共聚物接枝蛋白离子交换色谱介质制备及性能

高容量蛋白质色谱介质是色谱过程高效化的材料基础和重要前提。采用原子转移自由基聚合（ATRP）技术,以甲基丙烯酸3-磺酸丙酯钾和甲基丙烯酸甲酯（MMA）为单体化合物合成了多种无规共聚物接枝离子交换色谱介质,并对其蛋白质吸附性能进行研究。单体总浓度一定情况下共聚物接枝色谱介质孔道半径（r_pore）随MMA浓度升高而增大,反映出接枝共聚物链渐趋塌陷的特征。蛋白质吸附结果表明,溶菌酶吸附容量取决于介质的离子交换容量;而抗体吸附容量则与rpore及相应的聚合物层厚度变化密切相关。随着聚合物层厚度的增大,聚合物层对抗体的空间排阻作用增强,抗体吸附容量下降。此外,引入MMA优化共聚物分子链可显著提高蛋白质吸附量,在SEP-gS30/M30介质中抗体和溶菌酶的饱和吸附量分别达到237 mg·g^-1和380 mg·g^-1。无规共聚物接枝离子交换色谱介质孔道内聚合物层厚度和蛋白质吸附也受无机盐浓度调控。     

接枝聚合物配基的蛋白质吸附层析

以离子交换、亲和结合和疏水性吸附为主的蛋白质吸附层析是药用蛋白质生产过程的核心技术,开发新技术和提高蛋白质吸附层析操作的分离效率(如选择性和动态吸附容量等)是该领域的主要研究目标。近年来聚合物配基接枝的层析介质由于同时具有较高的吸附容量和传质速率,得到产学界的广泛关注。本文针对聚合物配基接枝修饰的蛋白质吸附层析介质的配基化学特征、吸附和传质特性、层析分离应用和设计等方面进行评述。首先介绍不同种类的聚合物接枝介质,然后系统阐述聚合物配基化学特性对介质吸附和传质性能的影响机制,并分析上述性质对聚合物配基接枝层析介质分离特性的影响机理和应用,最后讨论和展望了高效聚合物配基接枝介质设计、开发和应用的前景。     

表面分子印迹聚合物载体研究新进展

简述了表面分子印迹聚合物载体研究的最新进展。根据载体种类以及表面修饰方法的不同,分别介绍了以无机材料为载体和以壳聚糖为基质的表面分子印迹技术,并对表面分子印迹聚合物载体的发展前景进行了展望。对无机材料的表面修饰主要通过引入烷基化试剂的功能基团（如氨基、苄基等）,再通过分子印迹的方法制备出理想的表面分子印迹聚合物;而对壳聚糖的修饰主要通过各种交联方法,从而获得单一基质载体或者壳聚糖杂化材料载体。文中指出,与传统方法相比,新型材料的吸附性能优良、回收利用率高、颗粒均一。但是,该材料制备过程中的微观行为模式以及功能单体同目标分子的成键规律等还有待进一步研究。     

表面接枝技术在光敏感材料制备中的应用

介绍了材料表面改性的方法,着重叙述了表面接枝技术在光敏感材料制备中的应用,分析了材料表面接枝共聚和材料表面偶合反应两种方法各自的优缺点。材料表面接枝聚合利用材料表面的活性中心引发乙烯基单体在材料表面接枝聚合,接枝层厚度不均匀,接枝效率较低,单体有浪费;材料表面偶合利用材料表面的活性基团与带有活性基团的小分子（或聚合物）反应,把具有特殊功能的基团修饰到材料表面,修饰厚度可控,单体利用率高。     

减电荷聚甲基丙烯酸钠接枝介质的制备及蛋白质吸附性能

离子交换容量（IC）为320mmol/L的聚甲基丙烯酸钠（pMA）接枝型介质（FF-pMA-320）对溶菌酶和γ-球蛋白具有较高的吸附容量,但其传质速率较低。在保持聚合物链长度的前提下,通过乙醇胺与接枝链上的羧基进行电荷中和反应,降低pMA接枝型介质的电荷密度,提升介质的蛋白质传质速率。将FF-pMA-320进行部分电荷中和修饰,制备得到离子交换容量分别为230mmol/L和170mmol/L的减电荷阳离子交换介质,分别命名为pMA-320-R230和pMA-320-R170。采用吸附平衡、吸附动力学和柱穿透实验,研究了溶菌酶和γ-球蛋白在这两种新型介质上的吸附行为,并与初始介质FF-pMA-320进行了比较。结果表明：随着介质的IC值（电荷密度）从320mmol/L降低到170mmol/L,介质对两种蛋白质吸附容量随之减少,这与电荷中和修饰降低蛋白质吸附位点有关。随着接枝聚合物电荷密度的降低,相邻聚合物链之间的静电排斥作用减弱,蛋白质吸附容量降低,造成接枝链的灵活性增加以及蛋白质排阻效应减弱。因此,溶菌酶和γ-球蛋白在pMA-320-R170上的传质速率分别是FF-pMA-320的1...     

