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2021 Volume 38 Issue 1
2021, 38(1): 1-10
doi: 10.19894/j.issn.1000-0518.200253
Abstract:
The microfluidic chip droplet technology is a new technology for manipulating tiny volumes of liquids, which can realize the generation and control of high-throughput microscopic samples, as well as the operation of independent droplets. The dispersed micro-droplet unit can be used as an ideal micro-reactor, showing great application potential in the fields of drug screening, material screening and high value-added micro-particle material synthesis in biomedicine. The droplet microfluidic chip uses the change of the fluid shear force to make the immiscible two-phase fluid generate stable and ordered droplets at its interface. The current generation methods of microdroplets mainly include hydrodynamic methods, pneumatic method, light control method and electric method, etc. Droplet-based microfluidic systems are increasingly used to perform complex multiple reactions, measurements and analyses, and can perform ultra-small volume and ultra-high throughput chemical and biological experiments. For the droplet microfluidic system, the speed, size and content of the droplet will affect the final inspection result. Therefore, the real-time detection of the droplet formation rate and the content of the droplet is very important, and it is most commonly used at present. The droplet detection methods include optical detection technology and electrical sensing detection technology. The two-phase flow droplet generation mechanism and the existing droplet generation technology are discussed and analyzed, and the droplet detection technology is also reviewed.
The microfluidic chip droplet technology is a new technology for manipulating tiny volumes of liquids, which can realize the generation and control of high-throughput microscopic samples, as well as the operation of independent droplets. The dispersed micro-droplet unit can be used as an ideal micro-reactor, showing great application potential in the fields of drug screening, material screening and high value-added micro-particle material synthesis in biomedicine. The droplet microfluidic chip uses the change of the fluid shear force to make the immiscible two-phase fluid generate stable and ordered droplets at its interface. The current generation methods of microdroplets mainly include hydrodynamic methods, pneumatic method, light control method and electric method, etc. Droplet-based microfluidic systems are increasingly used to perform complex multiple reactions, measurements and analyses, and can perform ultra-small volume and ultra-high throughput chemical and biological experiments. For the droplet microfluidic system, the speed, size and content of the droplet will affect the final inspection result. Therefore, the real-time detection of the droplet formation rate and the content of the droplet is very important, and it is most commonly used at present. The droplet detection methods include optical detection technology and electrical sensing detection technology. The two-phase flow droplet generation mechanism and the existing droplet generation technology are discussed and analyzed, and the droplet detection technology is also reviewed.
2021, 38(1): 11-23
doi: 10.19894/j.issn.1000-0518.200158
Abstract:
High-throughput next-generation sequencing (NGS) is a revolutionary technology in gene sequencing. It is widely used in various solutions in biomedical-relevant fields. Library preparation with high quality and low-cost is the key for NGS. With the development of such sequencing platforms, different library preparation technologies have been built. However, these technologies also possess their own strengths and weaknesses. In this review, we first summarized various library preparation methods for NGS, then discussed the complete process of library preparation in single cell sequencing. We hope that this review can help researchers on the optimal selection of library preparation strategies and also offer suggestions for the development of new NGS library preparation technologies, especially in the exploitation of homebred kits.
High-throughput next-generation sequencing (NGS) is a revolutionary technology in gene sequencing. It is widely used in various solutions in biomedical-relevant fields. Library preparation with high quality and low-cost is the key for NGS. With the development of such sequencing platforms, different library preparation technologies have been built. However, these technologies also possess their own strengths and weaknesses. In this review, we first summarized various library preparation methods for NGS, then discussed the complete process of library preparation in single cell sequencing. We hope that this review can help researchers on the optimal selection of library preparation strategies and also offer suggestions for the development of new NGS library preparation technologies, especially in the exploitation of homebred kits.
