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Biomedical subjects

Xiangmin Zhang

Publications and source records attributed to Xiangmin Zhang.

At least 19 recordsLinked to original sources
PubMed2006

Multidimensional capillary array liquid chromatography and matrix-assisted laser desorption/ionization tandem mass spectrometry for high-throughput proteomic analysis.

A two-dimensional capillary array liquid chromatography system coupled with matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) was developed for high-throughput comprehensive proteomic analysis, in which one strong cation-exchange (SCX) capillary chromatographic column was used as the first separation dimension and 10 parallel reversed-phase liquid chromatographic (RPLC) capillary columns were used as the second separation dimension. A novel multi-channel interface was designed and fabricated for on-line coupling of the SCX to RPLC column array system. Besides the high resolution based on the combination of SCX and RPLC separation, the developed new system provided the most rapid two-dimensional liquid chromatography (2D-LC) separation. Ten three-way micro-splitter valves used as stop-and-flow switches in transferring SCX fractions onto RPLC columns. In addition, the three-way valves also acted as mixing chambers of RPLC effluent with matrix. The system enables on-line mixing of the LC array effluents with matrix solution during the elution and directly depositing the analyte/matrix mixtures on MALDI plates from the tenplexed channels in parallel through an array of capillary tips. With the novel system, thousands of peptides were well separated and deposited on MALDI plates only in 150min for a complex proteome sample. Compared with common 2D-LC system, the parallel 2D-LC system showed about 10-times faster analytical procedure. In combination with a high throughput tandem time of flight mass spectrometry, the system was proven to be very effective for proteome analysis by analyzing a complicated sample, soluble proteins extracted from a liver cancer tissue, in which over 1202 proteins were identified.

Chromatography, Liquid↗
PubMed2006

Analytical solutions of the ideal model for gradient liquid chromatography.

The analytical solutions of the ideal model for gradient elution that ignores the influence of the solute concentration on the retention factor (k) were studied by using the method of characteristics for solving partial differential equations. It is found for any gradient profiles and solvent strength models used that the concentration of the solute will be discontinuous where the mobile-phase composition is. On a given characteristic curve, the product of the concentration and the retention factor is kept constant at the point where the concentration is continuous. At the point where the concentration is discontinuous, the product on the left side of this point is equal to that on the right side. We also discussed the basic equations to predict the retention time in gradient elution and introduced the injection time into them. For linear solvent strength stepwise and linear gradient elution, general expressions were proposed for the prediction and they can be used as the basis to derive others for specific gradient modes such as single linear, stepwise, and ladderlike gradients. For these modes, simple expressions to account for the band compression and the concentration change during the elution were also given.

Algorithms↗
PubMed2006

Development of gas chromatography-mass spectrometry following microwave distillation and simultaneous headspace single-drop microextraction for fast determination of volatile fraction in Chinese herb.

In this work, for the first time, microwave distillation (MD) coupled with simultaneous headspace single-drop microextraction (HS-SDME) was developed for the determination of the volatile components in the Chinese herb, Artemisia capillaris Thunb. The volatile components were rapidly isolated by MD, and simultaneously extracted and concentrated by using a dodecane microdrop. The volatile oil extracted in the microdrop solvent was analyzed by gas chromatography-mass spectrometry (GC-MS). The experimental parameters of solvent selection, microdrop volume, microwave power, irradiation time and sample amount were investigated, and the method precision was also studied. The optimal parameters were extraction solvent of dodecane, solvent volume of 2.0 microL, microwave power of 400 W, irradiation time of 4 min, and sample amount of 2.0 g. Thirty-five volatile compounds present in Artemisia capillaris Thunb. were identified by using the proposed method, which were identical with those obtained by the conventional steam distillation method. The experimental results showed that MD-HS-SDME is a simple, rapid, reliable, and solvent-free technique for the determination of volatile compounds in Chinese herbs.

Analytic Sample Preparation Methods↗
PubMed2006

Gas chromatography-mass spectrometry following microwave distillation and headspace solid-phase microextraction for fast analysis of essential oil in dry traditional Chinese medicine.

