Hydroxyethylcellulose-graft-poly (N,N-dimethylacrylamide) copolymer as a multifunctional separation medium for CE

A new multifunctional separation medium, hydroxyethylcellulose-graft-poly (N,N-dimethylacrylamide) copolymer synthesized in our laboratory for application in both basic protein separation and dsDNA separation by CE, is presented in this paper. As a noncovalent coating, this medium showed a powerful capability in resisting basic protein adsorption. Highly efficient and rapid protein separation had been obtained at four different pH values. Meanwhile, the 11 fragments of the dsDNA sample could be baseline separated using this grafted copolymer as sieving matrix at an appropriate concentration.     

Enantioseparation by CE with vancomycin as chiral selector: Improving the separation performance by dynamic coating of the capillary with poly(dimethylacrylamide)

An approach for improving the separation performance of the enantioseparation by CE with vancomycin as chiral selector is described. In the present method, a solution of poly(dimethylacrylamide) (PDMA) was used for dynamic coating of the capillary wall to minimize the adsorption of vancomycin onto the capillary wall, and to depress the EOF. Compared with the bare fused-silica capillaries and the capillaries coated with the polycationic polymer hexadimethrine bromide (HDB), the PDMA-coated capillary displayed the best separation performance. The resulting coating could withstand hundreds of runs without losing its function. Moreover, a partial filling technique was applied to avoid interference in detection caused by the presence of vancomycin in the buffer. The separation time was shortened when a short-end-injection technique was applied. Several parameters such as buffer pH, vancomycin concentration and plug length of the vancomycin solution for the separation were optimized. Under the optimal conditions, all tested enantiomers, including FMOC amino acids derivatives, ketoprofen and fenoprofen, were baseline-separated in less than 4.2 min.     

Size-based separations of proteins by capillary electrophoresis using linear polyacrylamide as a sieving medium: model studies and analysis of cider proteins

Electrophoretic conditions to separate sodium dodecyl sulfate (SDS)-protein complexes according to their relative molecular mass by capillary electrophoresis (CE) using linear polyacrylamide as a sieving matrix were examined. Five purified proteins with relative molecular masses between 14 400 and 66 200 Da were separated on a coated fused-silica capillary with an internal diameter of 100 microm and an effective length of 24 cm (total length, 32.5 cm). Benzoic acid was added to the solution of purified proteins as internal standard; beta-mercaptoethanol was also added as reducing agent. The running buffer composition was 0.05 M tris(hydroxymethyl)aminomethane (Tris), 0.035 M aspartic acid, 0.1% m/v SDS, 4% m/v acrylamide, the resulting pH being 8.0. The applied voltage was 7 kV (reversed voltage polarity) in order to avoid high current intensities. Under optimized conditions, the five proteins were separated in less than 15 min, with a % relative standard deviation (RSD) between 0.2 and 0.4 for migration times in the same day. Good efficiency (values between 150 000 and 40 000 N/m) and resolution (values between 2 and 2.8) were obtained. The inverse of relative migration times was found to correlate with the logarithm of their relative molecular mass. Finally, cider proteins were analyzed and their relative molecular masses were determined. These results were compared with those obtained by SDS-polyacrylamide gel electrophoresis (SDS-PAGE).     

Brush-like copolymer as a physically adsorbed coating for protein separation by capillary electrophoresis

A brush-like copolymer consisting of poly(ethylene glycol) methyl ether methacrylate and N,N-dimethylacrylamide (PEGMA-DMA) was synthesized and used as a novel static physically adsorbed coating for protein separation by capillary electrophoresis for the first time, in order to stabilize electroosmotic flow (EOF) and suppress adsorption of proteins onto the capillary wall. Very stable and low EOF was obtained in PEGMA-DMA-coated capillary at pH 2.2-7.8. The effects of molar ratio of PEGMA to DMA, copolymer molecular mass, and pH on the separation of basic proteins were discussed. A comparative study of bare capillary with PEGMA-DMA-coated capillary for protein separation was also performed. The basic proteins could be well separated in PEGMA-DMA-coated capillary over the investigated pH range of 2.8-6.8 with good repeatability and high separation efficiency because the copolymer coating combines good protein-resistant property of PEG side chains with excellent coating ability of PDMA-contained backbone. Finally, the coating was successfully applied to the fast separation of other protein samples, such as protein mixture and egg white, which reveals that it is a potential coating for further proteomics analysis.     