反离子对牛血清白蛋白在荷电葡聚糖接枝介质中色谱行为的影响

从前期开发的具有极高的吸附容量及传质速率的二乙氨乙基葡聚糖接枝离子交换介质中选取FF-D50-DexD100和FF-DexD100为典型代表,利用Cl^-、SCN^-、SO₄^2-、HPO₄^2-为模型反离子,以牛血清白蛋白（BSA）为模型蛋白,以商品化介质（Q Sepharose FF、Q Sepharose XL、DEAE Sepharose FF）为对照,在离子强度为0.06mol/L下,系统研究反离子对二乙氨乙基葡聚糖接枝介质的蛋白质吸附与洗脱行为的影响。结果表明,二乙氨乙基葡聚糖接枝介质对不同反离子的偏好性存在差异,且该偏好性差异与基团所处位置（接枝链配基或表面配基）无关。同时,介质偏好性弱的反离子会通过促进二乙氨乙基葡聚糖接枝介质的“链传递”效应加快蛋白质的传质速率,从而提高动态吸附容量。因此,在使用二乙氨乙基葡聚糖接枝介质进行蛋白质色谱柱分离过程中,可在吸附操作中使用HPO₄^2-,在洗脱操作中使用SCN^-来优化分离效果。     

高生物活性聚醚醚酮化学改性研究进展

由于聚醚醚酮（PEEK）表面疏水及生物惰性，用作骨科材料难以与周围细胞、骨组织结合。通过化学改性在PEEK分子链中引入具有生物活性的功能化基团是提高其表面细胞黏附、增殖和成骨分化能力最有效的方式。基于功能化基团引入位置的不同，本文将PEEK化学改性分为苯环位改性、酮基位改性和共聚改性等三种，并且重点综述了这些不同化学改性方法的原理和特性及其对PEEK材料生物活性的影响。苯环位改性主要是通过强酸处理引入羧基等官能团，但会残留含硫或含硝化合物，对细胞有一定的毒害作用；酮基位改性是通过胺类、硼氢化钠等试剂与酮基反应，进一步接枝引入功能化基团，但是会破坏PEEK主链上的醚酮比，影响物理性能和热性能。通过亲电、亲核及卤代改性等共聚方式在PEEK侧链引入功能化基团，能保持聚合物主链醚酮比基本不变，同时提升材料生物活性，具有良好的应用前景。在化学改性的基础上，研究多种功能基团的协同作用，进一步引入物理改性，优化面向不同场景的综合性能，是拓宽其在医疗领域应用的发展趋势。     

聚合物刷子的合成进展

聚合物在材料表面物理吸附或化学接枝所形成的刷子状单分子层被称为聚合物刷子,本文介绍了聚合物刷子的概念、分类以及合成方法。     

氨基化MIL-101表面印迹聚合物的制备及其吸附行为

研究了金属有机骨架材料MIL-101表面印迹聚合物的制备方法及其吸附行为。以MIL-101为载体,先通过化学修饰氨基制备了ED-MIL-101材料,再以京尼平苷为模板,甲基丙烯酸为功能单体,二乙烯基苯为交联剂,表面接枝京尼平苷分子印迹聚合物制备了MIPs@MIL-101印迹聚合物。通过傅里叶红外光谱（FTIR）、X射线衍射光谱（XRD）、扫描电镜（SEM）对聚合物进行结构表征,测试了聚合物的等温吸附及吸附动力学性能,探讨了聚合物的固相萃取性能。红外光谱及XRD衍射分析表明了MIL-101氨基化修饰及表面接枝复合材料的成功制备。吸附动力学研究表明当分子印迹聚合物用于吸附京尼平苷时,可在270min内达到吸附平衡。当温度为298K、308K、318K、328K时,印迹聚合物对模板的吸附量分别为55.94mg/g、46.16mg/g、38.98mg/g、31.47mg/g。吸附热ΔH为26.997kJ/mol。分子印迹固相萃取杜仲提取物中的京尼平苷时,总回收率达95.0%。     