2021, 38(1): 24-35
doi: 10.19894/j.issn.1000-0518.200150
Abstract:
Reactive extraction has attracted great attentions and applications because the energy of its chemical bond is generally 10~60 kJ/mol, which not only facilitates the formation of complexes and phase transfer, but also makes the regeneration of complexing agent easier in the stripping process.This work summarizes the recent research progress on reactive extraction of amphoteric organics from the dilute solutions. The discussions mainly focus on the reactive extractions of various amphoteric organics, the kinetics of reactive extraction and new reactive extraction technique (i.e., flotation complexation extraction). In particular, the reactive extractions of amino acids, picolinic acid, hydroxypyridine, 4, 4 '-diaminostilbene-2, 2' -disulfonic acid, aminophenols, hydroxyquinoline and other commonly used amphoteric compounds are concluded. At last, the current research situation in this field is prospected. It points out that the weak industrial foundation and the lack of efficient green extractants are the main problems in the field, as well as some suggestions are put forward for the future research and industrial application.
Reactive extraction has attracted great attentions and applications because the energy of its chemical bond is generally 10~60 kJ/mol, which not only facilitates the formation of complexes and phase transfer, but also makes the regeneration of complexing agent easier in the stripping process.This work summarizes the recent research progress on reactive extraction of amphoteric organics from the dilute solutions. The discussions mainly focus on the reactive extractions of various amphoteric organics, the kinetics of reactive extraction and new reactive extraction technique (i.e., flotation complexation extraction). In particular, the reactive extractions of amino acids, picolinic acid, hydroxypyridine, 4, 4 '-diaminostilbene-2, 2' -disulfonic acid, aminophenols, hydroxyquinoline and other commonly used amphoteric compounds are concluded. At last, the current research situation in this field is prospected. It points out that the weak industrial foundation and the lack of efficient green extractants are the main problems in the field, as well as some suggestions are put forward for the future research and industrial application.
2021, 38(1): 36-43
doi: 10.19894/j.issn.1000-0518.200183
Abstract:
In order to find antitumor compounds, fifteen dipeptide phosphonate derivatives(Ⅲa-Ⅲo) were designed and synthesized based on the phosphonate derivatives containing one amino acid fragment. Their antitumor activities in vitro were evaluated by the MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) assay. The results show that the compounds inhibit the proliferation of the tumor cells. Among the active compounds, compound Ⅲf has better inhibition effect on A-549 (human lung cancer cells) and EC-109 (human esophageal cancer cells) growth with the half maximal inhibitory concentration (IC50) values of (6.9±1.2) and (6.3±1.0) μmol/L, respectively, and compound Ⅲn shows more potent antitumor activities against SGC-7901(human gastric cancer cells) and EC-109 with the IC50 values of (6.7±1.0) and (6.1±1.0) μmol/L, respectively, close to that of cisplatin.
In order to find antitumor compounds, fifteen dipeptide phosphonate derivatives(Ⅲa-Ⅲo) were designed and synthesized based on the phosphonate derivatives containing one amino acid fragment. Their antitumor activities in vitro were evaluated by the MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide) assay. The results show that the compounds inhibit the proliferation of the tumor cells. Among the active compounds, compound Ⅲf has better inhibition effect on A-549 (human lung cancer cells) and EC-109 (human esophageal cancer cells) growth with the half maximal inhibitory concentration (IC50) values of (6.9±1.2) and (6.3±1.0) μmol/L, respectively, and compound Ⅲn shows more potent antitumor activities against SGC-7901(human gastric cancer cells) and EC-109 with the IC50 values of (6.7±1.0) and (6.1±1.0) μmol/L, respectively, close to that of cisplatin.
2021, 38(1): 44-50
doi: 10.19894/j.issn.1000-0518.190334
Abstract:
An activated carbon supported sulfuric acid catalyst (H2SO4/AC) was prepared and characterized by Fourier transform infrared (FT-IR) spectrometry and X-ray diffraction (XRD). Various cyclopenta[d]pyrimidinones and hexahydroquinazolinones were synthesized by the reaction of aromatic aldehyde with urea and cyclopentone(cyclohexanone) catalyzed by H2SO4/AC in the absence of solvent. This method is simple and environmentally benign. The catalyst can be easily recovered and its activity maintains after being reused for 3 times.
