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2016 Volume 44 Issue 4
2016, 44(4): 491-499
doi: 10.11895/j.issn.0253-3820.160131
Abstract:
A brief review and comment on recent development of microfluidic research and industrialization were given here. Minding the fact that the main-stream research in microfluidics has shifted from the establishment of platforms and the development of methodology to a broad spectrum of applications, our review focused on the trend in applications of Lab-on-a-chip in modern biochemical analysis, point of care, novel material screening/synthesis and tissue/organ bio-mimic construction. Also, in this review, the impact and challenge of 3D printing advances on microfluidics were addressed. And further, the global advances in the industrialization of microfluidics, which may emerge as a potential scientific and technical arena for national industrial transformation and upgrading, were discussed. 69 references were cited in this review.
A brief review and comment on recent development of microfluidic research and industrialization were given here. Minding the fact that the main-stream research in microfluidics has shifted from the establishment of platforms and the development of methodology to a broad spectrum of applications, our review focused on the trend in applications of Lab-on-a-chip in modern biochemical analysis, point of care, novel material screening/synthesis and tissue/organ bio-mimic construction. Also, in this review, the impact and challenge of 3D printing advances on microfluidics were addressed. And further, the global advances in the industrialization of microfluidics, which may emerge as a potential scientific and technical arena for national industrial transformation and upgrading, were discussed. 69 references were cited in this review.
2016, 44(4): 500-511
doi: 10.11895/j.issn.0253-3820.160111
Abstract:
This paper briefly introduced the international conference on miniaturized systems of microfluidic chip for chemistry and life sciences(MicroTAS conference). Current research focus and trend in the research field of microfluidic chip revealed from the conference were discussed, including the technology of droplet-based microfluidics, paper-based chip, 3D printing, and chip detection, as well as the application of microfluidic chips in cell separation/capture, single cell analysis, organs-on-a-chip, and point-of-care testing/clinical diagnosis.
This paper briefly introduced the international conference on miniaturized systems of microfluidic chip for chemistry and life sciences(MicroTAS conference). Current research focus and trend in the research field of microfluidic chip revealed from the conference were discussed, including the technology of droplet-based microfluidics, paper-based chip, 3D printing, and chip detection, as well as the application of microfluidic chips in cell separation/capture, single cell analysis, organs-on-a-chip, and point-of-care testing/clinical diagnosis.
2016, 44(4): 512-521
doi: 10.11895/j.issn.0253-3820.160120
Abstract:
Recently, micro/nano-scaled fluidic control technologies have been developed to be the alternative to traditional analysis approaches over several decades due to the capability of realizing miniaturized multiphase and multistep reactions. The perfect combination of these techniques and nucleic acid amplification methods effectively promoted the establishment and development of digital nucleic acid detection(dNAD) techniques. As a single-molecule analysis approach, dNAD played an essential role in molecular diagnosis. In this paper, the research and application progress of dNAD techniques were reviewed, including the development history, principle, superiority, and the future prospects of dNAD.
Recently, micro/nano-scaled fluidic control technologies have been developed to be the alternative to traditional analysis approaches over several decades due to the capability of realizing miniaturized multiphase and multistep reactions. The perfect combination of these techniques and nucleic acid amplification methods effectively promoted the establishment and development of digital nucleic acid detection(dNAD) techniques. As a single-molecule analysis approach, dNAD played an essential role in molecular diagnosis. In this paper, the research and application progress of dNAD techniques were reviewed, including the development history, principle, superiority, and the future prospects of dNAD.
2016, 44(4): 522-532
doi: 10.11895/j.issn.0253-3820.160003
Abstract:
Microfluidic technology has become a powerful tool in cell-based research due to its inherent advantages. The research progress of cell culture on chips, simulation and manipulation of cell microenvironment on chips, single cell analysis on chips, organ-on-a-chip, and chip-mass spectrometry technology was introduced in this review. Morover, the summary and prospect on the microfluidic technology were introduced to give some insights for researchers who were interested in developing microfluidic platforms for cell-based research.
Microfluidic technology has become a powerful tool in cell-based research due to its inherent advantages. The research progress of cell culture on chips, simulation and manipulation of cell microenvironment on chips, single cell analysis on chips, organ-on-a-chip, and chip-mass spectrometry technology was introduced in this review. Morover, the summary and prospect on the microfluidic technology were introduced to give some insights for researchers who were interested in developing microfluidic platforms for cell-based research.
2016, 44(4): 533-541
doi: 10.11895/j.issn.0253-3820.150857
Abstract:
Microfluidic chips are significant platforms of cell culture in vitro. Microfluidic chip-based organs-on-chips technology has received attention because it can mimic the complex structures and functions of human organs. In this review, the recent advances of organs-on-chips technology in different organs are reported including the build of human physiological models, drug discovery and toxicology research. And the development of this technology is proposed.
Microfluidic chips are significant platforms of cell culture in vitro. Microfluidic chip-based organs-on-chips technology has received attention because it can mimic the complex structures and functions of human organs. In this review, the recent advances of organs-on-chips technology in different organs are reported including the build of human physiological models, drug discovery and toxicology research. And the development of this technology is proposed.
