UV光引发表面接枝两性离子水凝胶层的制备及抗细菌黏附性能

采用聚合和交联的SiO₂有机/无机杂化溶胶作为基材, 通过与两性离子单体层之间的过渡层, 在紫外光作用下引发杂化溶胶和两性离子单体溶液中的双键反应, 使生成的杂化层在基材和表面的两性离子聚合物之间形成辅助性黏接作用, 从而在基材表面构筑两性离子水凝胶层. 通过傅里叶红外光谱(FTIR)、 原子力显微镜(AFM)和接触角测试等方法对所制备的两性离子水凝胶层和杂化层的表面进行了表征. 以空白玻璃片为对照样品, 以金黄色葡萄球菌和大肠杆菌为试验菌, 研究了用两性离子凝胶层修饰的玻璃表面的抗细菌黏附性能. 结果表明, 在SiO₂杂化过渡层中引入线型-Si-(CH₂)₂-O-链段可有效提高杂化过渡层对基材的附着力, 并改善其柔韧性. 与对照样品相比, 用两性离子凝胶层修饰的玻璃表面具有优异的抗菌黏附性能.     

聚氨酯表面构建磺铵两性离子结构及其抗血小板粘附性的研究

通过己二异氰酸酯(HDI)在聚醚氨酯(PU)表面构建磺铵两性离子结构,以改善其不凝血性能,首先用HDI活化PU表面,生成PU-NCO衍生物;然后通过N,N-二甲基乙醇胺(DMEEA)中的-OH和PU表面的-NCO反应生成PU-N(CH₃)₂;最后用丙磺酸内酯(PS)进行开环.生成磺铵两性离子结构,用ATR-IR表征了各步反应,对构建前后材料的抗血小板粘附性能进行了比较,结果表明,磺铵两性离子结构具有优异的抗血小板粘附性.     

Preparation and characterization of zwitterionic surfactant-modified montmorillonites

A series of zwitterionic surfactant-modified montmorillonites (ZSMMs) were synthesized using montmorillonite and three zwitterionic surfactants with different alkyl chain lengths at different concentrations [0.2-4.0 cation exchange capacity (CEC)]. These ZSMMs were characterized by X-ray diffraction (XRD), thermo-gravimetric analysis and differential thermo-gravimetric (TG/DTG) analyses. The zwitterionic surfactant could be intercalated into the interlayer spaces of montmorillonites and causing interlayer space-swelling. From XRD measurements, the amount of the surfactants loaded and the basal spacing increased with surfactant concentration and alkyl chain length. One endothermic DTG peak occurred at ~390 °C, which was assigned to the decomposition of the zwitterionic surfactant on the organo-montmorillonites from 0.2 to 0.6 CEC. When the surfactant loading was increased, a new endothermic peak appeared at ~340 °C. From the microstructures of these ZSMMs, the mechanism of zwitterionic surfactant adsorption was proposed. At relatively low loadings of the zwitterionic surfactant, most of surfactants enter the spacing by an ion-exchange mechanism and are adsorbed onto the interlayer cation sites. When the concentration of the zwitterionic surfactant exceeds the CEC of montmorillonite, the surfactant molecules then adhere to the surface-adsorbed surfactant. Some surfactants enter the interlayers, whereas the others are attached to the clay surface. When the concentration of surfactant increases further beyond 2.0 CEC, the surfactants may occupy the inter-particle space within the house-of-cards aggregate structure.     

Synthesis and property of a novel sulfonated poly(ether ether ketone) with high selectivity for direct methanol fuel cell applications

A novel membrane material based on random copolymer composed of poly(acrylonitrile-([3-(methacryloylamino)propyl]-dimethyl(3-sulfopropyl) ammonium hydroxide)) (PAN–MPDSAH) was synthesized by the water phase suspension polymerization. The zwitterionic PAN-based membranes were prepared through blending PAN and PAN–MPDSAH copolymer by a phase inversion method. The zwitterionic PAN-based membranes have higher hydrophilicity and wettability, and lower protein adsorption in comparison with the control PAN membrane. Ultrafiltration experiments revealed that membrane fouling, especially irreversible membrane fouling, for the zwitterionic PAN-based membranes is remarkably reduced due to the incorporation of zwitterionic PMPDSAH segments on the membrane surfaces. Moreover, the reversible membrane fouling during ultrafiltration process can be easily washed away by simple water cleaning. The zwitterionic PAN-based membranes can run for a long time and be reused without significant decrease of separation performance.     