An activated carbon supported sulfuric acid catalyst (H2SO4/AC) was prepared and characterized by Fourier transform infrared (FT-IR) spectrometry and X-ray diffraction (XRD). Various cyclopenta[d]pyrimidinones and hexahydroquinazolinones were synthesized by the reaction of aromatic aldehyde with urea and cyclopentone(cyclohexanone) catalyzed by H2SO4/AC in the absence of solvent. This method is simple and environmentally benign. The catalyst can be easily recovered and its activity maintains after being reused for 3 times.
2021, 38(1): 51-59
doi: 10.19894/j.issn.1000-0518.200214
Abstract:
Skin wound infections seriously threaten the lives of patients. Although traditional antibacterial hydrogels containing biocides such as silver ions or small molecule antibiotics have a broad-spectrum bactericidal effect and are used as wound dressings, the biological toxicity of silver ions and drug resistance of small molecule antibiotics cannot meet the requirements of long-term clinical application. The imidazolium salt-based poly(ionic liquids) are novel polymer antibacterial agents that exhibit strong antibacterial property, owing to their strong positive charge effect and hydrophobic polymer segments. In this study, imidazolium salt-based poly(ionic liquids) contained furan functional groups as strong antibacterial agents were synthesized by Radziszewski reaction. Then, the imidazolium salt-based poly(ionic liquids) were compounded with hyaluronic acid/polyethylene glycol by Diels-Alder "click" reaction to prepare antibacterial hydrogels. The in vitro assays show that the antibacterial hydrogels containing imidazolium salt-based poly(ionic liquids) can quickly kill bacteria and also have low toxicity towards human skin fibroblasts. This kind of hydrogels can be applied in various biomedical fields.
Skin wound infections seriously threaten the lives of patients. Although traditional antibacterial hydrogels containing biocides such as silver ions or small molecule antibiotics have a broad-spectrum bactericidal effect and are used as wound dressings, the biological toxicity of silver ions and drug resistance of small molecule antibiotics cannot meet the requirements of long-term clinical application. The imidazolium salt-based poly(ionic liquids) are novel polymer antibacterial agents that exhibit strong antibacterial property, owing to their strong positive charge effect and hydrophobic polymer segments. In this study, imidazolium salt-based poly(ionic liquids) contained furan functional groups as strong antibacterial agents were synthesized by Radziszewski reaction. Then, the imidazolium salt-based poly(ionic liquids) were compounded with hyaluronic acid/polyethylene glycol by Diels-Alder "click" reaction to prepare antibacterial hydrogels. The in vitro assays show that the antibacterial hydrogels containing imidazolium salt-based poly(ionic liquids) can quickly kill bacteria and also have low toxicity towards human skin fibroblasts. This kind of hydrogels can be applied in various biomedical fields.
2021, 38(1): 60-68
doi: 10.19894/j.issn.1000-0518.200236
Abstract:
The blends of poly(L-lactic acid) (PLLA) and poly(L-2-hydroxy-3-methylbutanoic acid) (PL-2H3MB) with different compositions were prepared by solution casting. The crystallization, melting and pyrolysis properties of the blends were investigated by differential scanning calorimetry (DSC), polarized optical microscope (POM), wide angle X-ray diffractometry (WAXD) and thermogravimetric analysis (TGA). The formation of PLLA and PL-2H3MB co-crystals was speculated due to the observation of the new melting peak in DSC first heating profile. The co-crysals significantly increased the initial crystallization temperature of PLLA and the characteristic diffraction peaks in WAXD profile were also shifted, which both confirmed the co-crystallization phenomenon in solution casting blend. At the same time, the thermal stability of PLLA/PL-2H3MB blends was better than that of neat PLLA or PL-2H3MB. The co-crystallization behavior of PLLA and PL-2H3MB may provided a new potential method to regulate the thermal stability, mechanical properties and degradation properties of PLLA.
