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1.
We demonstrate, for the first time, the multiplexed determination of microbial species from whole blood using the paper‐folding technique of origami to enable the sequential steps of DNA extraction, loop‐mediated isothermal amplification (LAMP), and array‐based fluorescence detection. A low‐cost handheld flashlight reveals the presence of the final DNA amplicon to the naked eye, providing a “sample‐to‐answer” diagnosis from a finger‐prick volume of human blood, within 45 min, with minimal user intervention. To demonstrate the method, we showed the identification of three species of Plasmodium, analyzing 80 patient samples benchmarked against the gold‐standard polymerase chain reaction (PCR) assay in an operator‐blinded study. We also show that the test retains its diagnostic accuracy when using stored or fixed reference samples.  相似文献   

2.
Monolithic materials were synthesized in capillaries by in situ polymerization with N‐isopropylacrylamide, glycidyl methacrylate, and ethylene dimethacrylate as the monomers, and methanol and PEG as the porogens. With γ‐alumina nanoparticles attached to the surface of the porous monolithic column via epoxide groups, a novel polymer monolith microextraction (PMME) material was prepared with a good mechanical stability and a high extraction capacity. SEM and X‐ray photoelectron spectroscopy were employed to characterize the modified monolithic column, demonstrating that γ‐alumina nanoparticles were effectively functionalized onto the monolithic column. In addition, a new method was developed for the analysis of Sudan I–IV dyes using PMME coupled with HPLC. In order to obtain the optimum extraction efficiency, the PMME conditions including desorption solvent type, sample pH, sample volume, sample flow rate, and eluent flow rate were investigated. Under the optimum conditions, we obtained acceptable linearities, low LODs, and good intra‐ and interday RDSs. When applied to the determination of Sudan I–IV dyes in red wine samples, satisfactory recoveries were obtained in the range of 84.0–115.9%.  相似文献   

3.
In this study, we developed a simple and selective spin column extraction technology utilizing hydrophilic molecularly imprinted polymers as the sorbents for extracting nitrophenol pollutants in water samples (the East Lake, the Yangtze River, and wastewater). The whole procedure was achieved by centrifugation of the spin column, and multiple samples were simultaneously processed with a low volume of solvent and without evaporation. Under the optimized condition, recoveries of nitrophenol compounds on the spin column packed with hydrophilic molecularly imprinted polymers ranged from 87.3 to 92.9% and an excellent purification effect was obtained. Compared with activated carbon, multi‐walled carbon nanotubes, LC‐C18 sorbents, hydrophilic molecularly imprinted polymers exhibited a highly selective recognition ability for nitrophenol compounds and satisfactory sample extraction efficiency. Subsequently, the spin column extraction coupled with high‐performance liquid chromatography was established, which was found to be linear in the range of 2–1000 ng/mL for 2,4‐dinitropehnol and 2‐nitrophenol, and 6–1000 ng/mL for 4‐nitrophenol with correlation coefficients greater than 0.998. The detection limits ranged from 0.3–0.5 ng/mL. It is shown that the proposed method can be used for the determination of trace nitrophenol pollutants in complex samples, which is not only beneficial for water quality analysis but also for environmental risk assessment.  相似文献   