共聚物接枝蛋白离子交换色谱介质制备及性能

高容量蛋白质色谱介质是色谱过程高效化的材料基础和重要前提。采用原子转移自由基聚合(ATRP)技术,以甲基丙烯酸3-磺酸丙酯钾和甲基丙烯酸甲酯(MMA)为单体化合物合成了多种无规共聚物接枝离子交换色谱介质,并对其蛋白质吸附性能进行研究。单体总浓度一定情况下共聚物接枝色谱介质孔道半径(r_(pore))随MMA浓度升高而增大,反映出接枝共聚物链渐趋塌陷的特征。蛋白质吸附结果表明,溶菌酶吸附容量取决于介质的离子交换容量;而抗体吸附容量则与r_(pore)及相应的聚合物层厚度变化密切相关。随着聚合物层厚度的增大,聚合物层对抗体的空间排阻作用增强,抗体吸附容量下降。此外,引入MMA优化共聚物分子链可显著提高蛋白质吸附量,在SEP-g S30/M30介质中抗体和溶菌酶的饱和吸附量分别达到237 mg·g~(-1)和380 mg·g~(-1)。无规共聚物接枝离子交换色谱介质孔道内聚合物层厚度和蛋白质吸附也受无机盐浓度调控。     

Surfactant modification of the surface energetics of hydrophobic polymers and protein adsorption

A low interfacial free energy between a polar surface and water is expected to lead to a smaller amount of protein adsorbed. However, nonpolar surfaces have high interfacial free energies with water. They can acquire lower interfacial free energies by modifying the polar and dispersion components of their surface free energy so that they approach those of water. The two-phase method, in which an aqueous solution of surfactant and chloroform constitute the two-phase system, can be used for the modification of the hydrophobic surface. The hydrophobic polymer is immersed for a short time in chloroform (which is a solvent for the polymer). This allows disentanglement of the surface chains. Subsequently, the polymer is pulled out through the solvent-water interface and further through the water phase. The monolayer of adsorbed surfactant present at the water-chloroform interface is thus transferred to the surface of the polymer. The hydrophobic chains of the surfactant and polymer entangle and the polar head groups orient towards the water phase. Protein adsorption experiments carried out with albumin and fibrinogen showed that the amounts of protein adsorbed on unmodified PMMA surfaces can be significantly higher than those on SDS- and Brij 35-modified surfaces. The sequence for adsorption is unmodified surface > SDS-modified surface > Brij 35-modified surface.     

Influence of the acid–basic character of oxide surfaces in dispersants effectiveness

Physical–chemical surface character has been described as a determinant factor in adsorbing polyelectrolytes onto oxide surfaces. Since basically composed by hydroxyl groups, the acidity or basicity induced by the bulk lattice in such groups seems to be of great relevance in the adsorption process. The influence of such properties in the adsorption of polyacrylic acid derivated polymers onto SnO₂ and Al₂O₃ surfaces is, therefore, studied in this paper. Polyacrylate acid molecules are observed to hardly adsorb onto the SnO₂ surface but strongly adsorb, as reported previously, onto the alumina surface. This behavior is explained based on the pronounced difference in relation to the acidity of both surfaces and, in this sphere of thought, a basic polymer (Chitosan; CS) is discussed as a functional dispersant for powders with acid surface character, such as SnO₂. Zeta potential measurements showed that this polymer raises the SnO₂ potential to +30 mV without pH variations.     

XPS studies of in situ plasma-modified polymer surfaces

X-ray photoelectron spectroscopy (XPS) has been used to study the chemical effects of both inert (argon) and reactive (oxygen, nitrogen, and mixed gas) plasma treatments done in situ on a variety of polymer surfaces. Inert gas plasma treatments introduce no new detectable chemical species onto the polymer surface but can induce degradation and rearrangement of the polymer surface. However, plasma treatments with reactive gases create new chemical species which drastically alter the chemical reactivity of the polymer surface. These studies have also shown that the surface population of chemical species formed after plasma treatment is dependent on both the chemical structure of the polymer and the plasma gas. The effects of direct and radiative energy-transfer processes in a plasma have also been studied. Polymers containing certain functional groups were found to be more susceptible to damage via radiative energy transfer. Ageing studies of plasma-modified polymer surfaces exposed to the atmosphere have shown that the ageing process consists of two distinct phases. The initial phase, which occurs rapidly, involves adsorption of atmospheric contaminants and, in some cases, specific chemical reactions. The second phase, which occurs slowly, is due to surface reorganization.     

