd-Cu/ZrO2 catalyst were 40.0% and 80.9% higher than that over the Cu/ZrO2 catalyst at 250℃, 2 MPa, 12000 mL/(g·h) and V(H2):V(CO2)=3:1. Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy analysis (FT-IR), N2 adsorption-desorption (BET), X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction of H2(H2-TPR) results indicated that addition of Pd improved the dispersion and surface area of the catalyst. The strong interaction between Pd and Cu species leads to the shift of Cu2p to low binding energies and decreases the catalyst reduction temperature, which exhibits high catalytic performance for hydrogenation of CO2.
Cu/ZrO2 catalysts with the Cu/Zr molar ratio of 1:1, 1:2, 1:4 and 1:8 were prepared by the sol-gel method. When n(Cu):n(Zr)=1:4, a high CO2 conversion (8.0%) with methanol selectivity of 59.5% was achieved. To increase CO2 conversion and CH3OH selectivity, Pd-Cu/ZrO2 catalyst with the Cu/Zr molar ratio of 1:4 and 1% mass fraction of Pd was synthesized by the impregnation method. The results showed that CO2 conversion and CH3OH yield over the Pd-Cu/ZrO2 catalyst were 40.0% and 80.9% higher than that over the Cu/ZrO2 catalyst at 250℃, 2 MPa, 12000 mL/(g·h) and V(H2):V(CO2)=3:1. Powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy analysis (FT-IR), N2 adsorption-desorption (BET), X-ray photoelectron spectroscopy (XPS) and temperature-programmed reduction of H2(H2-TPR) results indicated that addition of Pd improved the dispersion and surface area of the catalyst. The strong interaction between Pd and Cu species leads to the shift of Cu2p to low binding energies and decreases the catalyst reduction temperature, which exhibits high catalytic performance for hydrogenation of CO2.
2020, 37(2): 168-174
doi: 10.11944/j.issn.1000-0518.2020.02.190189
Abstract:
L-Phenylglycine is an important class of chiral non-natural amino acids, and can be used to synthesize a variety of important pharmaceutical intermediate. Exploiting the green synthesis process of phenylacetone acid has significant economic value. In this study, novel and highly active D-mandelate dehydrogenase (LhDMDH) and L-leucine dehydrogenase (EsLeuDH) are coupled to achieve bio-transformation of D-mandelic acid into L-phenylglycine on the premise of coenzyme circulation, and this reaction only requires a lower concentration of coenzyme. By optimizing the transformation conditions including added amount of enzyme, β-nicotinamide adenine dinucleotide (NAD+) concentration, NH4+ concentration and substrate concentration, we obtain the most economical condition:200 mmol/L D-mandelic acid, 6.5 kU/L enzyme, 0.1 mmol/L NAD +, 0.5 mol/L NH4+ and 30℃ for 12 h. The product yield and enantionmeric excess (e.e.) value can reach more than 98% and 99% under the most economical condition, respectively. This transformation has large industrialization potential, and lays a solid foundation for achieving large-scale biosynthesis of L-phenylglycine.
L-Phenylglycine is an important class of chiral non-natural amino acids, and can be used to synthesize a variety of important pharmaceutical intermediate. Exploiting the green synthesis process of phenylacetone acid has significant economic value. In this study, novel and highly active D-mandelate dehydrogenase (LhDMDH) and L-leucine dehydrogenase (EsLeuDH) are coupled to achieve bio-transformation of D-mandelic acid into L-phenylglycine on the premise of coenzyme circulation, and this reaction only requires a lower concentration of coenzyme. By optimizing the transformation conditions including added amount of enzyme, β-nicotinamide adenine dinucleotide (NAD+) concentration, NH4+ concentration and substrate concentration, we obtain the most economical condition:200 mmol/L D-mandelic acid, 6.5 kU/L enzyme, 0.1 mmol/L NAD +, 0.5 mol/L NH4+ and 30℃ for 12 h. The product yield and enantionmeric excess (e.e.) value can reach more than 98% and 99% under the most economical condition, respectively. This transformation has large industrialization potential, and lays a solid foundation for achieving large-scale biosynthesis of L-phenylglycine.