2016, 44(4): 542-550
doi: 10.11895/j.issn.0253-3820.160058
Abstract:
Gene is the genetic code of human beings, and has only 0.1‰ difference among individuals but creates a weelthy divesity. Thus it has a huge application value to explore the difference. Polymerase chain reaction(PCR) is one of the technologies mostly used in genetic research. But traditional thermal cyclers are not only time and energy-consuming, but also difficult to be integrated and portable. The combination of microfluidics and PCR can decrease the reaction volume significantly and increase the reaction efficiency with easy integration and miniaturization. In this review, we briefly introduced microchamber PCR chip and continuous-flow PCR chip according to their structures, and online detection methods including capillary electrophoresis, fluorescence, electrochemistry and DNA hybridization array. At last, we summarized the recent advances and pointed out the future development about microfluidic PCR chip.
Gene is the genetic code of human beings, and has only 0.1‰ difference among individuals but creates a weelthy divesity. Thus it has a huge application value to explore the difference. Polymerase chain reaction(PCR) is one of the technologies mostly used in genetic research. But traditional thermal cyclers are not only time and energy-consuming, but also difficult to be integrated and portable. The combination of microfluidics and PCR can decrease the reaction volume significantly and increase the reaction efficiency with easy integration and miniaturization. In this review, we briefly introduced microchamber PCR chip and continuous-flow PCR chip according to their structures, and online detection methods including capillary electrophoresis, fluorescence, electrochemistry and DNA hybridization array. At last, we summarized the recent advances and pointed out the future development about microfluidic PCR chip.
2016, 44(4): 551-561
doi: 10.11895/j.issn.0253-3820.160119
Abstract:
In recent years, microfluidics technology has been widely used in biological and medical diagnosis, which demonstrated great advantages compared with other traditional methods. However, there are financial and technology barriers for users to benefit from microfluidics technology when using the standard microfabrication technologies inherited from IC industry. With the booming of three dimensional(3D) printing technologies in recent years, more and more researchers are trying to apply 3D printing technology to fabricate the microfluidic chips for biological and medical applications. Compared with traditional microfabrication method, 3D printing technology shows great advantages in rapid fabrication, flexibility on material selection and low cost. This paper reviewed the most recent research progresses for 3D printed microfluidic technology, especially for the application of 3D printed microfluidic devices respectively fabricated by micro-stereolithography, fused deposition modelling and inkjet printing method in analytical chemistry, biological and medical diagnosis. The outlook of the research trend in 3D printed microfluidic technology was also discussed.
In recent years, microfluidics technology has been widely used in biological and medical diagnosis, which demonstrated great advantages compared with other traditional methods. However, there are financial and technology barriers for users to benefit from microfluidics technology when using the standard microfabrication technologies inherited from IC industry. With the booming of three dimensional(3D) printing technologies in recent years, more and more researchers are trying to apply 3D printing technology to fabricate the microfluidic chips for biological and medical applications. Compared with traditional microfabrication method, 3D printing technology shows great advantages in rapid fabrication, flexibility on material selection and low cost. This paper reviewed the most recent research progresses for 3D printed microfluidic technology, especially for the application of 3D printed microfluidic devices respectively fabricated by micro-stereolithography, fused deposition modelling and inkjet printing method in analytical chemistry, biological and medical diagnosis. The outlook of the research trend in 3D printed microfluidic technology was also discussed.
2016, 44(4): 562-568
doi: 10.11895/j.issn.0253-3820.160144
Abstract:
Droplet-based microfluidics is one of the important branches of microfluidics. On account of its various unique advantages, it has been extensively applied and studied. In this review, we introduced the characteristics and the fundamentals of the droplet-based microfluidics. Meanwhile, its recent applications in biomedicine were reviewed. At last, the development of the droplet-based microfluidics was prospected.
Droplet-based microfluidics is one of the important branches of microfluidics. On account of its various unique advantages, it has been extensively applied and studied. In this review, we introduced the characteristics and the fundamentals of the droplet-based microfluidics. Meanwhile, its recent applications in biomedicine were reviewed. At last, the development of the droplet-based microfluidics was prospected.
2016, 44(4): 569-578
doi: 10.11895/j.issn.0253-3820.150589
Abstract:
Current next generation sequencing works faster and the price is coming down. However, the workflows have numerous manual processes, which contribute to bottleneck and process inefficiency. One of the most time consuming steps is electrophoretic gel-based fractionation of a large number of fragments of interest from the library generation process. In recent years, several instruments were first introduced into the market, and then were tested soon by many famous DNA sequencing centers and platforms. This paper introduces the development of DNA fractionation techniques including capillary electrophoresis and microfluidic devices. Moreover, our argument raises the bottleneck in fractionating DNA fragments on the chips. Finally, we provide insights into the challenges of DNA fractionation and perspectives.