The blends of poly(L-lactic acid) (PLLA) and poly(L-2-hydroxy-3-methylbutanoic acid) (PL-2H3MB) with different compositions were prepared by solution casting. The crystallization, melting and pyrolysis properties of the blends were investigated by differential scanning calorimetry (DSC), polarized optical microscope (POM), wide angle X-ray diffractometry (WAXD) and thermogravimetric analysis (TGA). The formation of PLLA and PL-2H3MB co-crystals was speculated due to the observation of the new melting peak in DSC first heating profile. The co-crysals significantly increased the initial crystallization temperature of PLLA and the characteristic diffraction peaks in WAXD profile were also shifted, which both confirmed the co-crystallization phenomenon in solution casting blend. At the same time, the thermal stability of PLLA/PL-2H3MB blends was better than that of neat PLLA or PL-2H3MB. The co-crystallization behavior of PLLA and PL-2H3MB may provided a new potential method to regulate the thermal stability, mechanical properties and degradation properties of PLLA.
2021, 38(1): 69-76
doi: 10.19894/j.issn.1000-0518.200170
Abstract:
Two tandem catalytic systems, Cat.Ⅰ/Cat.Ⅱ {Cat.Ⅰ: [ArNCH-C8H3(CH2)2(C6H5)O]2ZrBn2; Cat.Ⅱ: (η5-C5Me4)Si(Me)2NtBuTiCl2} and Cat.Ⅰ/Cat.Ⅲ (Cat.Ⅲ: tans-Et(Ind)2ZrCl2), were employed respectively to prepare long chain branched polyethylene (LCBPE) by using ethylene as the sole monomer. Ethylene is initially acted upon by Cat.Ⅰ to give ethylene oligomers with terminal vinyl groups. Subsequently, the copolymerization of the resultant oligomers with ethylene is promoted by Cat.Ⅱ and Cat.Ⅲ respectively and affords long chain branched polyethylene (LCBPE). By varying the molar ratio of Cat.Ⅰ/Cat.Ⅱ as well as Cat.Ⅰ/Cat.Ⅲ, a series of LCBPEs with controllable branching molar fraction (0.84%~3.95%) was prepared successfully. All of these obtained polymers exhibits a unimodal distribution, indicating that all of the obtained polymers are pure LCBPEs rather than the blends of ethylene oligomers and linear PE. The LCBPEs show lower crystallinity than the linear PE. Because of the entanglement of the long chain branches, the resultant LCBPEs show more obvious shear-thinning phenomenon and higher elongation. However, the lower crystallinity of the LCBPEs results in lower tensile strength.
Two tandem catalytic systems, Cat.Ⅰ/Cat.Ⅱ {Cat.Ⅰ: [ArNCH-C8H3(CH2)2(C6H5)O]2ZrBn2; Cat.Ⅱ: (η5-C5Me4)Si(Me)2NtBuTiCl2} and Cat.Ⅰ/Cat.Ⅲ (Cat.Ⅲ: tans-Et(Ind)2ZrCl2), were employed respectively to prepare long chain branched polyethylene (LCBPE) by using ethylene as the sole monomer. Ethylene is initially acted upon by Cat.Ⅰ to give ethylene oligomers with terminal vinyl groups. Subsequently, the copolymerization of the resultant oligomers with ethylene is promoted by Cat.Ⅱ and Cat.Ⅲ respectively and affords long chain branched polyethylene (LCBPE). By varying the molar ratio of Cat.Ⅰ/Cat.Ⅱ as well as Cat.Ⅰ/Cat.Ⅲ, a series of LCBPEs with controllable branching molar fraction (0.84%~3.95%) was prepared successfully. All of these obtained polymers exhibits a unimodal distribution, indicating that all of the obtained polymers are pure LCBPEs rather than the blends of ethylene oligomers and linear PE. The LCBPEs show lower crystallinity than the linear PE. Because of the entanglement of the long chain branches, the resultant LCBPEs show more obvious shear-thinning phenomenon and higher elongation. However, the lower crystallinity of the LCBPEs results in lower tensile strength.