2020, 37(2): 175-181
doi: 10.11944/j.issn.1000-0518.2020.02.190224
Abstract:
Herein, oligo-L-tyrosine (O-L-Try) was synthesized from L-tyrosine methyl ester with bromelain as the catalyst. The maximal value of O-L-Try yield reached 65% under the optimum reaction conditions of 0.8 U/mL of bromelain, volume fraction 7.5% of dimethyl sulfoxide(DMSO) in phosphate solution (pH=7.5, 0.2 mol/L) and 0.23 g/mL of L-tyrosine methyl ester at 50℃ for five hours.The structure of O-L-Try was characterized by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), hydrogen nuclear magnetic resonance spectroscopy (1H NMR), Raman spectroscopy and Fourier transform infrared spectrometry (FTIR). The polymerization degree of O-L-Try is mainly 10 as measured by MALDI-TOF-MS. The average degree of polymerization of O-L-Try is 8 as determined by 1H NMR analysis. Raman spectroscopy shows that O-L-Try has the characteristic peaks at 1623 cm-1 (amide Ⅰ band), 1447 cm-1 (amide Ⅱ band), 1270 cm-1 (amide Ⅲ band) and 648 cm-1 (amide Ⅳ band).
Herein, oligo-L-tyrosine (O-L-Try) was synthesized from L-tyrosine methyl ester with bromelain as the catalyst. The maximal value of O-L-Try yield reached 65% under the optimum reaction conditions of 0.8 U/mL of bromelain, volume fraction 7.5% of dimethyl sulfoxide(DMSO) in phosphate solution (pH=7.5, 0.2 mol/L) and 0.23 g/mL of L-tyrosine methyl ester at 50℃ for five hours.The structure of O-L-Try was characterized by matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS), hydrogen nuclear magnetic resonance spectroscopy (1H NMR), Raman spectroscopy and Fourier transform infrared spectrometry (FTIR). The polymerization degree of O-L-Try is mainly 10 as measured by MALDI-TOF-MS. The average degree of polymerization of O-L-Try is 8 as determined by 1H NMR analysis. Raman spectroscopy shows that O-L-Try has the characteristic peaks at 1623 cm-1 (amide Ⅰ band), 1447 cm-1 (amide Ⅱ band), 1270 cm-1 (amide Ⅲ band) and 648 cm-1 (amide Ⅳ band).
2020, 37(2): 182-189
doi: 10.11944/j.issn.1000-0518.2020.02.190144
Abstract:
In this paper, a series of waterborne polyurethane coatings with different concentration of color paste was prepared, and the coating was sprayed at the backside of polyvinyl chloride (PVC) skin of automotive instrument panel to form a composite. The spraying property of the coating was evaluated by measuring the viscosity of coating by rheometer; the glass transition temperature (Tg) of sample was characterized by differential scanning calorimeter; the tensile properties and tear resistance of sample under -30℃ were characterized by universal material testing machine; and the damping factor of sample was characterized by dynamic mechanical thermal analysis. It was observed that the coating with different mass fraction of color paste can be sprayed. The blasting property of PVC skin at -30℃ was found to be related with the damping factor of the sample rather than the Tg, tensile properties and tear resistance of sample under low temperature. The bigger the value of damping factor was, the better the lasting property of PVC skin with coating layer had.
In this paper, a series of waterborne polyurethane coatings with different concentration of color paste was prepared, and the coating was sprayed at the backside of polyvinyl chloride (PVC) skin of automotive instrument panel to form a composite. The spraying property of the coating was evaluated by measuring the viscosity of coating by rheometer; the glass transition temperature (Tg) of sample was characterized by differential scanning calorimeter; the tensile properties and tear resistance of sample under -30℃ were characterized by universal material testing machine; and the damping factor of sample was characterized by dynamic mechanical thermal analysis. It was observed that the coating with different mass fraction of color paste can be sprayed. The blasting property of PVC skin at -30℃ was found to be related with the damping factor of the sample rather than the Tg, tensile properties and tear resistance of sample under low temperature. The bigger the value of damping factor was, the better the lasting property of PVC skin with coating layer had.