Current next generation sequencing works faster and the price is coming down. However, the workflows have numerous manual processes, which contribute to bottleneck and process inefficiency. One of the most time consuming steps is electrophoretic gel-based fractionation of a large number of fragments of interest from the library generation process. In recent years, several instruments were first introduced into the market, and then were tested soon by many famous DNA sequencing centers and platforms. This paper introduces the development of DNA fractionation techniques including capillary electrophoresis and microfluidic devices. Moreover, our argument raises the bottleneck in fractionating DNA fragments on the chips. Finally, we provide insights into the challenges of DNA fractionation and perspectives.
2016, 44(4): 579-585
doi: 10.11895/j.issn.0253-3820.151025
Abstract:
This paper describes a multi-layer paper-supported breast cancer tissue array. The paper-based microchip with arrayed hydrophilic spots was fabricated by wax printing. After cell seeding, the microchip was folded to form an artificial solid tumor, and the multilayer paper was covered by a layer of microporous membrane that mimics endothelial layer. After culturing the paper-supported breast cancer tissue for a certain period of time, the multi-layer device was unfold thus enabling detections of cell survival, proliferation, morphology and metabolism on different layers. Breast cancer cells cultured on paper had a survival rate >80% and aggregated into tumor spheroids. Intracellular lactic acid levels increased with the extension of culture time. Compared to two dimensional(2D) counterparts, the decreased fraction of S phase cell(15% vs 60%) was detected. The paper-supported breast cancer tissue showed a drug response mechanism similar to the tumor in vivo. Cancer cells within the tissue were less sensitive to doxorubicin and the IC50 value detected was significantly higher than that obtained with 2D cultures(5μmol/L vs 1.14μmol/L). The multi-layer paper-supported breast cancer tissue array developed in this work featured simple tissue reconstruction and easy operation, thus providing an ideal tool for anti-cancer drug testing.
This paper describes a multi-layer paper-supported breast cancer tissue array. The paper-based microchip with arrayed hydrophilic spots was fabricated by wax printing. After cell seeding, the microchip was folded to form an artificial solid tumor, and the multilayer paper was covered by a layer of microporous membrane that mimics endothelial layer. After culturing the paper-supported breast cancer tissue for a certain period of time, the multi-layer device was unfold thus enabling detections of cell survival, proliferation, morphology and metabolism on different layers. Breast cancer cells cultured on paper had a survival rate >80% and aggregated into tumor spheroids. Intracellular lactic acid levels increased with the extension of culture time. Compared to two dimensional(2D) counterparts, the decreased fraction of S phase cell(15% vs 60%) was detected. The paper-supported breast cancer tissue showed a drug response mechanism similar to the tumor in vivo. Cancer cells within the tissue were less sensitive to doxorubicin and the IC50 value detected was significantly higher than that obtained with 2D cultures(5μmol/L vs 1.14μmol/L). The multi-layer paper-supported breast cancer tissue array developed in this work featured simple tissue reconstruction and easy operation, thus providing an ideal tool for anti-cancer drug testing.
2016, 44(4): 586-590
doi: 10.11895/j.issn.0253-3820.160135
Abstract:
The paper-based microfluidic devices have emerged as simple yet powerful platforms for performing low-cost analytical tests. A novel paper-based microfluidic chip for potentiometric detection using the principle of concentration cell was developed and examined for smartphone-based pesticide detection. Paper-based device was fabricated via wax printing and preloaded with reagents. After sample introduction and reaction for 5 minutes, screen-printed electrodes were attached and assembled into a 3D-printed holder for the potentiometric measurement using the smartphone-based reader. For the proof-of-concept, a pesticide(trichlorfon) was quantitatively detected with a limit of detection of 0.89μmol/L.
The paper-based microfluidic devices have emerged as simple yet powerful platforms for performing low-cost analytical tests. A novel paper-based microfluidic chip for potentiometric detection using the principle of concentration cell was developed and examined for smartphone-based pesticide detection. Paper-based device was fabricated via wax printing and preloaded with reagents. After sample introduction and reaction for 5 minutes, screen-printed electrodes were attached and assembled into a 3D-printed holder for the potentiometric measurement using the smartphone-based reader. For the proof-of-concept, a pesticide(trichlorfon) was quantitatively detected with a limit of detection of 0.89μmol/L.
2016, 44(4): 591-596
doi: 10.11895/j.issn.0253-3820.160140
Abstract:
A low-cost, simple and sensitive colorimetric detection method of alkaline phosphatase(ALP) has been developed on microfluidic paper-based analysis devices. In a typical colorimetric detection, 5-bromo-4-chloro-3-indolyl phosphate disodium salt(BCIP) and nitro blue tetrazolium(NBT) were firstly added onto the circle array zones of paper devices. Then ALP solutions were spotted to the array zones to perform the colorimetric reaction. The color results were recorded by both Gel Documentation systems and a common camera, and analyzed with Quantity One software. All the reaction conditions were aptimized. Under the optimal conditions, the colorimetric intensity showed a linear correlation to the concentration of ALP in the range of 1.5 to 20 U/L with the limit of detection(LOD) of 0.78 U/L(3σ), which was about two orders of magnitude lower than that of the reported method on μPADs. Besides, it could be applied in spiked real sample analysis with a satisfactory result. In addition, a dual-color array-based paper strip has been fabricated for the semiquantitative detection of ALP. The approximate activity of ALP could be simply distinguished by observing the color change with naked eyes.