In this paper, a novel method based on gas chromatography-mass spectrometry (GC-MS) following microwave distillation-headspace solid-phase microextraction (MD-HS-SPME) was developed for the determination of essential oil in dry traditional Chinese medicine (TCM). TCM is dried before being preserved and used, there is too little water to absorb microwave energy and heat the TCM samples. In the work, carbonyl iron powders (CIP) was added and mixed with the dried TCM sample, which was used as microwave absorption solid medium for dry distillation of the TCM. At the same time, SPME was used for the extraction and concentration of essential oil after MD. The dry rhizomes of Atractylodes lancea DC was used as the model TCM, and used in the study. The MD-HS-SPME parameters including fiber coating, microwave power, irradiation time, and the amount of added CIP, were studied. To demonstrate the method feasibility, the conventional HS-SPME method was also used for the analysis of essential oil in the TCM. Experimental results show that more compounds were isolated and identified by MD-HS-SPME than those by HS-SPME. Compared to conventional HS-SPME, the advantages of the proposed method are: short extraction time and high extraction efficiency. All experimental results show that the proposed method is an alternative tool for fast analysis of essential oils in dry TCMs.

Chemical Fractionation↗
PubMed2006

Development of gas chromatography-mass spectrometry following headspace single-drop microextraction and simultaneous derivatization for fast determination of short-chain aliphatic amines in water samples.

In this work, for the first time, gas chromatography-mass spectrometry (GC-MS) following headspace single-drop microextraction (HS-SDME) and simultaneous derivatization was developed for fast determination of short-chain aliphatic amines (SCAAs) in water samples. In the proposed method, SCAAs in water samples were headspace extracted and concentrated by suspending a microdrop of solvent, and SCAAs extracted in the microdrop of solvent were simultaneously and rapidly reacted with pentafluorobenzaldehyde (PFBAY). The formed SCAA derivatives were analyzed by GC-MS. The HS-SDME parameters of solvent selection, solvent volume, sample temperature, extraction time and stirring rate were studied, and the method linearity, precision and detection limits, were also studied. The results show that the proposed method provided good linearity (R(2)>0.99, 5.0-500 ng/ml), low detection limit (0.6-1.1 ng/ml), and good precision (RSD value less than 10%). The proposed method was further tested by its application to quantitative analysis of SCAAs in four wastewater samples. The experiment results have demonstrated that GC-MS following HS-SDME and simultaneous derivatization is a simple, rapid and low-cost method for the determination of SCAAs in water samples.

Amines↗
PubMed2006

Fast determination of curcumol, curdione and germacrone in three species of Curcuma rhizomes by microwave-assisted extraction followed by headspace solid-phase microextraction and gas chromatography-mass spectrometry.

Curcumol, germacrone and curdione are the main active ingredients in a common traditional Chinese medicine (TCM) of Rhizoma Curcuma, and commonly used as the TCM quality control markers. In the present work, microwave-assisted extraction (MAE) followed by headspace solid-phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS) was developed for the quantitative analysis of curcumol, curdione and germacrone in Rhizoma Curcuma. The MAE and HS-SPME parameters were studied, and the method was validated. The optimal MAE conditions obtained were: microwave power of 700 W and irradiation time of 4 min, and HS-SPME optimal conditions were: fiber coating of 100 microm PDMS, extraction temperature of 80 degrees C, extraction time of 20 min, stirring rate of 1,100 rpm, and salt concentration of 30% NaCl. The proposed method provided good precision (RSD less than 12%) and recoveries between 86% and 93%. The proposed method was applied to the determination of the three marker compounds in three species of Curcuma rhizomes (Curcuma wenyujin, Curcuma phaeocaulis, and Curcuma kwangsiensis). To demonstrate the proposed method reliability, a conventional technique of steam distillation was also used for the analysis of curcumol, germacrone and curdione in the TCMs. The results show that MAE-HS-SPME is a simple, rapid, solvent-free and reliable method for the determination of curdione, curcumol and germacrone in TCM, and also a potential and powerful tool for quality assessment of Rhizoma Curcuma.

Curcuma↗
PubMed2006

Mass transfer kinetics and breakthrough and elution curves for bovine serum albumin using cibacron blue cellulose membranes.

The mass transfer of bovine serum albumin onto a stack of cibacron blue cellulose membranes in the loading and elution stages were studied. The breakthrough curves obtained in the loading stage were fitted to the pore and the lumped kinetic (LK) models, respectively. Then experimental data obtained in the elution stage were described by using the LK model in which the kinetic equation, the initial and the boundary conditions were rewritten according to the operation. For the breakthrough curves it was found that the contribution of the sorption kinetics to band broadening was significant whereas that of axial dispersion was negligible. In contrast, both of these contributions were significant to the profile of the elution curve. By studying the mass transfer kinetics in the elution stage, information about the influence of the module geometry on the performance of affinity membrane separations may be obtained.