2020, 37(2): 190-197
doi: 10.11944/j.issn.1000-0518.2020.02.190238
Abstract:
Using COMSOL Multiphysics 5.3 package, we establish a three-dimensional finite element model to calculate the mechanical properties of polyimide fibers with the temperature field generated by the solid heat transfer and surface radiation heat transfer. We analyze the effects of the size and location of holes and the difference of thermal expansion coefficient on the mechanical properties of polyimide fibers. The results indicate that under the condition of polyimide fiber with fixed constraints at both ends, the stress exhibits the similar trends in the temperature fields generated by solid heat transfer and surface radiation heat transfer. The holes in the polyimide fiber reduce the mechanical properties, which results in the larger holes corresponding to the more unbalanced stress distribution. This is more unfavorable to the stability of the polyimide fibers. Meanwhile, the stress decreases with the increase of negative axial coefficient of thermal expansion.
Using COMSOL Multiphysics 5.3 package, we establish a three-dimensional finite element model to calculate the mechanical properties of polyimide fibers with the temperature field generated by the solid heat transfer and surface radiation heat transfer. We analyze the effects of the size and location of holes and the difference of thermal expansion coefficient on the mechanical properties of polyimide fibers. The results indicate that under the condition of polyimide fiber with fixed constraints at both ends, the stress exhibits the similar trends in the temperature fields generated by solid heat transfer and surface radiation heat transfer. The holes in the polyimide fiber reduce the mechanical properties, which results in the larger holes corresponding to the more unbalanced stress distribution. This is more unfavorable to the stability of the polyimide fibers. Meanwhile, the stress decreases with the increase of negative axial coefficient of thermal expansion.
2020, 37(2): 198-204
doi: 10.11944/j.issn.1000-0518.2020.02.190236
Abstract:
Although calix[4]quinone (C4Q) has a theoretical specific capacity up to 447 mA·h/g, its high solubility in liquid electrolytes and low conductivity make it impractical in lithium-ion batteries (LIBs). In order to solve these problems, N-doped amorphous carbon nanofibers (NACF) were obtained by high-temperature carbonization with chitin as raw material, and were used to adsorb C4Q to prepare C4Q/NACF (mass ratio is 1:1) composite material. The as-assembled LIBs delivered an initial discharge capacity of 426 mA·h/g, and maintained 213 mA·h/g after 100 cycles at 0.1 C. Even at a high rate of 1 C, the capacity could still reach 188 mA·h/g. These experimental results show that the performance of LIBs is effectively improved by using NACF biomass carbon to immobilize C4Q.
Although calix[4]quinone (C4Q) has a theoretical specific capacity up to 447 mA·h/g, its high solubility in liquid electrolytes and low conductivity make it impractical in lithium-ion batteries (LIBs). In order to solve these problems, N-doped amorphous carbon nanofibers (NACF) were obtained by high-temperature carbonization with chitin as raw material, and were used to adsorb C4Q to prepare C4Q/NACF (mass ratio is 1:1) composite material. The as-assembled LIBs delivered an initial discharge capacity of 426 mA·h/g, and maintained 213 mA·h/g after 100 cycles at 0.1 C. Even at a high rate of 1 C, the capacity could still reach 188 mA·h/g. These experimental results show that the performance of LIBs is effectively improved by using NACF biomass carbon to immobilize C4Q.