A low-cost, simple and sensitive colorimetric detection method of alkaline phosphatase(ALP) has been developed on microfluidic paper-based analysis devices. In a typical colorimetric detection, 5-bromo-4-chloro-3-indolyl phosphate disodium salt(BCIP) and nitro blue tetrazolium(NBT) were firstly added onto the circle array zones of paper devices. Then ALP solutions were spotted to the array zones to perform the colorimetric reaction. The color results were recorded by both Gel Documentation systems and a common camera, and analyzed with Quantity One software. All the reaction conditions were aptimized. Under the optimal conditions, the colorimetric intensity showed a linear correlation to the concentration of ALP in the range of 1.5 to 20 U/L with the limit of detection(LOD) of 0.78 U/L(3σ), which was about two orders of magnitude lower than that of the reported method on μPADs. Besides, it could be applied in spiked real sample analysis with a satisfactory result. In addition, a dual-color array-based paper strip has been fabricated for the semiquantitative detection of ALP. The approximate activity of ALP could be simply distinguished by observing the color change with naked eyes.
2016, 44(4): 597-603
doi: 10.11895/j.issn.0253-3820.160142
Abstract:
Aesculin and aesculetin hydrolysis were studied on-line using sweeping-flow injection-chip micellar electrokinetic chromatography(Sweeping-FI-chip MEKC). With this method, all the analytes in the sample are well separated within 5 min, and a sampling rate of 12 per hour is achieved. At this sampling frequency, a rate constant can be obtained within 30 min. In contrast to off-line methods, it was quite time-saving. And the aesculin hydrolysis mixture solution is directly injected and analyzed without quenching the reaction, thus the information of the hydrolysis process can be obtained from the electrophorogram of a sequence injection. Under the optimum conditions, the hydrolysis rate constants for aesculin at 25, 30, 35, 40 and 45℃ using 0.1 mol/L KOH as hydrolyte are obtained as 3.65×10-2/min, 5.24×10-2/min, 7.12×10-2/min, 10.5×10-2/min and 16.3×10-2/min, respectively. The activation energy for aesculin hydrolysis is 58.57 kJ/mol. The hydrolysis rate constants for aesculetin at 15, 20, 25, 30 and 35℃ using 10 mmol/L KOH as hydrolyte are obtained as 2.26×10-2/min, 2.85×10-2/min, 3.55×10-2/min, 4.38×10-2/min and 5.29×10-2/min, respectively. The activation energy for aesculin hydrolysis is 31.55 kJ/mol.
Aesculin and aesculetin hydrolysis were studied on-line using sweeping-flow injection-chip micellar electrokinetic chromatography(Sweeping-FI-chip MEKC). With this method, all the analytes in the sample are well separated within 5 min, and a sampling rate of 12 per hour is achieved. At this sampling frequency, a rate constant can be obtained within 30 min. In contrast to off-line methods, it was quite time-saving. And the aesculin hydrolysis mixture solution is directly injected and analyzed without quenching the reaction, thus the information of the hydrolysis process can be obtained from the electrophorogram of a sequence injection. Under the optimum conditions, the hydrolysis rate constants for aesculin at 25, 30, 35, 40 and 45℃ using 0.1 mol/L KOH as hydrolyte are obtained as 3.65×10-2/min, 5.24×10-2/min, 7.12×10-2/min, 10.5×10-2/min and 16.3×10-2/min, respectively. The activation energy for aesculin hydrolysis is 58.57 kJ/mol. The hydrolysis rate constants for aesculetin at 15, 20, 25, 30 and 35℃ using 10 mmol/L KOH as hydrolyte are obtained as 2.26×10-2/min, 2.85×10-2/min, 3.55×10-2/min, 4.38×10-2/min and 5.29×10-2/min, respectively. The activation energy for aesculin hydrolysis is 31.55 kJ/mol.
2016, 44(4): 604-609
doi: 10.11895/j.issn.0253-3820.150596
Abstract:
An integrated microfluidic chip with arrayed micro channels that consisted of eight repeat arrayed 6×6 cell culture chamber was designed and fabricated. The analytical microsystem combined with designed microchip, measuring device and environmental control unit was established for cell culture and parallel cellular antioxidant activity(CAA) analysis of plant antioxidants. The microfluidic chip included a polydimethylsiloxane(PDMS) cover and glass substrate that consisted of two hundreds and eighty-eight round cell culture microchambers and forty-eight independent parallel array channels. Eight groups of different samples with six different concentrations could be investigated simultaneously with multimode reader in one test. HepG2 cells were successfully cultured on the microchip. Moreover, the viability percentage of the HepG2 cells exposed to these plant antioxidants solutions at different concentrations for 24 h was higher than 90%. With 2', 7'-Dichlorofluorescin diacetate(DCFH-DA) as a fluorescence probe, 2, 2'-azobis(2-amidinopropane) dihydrochloride(ABAP) as the initiator of intracellular reactive oxygen species(ROS), we tested the inhibitory effect of several plant antioxidants such as quercetin, rutin and kaempferol on free radicals. The CAA units were calculated by the data measured from cellular morphology and fluorescence intensity over time. It was shown that the CAA units of quercetin, rutin and kaempferol were 71.42±0.19, 74.31±0.36 and 69.92±0.09(x±s, n=3), while the calculated IC50 were(7.20±0.06) μmol/L,(52.06±0.14) μmol/L and(32.55±0.03) μmol/L(x±s, n=3), respectively.
