Liquid Phase Separation Technique Research Articles

Poly (methyl methacrylate–acrylic acid–vinyl pyrrolidone) terpolymer modified polyethersulfone hollow fiber membrane with pH sensitivity and protein antifouling property

In this study, the functional terpolymer of poly (methyl methacrylate–acrylic acid–vinyl pyrrolidone) was synthesized via free radical solution polymerization using dimethylacetamide (DMAC) as the solvent. The terpolymer can be directly blended with polyethersulfone (PES) using DMAC as the solvent to prepare PES hollow fiber membrane by using a dry-wet spinning technique based on a liquid–liquid phase separation technique. The blended PES hollow fiber membranes showed evident pH sensitivity; and the pH-valve effect was observed at the pH values between 7.0 and 10.0. The fluxes under acid conditions were over 10 times larger than those under basic conditions, and with the increase of the terpolymer blended in the membranes, the flux change increased. The fluxes also showed pH reversibility. Both the pore size change and the electroviscous effect had great effect on the pH sensitivity. Furthermore, the hydrophilicity of the blended membranes increased, and the membranes showed good protein antifouling property.

Optimisation of polymer scaffolds for retinal pigment epithelium (RPE) cell transplantation

AimTo evaluate a variety of copolymers as suitable scaffolds to facilitate retinal pigment epithelium (RPE) transplantation.MethodsFive blends of poly(l-lactic acid) (PLLA) with poly(d,l-lactic-glycolic acid) (PLGA) were manufactured by a solid–liquid...

Preparation and characterization of pH-sensitive polyethersulfone hollow fiber membrane for flux control

In this study, a simplified method to prepare pH-sensitive polyethersulfone (PES) hollow fiber membranes was provided by blending with a copolymer of acrylonitrile and acrylic acid (PANAA). The copolymer PANAA was synthesized by free radical solution polymerization using N-methyl pyrrolidone (NMP) as the solvent. The PANAA copolymer solution can be directly blended with PES solution (using NMP as the solvent) to prepare hollow fibers by using a dry–wet spinning technique based on the liquid–liquid phase separation technique. The blended PES hollow fiber membranes showed evident pH-sensitivity and pH reversibility; and the pH-valve effect was observed at the pH between 4.5 and 11.0. We also proved that the electroviscous effects played the most important role on the pH-sensitivity and flux control for the blended membranes.

Molecularly imprinted polyethersulfone microfibers for the binding and recognition of bisphenol A

AbstractBisphenol A (BPA)‐imprinted polyethersulfone (PES) microfibers for the recognition of BPA were prepared by means of wet‐spinning method based on the liquid–liquid phase separation technique. Two kinds of the BPA‐imprinted microfibers were fabricated with the diameters of about 85 μm and 265 μm, respectively. Extraction of BPA from the microfibers was carried out by immersing the imprinted microfibers into ethanol. In the recognition experiments, the binding amounts were about 24.0, 43.0, and 70.0 μmol/g for the nonimprinted microfibers, whereas those were about 50.0, 87.0, 120.0 μmol/g for the imprinted PES microfibers with the diameter of about 85 μm in 100, 200, and 400 μM BPA solution, respectively. Both of the binding amounts and the adsorption rate for the imprinted microfibers with smaller diameter were higher than that for the microfibers with larger diameters. The selectivity results indicated that the BPA‐imprinted microfibers showed higher recognition coefficient (α) for BPA than phenol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Electrokinetic and Hydrodynamic Injection: Making The Right Choice for Capillary Electrophoresis

CE is a powerful liquid-phase separation technique that is an attractive alternative to HPLC because of its small sample requirements, high resolving power and excellent mass detection limits. While there are many similarities between the two techniques, there are also many differences, some obvious, some subtle. One of the often overlooked differences is the way sample is injected. In HPLC, injection is a very minor component of the method and the choice is predominantly restricted to the choice of solvent and the injection volume. But in CE, it is vastly more complex, and development of an appropriate injection strategy should be given consideration during any method development. While the choice between hydrodynamic or electrokinetic injection may not initially be given any thought, selection of the right approach for the right application can lead to significant improvements in performance, particularly with regard to achieving the lowest detection limits possible. The question is how to decide the best way to inject for each application?

Thematic Review Series: Proteomics. Proteomic analysis of lipid-protein complexes

There is intense interest in comprehensive proteomic approaches for analyzing integral membrane proteins and lipoproteins. Key features of mass spectrometric analysis center on enriching biological material for proteins of interest, efficiently digesting them, extracting the resulting peptides, and using fractionation methods to comprehensively sample proteins or peptides by tandem mass spectrometry. However, lipid-associated proteins are generally rich in hydrophobic domains and are often low in abundance. These features, together with the associated lipid, make their mass spectrometric analysis technically challenging. In this article, we review analytical strategies for successful proteomic analysis of lipid-associated proteins.