2020, 37(2): 205-210
doi: 10.11944/j.issn.1000-0518.2020.02.190196
Abstract:
Metal organic framework UTSA-74 synthesized via hydrothermal method could efficiently remove both arsenate and arsenite from water. A batch test with aqueous solutions was performed, and 95% of As(Ⅴ) and 85% of As(Ⅲ) removal was obtained with the lower concentration of arsenic(~1 mg/L). This experiment data matched the pseudo-second-order model and Freundlich model. In addition, when Cl-, NO3- and PO43- all existed in solutions, PO43- affected the adsorption of arsenic obviously. After adsorption, we eluted UTSA-74@arsenic by 0.1 mol/L NaOH, the removal rate of arsenic was still up to around 70% after three cycles. XRD, SEM and IR analyses showed that the excellent adsorption capacity was due to the reformed Zn—O—As bond between arsenic and adsorbent. In a word, UTSA-74 can be the candidate for removing arsenic.
Metal organic framework UTSA-74 synthesized via hydrothermal method could efficiently remove both arsenate and arsenite from water. A batch test with aqueous solutions was performed, and 95% of As(Ⅴ) and 85% of As(Ⅲ) removal was obtained with the lower concentration of arsenic(~1 mg/L). This experiment data matched the pseudo-second-order model and Freundlich model. In addition, when Cl-, NO3- and PO43- all existed in solutions, PO43- affected the adsorption of arsenic obviously. After adsorption, we eluted UTSA-74@arsenic by 0.1 mol/L NaOH, the removal rate of arsenic was still up to around 70% after three cycles. XRD, SEM and IR analyses showed that the excellent adsorption capacity was due to the reformed Zn—O—As bond between arsenic and adsorbent. In a word, UTSA-74 can be the candidate for removing arsenic.
2020, 37(2): 211-217
doi: 10.11944/j.issn.1000-0518.2020.02.190214
Abstract:
A simple and rapid microfluidic enzymatic reaction method was used to visualize the urea concentration. In the aqueous two-phase system (ATPS), ammonium carbonate produced by the enzymatic reaction discolors the neutral red indicator in droplets, and the color intensity of droplets is analyzed to determine the concentration of urea in the sample to be tested. The detection range can reach 0~50 mg/mL. The microfluidic ATPS droplet flow overcomes the challenge of low biocompatibility of traditional detection platforms based on oil-water droplet. Less consumption, extremely large specific surface area and micro-scale diffusion distance of droplet flow result in the high enzymatic reaction rate. The reaction rate is many times faster than that of traditional beaker method. The detection time is reduced to 20 s. The study aims to provide new ideas and reference for the rapid urea detection in the field of applied chemistry.
A simple and rapid microfluidic enzymatic reaction method was used to visualize the urea concentration. In the aqueous two-phase system (ATPS), ammonium carbonate produced by the enzymatic reaction discolors the neutral red indicator in droplets, and the color intensity of droplets is analyzed to determine the concentration of urea in the sample to be tested. The detection range can reach 0~50 mg/mL. The microfluidic ATPS droplet flow overcomes the challenge of low biocompatibility of traditional detection platforms based on oil-water droplet. Less consumption, extremely large specific surface area and micro-scale diffusion distance of droplet flow result in the high enzymatic reaction rate. The reaction rate is many times faster than that of traditional beaker method. The detection time is reduced to 20 s. The study aims to provide new ideas and reference for the rapid urea detection in the field of applied chemistry.
2020, 37(2): 218-226
doi: 10.11944/j.issn.1000-0518.2020.02.190235
Abstract:
In this article, solid phase microextraction (SPME) fibers were assembled by in situ anodization on the surface of titanium wire with a constant voltage and anodization time. Effect of the electrolyte solutions of different concentrations (concentration of NH4F and ethylene glycol) and electrolysis time on the formation and size of TiO2 nanotubes (TiO2NTs) was investigated. TiO2NTs arrays were arranged with the wall thickness of 25 nm and the pore diameter of 100 nm in ethylene glycol and water (volume ratio 1:1) containing 0.5% mass fraction of NH4F at 20 V for 30 min at 25℃. Development of titanium dioxide nanotube array as a fiber coating for solid-phase microextraction coupled to high performance liquid chromatography for sensitive determination of polycyclic aromatic hydrocarbons (PAHs) in water. Under the optimized SPME conditions, this method has a higher sensitivity, wider linear range, better selectivity and repetition, and was easier to operate. The proposed method was successfully applied to the preconcentration and determination of target PAHs in river water and wastewater samples with satisfactory analytical results.