2021, 38(1): 77-83
doi: 10.19894/j.issn.1000-0518.200181
Abstract:
In this paper, the effects of three kinds of methacrylate-based water-soluble monomer on the emulsifying activity of poly(vinyl alcohol)(PVA-1788) in CO2-in-water high interval phase emulsion (HIPE) were first investigated, and then two kinds of macroporous materials were prepared separately by the CO2-in-water high interval phase templating-polymerization. The results indicate that the presence of methacrylic acid-β-hydroxyethyl ester, or 2-(dimethylamino) ethyl methacrylate reduces the stability of HIPEs. In contrast, the methacryloxyethyltrimethyl ammonium chloride shows active effects on the formation and stability of HIPEs, and the HIPE can keep stable for 48 h. Scannning electron microscopy results indicate that the two macroporous materials have abundant pore structures and the percentage of the pore size above 10 μm is as high as 50% for both macroporous materials.
In this paper, the effects of three kinds of methacrylate-based water-soluble monomer on the emulsifying activity of poly(vinyl alcohol)(PVA-1788) in CO2-in-water high interval phase emulsion (HIPE) were first investigated, and then two kinds of macroporous materials were prepared separately by the CO2-in-water high interval phase templating-polymerization. The results indicate that the presence of methacrylic acid-β-hydroxyethyl ester, or 2-(dimethylamino) ethyl methacrylate reduces the stability of HIPEs. In contrast, the methacryloxyethyltrimethyl ammonium chloride shows active effects on the formation and stability of HIPEs, and the HIPE can keep stable for 48 h. Scannning electron microscopy results indicate that the two macroporous materials have abundant pore structures and the percentage of the pore size above 10 μm is as high as 50% for both macroporous materials.
2021, 38(1): 84-91
doi: 10.19894/j.issn.1000-0518.200294
Abstract:
ZIF-8, a classical metal-organic frameworks (MOFs) material, was used as an adsorbent to study the effect of particle size on its uranium adsorption performance. ZIF-8 particles with different sizes were synthesized by three methods, and characterized by scanning electron microscope (SEM), X-ray powder diffraction (XRD), surface area and porosity analyzer. The adsorption of ZIF-8 particles with different sizes for U(Ⅵ) from uranyl nitrate solution was tested under the same conditions. The parameters of adsorption isotherm and kinetics were calculated. The results show that ZIF-8 with high crystallinity and high purity is successfully prepared. The morphology of the product is rhombic dodecahedron, and the sizes of the particles are about 50 nm, 150 nm and 2 μm with narrow distributions. The three samples have single uniform micropore structures and their BET surface areas are highly related to the particle size. All the ZIF-8 particles with different sizes can quickly adsorb 90% of U(Ⅵ) from the initial concentration of 200 mg/L of U(Ⅵ) solution in 70 min (at room temperature, pH=3).The particles with smaller size (about 50 nm) show better adsorption performance, and the saturated adsorption capacity reaches 520.26 mg/g. The adsorption kinetics conforms to the second order kinetic equation, and the adsorption isotherm conforms to the Langmuir model, which indicate that the adsorption for U(Ⅵ) of ZIF-8 belongs to chemical monolayer adsorption. After 4 cycles of adsorption and desorption, their removal rates for U(Ⅵ) are still above 70%.