Liquid‐phase‐based separation systems for depletion, prefractionation and enrichment of proteins in biological fluids for in‐depth proteomics analysis

This review article is concerned with (i) proteomic sample preparation including among other things the depletion of high-abundance proteins and the concentration of low-abundance proteins and (ii) their subsequent prefractionation for further analysis. Subjects (i) and (ii) are essentials for in-depth proteomic analysis by multidimensional liquid-phase separation techniques (e.g. multidimensional electrophoresis and LC in various formats) followed by mass spectrometric identification and bioinformatic. More than 90 papers published in the period covering early 2000 to the present have been reviewed. It should be noted that this review article is by no means exhaustive, and the aim was to rather provide a concise description of the latest developments in the field.

Modification of polyethersulfone membrane by grafting bovine serum albumin on the surface of polyethersulfone/poly(acrylonitrile-co-acrylic acid) blended membrane

Polyethersulfone (PES) membrane was modified by blending with a copolymer of acrylonitrile (AN) and acrylic acid (AA), followed by grafting bovine serum albumin (BSA) onto the surface of the membrane. The PES and PAN-AA blending membranes were prepared through spin coating coupled with a liquid–liquid phase separation technique. The Micro BCA™ protein assay, XPS and FTIR/ATR analysis confirmed that BSA was successfully grafted onto the surface of the membranes. The pre-activated carboxyl groups of the copolymer and the amino groups of the protein contributed to the formation of BSA-PES membrane conjugates. The water contact angle, protein adsorption and platelet adhesion were obviously decreased after grafting BSA onto the membrane surface, meanwhile the water flux of the membrane was significantly increased. All these results indicated that the hydrophilicity and blood compatibility of the modified PES membranes were improved.

Preparation of polyethersulfone–organophilic montmorillonite hybrid particles for the removal of bisphenol A

Polyethersulfone (PES)–organophilic montmorillonite (OMMT) hybrid particles, with various proportions of OMMT, were prepared by using a liquid–liquid phase separation technique, and then were used for the removal of bisphenol A (BPA) from aqueous solution. The adsorbed BPA amounts increased significantly when the OMMT were embedded into the particles. The structure of the particle was characterized by using scanning electron microscopy (SEM); and these particles hardly release small molecules below 250 °C which was testified by using thermogravimetric analysis (TGA). The experimental data of BPA adsorption were adequately fitted with Langmuir equations. Three simplified kinetics model including the pseudo-first-order (Lagergren equation), the pseudo-second-order, and the intraparticle diffusion model were used to describe the adsorption process. Kinetic studies showed that the adsorbed BPA amount reached an equilibrium value after 300 min, and the experimental data could be expressed by the intraparticular mass transfer diffusion model. Furthermore, the adsorbed BPA could be effectively removed by ethanol, which indicated that the hybrid particles could be reused. These results showed that the PES–OMMT hybrid particles have the potential to be used in the environmental application.

Sol–gel methyl coating in capillary microextraction hyphenated on-line with high-performance liquid chromatography: Counterintuitive extraction behavior for polar analytes

A sol–gel coating with anchored methyl groups was developed for capillary microextraction hyphenated on-line with high-performance liquid chromatography (HPLC). This was accomplished by using methyltrimethoxysilane as the sol–gel precursor. The methyl group on the sol–gel precursor ultimately turned into a pendant group on the created sol–gel coating and was primarily responsible for the extraction of nonpolar analytes. A 40-cm segment of 0.25 mm I.D. fused silica capillary containing the sol–gel methyl coating on the inner surface was installed as a sampling loop in an HPLC injection port. The analytes were extracted by the coating when an aqueous sample containing the analytes was passed through this capillary. The extracted analytes were then transferred to the HPLC column using isocratic elution with an acetonitrile/water mobile phase. This capillary demonstrated excellent extraction capability for polycyclic aromatic hydrocarbons and ketones. Unexpectedly, this coating also provided good extraction for polar analytes, including aromatic phenols, alcohols, and amines. Considering the fact that the methyl group is nonpolar in nature, such an extraction behavior of sol–gel methyl coating toward polar analytes is counterintuitive. Thus, sol–gel sorbents with short alkyl side chains have the potential to offer a polymer-free alternative to traditional sol–gel capillary microextraction (CME) media commonly prepared with the use of polymers in the sol solution. Elimination of polymers from the sol–gel coating solution is conducive to improving thermal stability and solvent tolerance of the created sol–gel extracting phase. This also makes the preparation of sol–gel coatings facile and cost-effective. Possessing excellent solvent stability, such sol–gel coatings offer the opportunity for effective on-line hyphenation of capillary microextraction with HPLC and other liquid-phase separation techniques that employ organo-aqueous mobile phases.