An integrated microfluidic chip with arrayed micro channels that consisted of eight repeat arrayed 6×6 cell culture chamber was designed and fabricated. The analytical microsystem combined with designed microchip, measuring device and environmental control unit was established for cell culture and parallel cellular antioxidant activity(CAA) analysis of plant antioxidants. The microfluidic chip included a polydimethylsiloxane(PDMS) cover and glass substrate that consisted of two hundreds and eighty-eight round cell culture microchambers and forty-eight independent parallel array channels. Eight groups of different samples with six different concentrations could be investigated simultaneously with multimode reader in one test. HepG2 cells were successfully cultured on the microchip. Moreover, the viability percentage of the HepG2 cells exposed to these plant antioxidants solutions at different concentrations for 24 h was higher than 90%. With 2', 7'-Dichlorofluorescin diacetate(DCFH-DA) as a fluorescence probe, 2, 2'-azobis(2-amidinopropane) dihydrochloride(ABAP) as the initiator of intracellular reactive oxygen species(ROS), we tested the inhibitory effect of several plant antioxidants such as quercetin, rutin and kaempferol on free radicals. The CAA units were calculated by the data measured from cellular morphology and fluorescence intensity over time. It was shown that the CAA units of quercetin, rutin and kaempferol were 71.42±0.19, 74.31±0.36 and 69.92±0.09(x±s, n=3), while the calculated IC50 were(7.20±0.06) μmol/L,(52.06±0.14) μmol/L and(32.55±0.03) μmol/L(x±s, n=3), respectively.
2016, 44(4): 610-616
doi: 10.11895/j.issn.0253-3820.160035
Abstract:
A microfluidic chip assay was described for bacteria identification and antibiotic susceptibility test(AST). Filter paper pads were embedded in arrayed microchambers, with immobilized antibiotics and chromogenic medium. By taking advantage of the polyvinylidene fluoride(PVDF) membrane based valves, urine sample introduced was distributed in individual chambers without cross contamination. The simultaneous analysis of multiple bacteria was achieved by using the culture chamber array design. The identification of a bacterium was based on its specific colorimetric result. The density of a bacterium was determined by real-time monitoring color intensity in the chamber, and its susceptibility to an antibiotic was determined relying on the lowest antibiotic concentration that inhibited the colorimetric reaction. A set of three common uropathogenic bacteria were selected as models to test the microfluidic approach. Our results showed that the developed microfluidic assay was able to complete bacteria identification and the six-antibiotic AST in 18 h. In comparison with the conventional method, the microchip method showed a coincidence of 94.1% and 93.9% with regard to bacteria identification and AST, respectively. The developed microfluidic approach is simple and rapid, thus hold the potential to serve as a powerful tool for bacterial analysis under conditions of poor medical resource.
A microfluidic chip assay was described for bacteria identification and antibiotic susceptibility test(AST). Filter paper pads were embedded in arrayed microchambers, with immobilized antibiotics and chromogenic medium. By taking advantage of the polyvinylidene fluoride(PVDF) membrane based valves, urine sample introduced was distributed in individual chambers without cross contamination. The simultaneous analysis of multiple bacteria was achieved by using the culture chamber array design. The identification of a bacterium was based on its specific colorimetric result. The density of a bacterium was determined by real-time monitoring color intensity in the chamber, and its susceptibility to an antibiotic was determined relying on the lowest antibiotic concentration that inhibited the colorimetric reaction. A set of three common uropathogenic bacteria were selected as models to test the microfluidic approach. Our results showed that the developed microfluidic assay was able to complete bacteria identification and the six-antibiotic AST in 18 h. In comparison with the conventional method, the microchip method showed a coincidence of 94.1% and 93.9% with regard to bacteria identification and AST, respectively. The developed microfluidic approach is simple and rapid, thus hold the potential to serve as a powerful tool for bacterial analysis under conditions of poor medical resource.