4.
There is a great need to improve the biocompatibility of silicon‐based lab‐on‐chip substrate materials for reliable quantitative analysis of biological solutions. These advanced microdevice surfaces need not only be biocompatible but also have surfaces of defined wettability characteristics. The inhibition of biomolecular activity due to microdevice surface interaction is common and can result in inaccurate results or decreased reaction yields. In this work we investigate different techniques for the chemical functionalization of oxidized silicon (SiOx) surfaces in order to: (i) obtain defined hydrophobic/hydrophilic surfaces; and (ii) increase the efficiency of performing Real‐Time Polymerase Chain Reaction (PCR) on a silicon‐based lab‐on‐chip. Silicon oxide surfaces are functionalized by grafting alkylic chain silanes and poly(ethylene glycol) (PEG) chains to the surfaces, rendering them hydrophobic or hydrophilic. Functionalized surfaces are characterized through contact angle and atomic force microscopy (AFM) measurements, showing stable hydrophobic surfaces with contact angles of 69–78° and layer thicknesses of 11–15 Å and hydrophilic surfaces displaying contact angles of 5–6° and thicknesses of 22–52 Å. PCR experiments carried out directly on bare silicon oxide lab‐on‐chip surfaces show low yields of DNA amplification. Hydrophobic surfaces decrease the inhibition of PCR. Hydrophilic surfaces are a major improvement on the bare silicon oxide exhibiting the same maximum reaction yield as obtained with a standard thermocycler. We have found that the best results are associated with PEG modified surfaces, which prove very suitable for the fabrication of reliable PCR silicon lab‐on‐chips. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

5.
The effect of addition of poly(ethylene glycol)‐400 (PEG‐400) and carbon (0, 1, 2 and 3 wt%) as substrates were investigated systematically to get the desired phase of carbon‐doped MoO3 material. The carbon source was prepared from the Acacia arabica plant wood. The resulting samples were calcined at 500°C. The effect of PEG‐400 and carbon composite on the structure, particle size and morphology were investigated. The prepared samples were characterized by XRD, SEM‐EDS and FT‐IR techniques. The samples with PEG‐400 and carbon addition give better control of particle size and porosity. The prepared catalysts were tested for the synthesis of 3,4‐dihydropyrimidones via the Biginelli‐type condensation reaction. This new method consistently has the advantage of excellent yields (88%–93%) and short reaction times (1.5–3 h) than do classical Biginelli reaction conditions.  相似文献   

6.
Tetracycline (TC)‐imprinted microspheres have been synthesized by reversible addition–fragmentation chain‐transfer precipitation polymerization using PEG as a coporogen. In the synthesis, methacrylic acid and ethylene dimethacrylate were used as the functional monomer and cross‐linker, respectively. 2,2′‐Azobisisobutyronitrile was the initiator, and cumyl dithiobenzoate was the chain‐transfer reagent. Although monodispersed microspheres were obtained using acetonitrile as porogen, the particles cannot be used in the column extraction because of the high backpressure. To increase the porosity of the material, PEG was introduced as a coporogen. The influence of the molecular weight and concentration of PEG on the morphology, binding affinity, and porosity of the molecularly imprinted polymers (MIPs) have been studied. The results demonstrated that PEG as a macroporogen increased the porosity of the polymers. Meanwhile, the column backpressure was reduced using the MIPs with higher porosity. The binding affinity of the MIPs was increased when a low concentration of PEG was employed, while it was decreased when the ratio of PEG 12 000/monomers was >0.8%. Under the optimized conditions, TC‐imprinted microspheres with good selectivity and size uniformity have been obtained, which facilitates its application in the column extraction for TC determinations.  相似文献   

7.
An allele‐specific voltammetric genoassay for the detection of allele‐specific toll‐like receptor‐2 gene arg753gln polymorphism (TLR‐2) from polymerase chain reaction (PCR) amplified real samples was described in this study. Meldola blue (MDB), an intercalator molecule, was used as hybridization label. The wild‐type and mutant type oligonucleotide probes were immobilized onto disposable graphite electrode surfaces by covalent attachment method. The extent of hybridization between probe and target sequences was determined by using differential pulse voltammetry (DPV). As a result of the interaction between MDB and DNA at electrode surface, the MDB signal observed from probe sequence before hybridization and after hybridization with MM sequence is lower than that observed after hybridization with complementary sequence. The differences between the MDB reduction peaks obtained from probe modified, hybrid modified and MM modified electrode were used to detect TLR‐2 from PCR amplified real samples. The discrimination of homozygous and heterozygous alleles was also established by comparing the peak currents of MDB reduction signals. Numerous factors affecting the target hybridization and indicator binding reactions are optimized to maximize the sensitivity.  相似文献   