Polysulfone‐Activated Carbon Hybrid Particles for the Removal of BPA

Polysulfone‐activated carbon (PSF‐AC) hybrid particles are prepared using a liquid–liquid phase separation technique. The PSF‐AC hybrid particles are then used for the removal of bisphenol A (BPA) from its aqueous solutions. The PSF‐AC hybrid particles have similar structure as the polysulfone beads; both of them have a skin layer outside and a porous structure inside. The adsorption ability increased significantly when activated carbons were embedded into the particles, and the hybrid particles showed relatively more adsorption ability when the activated carbon content was 50%. The adsorbed BPA to the hybrid particles could be effectively removed by ethanol, which indicates that the hybrid particles can be reused. It is easy to prepare the particle column using these kinds of hybrid particles and the hybrid particle column could more effectively remove BPA. The results suggested that the PSF‐AC hybrid particles have a potential to be used for the removal of BPA in environmental application.

Inexpensive, High Throughput Microplate Format for Plant Nucleic Acid Extraction: Suitable for Multiplex Southern Analyses of Transgenes

To achieve high throughput analysis of genomic DNA from small amounts of plant tissue, a standard nucleic acid extraction was formatted to microplates by linking a novel series of interlocking plates. The protocol integrates steel pellet tissue homogenization and unique liquid handling and phase separation techniques with minimal special equipment. The method was validated for difficult plant DNAs, such as hop (Humulus lupulus L.), soybean [Glycine max (L.) Merr.], and tobacco (Nicotiana tabacum L.), with agarose gel separations of restriction fragments and Southern blot analysis of transgene integrants in soybean. The range of success rates for Southern blots was 73 to 92% per sample per plate (n = 2016 samples). Variation in absolute yield was quantified by PicoGreen microplate flourimetry. The variation in yield among samples per plate was small enough to obviate individual sample concentration adjustment before Southern analysis. Average absolute yield for the barley (Hordeum vulgare L.) mapping population based on flourimetry was 6.8 μg ± 0.85 SE, n = 96; providing enough pure, stable DNA for many individual polymerase chain reaction (PCR) reactions. Intersample cross‐contamination and suitability for PCR analysis were validated by simple sequence repeat (SSR) display of a previously characterized barley mapping population. Cost calculation from a materials detail was U.S. $0.17 per sample extraction. Although the implementation requires some skill and practice, we find it to be a robust, adaptable, and versatile alternative to expensive commercial kits.

DNA‐loaded porous polyethersulfone particles for environmental applications I. preparation

AbstractDNA‐loaded porous poly(ether sulfone) (PES) particles are prepared for environmental applications by means of a liquid–liquid phase separation technique. The particles prepared by this method have very large porosity and specific surface area, which are useful as absorbents. By manipulating the fabrication conditions, we could control the microsphere structure, including the diameter and porosity of the particles, the pore size, and the specific surface area. Increasing the polymer concentration, which causes lower porosity and smaller pores on the outer surface of the microspheres, led to increased stability of the DNA‐loaded particles and high DNA incorporation efficiency. The DNA‐loaded porous PES particles could accumulate and remove a DNA intercalating pollutant, ethidium bromide (EB). Both the DNA amount incorporated in the particles and the microsphere structure have great effect on the EB removal ratio. These results indicate that the DNA‐loaded PES particles have the potential to be used in environmental applications, which will be further discussed in the following paper. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1668–1673, 2005

Molecularly imprinted polyethersulfone microspheres for the binding and recognition of bisphenol A

BPA-imprinted polyethersulfone (PES) microspheres for the binding and recognition of bisphenol A (BPA) were fabricated by means of a liquid–liquid phase separation technique. The imprinted novel PES microspheres had a porous structure with a skin layer, under which was followed by a finger-like structure. The recognition experiments with the BPA-imprinted microspheres were carried out by applying the microspheres to various BPA solutions. In water, high binding amounts of BPA were observed in the range of 19–42 μmol/g capacity, but the recognition was low in the BPA water solution. With the increase of the concentration in BPA solution, the binding amounts and the recognition coefficient increased. However, 1,4-butylene glycol/water media showed high recognition of the imprinted microspheres with a low binding capacity of BPA. In addtion, with the increase of the BPA amounts in the PES solution used to prepare the imprinted microspheres, the specific recognition sites increased, and the recognition ability increased. Evidence revealed that microsphere recognition was effective for BPA due to the binding to specific recognition sites [ S] (sites). The imprinted microspheres showed the selectivity for BPA in the wine including BPA and other organic compounds. Charge transfer and special cavities could be employed to explain the mechanism.