2016, 44(4): 617-624
doi: 10.11895/j.issn.0253-3820.150708
Abstract:
Field asymmetric ion mobility spectrometry(FAIMS) technology was used for the rapid analysis of phenylalanine(PHE) using a metal diffusion tube-microchip FAIMS system. The test pressure was set at 250 kPa, and the temperature of the gas generator for the diffusion tube was at 190℃. The ion characteristic spectra were acquired under the optimized conditions with a gas flow rate of 2000 mL/min, a dispersion voltage of 152.8 V and a compensation voltage value of-0.62 V for phenylalanine in positive mode. Phenylalanine gas samples with different concentrations were analyzed by FAIMS. The results showed that the ion intensity was linearly correlated to phenylalanine concentration in the range from 6 mg/L to 20 mg/L, and the limit of detection for phenylalanine was 5.9 mg/L. This investigation shows the feasibility of FAIMS technique for rapid detection of phenylalanine. The FAIMS instrument is simple and sensitive, and can be used for rapid detection of phenylalanine.
Field asymmetric ion mobility spectrometry(FAIMS) technology was used for the rapid analysis of phenylalanine(PHE) using a metal diffusion tube-microchip FAIMS system. The test pressure was set at 250 kPa, and the temperature of the gas generator for the diffusion tube was at 190℃. The ion characteristic spectra were acquired under the optimized conditions with a gas flow rate of 2000 mL/min, a dispersion voltage of 152.8 V and a compensation voltage value of-0.62 V for phenylalanine in positive mode. Phenylalanine gas samples with different concentrations were analyzed by FAIMS. The results showed that the ion intensity was linearly correlated to phenylalanine concentration in the range from 6 mg/L to 20 mg/L, and the limit of detection for phenylalanine was 5.9 mg/L. This investigation shows the feasibility of FAIMS technique for rapid detection of phenylalanine. The FAIMS instrument is simple and sensitive, and can be used for rapid detection of phenylalanine.
2016, 44(4): 625-632
doi: 10.11895/j.issn.0253-3820.151007
Abstract:
A cytometric bead array(CBA) method based on indirect competition mode was developed for the sensitive and rapid detection of ochratoxin A(OTA) in malt. The malt samples were extracted by 60% methanol/PBS and the extracts were diluted five times by 20% methanol/PBS, then the supernatant was collected to prepare sample solution for analysis. The fluorescence microsphere surface was labeled with bovine serum albumin-OTA(BSA-OTA) to compete with OTA in the sample for anti-OTA monoclonal antibody(mAb). Then FITC-IgG was added to bind with the captured mAb on the microsphere. Finally, the mean fluorescence intensity of FITC on the surface of microsphere was detected by a BD FACSCalibur analyzer for accurate qualitative and quantitative analysis of OTA. The results showed that the half inhibitory concentration(IC50) was 1.20 ng/mL with a correlation coefficient(R2) of 0.9892, and the limit of detection(LOD) for OTA was 0.12 ng/mL. The average recoveries in malt samples were 93.9%-97.4% with the relative standard deviations(RSDs) less than 3.6% at three spiked levels. Sixteen malt samples were analyzed and OTA was found in two samples with the contents less than 3.83μg/kg, which was lower than the maximum permitted residue level(5.0μg/kg) proposed by the European Union. All the positive samples were confirmed by LC-MS/MS. In this study, the CBA technique based on indirect competition was developed for the first time for successful detection of OTA in malt samples. This method was easy, rapid, sensitive and reliable, and exhibited high potential in the qualitative and quantitative determination of multiple mycotoxins in other complex matrices.
A cytometric bead array(CBA) method based on indirect competition mode was developed for the sensitive and rapid detection of ochratoxin A(OTA) in malt. The malt samples were extracted by 60% methanol/PBS and the extracts were diluted five times by 20% methanol/PBS, then the supernatant was collected to prepare sample solution for analysis. The fluorescence microsphere surface was labeled with bovine serum albumin-OTA(BSA-OTA) to compete with OTA in the sample for anti-OTA monoclonal antibody(mAb). Then FITC-IgG was added to bind with the captured mAb on the microsphere. Finally, the mean fluorescence intensity of FITC on the surface of microsphere was detected by a BD FACSCalibur analyzer for accurate qualitative and quantitative analysis of OTA. The results showed that the half inhibitory concentration(IC50) was 1.20 ng/mL with a correlation coefficient(R2) of 0.9892, and the limit of detection(LOD) for OTA was 0.12 ng/mL. The average recoveries in malt samples were 93.9%-97.4% with the relative standard deviations(RSDs) less than 3.6% at three spiked levels. Sixteen malt samples were analyzed and OTA was found in two samples with the contents less than 3.83μg/kg, which was lower than the maximum permitted residue level(5.0μg/kg) proposed by the European Union. All the positive samples were confirmed by LC-MS/MS. In this study, the CBA technique based on indirect competition was developed for the first time for successful detection of OTA in malt samples. This method was easy, rapid, sensitive and reliable, and exhibited high potential in the qualitative and quantitative determination of multiple mycotoxins in other complex matrices.