ZIF-8, a classical metal-organic frameworks (MOFs) material, was used as an adsorbent to study the effect of particle size on its uranium adsorption performance. ZIF-8 particles with different sizes were synthesized by three methods, and characterized by scanning electron microscope (SEM), X-ray powder diffraction (XRD), surface area and porosity analyzer. The adsorption of ZIF-8 particles with different sizes for U(Ⅵ) from uranyl nitrate solution was tested under the same conditions. The parameters of adsorption isotherm and kinetics were calculated. The results show that ZIF-8 with high crystallinity and high purity is successfully prepared. The morphology of the product is rhombic dodecahedron, and the sizes of the particles are about 50 nm, 150 nm and 2 μm with narrow distributions. The three samples have single uniform micropore structures and their BET surface areas are highly related to the particle size. All the ZIF-8 particles with different sizes can quickly adsorb 90% of U(Ⅵ) from the initial concentration of 200 mg/L of U(Ⅵ) solution in 70 min (at room temperature, pH=3).The particles with smaller size (about 50 nm) show better adsorption performance, and the saturated adsorption capacity reaches 520.26 mg/g. The adsorption kinetics conforms to the second order kinetic equation, and the adsorption isotherm conforms to the Langmuir model, which indicate that the adsorption for U(Ⅵ) of ZIF-8 belongs to chemical monolayer adsorption. After 4 cycles of adsorption and desorption, their removal rates for U(Ⅵ) are still above 70%.
2021, 38(1): 92-98
doi: 10.19894/j.issn.1000-0518.190335
Abstract:
Hexagonal MoO3-x microrods with rich surface oxygen vacancies were prepared from MoO3 using a facile and controllable one-step reduction method with ascorbic acid as the reducing agent. The as-prepared MoO3-x microrods exhibit much better photocatalytic activity than MoO3 for degrading Rhodamine B due to the narrower band gap and wider range of sunlight absorption. Moreover, the photocatalytic activity of MoO3-x increases significantly with an increase in surface oxygen vacancies. For the MoO2.799 sample with a Mo5+ content of 20.1%, it only takes 60 minutes to degrade 90% of Rhodamine B in a solution with an initial concentration of 10 mg/L. This study may present a new strategy to synthesize semiconductor photocatalysts.
Hexagonal MoO3-x microrods with rich surface oxygen vacancies were prepared from MoO3 using a facile and controllable one-step reduction method with ascorbic acid as the reducing agent. The as-prepared MoO3-x microrods exhibit much better photocatalytic activity than MoO3 for degrading Rhodamine B due to the narrower band gap and wider range of sunlight absorption. Moreover, the photocatalytic activity of MoO3-x increases significantly with an increase in surface oxygen vacancies. For the MoO2.799 sample with a Mo5+ content of 20.1%, it only takes 60 minutes to degrade 90% of Rhodamine B in a solution with an initial concentration of 10 mg/L. This study may present a new strategy to synthesize semiconductor photocatalysts.
2021, 38(1): 99-106
doi: 10.19894/j.issn.1000-0518.200203
Abstract:
The heterojunction type Bi-TiO2, (BiO)2CO3-TiO2 and (BiO)2CO3-Bi-TiO2 composite nanofibers were synthesized via a facile one-step solvothermal method, using electrospun TiO2 nanofibers as the substrate and glucose as reducing agent, in acidic or alkaline environments. The obtained materials were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) and photoluminescence (PL) spectroscopy. The photocatalytic activities of the samples were evaluated by photodegradation of lomefloxacin, ciprofloxacin and norfloxacin as the target pollutants, under simulated sunlight irradiation, and the degradation reaction mechanism was explored. The results show that (BiO)2CO3-Bi-TiO2 photocatalyst exhibits the highest photocatalytic activity, with the degradation rate of norfloxacin, lomefloxacin and ciprofloxacin of 93.2%, 97.5% and 100%, respectively, under simulated sunlight irradiation for 60 min.