Poly(1-allylimidazole)-grafted silica,a new specific stationary phase for reversed-phase and anion-exchange liquid chromatography

A new specific stationary phase based on poly(1-allylimidazole)-grafted silica has been synthesized and characterized, by infrared spectra, elemental analysis, thermogravimetric analysis and X-ray photoelectron spectroscopy. The results of test showed that poly(1-allylimidazole) can effectively mask the residual silanol groups and reduce the adverse effect of residual silanol. Using this stationary phase, phenol compounds, aniline compounds, and polycyclic aromatic hydrocarbons were successfully separated with symmetric peak shapes in the reversed-phase chromatography. Inorganic anions (IO₃⁻, BrO₃⁻, Br⁻, NO₃⁻, I⁻, SCN⁻) were also separated completely in the anion-exchange chromatography using sodium chloride solution as the mobile phase. The effects of pH and the concentration of eluent on the separation of inorganic anions were studied. The separation mechanism appears to involve the mixed interactions of hydrogen bonding, hydrophobic, π–π, electrostatic, and anion-exchange interactions.     

Toughening of poly(propylene carbonate) by carbon dioxide copolymer poly(urethane-amine) via hydrogen bonding interaction

A carbon dioxide copolymer poly(urethane-amine)(PUA) was blended with poly(propylene carbonate)(PPC) in order to improve the toughness and flexibility of PPC without sacrificing other mechanical properties. Compared with pure PPC, the PPC/PUA blend with 5 wt% PUA loading showed a 400% increase in elongation at break, whilst the corresponding yielding strength remained as high as 33.5 MPa and Young's modulus showed slightly decrease. The intermolecular hydrogen bonding interaction in PPC/PUA blends was comfirmed by FTIR, 2D IR and XPS spectra analysis, and finely dispersed particulate structure of PUA in PPC was observed in the SEM images, which provided good evidence for the toughening mechanism of PPC.     

A well-defined diblock copolymer of poly-(ethylene oxide)-block-poly (4-vinylpyridine) for separation of basic proteins by capillary zone electrophoresis

A series of well-defined diblock copolymers, poly(ethylene oxide)-block-poly(4-vinylpyridine) (PEO-b-P4VP) used as physical coating of capillaries, were synthesized by atom transfer radical polymerization (ATRP). EOF measurement results showed that all synthesized PEO-b-P4VP diblock copolymer-coated capillaries in this report could suppress EOF effectively compared to the bare fused-silica capillaries, and efficient separations of basic proteins were achieved. The effects of the molecular weight of P4VP block in PEO-b-P4VP and buffer pH on the separation of basic proteins for CE were investigated in detail. Moreover, the relationships between morphologies of PEO-b-P4VP diblock copolymers in buffer, which were studied by transmission electron microscopy, and the separation efficiencies of basic protein with PEO-b-P4VP diblock copolymers coatings were discussed.     

C60接枝聚(N-乙烯基咔唑)的合成、表征及光电导性能

自从Ｃ６０被发现和被制备出来以后,其特殊的结构和独特的物理和化学性质受到各研究领域学者的广泛青睐．聚（Ｎ－乙烯基咔唑）（ＰＶＫ）体系经 Ｃ６０掺杂后光电导性能有很大幅度提高．但掺杂体系不稳定,因而限制了对该类材料的应用．为了克服这种缺点,我们尝试用各种简单的方法把Ｃ６０化学键合到高分子链中,制备具有光电导性能的Ｃ６０高分子衍生物． 最近,唐本忠［１］和 Ｐａｔｉｌ［２］等分别用常规的自由基聚合方法,将Ｃ６０接枝到聚合物分子主链上,我们已研究了不含导电高分子的Ｃ６０共聚物的光电导性能［３］,本文采用…     

CE of poly(amidoamine) succinamic acid dendrimers using a poly(vinyl alcohol)-coated capillary