In this article, solid phase microextraction (SPME) fibers were assembled by in situ anodization on the surface of titanium wire with a constant voltage and anodization time. Effect of the electrolyte solutions of different concentrations (concentration of NH4F and ethylene glycol) and electrolysis time on the formation and size of TiO2 nanotubes (TiO2NTs) was investigated. TiO2NTs arrays were arranged with the wall thickness of 25 nm and the pore diameter of 100 nm in ethylene glycol and water (volume ratio 1:1) containing 0.5% mass fraction of NH4F at 20 V for 30 min at 25℃. Development of titanium dioxide nanotube array as a fiber coating for solid-phase microextraction coupled to high performance liquid chromatography for sensitive determination of polycyclic aromatic hydrocarbons (PAHs) in water. Under the optimized SPME conditions, this method has a higher sensitivity, wider linear range, better selectivity and repetition, and was easier to operate. The proposed method was successfully applied to the preconcentration and determination of target PAHs in river water and wastewater samples with satisfactory analytical results.
2020, 37(2): 227-234
doi: 10.11944/j.issn.1000-0518.2020.02.190226
Abstract:
In this paper, the nitrogen-doped carbon dots (NCDs) were synthesized using the natural material dendrobe as the raw material by one-step hydrothermal method. The synthesized carbon dots were characterized by transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible(UV-Vis) absorption spectroscopy and photoluminescence spectroscopy (PL). The experiment results show that NCDs are spherical or quasi-spherical, uniformly dispersed with the size ranges from 1 to 5 nm, which can emit strong blue fluorescence. The surface of the synthesized NCDs is rich in water-soluble groups such as COOH, OH and NH2. The optimal excitation and emission wavelengths of NCDs are 350 and 435 nm, respectively. Meanwhile, the fluorescence emission has good luminescence stability. The fluorescence quantum yield of the carbon dots is as high as 29.19%. The effects of different substances on the fluorescence of NCDs were measured in a buffer solution with pH=7.4. Under the same conditions, only amoxicillin is able to significantly quench the fluorescence of NCDs, indicating the synthesized NCDs can selectively interact with amoxicillin. A sensitive sensor was constructed for detecting amoxicillin by changing the fluorescence intensity of carbon dots. The linear detection range for amoxicillin is from 2.6 to 30 μmol/L and the detection limit is 0.15 μmol/L.
In this paper, the nitrogen-doped carbon dots (NCDs) were synthesized using the natural material dendrobe as the raw material by one-step hydrothermal method. The synthesized carbon dots were characterized by transmission electron microscopy(TEM), X-ray photoelectron spectroscopy(XPS), Fourier transform infrared (FTIR) spectroscopy, ultraviolet-visible(UV-Vis) absorption spectroscopy and photoluminescence spectroscopy (PL). The experiment results show that NCDs are spherical or quasi-spherical, uniformly dispersed with the size ranges from 1 to 5 nm, which can emit strong blue fluorescence. The surface of the synthesized NCDs is rich in water-soluble groups such as COOH, OH and NH2. The optimal excitation and emission wavelengths of NCDs are 350 and 435 nm, respectively. Meanwhile, the fluorescence emission has good luminescence stability. The fluorescence quantum yield of the carbon dots is as high as 29.19%. The effects of different substances on the fluorescence of NCDs were measured in a buffer solution with pH=7.4. Under the same conditions, only amoxicillin is able to significantly quench the fluorescence of NCDs, indicating the synthesized NCDs can selectively interact with amoxicillin. A sensitive sensor was constructed for detecting amoxicillin by changing the fluorescence intensity of carbon dots. The linear detection range for amoxicillin is from 2.6 to 30 μmol/L and the detection limit is 0.15 μmol/L.