8.
We present herein a mild and rapid method to create diblock copolymer brushes on a silicon surface via photoinitiated “thiol‐ene” click reaction. The silicon surface was modified with 3‐mercaptopropyltrimethoxysilane (MPTMS) self‐assembled monolayer. Then, a mixture of divinyl‐terminated polydimethylsiloxane (PDMS) and photoinitiator was spin‐coated on the MPTMS surface and exposed to UV‐light. Thereafter, a mixture of thiol‐terminated polyethylene glycol (PEG) and photoinitiator were spin‐coated on the vinyl‐terminated PDMS‐treated surface, and the sequent photopolymerization was carried out under UV‐irradiation. The MPTMS, PDMS, and PEG layers were carefully identified by X‐ray photoelectron spectroscopy, atomic force microscopy, ellipsometry, and water contact angle measurements. The thickness of the polydimethylsiloxane‐block‐poly(ethylene glycol) (PDMS‐b‐PEG) diblock copolymer brush could be controlled by the irradiation time. The responsive behavior of diblock copolymer brushes treated in different solvents was also discussed. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012  相似文献   

9.
We have developed and validated a high‐performance liquid chromatography method that uses monolithic silica disk‐packed spin columns and a monolithic silica column for the simultaneous determination of NG‐monomethyl‐l ‐arginine, NG,NG‐dimethyl‐l ‐arginine, and NG,NG′‐dimethyl‐l ‐arginine in human plasma. For solid‐phase extraction, our method employs a centrifugal spin column packed with monolithic silica bonded to propyl benzenesulfonic acid as a cation exchanger. After pretreatment, the methylated arginines are converted to fluorescent derivatives with 4‐fluoro‐7‐nitro‐2,1,3‐benzoxadiazole, and then the derivatives are separated on a monolithic silica column. l ‐Arginine concentration was also determined in diluted samples. Standard calibration curves revealed that the assay was linear in the concentration range 0.2–1.0 μM for methylated arginines and 40–200 μM for l ‐arginine. Linear regression of the calibration curve yielded equations with correlation coefficients of 0.999 (r2). The sensitivity was satisfactory, with a limit of detection ranging from 3.75 to 9.0 fmol for all four compounds. The RSDs were 4.3–4.8% (intraday) and 3.0–6.8% (interday). When this method was applied to samples from six healthy donors, the detected concentrations of NG‐monomethyl‐l ‐arginine, NG,NG‐dimethyl‐l ‐arginine, NG,NG′‐dimethyl‐l ‐arginine and l ‐arginine were 0.05 ± 0.01, 0.41 ± 0.07, 0.59 ± 0.11, and 83.8 ± 30.43 μM (n = 6), respectively.  相似文献   

10.
Maltol, ethyl maltol, vanillin, and ethyl vanillin are important food additives as flavor enhancers. To quantify the four additives in milk powder, a novel 2D liquid chromatographic (2DLC) method was developed in this article. In such a 2DLC system, the target fractions eluted from the first dimensional column (C4) are stored onto the trapping column (C8) for subsequent analysis; after that, they were switched into the second dimensional column (C18) by a two‐position six‐port switching valve. A one‐step sample preparation method was used prior to 2DLC chromatographic analysis, which was easy and convenient. After optimization of all experimental parameters, the new method was validated in terms of linearity, LODs, and LOQs, intra‐ and interday precision, and accuracy. A conventional single‐dimensional liquid chromatographic method was also proposed in this work for comparison. In order to evaluate the applicability of the new 2DLC method, five brands of commercial milk powder samples (n = 8) were analyzed. Vanillin and ethyl vanillin were detected in two samples, respectively. It is showed that the 2DLC method is effective in quality control programs of milk powder products.  相似文献   