Various generations (G1-G8) of negatively charged poly(amidoamine) (PAMAM) succinamic acid dendrimers (PAMAM-SAH) were analyzed by CE using a poly(vinyl alcohol)-coated capillary. Due to its excellent stability and osmotic flow-shielding effect, highly reproducible migration times were achieved for all generations of dendrimer (e.g., RSD for the migration times of G5 dendrimer was 0.6%). We also observed a reverse trend in migration times for the PAMAM-SAH dendrimers (i.e., higher generations migrated faster than lower generation dendrimers) compared to amine-terminated PAMAM dendrimers reported in the literature. This reversal in migration times was attributed to the difference in counterion binding around these negatively charged dendrimers. This reverse trend allowed a generational separation for lower generation (G1-G3) dendrimers. However, a sufficient resolution for the migration peaks of higher generations (G4-G5) in a mixture could not be achieved. This could be due to their nearly identical charge/mass ratio and dense molecular conformations. In addition, we show that dye-functionalized PAMAM-SAH dendrimers can also be analyzed with high reproducibility using this method.     

A very thin coating for capillary zone electrophoresis of proteins based on a tri(ethylene glycol)-terminated alkyltrichlorosilane

We describe the use of a tri(ethylene glycol)-terminated alkyltrichlorosilane to create a very thin, protein-resistant "self-assembled monolayer" coating on the inner surface of a fused-silica capillary. The same compound has been demonstrated previously on flat silica substrates to resist adsorption of many proteins. As a covalently bound capillary coating, it displays good resistance to the adsorption of cationic proteins, providing clean separations of a mixture of lysozyme, cytochrome c, ribonuclease A, and myoglobin for more than 200 consecutive runs. Electroosmotic flow (EOF) was measured as a function of pH; the coated capillary retains significant cathodal EOF, with roughly 50% of the EOF of an uncoated capillary at neutral pH, making this coating promising for applications requiring some EOF. The EOF was reasonably stable, with a 2.9% relative standard deviation during a 24 h period consisting of 72 consecutive separations of cationic proteins. Efficiencies for cationic protein separations were moderate, in the range of 190,000-290,000 theoretical plates per meter. The coating procedure was simple, requiring only a standard cleaning procedure followed by a rinse with the silane reagent at room temperature. No buffer additives are required to maintain the stability of the coating, making it flexible for a range of applications, potentially including capillary electrophoresis-mass spectrometry (CE-MS).     

壳聚糖修饰PLGA阳离子型纳米微球的制备与表征

采用单乳化-溶剂(O/W)挥发技术制备表面带正电荷的壳聚糖(CHS)修饰聚乙/丙交酯(PLGA)纳米微球(PLGA/CHS), 通过正交试验优化了纳米微球的制备条件. 结果表明, 微球粒径可控制在150～200 nm内, 在pH=4时, 纳米微球表面电位最高为55 mV. 影响微球粒径的主要因素是聚合物的浓度, CHS的分子量和浓度以及介质的pH值对微球表面电位也有明显影响. 制备粒径较小而表面电位较高的PLGA/CHS纳米微球条件为: ρ(CHS)=3 mg/mL, ρ(PLGA)=10 mg/mL, Vo/Va=1/4. SEM图像显示经CHS修饰的PLGA的纳米微球形状规整, 荧光显微观察和XPS分析结果证实CHS包覆于微球表面.     

Poly(N,N‐dimethylacrylamide)‐Based Microspheres Prepared by Heterogeneous Polymerizations

PDMAAm microspheres have been obtained by inverse suspension, inverse emulsion, and dispersion polymerization. Conventional inverse suspension polymerization in toluene/trichloroethene is modified by the use of ultrasound. The resulting hydrogel microspheres are examined by dynamic light scattering and scanning electron microscopy to afford the morphology, dispersity, and size of the microspheres. Inverse suspension polymerization yields 100‐µm particles, while those obtained by inverse emulsion polymerization are 0.13–1 µm in diameter. While the inverse techniques produce particles of broad size distribution, monodisperse microspheres are obtained by the Kraton G 1650‐stabilized dispersion polymerization of DMAAm in a toluene/heptane medium. The particle size and polydispersity could be controlled by the addition of water into the dispersed phase, and by varying the cellulose acetate butyrate or Kraton G 1650 concentration and the toluene/trichloroethene or toluene/heptane ratio.