Cellulose↗
PubMed2006

Comprehensive two-dimensional separation in coupling of reversed-phase chromatography with capillary isoelectric focusing followed by MALDI-MS identification using on-target digestion for intact protein analysis.

A coupling of capillary RP LC as the first dimension with CIEF as the second dimension followed by MALDI-MS identification was demonstrated. Based on 2-D separation system developed by our group (Electrophoresis 2003, 24, 3289-3295), this paper focused on incorporating tryptic digestion into the top-down proteomics methodology, retaining the benefits of the top-down method. Hydrophobic layer of packing-material C18 coated with SE-30 on the MALDI-target surface was used to permit the CIEF fractions to be easily concentrated and free of ampholytes using on-target washing. Following the removal of ampholytes, on-target tryptic digestion was performed to generate PMF for protein identification. Using the proteome analytical strategy, we could obtain not only intact protein pI value but also PMF for accurate protein identification. The feasibility of the strategy was first tested with a mixture of model proteins with different pIs and molecular masses. Proteome of rat liver tissue extracts was further analyzed using the system for verification. The results have shown that the system is effective for complex proteomic analysis.

Animals↗
PubMed2006

Indirect laser-induced fluorescence detection of diuretics separated by capillary electrophoresis.

Indirect LIF detection was applied to the detection of four acidic diuretics separated by CZE. Semiconductor laser was employed to provide the stable excitation of 473 nm. With an optimized electrophoretic buffer system which contained 5 mM of triethylamine, 0.1 microM of fluorescein, and 5% of n-butanol, fast separation of four diuretics (ethacrynic acid, chlorthalidone, bendroflumethiazide, and bumetanide) can be performed within 3 min with the detection limits of 0.2-2 microg/mL. The impacts of buffer components including the concentrations of the electrolytes, fluorescence probe, and the organic additives were demonstrated. The method was applied for the detection of diuretics in urine. As an alternative way for the fast analysis of diuretics, this indirect detection method provided the technical support for future microchip performances, in which diuretics may be detected in the microchip by the common LIF detector without derivatization.

Buffers↗
PubMed2006

Array based capillary IEF with a whole column image of laser-induced fluorescence in coupling to capillary RPLC as a comprehensive 2-D separation system for proteome analysis.

Based on array CIEF (ACIEF) and a novel whole column imaging detection (WCID), a comprehensive 2-D system with laser-induced fluorescence was developed for protein mapping. By coupling capillary RPLC (CRPLC) as the first dimension and ACIEF as the second dimension, a high-throughput and high-resolution proteomic expression profiling was obtained. An array of up to 60 capillaries was assembled, with electrical connections made through filling small breaks, created on each capillary at positions of buffer reservoirs, with a porous polymer. A whole column image system with laser-induced fluorescence (LIF) was devised. Spot excitation was performed with a laser converted to produce linear light, and a CCD camera was employed to take images of the protein fluorescence during line laser scanning of the capillary array. Quantitative detection of thousands of focusing protein bands in the capillary array was achieved. Details on the capillary array fabrication and scanning LIF detection system devices are discussed. The efficiency of this CRPLC-ACIEF-LIF-WCID system was further demonstrated using samples of soluble proteins extracted from liver cancer tissue. The overall peak capacity was estimated to be around 18 000 in an analysis time of less than 3 h. The reproducibility of consecutive runs and different columns were assessed as having an RSD of 1.5% and 2.2% in focusing positions, respectively.

Animals↗
PubMed2006

Expressed proteome analysis of human hepatocellular carcinoma in nude mice (LCI-D20) with high metastasis potential.

We report for the first time an expressed proteome for human hepatocellular carcinoma (HCC) in nude mice model. Most cases of human liver cancer are HCC with highly metastatic ability. Therefore, the early prediction or diagnosis and effective treatment are the key points of research. We have previously successfully established a human HCC nude mice model (LCI-D20) with high metastasis potential. To understand better the tumor biology of HCC it is worth to explore the relativity of all expressed protein profiles in the LCI-D20 HCC nude mice model. With advanced proteomics technologies, we have carried out a proteomic analysis with following stages: protein sample preparation of cancer tissue, including total cellular extraction and sequential fractionation, 2-DE and 2-D LC separation, ESI/MALDI-MS/MS identification, as well as data-dependent bioinformatics. The identified proteins were classified bioinformatically respective to their function, biological process and intracellular localization. Some important proteins found in HCC, e.g. metabolism enzymes, proteins regulating cell motility, signaling proteins, and heat shock proteins, are discussed in terms of their metastasis.