2016, 44(4): 633-639
doi: 10.11895/j.issn.0253-3820.160045
Abstract:
A kind of easily assembled self-driving test card was developed for the rapid detection and quantification of heart-type fatty acid binding protein(H-FABP) by using time-resolved fluorescence microspheres as signal probes. It was easy to make microfluidic channel structures with double-sided adhesive and cut out of test card substrate and cover based on polymethyl methacrylate(PMMA) material by laser cutting technology. The membrane of polystyrene containing maleic anhydride functional groups was coated on PMMA plate surface by dip-coating method. Further, the capture antibody was immobilized effectively on PMMA surface by covalent binding with maleic anhydride groups. The cover was treated with plasma treatment to improve the hydrophilic ability, so that liquid could flow smoothly in the microchannel. The whole analysis process could be completed within 10 min. There was a very good linear correlation between response and H-FABP concentration in the range of 0.5-100 ng/mL(R2=0.9966), and the detection limit was 0.1 ng/mL(S/N=3). The intra-assay precision(RSD) was less than 10% and the inter-assay RSD was less than 15%. This detection method has the advantages such as high sensitivity, fast detection and good accuracy.
A kind of easily assembled self-driving test card was developed for the rapid detection and quantification of heart-type fatty acid binding protein(H-FABP) by using time-resolved fluorescence microspheres as signal probes. It was easy to make microfluidic channel structures with double-sided adhesive and cut out of test card substrate and cover based on polymethyl methacrylate(PMMA) material by laser cutting technology. The membrane of polystyrene containing maleic anhydride functional groups was coated on PMMA plate surface by dip-coating method. Further, the capture antibody was immobilized effectively on PMMA surface by covalent binding with maleic anhydride groups. The cover was treated with plasma treatment to improve the hydrophilic ability, so that liquid could flow smoothly in the microchannel. The whole analysis process could be completed within 10 min. There was a very good linear correlation between response and H-FABP concentration in the range of 0.5-100 ng/mL(R2=0.9966), and the detection limit was 0.1 ng/mL(S/N=3). The intra-assay precision(RSD) was less than 10% and the inter-assay RSD was less than 15%. This detection method has the advantages such as high sensitivity, fast detection and good accuracy.
2016, 44(4): 640-646
doi: 10.11895/j.issn.0253-3820.150172
Abstract:
A multi-residue analytical method was established for the simultaneous detection of ractopamine(RAC), clenbuterol(CL) and salbutamol(SAL) by suspension array technology. Based on the principle of indirect competitive enzyme linked immunosorbent assay, three veterinary antigens coupled with different fluorescent microspheres as probes were prepared and the phycoerythrin(PE)-labeled secondary antibodies were used as reporter signal. Standard curves of three veterinary drugs were separately established under optimum conditions. According to the specific recognition experiment, the standard curves for simultaneous detection of those three veterinary drugs were established. Good linearity was obtained in the concentration range of 1-500μg/L, 0.1-500μg/L, 1-100μg/L, and the detection limits were 0.68, 0.095 and 0.884μg/L for RAC, CL, SAL, respectively, with correlation coefficients(R2)>0.99 for all three drugs. The cross-reactivity of other structural analogues was lower than 1.5%. Good recoveries were found at four spiked levels for both single and mixed standards in real samples.
A multi-residue analytical method was established for the simultaneous detection of ractopamine(RAC), clenbuterol(CL) and salbutamol(SAL) by suspension array technology. Based on the principle of indirect competitive enzyme linked immunosorbent assay, three veterinary antigens coupled with different fluorescent microspheres as probes were prepared and the phycoerythrin(PE)-labeled secondary antibodies were used as reporter signal. Standard curves of three veterinary drugs were separately established under optimum conditions. According to the specific recognition experiment, the standard curves for simultaneous detection of those three veterinary drugs were established. Good linearity was obtained in the concentration range of 1-500μg/L, 0.1-500μg/L, 1-100μg/L, and the detection limits were 0.68, 0.095 and 0.884μg/L for RAC, CL, SAL, respectively, with correlation coefficients(R2)>0.99 for all three drugs. The cross-reactivity of other structural analogues was lower than 1.5%. Good recoveries were found at four spiked levels for both single and mixed standards in real samples.
2016, 44(4): 647-653
doi: 10.11895/j.issn.0253-3820.160081
Abstract:
3-Methacryloxypropyltrimethoxy silane modified Fe3O4 was employed as the carrier material to prepare core-shell magnetic molecularly imprinted polymers(Fe3O4@SiO2-MIPS) by using a surface molecular imprinting technology with propyl gallate as the template. The magnetic composites were loaded into a microchip and coupled with high-performance liquid chromatography to separate and preconcentrate synthetic phenolic antioxidants(SPAs). The structures of the resulting complex were characterized by scanning electron microscopy, vibrating sample magnetoeter, thermogravimetric analysis/differential thermal gravity analysis, Fourier-transformed infrared spectroscopy and X-ray diffraction spectrometry. Under the optimal conditions(3 mL of sample solution, sample pH of 5.0, sample flow rate of 0.5 mL/min, and eluent flow rate of 0.3 mL/min), the magnetic MIPS displayed enhanced adsorption ability for phenolic antioxidants. The calibration curves showed good linearity with correlation coefficients greater than 0.9901. Intra-day and inter-day relative standard deviations(RSD) were less than 2.8% and 3.5%, respectively. The present method was applied to the determination of phenolic antioxidants in cosmetics samples, illustrating satisfactory recovery(87.9%-104.0%) and reproducibility(RSD less than 3.7%).