     

Interpolymer Complexes of Poly(N,N-Dimethylacrylamide/Poly(Styrene-co-Acrylic Acid): Thermal Stability and FTIR Analysis

Summary: This contribution will focus on the elaboration and characterizations of new materials with optimal properties as interpolymer complexes, upon mixing poly (styrene-co-acrylic acid containing 18, 27 and 32 mol % of acrylic acid (SAA-x) and poly (N,N-dimethylacrylamide) (PDMA), through the control of the densities, strength, self-association and accessibility of the interacting species. These elaborated interpolymer complexes, of different structures, investigated by DSC and TGA, exhibited a significant improved thermal stability. Their DSC analysis showed that all these materials showed one composition-dependence glass transition temperature Tg, indicating the formation of a single homogeneous phase. The different behaviors of Tg-initial composition observed with these systems were analyzed by the approaches of Kwei and Brostow et al., recently developed. The specific interactions that occurred within the elaborated materials were evidenced qualitatively by ATR/FTIR spectroscopy, from the appearance of new bands in the 1800–1550 cm⁻¹ region.     

TH‐11, a Streptomyces sp. Strain that Degrades Poly(3‐Hydroxybutyrate) and Poly(Ethylene Succinate)

TH‐11, a bacterial strain with strong depolymerase activity that breaks down aliphatic esters such as poly(3‐hydroxybutyrate) (PHB) and poly(ethylene succinate) (PES) was isolated from a soil sample collected from the sediment of Tou‐Chain River, Taiwan, R.O.C. It was phenotypically and genetically characterized to be a Streptomyces strain. The degradation of PHB and PES were tested both using emulsified polymers in solid agar and thin polymer films in liquid culture media. The degradations were measured by clear‐zone formation on solid agar plates, or direct weight measurements and electromicroscope inspection of the incubated polymer films in the liquid culture. The depolymerase activities can be detected in the cell‐free preparation of the culture medium, and can be enhanced by gelatin.     

Poly(N,N-dimethylaminoethyl methacrylate) grafted poly(vinyl chloride)s synthesized via ATRP process and their membranes for dye separation

To functionalize poly(vinyl chloride)(PVC) for various applications, monomers containing tertiary amine group are incorporated into PVC via atom transfer radical polymerization(ATRP) initiated by the labile chlorines in their backbones. The kinetics of synthesis was carefully investigated, and it is proven that the grafting polymerization process can be effectively controlled by regulating the reaction time. The membranes are fabricated using PVC and copolymers by non-solvent induced phase separation(NIPS) process. The hydrophilicity and pore structure of copolymer membranes were enhanced as well, these membranes are endowed with positive charge. When PDMA%(i.e., the PDMA weight percentage in copolymer) is 31.1%, the flux and Victoria blue B rejection are 26.0 L?m?2?h?1(0.5 MPa) and 91.2%, respectively. Thus, the newly synthesized polymer is proven to be a promising material for dye separation with positive charges.     

Performance of a novel sieving matrix of poly(vinyl alcohol)/acrylamide copolymer in electrophoretic separations of high molecular weight proteins from red cell membrane

The analysis of high molecular weight (HMW) proteins from complex mixtures is still a challenge in proteomics. This work introduces a novel hydrogel obtained by the copolymerization of an allyl‐PVA derivative with acrylamide and bisacrylamide and applies this matrix to the electrophoretic separation of HMW proteins. By inducing gelation of polyacrylamide in the presence of variable amounts of allyl‐PVA, it is possible to control and vary the average gel porosity. This gel is easy to produce and handle and offers the advantage of being highly mechanically resistant and macroporous. The new matrix was tested in mono‐dimensional separations of complex protein mixtures extracted from red cell membranes with different detergents. The improved performance of this macroporous matrix allowed to identify new proteins by MS and immunoblot analysis using specific antibodies. In particular, the resolution of proteins ranging in size between 97 and 279 kDa was greatly improved here compared to standard polyacrylamide gels, suggesting that this matrix can be a useful tool in routine analysis of HMW proteins in cell biology.     