Role of PLLA plasma surface modification in the interaction with human marrow stromal cells

The effects of oxygen‐based radio frequency plasma enhanced chemical vapor deposition (rf PECVD) on the surface of poly(L ‐lactide) (PLLA) polymers and the influence thereof on protein adsorption and on bone–cell behavior have been studied. Thin films and porous scaffolds based on PLLA polymer were developed, and the role of surface modifications were investigated extensively. PECVD surface treatments were used to alter surface functionality and modulate protein adsorption on the PLLA polymer matrix. In particular, Bovine Serum Albumine fluorescein isothiocyanate (fitc‐BSA) conjugate adsorption on patterned surfaces of treated PLLA was analyzed by fluorescence microscopy. Human marrow stromal cells (MSCs) were cultured on scaffolds and cell adhesion and morphology were assessed using fluorescence microscopy. The results indicated that the PLLA surface became hydrophilic and its roughness increased with the treatment time and it had a dominant influence on the adsorption process of the protein. The outcome of the plasma treatment of various PLLA surfaces has been shown to be the up‐regulator of the cell‐adhesive proteins expression and consequently the improvement of cell adhesion and growth. Oxygen‐treated PLLA promoted higher adhesion and proliferation of the MSCs in comparison to the untreated samples. It can be concluded that following plasma treatment, PLLA samples show enhanced affinity for osteoprogenitor cells. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

A comparison of the interfacial bonding properties of carboxylic acid functional groups on zinc and iron substrates

The present work investigates the molecular interfacial bonds between carboxylic functional groups and zinc and iron substrates. Succinic acid models the functionality of many commonly used adhesives and organic coatings. On the other hand, iron and zinc form the major surface composition of galvanized steel. Consequently, studying the interfacial properties of the polymer functional groups and zinc or iron substrates illuminates the correlation of the polymer bonding characteristics and surface chemical properties of galvanized steel. In this work, X-ray photoelectron spectroscopy (XPS) and fourier transform infrared reflection absorption spectroscopy (FTIR-RAS) are combined to evaluate the surface compositions, the amount of adsorbed molecules and the interaction mechanism between the succinic acid functionalities and the differently pretreated surfaces. The results show that variation of the treatments prior to succinic molecule adsorption results in different adsorption properties, which are related to the changes in chemistry and composition of the oxide layer.     

铈盐引发高吸附量氨基化PGMA高分子微球合成及去除废水中Cr(VI)(英文)

A novel polyglycidylmethacrylate(PGMA) microspheres with high adsorption capacity of Cr(VI) was prepared by cerium(IV) initiated graft polymerization of tentacle-type polymer chains with amino group on polymer microspheres with hydroxyl groups.The micron-sized PGMA microspheres were prepared by a dispersion polym-erization method and subsequently modified by ring-opening reaction to introduce functional hydroxyl groups.The polymer microspheres were characterized by scanning electron microscopy(SEM) and Fourier transform infrared spectroscopy(FTIR).The results indicated that the polymer microspheres had an average diameter of 5 μm with uniform size distribution.The free amino group content was determined to be 5.13 mmol?g?1 for g-PGMA-NH2 mi-crospheres by potentiometric and conductometric titration methods.The Cr(VI) adsorption results indicated that the graft polymerization of tentacle-type polymer chains on the polymer microspheres could produce adsorbents with high adsorption capacity(500 mg?g?1).The polymer microspheres with grafted tentacle polymer chains have poten-tial application in large-scale removal of Cr(VI) in aqueous solution.     