3-Methacryloxypropyltrimethoxy silane modified Fe3O4 was employed as the carrier material to prepare core-shell magnetic molecularly imprinted polymers(Fe3O4@SiO2-MIPS) by using a surface molecular imprinting technology with propyl gallate as the template. The magnetic composites were loaded into a microchip and coupled with high-performance liquid chromatography to separate and preconcentrate synthetic phenolic antioxidants(SPAs). The structures of the resulting complex were characterized by scanning electron microscopy, vibrating sample magnetoeter, thermogravimetric analysis/differential thermal gravity analysis, Fourier-transformed infrared spectroscopy and X-ray diffraction spectrometry. Under the optimal conditions(3 mL of sample solution, sample pH of 5.0, sample flow rate of 0.5 mL/min, and eluent flow rate of 0.3 mL/min), the magnetic MIPS displayed enhanced adsorption ability for phenolic antioxidants. The calibration curves showed good linearity with correlation coefficients greater than 0.9901. Intra-day and inter-day relative standard deviations(RSD) were less than 2.8% and 3.5%, respectively. The present method was applied to the determination of phenolic antioxidants in cosmetics samples, illustrating satisfactory recovery(87.9%-104.0%) and reproducibility(RSD less than 3.7%).
2016, 44(4): 654-659
doi: 10.11895/j.issn.0253-3820.150542
Abstract:
A tight gold layer was electroless plated on polyimide film coated with polydopamine. A polyurethane coated flexible glucose sensor was developed based on this two side gold layer structure, wherein the platinum black plating side was used as reference-counter electrode and another side that was successively modified by platinum black layer, Nafion/carbon nanotube(CNT) layer and glucose oxidase(Gox) layer as working electrode. The morphology of each layer and its influence on glucose sensing performance were investigated. The glucose biosensor showed a linear range from 2.0 to 32.0 mmol/L and the sensitivity was 25μA·(mmol/L)-1·cm-2 at low potential of 0.3 V, with a detection limit of 0.05 mmol/L(S/N=3). The biosensor could avoid the commonly coexisted interference and exhibited high stability in the continuous subcutaneous glucose monitoring.
A tight gold layer was electroless plated on polyimide film coated with polydopamine. A polyurethane coated flexible glucose sensor was developed based on this two side gold layer structure, wherein the platinum black plating side was used as reference-counter electrode and another side that was successively modified by platinum black layer, Nafion/carbon nanotube(CNT) layer and glucose oxidase(Gox) layer as working electrode. The morphology of each layer and its influence on glucose sensing performance were investigated. The glucose biosensor showed a linear range from 2.0 to 32.0 mmol/L and the sensitivity was 25μA·(mmol/L)-1·cm-2 at low potential of 0.3 V, with a detection limit of 0.05 mmol/L(S/N=3). The biosensor could avoid the commonly coexisted interference and exhibited high stability in the continuous subcutaneous glucose monitoring.
2016, 44(4): 660-664
doi: 10.11895/j.issn.0253-3820.150967
Abstract:
To increase the specific surface area of three-dimensional(3D) microarrays, we proposed a novel method using the inclined UV lithography of the negative thick SU-8 photoresist instead of the traditional lithography. Firstly, we studied the effects of the array arrangement on the surface area of the SU-8 photoresist-based microarrays with MATLAB simulation, and determined the best parameters of the width of single micro-column and the space of the microarrays. During the fabrication processes, photoresist spinning was firstly performed twice to deposit a thick SU-8 photoresist layer on 2-inch silicon substrate, while the rotational speed and time were respectively set to 1500 r/min and 35 s. Then, the samples were respectively placed on a baking plate for 20 min at 65℃ and 70 min at 95℃ for pre-baking. The next step was the inclined UV lithography from both sides, in which the width of micro pillars was 20μm, the space between the pillars was 30μm and the lithography angle was 20°. Finally, we successfully fabricated the stable "X" type microarray with high specific surface after the high-low temperature post exposure baking and 30 min developing.
To increase the specific surface area of three-dimensional(3D) microarrays, we proposed a novel method using the inclined UV lithography of the negative thick SU-8 photoresist instead of the traditional lithography. Firstly, we studied the effects of the array arrangement on the surface area of the SU-8 photoresist-based microarrays with MATLAB simulation, and determined the best parameters of the width of single micro-column and the space of the microarrays. During the fabrication processes, photoresist spinning was firstly performed twice to deposit a thick SU-8 photoresist layer on 2-inch silicon substrate, while the rotational speed and time were respectively set to 1500 r/min and 35 s. Then, the samples were respectively placed on a baking plate for 20 min at 65℃ and 70 min at 95℃ for pre-baking. The next step was the inclined UV lithography from both sides, in which the width of micro pillars was 20μm, the space between the pillars was 30μm and the lithography angle was 20°. Finally, we successfully fabricated the stable "X" type microarray with high specific surface after the high-low temperature post exposure baking and 30 min developing.