11.
Sensitive and reliable methods are required for the assessment of oxidative DNA damage, which can result from reactive oxygen species that are generated endogenously from cellular metabolism and inflammatory responses, or by exposure to exogenous agents. The development of a liquid chromatography/tandem mass spectrometry (LC/MS/MS) selected reaction monitoring (SRM) method is described, that utilises online column‐switching valve technology for the simultaneous determination of two DNA adduct biomarkers of oxidative stress, 8‐oxo‐7,8‐dihydro‐2′‐deoxyguanosine (8‐oxodG) and 8‐oxo‐7,8‐dihydro‐2′‐deoxyadenosine (8‐oxodA). To allow for the accurate quantitation of both adducts the corresponding [15N5]‐labelled stable isotope internal standards were synthesised and added prior to enzymatic hydrolysis of the DNA samples to 2′‐deoxynucleosides. The method required between 10 and 40 µg of hydrolysed DNA on‐column for the analysis and the limit of detection for both 8‐oxodG and 8‐oxodA was 5 fmol. The analysis of calf thymus DNA treated in vitro with methylene blue (ranging from 5 to 200 µM) plus light showed a dose‐dependent increase in the levels of both 8‐oxodG and 8‐oxodA. The level of 8‐oxodG was on average 29.4‐fold higher than that of 8‐oxodA and an excellent linear correlation (r = 0.999) was observed between the two adducts. The influence of different DNA extraction procedures for 8‐oxodG and 8‐oxodA levels was assessed in DNA extracted from rat livers following dosing with carbon tetrachloride. The levels of 8‐oxodG and 8‐oxodA were on average 2.9 (p = 0.018) and 1.4 (p = 0.018) times higher, respectively, in DNA samples extracted using an anion‐exchange column procedure than in samples extracted using a chaotropic procedure, implying artefactual generation of the two adducts. In conclusion, the online column‐switching LC/MS/MS SRM method provides the advantages of increased sample throughput with reduced matrix effects and concomitant ionisation suppression, making the method ideally suited when used in conjunction with chaotropic DNA extraction for the determination of oxidative DNA damage. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

12.
Affinity depletion of abundant proteins from human plasma has become a routine sample preparation strategy in proteomics used prior to protein identification and quantitation. To date, there have been limited published studies comparing the performance of commercially available depletion products. We conducted a thorough evaluation of six depletion columns using 2‐DE combined with sophisticated image analysis software, examining the following criteria: (i) efficiency of high‐abundance protein depletion, (ii) non‐specific removal of other than the targeted proteins and (iii) total number of protein spots detected on the gels following depletion. From all the products investigated, the Seppro IgY system provided the best results. It displayed the greatest number of protein spots on the depleted plasma gels, minimal non‐specific binding and high efficiency of abundant protein removal. Nevertheless, the increase in the number of detected spots compared with the second best performing and cheaper multiple affinity removal column (MARC) was not shown to be statistically significant. The ProteoPrep spin column, considered to be the “deepest” depletion technique available at the time of conducting the study, surprisingly displayed significantly fewer spots on the flow‐through fraction gels compared with both the Seppro and the MARC. The spin column format and low plasma capacity were also found to be impractical for 2‐DE. To conclude, we succeeded in providing an overview of the depletion columns performances with regard to the three examined areas. Our study will serve as a reference to other scientists when deciding on the optimal product for their particular projects.  相似文献   