Adhesion of polymer coils to a solid surface: influence of the depletion effect

The specific properties of polymer coils are often disregarded in theories of adhesion, but polymer properties are essential for the strength of the adhesive bond. Polymer coils are repelled entropically from impenetrable surfaces. This causes the depletion effect and creates a layer of reduced concentration right at the interface. To bond a polymer coil to a substrate, it must be forced actively towards the interface, driven by the gaining of adsorption energy. The adsorption of specific groups in the (co)polymer, which interact with 'polar' sites on the substrate, must be used to suppress the depletion. Adsorption diminishes the effective distance between the surface and the adhesive polymer. The balance between adsorption and depletion (rather than the effect of polar groups or pretreatments on the work of adhesion as such) is the most important chemical possibility of affecting adhesion. The strength of the bond between polymeric materials and solid surfaces varies as H^-3, with the effective distance H between the polymer and substrate. Therefore, it changes by an order of magnitude when the polymer adhesive is pulled towards the substrate by adsorption.     

Molecular dynamics simulation of polymers adsorbed onto an alumina surface

This work presents a relatively simple simulation procedure to demonstrate the effects of polymers on an alumina surface. The procedure employs molecular dynamics (MD) techniques to execute real-time simulations on the interactions of polyolefin, polyacrylate, polyoxide, polyol, and polyphenyl linkages with an idealized alumina surface. According to the technique, the adsorption energy is dependent on the geometrical structure of the monomers and decreases for polymer chains with alkyl side-groups in the backbone, but increases for those with functional groups. The results from this simulation procedure indicate that polymer chains with more -CH₂- or functional groups in the framework can markedly increase the adsorption energy. In addition, polyphenyl linkages reveal a wide range of the low-energy region in the rotations of torsional angles. The result is a favorable deformation of the polymer chains with phenylenes in the backbone, thereby leading to a large adsorption energy.     

Highly efficient synthesis of cylindrical polymer brushes with various side chains via click grafting-onto approach

Though much attention has been paid to synthesis of cylindrical polymer brushes, it is still not easy to prepare well-defined brushes by a general approach. Herein, well-defined cylindrical polymer brushes with various side chains were synthesized via grafting-onto approach by CuAAC click chemistry. Narrowly dispersed polymer backbones functionalized with azide groups were obtained by post-modification of poly(glycidyl methacrylate) (PGMA) which was prepared by reversible addition-fragmentation chain transfer (RAFT) mediated radical polymerization. The alkyne-terminated side chains, polystyrene, polyacrylates, polymethacrylates and poly(N-alkyl acrylamide)s, were synthesized by RAFT mediated radical polymerization with alkyne-containing chain transfer agents (CTAs). The CuAAC reactions between the backbone and side chain polymers were conducted with an equivalent feed of alkyne-terminated side chains and azide groups under mild conditions. Influences of reaction conditions and chemical composition of polymer side chains on grafting efficiency and molecular weight distribution of the polymer brushes were investigated. It is demonstrated that the side chains of polystyrene, polyacrylates and poly(N-alkyl acylamide)s were grafted at a density above 85% while that of polymethacrylates decreased to ca. 50%. The polymer brushes synthesized under the optimized reaction conditions had well-defined chemical composition and narrow distribution of molecular weight, and their wormlike morphology was visualized by atomic force microscopy (AFM).     

Adsorption of Hydroxypropyl Methyl Cellulose in an Aqueous System Containing Multicomponent Oxide Particles

The adsorption behavior of a hydroxypropyl methyl cellulose (HPMC) polymer in aqueous suspensions of alumina, silica, kaolin, and talc powders, two-component combinations, and one three-component combination was determined. Powders were well characterized by chemical analysis, XRD, DRIFT, SEM, particle size, surface area, and density analyses. The zeta-potential of each powder in aqueous suspension was determined over a range of pH to determine particle charging and the isoelectric point for each material. Alumina and silica powders having heavily hydroxylated surfaces were observed not to adsorb the HPMC polymer over a range of pH. The layer-type minerals talc, which was noticeably hydrophobic, and kaolin, which had differently hydrated basal planes, adsorbed the HPMC polymer but in different amounts per unit of surface area. In the two-component systems, HPMC polymer adsorption for systems of dispersed particles of like electrical charge (kaolin + silica, talc + silica or alumina, and kaolin + talc) was proportionate to the sum of the fraction x specific surface area x adsorption capacity for each particle type. In systems where particles had an opposite electrical charge (kaolin + alumina, kaolin + talc + alumina), the HPMC polymer adsorption was significantly lower than that calculated for a dispersed system. SEM analysis showed very fine, nonadsorbing alumina particles predominantly on the faces of the adsorbing kaolin particles that apparently masked polymer adsorption. Results suggested a hydrophobic mechanism for the HPMC polymer adsorption and adsorption on only one face of the kaolin particles.