The heterojunction type Bi-TiO2, (BiO)2CO3-TiO2 and (BiO)2CO3-Bi-TiO2 composite nanofibers were synthesized via a facile one-step solvothermal method, using electrospun TiO2 nanofibers as the substrate and glucose as reducing agent, in acidic or alkaline environments. The obtained materials were characterized by X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) and photoluminescence (PL) spectroscopy. The photocatalytic activities of the samples were evaluated by photodegradation of lomefloxacin, ciprofloxacin and norfloxacin as the target pollutants, under simulated sunlight irradiation, and the degradation reaction mechanism was explored. The results show that (BiO)2CO3-Bi-TiO2 photocatalyst exhibits the highest photocatalytic activity, with the degradation rate of norfloxacin, lomefloxacin and ciprofloxacin of 93.2%, 97.5% and 100%, respectively, under simulated sunlight irradiation for 60 min.
2021, 38(1): 107-115
doi: 10.19894/j.issn.1000-0518.200187
Abstract:
In this work, we reported one-pot chemical reduction method for the synthesis of proline-stabilized copper nanoclusters (Cu NCs), in which proline as the capping agent and hydroxylamine hydrochloride as the reducing agent. The optical properties of Cu NCs was measured by fluorescence spectroscopy and ultraviolet(UV)-visible absorption spectroscopy. The structure of Cu NCs was characterized using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The TEM image shows that the Cu NCs are highly dispersed and spherical in shape with a size of around 1.89 nm. The Cu NCs exhibit brown and blue fluorescence under sunlight and UV light irradiation, respectively. The Cu NCs solution shows the maximum emission peak at 458 nm under the excitation wavelength of 397 nm. Their fluorescence is selectively and sensitively quenched by picric acid. Under optimized conditions, the assay displays a linear response in the 0.5 to 15 μmol/L and 20 to 70 μmol/L picric acid (PA) concentration range, with a detection limit of 0.092 μmol/L based on an S/N ratio of 3. The possible mechanism is static quenching and the inner filter effect. In addition, the fluorescent probe has been successfully applied to the determination of PA in real water samples.
In this work, we reported one-pot chemical reduction method for the synthesis of proline-stabilized copper nanoclusters (Cu NCs), in which proline as the capping agent and hydroxylamine hydrochloride as the reducing agent. The optical properties of Cu NCs was measured by fluorescence spectroscopy and ultraviolet(UV)-visible absorption spectroscopy. The structure of Cu NCs was characterized using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The TEM image shows that the Cu NCs are highly dispersed and spherical in shape with a size of around 1.89 nm. The Cu NCs exhibit brown and blue fluorescence under sunlight and UV light irradiation, respectively. The Cu NCs solution shows the maximum emission peak at 458 nm under the excitation wavelength of 397 nm. Their fluorescence is selectively and sensitively quenched by picric acid. Under optimized conditions, the assay displays a linear response in the 0.5 to 15 μmol/L and 20 to 70 μmol/L picric acid (PA) concentration range, with a detection limit of 0.092 μmol/L based on an S/N ratio of 3. The possible mechanism is static quenching and the inner filter effect. In addition, the fluorescent probe has been successfully applied to the determination of PA in real water samples.
2021, 38(1): 116-122
doi: 10.19894/j.issn.1000-0518.200155
Abstract:
A new method of visualizing metal imprints on non-porous surfaces was studied using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol as the chromogenic reagent. The affecting factors such as contact time, time elapse from the contact to the reaction, type of substrates and transfer times were studied. The results show that imprints with good quality are obtained when the contact time is more than 1 s, the time interval is between 1~30 days and the metal imprints within 5 deposition times after the contact between hands and metal tools for 90 s. This method has the advantages of high sensitivity and easy operation and is used to establish the connection between suspects and metal tools, which has potential applications in forensic science.
A new method of visualizing metal imprints on non-porous surfaces was studied using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol as the chromogenic reagent. The affecting factors such as contact time, time elapse from the contact to the reaction, type of substrates and transfer times were studied. The results show that imprints with good quality are obtained when the contact time is more than 1 s, the time interval is between 1~30 days and the metal imprints within 5 deposition times after the contact between hands and metal tools for 90 s. This method has the advantages of high sensitivity and easy operation and is used to establish the connection between suspects and metal tools, which has potential applications in forensic science.