13.
6,7‐Dimethoxy‐3‐[4‐(4‐fluorobenzyloxy)‐3‐methoxyphenylmethyl] quinazolin‐4(3H)‐one (DFMQ‐19), a novel analog of 3‐benzylquinazolin‐4(3H)‐ones, may be considered as a drug candidate for the treatment of hypertension. The aim of this study was to develop and validate a reverse‐phase high‐performance liquid chromatography to determine the DFMQ‐19 in plasma and demonstrate its application in pharmacokinetic studies. Separation of DFMQ‐19 and IS (structural analog of DFMQ‐19) was performed using a Shim‐Pack VP‐ODS column and a mixture of acetonitrile and water as mobile phase. The HPLC method was validated according to the International Conference on Harmonization guidelines. The limit of detection and lower limit of quantitation were 0.05 and 0.1 μg/mL, respectively. The recovery rate of DFMQ‐19 from blood samples was >81% of the spiked amount. The RSD of the intra‐ and inter‐day precisions was within 7.5%, and RE of accuracy was between ?14.4 and 4.5%. This method was successfully applied to the pharmacokinetic study after administration of DFMQ‐19. The pharmacokinetic parameters, such as half‐life, mean residence time and maximum concentration were determined. Based on these pharmacokinetic parameters, the oral bioavailability of DFMQ‐19 was calculated to be 13.42% in rat. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

14.
15.
A restricted‐access material–hybrid monolithic column was prepared based on single‐component organosiloxane and dynamic grafting of δ‐gluconolactone for on‐line solid phase extraction of tetracycline antibiotic residues from milk. The hybrid monolithic column was prepared in a stainless‐steel chromatographic column using methyltrimethoxysilane as the single precursor. δ‐Gluconolactone was covalently coupled to aminopropyl derivatized hybrid monolithic column, which formed hydrophilic structures on the surface of the pore of the restricted‐access material–hybrid monolithic column. The columns were characterized by scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, nitrogen adsorption, contact angle analysis, dynamic adsorption, and chromatographic performance evaluation. The restricted‐access material–hybrid monolithic column was applied to the on‐line extraction of tetracycline residues from milk. An enrichment factor of 15.8 and a good sample clean‐up effect were obtained under the optimized conditions. The recoveries of the three spiked milk samples were between 81.7 and 102.5% with relative standard deviations (n = 3) in the range of 2–5%. The limits of detection (S/N = 3) for target compounds were in the range of 3.80–9.03 μg/kg. The results show that the on‐line extraction using the restricted‐access material–hybrid monolithic column was powerful for food sample pretreatment with high selectivity and good clean‐up effect.  相似文献   

16.
The carbon–carbon indirect nuclear spin–spin coupling constants in cyclopropane, aziridine and oxirane were investigated by means of ab initio calculations at the RPA, SOPPA and DFT/B3LYP levels. We found that the carbon–carbon couplings are by far dominated by the Fermi contact term. Our best SOPPA and DFT results are in a very good agreement with each other and with the experimental values, whereas calculations at the RPA level of theory strongly overestimate the carbon–carbon couplings. Significant differences in the basis set dependence of the calculated carbon–carbon coupling constants obtained with either wavefunction method, RPA or SOPPA, or the density functional method, DFT/B3LYP, are observed. The SOPPA results depend much more strongly on the quality of the basis set than the results of DFT/B3LYP calculations. The medium‐sized core‐valence basis sets cc‐pCVTZ and even cc‐pCVDZ were found to perform fairly well at the SOPPA level for the one‐bond carbon–carbon couplings investigated here. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

17.
Interactive materials being responsive to a biocompatible stimulus represent a promising approach for future therapeutic applications. In this study, we present a novel biohybrid material synthesized from biocompatible components being stimulus‐responsive to the pharmaceutically approved small‐molecule novobiocin. The hydrogel design is based on the gyrase B (GyrB) protein, which is covalently grafted to multi‐arm polyethylene glycol (PEG) using a Michael‐type addition reaction. Upon addition of the GyrB‐dimerizing substance coumermycin, stable hydrogels form which can be dissolved in a dose‐adjustable manner by the antibiotic novobiocin. The switchable properties of this PEG‐based hydrogel are favorable for future applications in tissue engineering and as externally controlled drug depot.  相似文献   