Incorporation of siloxanes in hydrolytically degradable structures: I. Poly(anhydride)s synthesis

New poly(anhydride)s containing amino acids and siloxane segments have been synthesized. The synthetic method involves the polycondensation in solution of the organic diacids (N-trimellitylimidoglycine, 1a, N-trimellitylimido-γ-aminobutiric acid, 1b, and N-trimellitylimido-ε-aminocapronic acid, 1c) obtained from the proper amino acids with a siloxane diacid (1,3-bis(3-carboxypropyl)tetramethyldisiloxane, 2a, α,ω-bis(3-carboxypropyl)oligodimethylsiloxane, 2b, or 1,3-bis(sebacomethyl)tetramethyl-disiloxane, 2c). The acetylation method was used for the activation of the two types of diacids (organic and siloxanic). Optimization of synthesis parameters was made.The structures and morphology of partial and final products were determined by IR and ¹H NMR spectroscopy and differential scanning calorimetry. Inherent viscosities were determined and some preliminary solubility and hydrolytic stability tests were also performed.     

High-performance capillary electrophoretic separation of double-stranded oligonucleotides using a poly-(ethylpyrrolidine methacrylate-co-methylmethacrylate)-coated capillary

Here we describe a capillary electrophoretic method for the separation of double-stranded oligonucleotides (ds-ODNs) ranging from 16-20 bp with 2 bp resolution using a low concentration of poly(ethylpyrrolidine methacrylate-co-methyl methacrylate) (PEPyM-co-PMMA) copolymer physically adsorbed to a capillary surface. Contrary to traditional DNA separations, we show that the ds-ODN with the highest molecular size eluted first and propose that this phenomena is due to a screening effect by the PEPyM-co-PMMA coating on the smaller ds-ODNs negative charge during elution. Key to the performance of this separation was a sample preparation time of less than 1 h and analysis time of 40 min. Repeatability of intraday migration time for the mixtures was typically < 1% relative standard deviation (n = 3). In addition, we demonstrate that the coating has an acceptable capillary lifetime of over 70 injections.     

Synthesis,hydrophilicity, and oxygen permeability of poly[(trimethylsilyl)propyne]-gr-poly(N,N-dimethylacrylamide)

N,N-dimethylacrylamide (DMAA) was graft copolymerized on poly[(trimethylsilyl)propyne] (PTMSP) by single electron reduction of PTMSP with potassium naphthalenide (K-Naph), followed by anion polymerization of DMAA from the carbanion formed in the reduction. A hard and practically non-water-swelling PTMSP-gr-poly(DMAA) was obtained under the conditions using controlled amount of K-Naph and DMAA. The graft copolymer was characterized with regard to structure, number-averaged molecular weight, and the amount of grafting poly(DMAA) determined by the relative absorbance of the IR absorption band assigned to the CO and SiC H functionalities (A_CO/A_{SiC H}). The oxygen permeability and water contact angle (θ) of the graft copolymer were evaluated while varying the amount of grafting poly(DMAA). The graft copolymer proved to be highly oxygen permeable (165 Barrers) and hydrophilic (θ = 27°). Its transparency was also elucidated with UV–vis spectra. This graft copolymer was proposed as a promising candidate for use as a hard contact lens material. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 603–610, 1998     

Dynamic modification of poly(methyl methacrylate) chips using poly(vinyl alcohol) for glycosaminoglycan disaccharide isomer separation

We describe a microchip electrophoresis (MCE) method for the assay of unsaturated disaccharides of chondroitin sulfates, dermatan sulfates, and hyaluronic acid (HA). Poly(vinyl alcohol) (PVA) could be irreversibly adsorbed onto poly(methyl methacrylate) (PMMA) substrates and this approach was applicable for dynamic coating. The characteristics of the PMMA surface with PVA coating were evaluated in terms of the wettability, EOF, and adsorption of 2-aminoacridone (AMAC)-labeled disaccharide. The water contact angle decreased from 73 degrees on a pristine PMMA surface to 37.5 degrees on a PVA-coated surface, indicating that the PVA coating increased hydrophilicity. EOF was reduced approximately twofold and was relatively stable. Scanning electron microscopy and fluorescence microscopy images showed that adsorption of AMAC-labeled disaccharides was dramatically suppressed. Using the PVA coating, baseline separation of two pairs of glycosaminoglycan (GAG) disaccharide isomers, DeltaDi-diS(B)/DeltaDi-diS(D) and DeltaDi-0S/DeltaDi-HA, was achieved in Tris-borate buffer within 130 s by MCE.