Animals↗
PubMed2006

Development of water-phase derivatization followed by solid-phase microextraction and gas chromatography/mass spectrometry for fast determination of valproic acid in human plasma.

In this study, a simple, rapid, and sensitive method was developed and validated for the quantification of valproic acid (VPA), an antiepileptic drug, in human plasma, which was based on water-phase derivatization followed by headspace solid-phase microextraction (HS-SPME) and gas chromatography/mass spectrometry (GC/MS). In the proposed method, VPA in plasma was rapidly derivatized with a mixture of isobutyl chloroformate, ethanol and pyridine under mild conditions (room temperature, aqueous medium), and the VPA ethyl ester formed was headspace-extracted and simultaneously concentrated using the SPME technique. Finally, the analyte extracted on SPME fiber was analyzed by GC/MS. The experimental parameters and method validations were studied. The optimal conditions were obtained: PDMS fiber, stirring rate of 1100 rpm, sample temperature of 80 degrees C, extraction time of 20 min, NaCl concentration of 30%. The proposed method had a limit of quantification (0.3 microg/mL), good recovery (89-97%) and precision (RSD value less than 10%). Because the proposed method combined a rapid water-phase derivatization with a fast, simple and solvent-free sample extraction and concentration technique of SPME, the sample preparation time was less than 25 min. This much shortens the whole analysis time of VPA in plasma. The validated method has been successfully used to analyze VPA in human plasma samples for application in pharmacokinetic studies. All these results show that water-phase derivatization followed by HS-SPME and GC/MS is an alternative and powerful method for fast determination of VPA in biological fluids.

Anticonvulsants↗
PubMed2006

Development of gas chromatography/mass spectrometry following headspace solid-phase microextraction for fast determination of asarones in plasma.

Asarones (alpha-asarone and beta-asarone) are the active components in the traditional Chinese medicine (TCM) of Acorus tatarinowii Schott, which has been used to treat epilepsy for several thousand years. To perform the pharmacokinetics (PK) study of alpha- and beta-asarone from the TCM essential oil, a simple, rapid and sensitive method was developed for the determination of asarones from the TCM in rabbit plasma, based on headspace solid-phase microextraction (HS-SPME) followed by gas chromatography/mass spectrometry (GC/MS) with electron ionization (EI). The extraction parameters of headspace volume, fiber coating, sample temperature, extraction time, stirring rate and ion strength were systemically optimized. Furthermore, the method linearity, detection limit and precision were also investigated. It was shown that the proposed method provided a good linearity (0.02-20 microg/mL, R(2) > 0.99), low detection limit (<2.0 ng/mL) and good precision (RSD < 7.0%). Finally, HS-SPME followed by GC/MS was applied to fast determination of alpha- and beta-asarone in rabbit plasma at different time points after oral adminstration of the essential oil from A. tatarinowii. The experimental results suggest that the proposed method provides an alternative approach to the PK studies of volatile compounds in TCMs.

Acorus↗
PubMed2006

Novel strategy of high-abundance protein depletion using multidimensional liquid chromatography.

In this study, for the first time, a comprehensive two-dimensional (2D) liquid-phase separation system, coupling strong cation exchange chromatography (SCX) to reversed-phase high performance liquid chromatography (RPLC), instead of specificity depletion method, was developed at the intact protein level for depletion of high-abundance proteins from rat liver. Proteins were prefractionated by SCX in the first dimensional separation, followed by RPLC with high resolution separation. UV absorption intensity was used to differentiate high-abundance proteins. The proteins with the absorbance intensity above 0.1 AU were defined as high abundance proteins and depleted. After removal of high-abundance proteins; other proteins were pooled, digested, and subsequently separated by capillary liquid chromatography coupled with MALDI-TOF/TOF mass spectrometry analysis. The high efficiency of the strategy was demonstrated by analyzing the soluble protein extracted from rat liver tissue. In total, 77 high-abundance proteins were depleted in one experiment flow. The ratio of depleted content of high-abundance proteins to that of total proteins was about 34.5%. In total, 1530 proteins were identified using the depletion strategy. Quantitative estimation of high-abundance proteins through liquid chromatography combined with UV absorption spectra was achieved. On the basis of the reproducible experimental results, a rapid and high-throughput depletion protocol was put forward. Along with depletion of the most (79.1%) high-abundance proteins and the separation of digested peptides, the total separation time could be less than 30 h. This strategy has no bias for depleting high-abundance proteins and enhances the number of identified proteins; therefore, it can be widely used in the global proteins analysis.