2020, 37(2): 235-241
doi: 10.11944/j.issn.1000-0518.2020.02.190190
Abstract:
We report on a facile and efficient construction of electrochemical biosensors by modifying the screen printed carbon electrodes (SPCE) with multifunctional polymeric nanoparticles. An amphiphilic random copolymer, poly(St-co-AA-co-VCz-co-DMAEMA) (PSACD), was first synthesized using styrene (St), acrylic acid (AA), N-vinylcarbazole (VCz) and dimethylaminoethyl methacrylate (DMAEMA) as hydrophobic, hydrophilic, electroactive and enzymatic compatible monomers, respectively. The polymeric nanoparticles (PSACD NPs) were then prepared through self-assembly of polymers in a selective solvent mixture of DMF/H2O. The obtained PSACD NPs were characterized by particle size analyzer and scanning electron microscope (SEM), and were used to fabricate the hydrogen peroxide (H2O2) biosensor with the functions of improving the specific surface areas, providing a suitable microenvironment for keeping the enzyme activity, and accelerating the electron transfer between enzymes and the electrodes. Specifically, the SPCE was successively modified by PSACD NPs suspensions, horseradish peroxidase (HRP) solution and perfluorosulfonic acid-PTFE copolymer (Nafion) solution. The properties of the proposed electrochemical biosensor were studied via an amperometric detection method. The results show that the biosensor has a short response time (less than 2 s) and a linear increasing response current with the concentration of H2O2 increasing from 0.02 to 7.48 mmol/L. The biosensor also has nice stability, good selectivity and excellent anti-interference performance.
We report on a facile and efficient construction of electrochemical biosensors by modifying the screen printed carbon electrodes (SPCE) with multifunctional polymeric nanoparticles. An amphiphilic random copolymer, poly(St-co-AA-co-VCz-co-DMAEMA) (PSACD), was first synthesized using styrene (St), acrylic acid (AA), N-vinylcarbazole (VCz) and dimethylaminoethyl methacrylate (DMAEMA) as hydrophobic, hydrophilic, electroactive and enzymatic compatible monomers, respectively. The polymeric nanoparticles (PSACD NPs) were then prepared through self-assembly of polymers in a selective solvent mixture of DMF/H2O. The obtained PSACD NPs were characterized by particle size analyzer and scanning electron microscope (SEM), and were used to fabricate the hydrogen peroxide (H2O2) biosensor with the functions of improving the specific surface areas, providing a suitable microenvironment for keeping the enzyme activity, and accelerating the electron transfer between enzymes and the electrodes. Specifically, the SPCE was successively modified by PSACD NPs suspensions, horseradish peroxidase (HRP) solution and perfluorosulfonic acid-PTFE copolymer (Nafion) solution. The properties of the proposed electrochemical biosensor were studied via an amperometric detection method. The results show that the biosensor has a short response time (less than 2 s) and a linear increasing response current with the concentration of H2O2 increasing from 0.02 to 7.48 mmol/L. The biosensor also has nice stability, good selectivity and excellent anti-interference performance.
2020, 37(2): 242-244
doi: 10.11944/j.issn.1000-0518.2020.02.190215
Abstract:
Both o-nitrophenyl β-D-galactopyranoside(ONPG) method and disaccharase method are commonly used for the determination of lactase activity. This paper compared the linear range, detection limit, precision, accuracy and stability of these two methods. It is found that ONPG method is better than disaccharase method in linear range, detection limit, precision and stability, but this method has poor repeatability and needs further optimization.
Both o-nitrophenyl β-D-galactopyranoside(ONPG) method and disaccharase method are commonly used for the determination of lactase activity. This paper compared the linear range, detection limit, precision, accuracy and stability of these two methods. It is found that ONPG method is better than disaccharase method in linear range, detection limit, precision and stability, but this method has poor repeatability and needs further optimization.