DNA-Loaded PSf Microspheres Used in Environmental Application

ABSTRACTDNA-loaded porous polysulfone (PSf) microspheres were prepared using a liquid–liquid phase separation technique. The microspheres were then used in environmental application. The DNA-loaded microspheres were stable in water. They could effectively accumulate the DNA-binding harmful pollutants and endocrine disruptors, such as ethidium bromide (EB), acridine orange (AO), biphenyl (BP), dibenzofuran (DBF), and dibenzo-p-dioxin (DBD), in their aqueous solutions. On the other hand, the microspheres were found to selectively remove heavy metal ions from their aqueous solutions. The DNA-loaded PSf microspheres have a potential ability to serve as functional materials in environmental application.

Hyphenating liquid phase separation techniques with mass spectrometry: on-line or off-line

The advantages of hyphenating analytical separation techniques to mass spectrometers have been recognised since the 1970s. The first attempts to couple liquid phase separations to mass spectrometry(MS) were problematic, but the development of electrospray ionisation (ES) in 1984 facilitated the production of routinely used, commercial interfaces. This review considers the most recent major developments in hyphenating liquid chromatographic and electrophoretic separations to mass spectrometry, and considers the role the post genomic sciences have played in driving them. It also considers why, despite all of the advances in hyphenation, the future appears to hold a major role for off-line analysis.

Preparation of polysulfone hollow microspheres encapsulating DNA and their functional utilization

Polysulfone hollow microspheres encapsulating DNA were prepared using a liquid–liquid phase separation technique. The microspheres were then used to absorb a DNA-binding intercalating material — ethidium bromide. The amount of DNA encapsulated in the microspheres depended on the concentration of the DNA solution used to prepare the microspheres, and the microsphere morphology depended on both the polymer concentration and the preparation conditions. The amount of ethidium bromide in the microspheres depended mainly on the amount of encapsulated DNA, and the microsphere morphology also affected the removal of the ethidium bromide. The new method of DNA encapsulation is proposed, and the microspheres encapsulating the DNA have the potential to be used in environmental applications.

Preparation of porous polysulfone beads for selective removal of endocrine disruptors

Porous polysulfone (PSf) beads are prepared using a liquid–liquid phase separation technique. The porous PSf beads are then used for the removal of endocrine disruptors, such as Biphenyl (BP), dibenzofuran (DBF), dibenzo- p-dioxin (DBD), biphenol A (BPA), and diethylstylbestrol (DES) from their aqueous solutions. The endocrine disruptors could be removed efficiently by a simple sorption method with hydrophobic porous PSf beads. The removal ratio was high for endocrine disruptors having high octanol–water distribution coefficients. The effect of sorption time, weight of PSf beads, ethanol amount in the solution, and the porosity of the beads on the removal of endocrine disruptors was investigated. The adsorbed endocrine disruptors in the PSf beads could be effectively removed by 2-propanol or ethanol, which indicated that the beads could be reused. The study suggested that the porous PSf beads have a potential ability to be used for the removal of endocrine disruptors in environmental application.

Preparation of DNA-loaded polysulfone microspheres by liquid–liquid phase separation and its functional utilization

DNA-loaded polysulfone (PSf) microspheres were fabricated by means of a liquid–liquid phase separation technique. The porous microspheres were then used to remove DNA-binding intercalating materials—ethidium bromide, acridine orange, and endocrine disruptors. The DNA-loaded PSf microspheres are stable in water. The stability of the DNA-loaded microspheres and/or the release rate of DNA from the microspheres can be controlled by manipulating the microsphere structure. Increasing the polymer concentration, which causes lower porosity and smaller pores on the outer surface of the microspheres, led to increased stability of the microspheres and decreased release rate of DNA. Additionally, the drying temperature also affected the stability of the microspheres. The DNA-loaded PSf microspheres could effectively accumulate harmful DNA-intercalating pollutants and endocrine disruptors, such as ethidium bromide, acridine orange, biphenyl, dibenzofuran, and dibenzo- p-dioxin. The amount of pollutants removed by the microspheres is dependent on the amount of incorporated DNA and on the microsphere structure. The DNA-loaded microspheres have the potential to be used in environmental applications.

Atmospheric pressure photoionization mass spectrometry.

Atmospheric pressure photoionization (APPI) is the last arrival in the family of atmospheric pressure ionization (API) methods to couple mass spectrometry (MS) to liquid-phase separation techniques. The basic idea was to further extend the fields of application of liquid chromatography (LC)-MS to those molecules that are not, or are poorly amenable, to electrospray (ESI) or APCI. The present review explores the literature. After a short introduction with an historical background and the premises for its development, we describe the technique, its physical principles, and the factors that affect its efficiency. The review also presents a survey of applications in different fields.