Animals↗
PubMed2006

Capillary array reversed-phase liquid chromatography-based multidimensional separation system coupled with MALDI-TOF-TOF-MS detection for high-throughput proteome analysis.

A high-throughput on-line capillary array-based two-dimensional liquid chromatography (2D-LC) system coupled with MALDI-TOF-TOF-MS proteomics analyzer for comprehensive proteomic analyses has been developed, in which one capillary strong-cation exchange (SCX) chromatographic column was used as the first separation dimension and 18 parallel capillary reversed-phase liquid chromatographic (RPLC) columns were integrated as the second separation dimension. Peptides bound to the SCX phase were "stepped" off using multiple salt pulses followed by sequentially loading of each subset of peptides onto the corresponding precolumns. After salt fractionation, by directing identically split solvent-gradient flows into 18 channels, peptide fractions were concurrently back-flushed from the precolumns and separated simultaneously with 18 capillary RP columns. LC effluents were directly deposited onto the MALDI target plates through an array of capillary tips at a 15-s interval, and then alpha-cyano-4-hydroxycinnamic acid (CHCA) matrix solution was added to each sample spot for subsequent MALDI experiments. This new system allows an 18-fold increase in throughput compared with serial-based 2D-LC system. The high efficiency of the overall system was demonstrated by the analysis of a tryptic digest of proteins extracted from normal human liver tissue. A total of 462 proteins was identified, which proved the system's promising potential for high-throughput analysis and application in proteomics.

Capillary Action↗
PubMed2006

Preparation of the capillary-based microchips for solid phase extraction by using the monolithic frits prepared by UV-initiated polymerization.

A microfluidic solid phase extraction (SPE) array for sample enrichment was prepared by a simple method, a hot embossing technique. Five fused-silica capillaries (250 microm i.d., 380 microm o.d.) were partly embedded parallel in a polymethyl methacrylate (PMMA) microchip to serve as the extraction channels. Within each of the channels, a 2-mm-long monolithic porous polymer was prepared by in-situ photoinitiated polymerization. This then acted as the frit for packing of the extraction materials (octadecylsilica beads, ODS). By defining the light-exposure window on the channels, one can easily control the length and location of the polymer frits and the ODS beads can be packed at the desired location. With this method, solid phase extraction channels for microfluidic use can be easily prepared without complex fabrication of microstructures. Several SPE channels can be conveniently made in one microchip since the frits can be prepared in different channels through one polymerization; packing of the different channels can also be performed simultaneously. With the use of dilute ephedrine solutions, the sample loading capacity, linearity, and reproducibility were characterized. Coupled with the fast capillary electrophoresis separation, this microchip SPE array was applied for the detection of ephedrines in human urine.

Calibration↗
PubMed2005

Development of microwave-assisted extraction followed by headspace single-drop microextraction for fast determination of paeonol in traditional Chinese medicines.

Paeonol is an important active component present in traditional Chinese medicines (TCMs), which was used for the treatment of many diseases such as eczema. In this work, microwave-assisted extraction (MAE) was firstly combined with headspace single-drop microextraction (HS-SDME), and applied to rapid determination of paeonol in two TCMs of Cynanchum paniculatum and Paeonia suffruticosa. In the proposed method, paeonol in TCMs was isolated by using MAE, followed by extraction and concentration by HS-SDME, and detected by gas chromatography-mass spectrometry (GC-MS). The experiment parameters of MAE and HS-SDME were discussed, and the method precision, recovery and detection limit were also studied. To further demonstrate the reliability of the quantification, both the proposed method and a standard method of steam distillation (SD) were simultaneously applied to quantitative analysis of paeonol in TCM samples from different growing areas. The experimental results show that MAE-HS-SDME is a simple and rapid method for the quantitative analysis of paeonol in TCMs, and is also a potential and alternative tool for quality monitoring for the two TCMs of C. paniculatum and P. suffruticosa.

Acetophenones↗