18.
The polymerase chain reaction (PCR) is a powerful method for exponentially amplifying very low amounts of target DNA from genetic, clinical, and forensic samples. However, the heating and cooling steps in PCR largely hamper the miniaturization of thermocyclers for on‐site detection of pathogens and point‐of‐care tests. Herein, we devise an ion‐mediated PCR (IM‐PCR) strategy by exploiting ion‐induced DNA denaturation/renaturation cycles. DNA duplexes are effectively denatured in alkaline solutions; whereas, the denatured single‐stranded DNA strands readily reform duplexes at neutral pH. By using an integrated microchip that can programmably control the solution pH simply switching the potential in a range of several hundred millivolts, we can trigger IM‐PCR at a constant temperature. Analogously to thermal cycling, 30 cycles of pH‐induced denaturation/renaturation were used to amplify protein DNA fragments as confirmed by DNA sequencing. We anticipate that this portable, low‐cost, and scalable IM‐PCR holds great promise for widespread biological, clinical, and environmental applications.  相似文献   

19.
Nucleobase‐directed spin‐labeling by the azide‐alkyne ‘click’ (CuAAC) reaction has been performed for the first time with oligonucleotides. 7‐Deaza‐7‐ethynyl‐2′‐deoxyadenosine ( 1 ) and 5‐ethynyl‐2′‐deoxyuridine ( 2 ) were chosen to incorporate terminal triple bonds into DNA. Oligonucleotides containing 1 or 2 were synthesized on a solid phase and spin labeling with 4‐azido‐2,2,6,6‐tetramethylpiperidine 1‐oxyl (4‐azido‐TEMPO, 3 ) was performed by post‐modification in solution. Two spin labels ( 3 ) were incorporated with high efficiency into the DNA duplex at spatially separated positions or into a ‘dA‐dT’ base pair. Modification at the 5‐position of the pyrimidine base or at the 7‐position of the 7‐deazapurine residue gave steric freedom to the spin label in the major groove of duplex DNA. By applying cw and pulse EPR spectroscopy, very accurate distances between spin labels, within the range of 1–2 nm, were measured. The spin–spin distance was 1.8±0.2 nm for DNA duplex 17 ( dA*7,10 ) ?11 containing two spin labels that are separated by two nucleotides within one individual strand. A distance of 1.4±0.2 nm was found for the spin‐labeled ‘dA‐dT’ base pair 15 ( dA*7 ) ?16 ( dT*6 ). The ‘click’ approach has the potential to be applied to all four constituents of DNA, which indicates the universal applicability of the method. New insights into the structural changes of canonical or modified DNA are expected to provide additional information on novel DNA structures, protein interaction, DNA architecture, and synthetic biology.  相似文献   

20.
In recent years, the efficient analysis of biological samples has become more important due to the advances of life science and pharmaceutical research and practice. Because biological sample pretreatment is the bottleneck for fast process, material development for efficient sample process in the high‐performance liquid chromatography analysis is highly desirable. In this research, a cation‐exchange restricted access monolithic column was synthesized by a reversible addition‐fragmentation chain transfer polymerization method. Utilizing the controlled/living property of the reversible addition‐fragmentation chain transfer method, a monolithic column of cross‐linked poly(sulfopropyl methacrylate) was prepared first and then linear poly(glycerol mono‐methacrylate) was immobilized covalently on the surface of the polymer. The monolithic material has both functionalities of cation‐exchange and protein exclusion. Protein recovery of 94.6% was obtained after grafting of poly(glycerol mono‐methacrylate) while the cation‐exchange property of the column is still retained. In the study, the relation between the synthetic conditions and properties of the materials was studied. The synthesis conditions including the porogen, monomer concentration, and ratio of monomers/initiator/reversible addition‐fragmentation chain transfer agent were optimized. The study provided a method for the preparation of restricted access monolithic columns: a bifunctional material by reversible addition‐fragmentation chain transfer polymerization method.  相似文献   

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