Conformational search for zwitterionic leucine and hydrated conformers of both the canonical and zwitterionic leucine using the DFT-CPCM model

The stable conformations for zwitterionic leucine have been searched for in solution as well as in gas phase. A total of 54 trial structures were generated by considering possible combinations of single bond rotamers. It is observed that zwitterions are not stable in gas phase. In order to investigate the zwitterions of leucine in solution, the calculations for all trial structures of zwitterions were performed initially at the PM3 level and 14 the lowest energy structures were reoptimized at the B3LYP/6-311G(d) level using the CPCM model. Seven of these conformers of zwitterionic leucine were found to be stable in solution. The five most stable conformers were then reoptimized at the B3LYP/6-311++G(d, p) level. The energy ordering of the canonical leucine(neutral) conformers were also considered on the basis of single point energy calculations at the B3LYP/6-311++G(d, p) level using the CPCM model. The chemical hardness, chemical potential, vertical ionization energy and vertical electron affinity were calculated for a few of the most stable canonical leucine and its zwitterions in solution. The effects of explicit addition of water molecules (microsolvation) on the structure and the energy of both canonical and zwitterionic conformers of leucine were investigated. It is noted that in gas phase, the singly and doubly hydrated canonical (neutral) forms are more stable than their zwitterionic counterparts. The solvated zwitterions and canonical structures of leucine were further investigated using the discrete/SCRF model with zero, one and two water molecules. In solution, the continuum solvent model shows that the bare zwitterionic form is more stable than the bare canonical form by 1.6 kcal/mol. This energy separation is increased to 3.8 and 4.8 kcal/mol with inclusion of one and two water molecules, respectively. The optimized structural parameters for the most stable zwitterionic leucine with zero, one and two water molecules in solution were compared with those reported for l-leucine crystal, which shows a close agreement between the optimized geometrical parameters of the zwitterionic leucine with two water molecules in solution with the experimental geometrical parameters for l-leucine crystal. It is also observed that when the structures of zwitterions with one and two explicit water molecules are optimized in solution, the geometrical parameters and their relative energies are found to be appreciably modified. We have also calculated the vibrational spectra of the most stable solvated zwitterionic leucine as well as for the most stable structure of zwitterionic leucine with one and two water molecules in solution.     

Polar bonded phase with the zwitterionic sulfobetaine functional group. Comparison to silica.

A new bonded phase has been prepared by the reaction of n-propylsultone with dimethylaminopropylsilane-modified silica. The resulting functional group is the zwitterionic ammonium propane sulfonate. Chromatographic solvents based on three strong solvents, methylene chloride, diisopropyl ether and acetonitrile, were prepared in hexane. Solutes, including substituted benzenes, polycyclic aromatic hydrocarbons and low-molecular-weight species commonly used as solvents, were chromatographed on the zwitterionic phase and on silica from the same supplier of the dimethylamino phase. The zwitterionic phase is a weaker adsorbent than silica and retentions are less influenced by the type of strong solvent employed, compared to silica. The retention (log k') of solutes on the zwitterionic phase is highly correlated with the free energy of transfer of solute from the vapor phase to water.     

Preparation and comparison of three zwitterionic stationary phases for hydrophilic interaction liquid chromatography

Surface‐bonded zwitterionic stationary phases have shown highlighted performances in separation of polar and hydrophilic compounds under hydrophilic interaction chromatography mode. So, it would be helpful to evaluate the characteristics of zwitterionic stationary phases with different arranged charged groups. The present work involved the preparation and comparison of three zwitterionic stationary phases. An imidazolium ionic liquid was designed and synthesized, and the cationic and anionic moieties respectively possessed positively charged imidazolium ring and negatively charged sulfonic groups. Then, the prepared ionic liquid, phosphorylcholine and an imidazolium‐based zwitterionic selector were bonded on the surface of silica to obtain three zwitterionic stationary phases. The selectivity properties were characterized and compared through the relative retention of selected solute pairs, and different kinds of hydrophilic solutes mixtures were used to evaluate the chromatographic performances. Moreover, the zwitterionic stationary phases were further characterized by the modified linear solvation energy relationship model to probe the multiple interactions. All the results indicated that the types and arrangement of charged groups in zwitterionic stationary phases mainly affect the retention and separation of ionic or ionizable compounds, and for interaction characteristics the contribution from n and π electrons and electrostatic interactions displayed certain differences.     

Determination of inorganic anions in biological fluids with direct sample injection by electrostatic ion chromatography using zwitterionic micelles in both stationary and mobile phases

A new ion chromatographic (IC) system, which uses zwitterionic (e.g., Zwittergent 3-14) micelles as both stationary and mobile phases, highly useful for the analysis of inorganic anions in biological samples, was developed. The zwitterionic micellar stationary phase (which is obtained by immobilizing the zwitterionic surfactant on surfaces of the reversed-phase ODS) showed high ability to confine the elution bands of the large amount of SO4(2-) and Cl- to narrow zones. As a result, a base-line separation of NO2-, Br- and NO3- from SO4(2-) and Cl- is always achieved. The zwitterionic micellar mobile phase, (which is obtained by dissolving the zwitterionic surfactant with a suppressive electrolytic solution, e.g., aqueous NaHCO3 solution), on the other hand, showed high ability for rapid elution of proteins. The separation column is therefore always being cleaned up even after the protein-containing sample is directly injected. The zwitterionic micelles are also insensitive to conductivity detection, therefore either the suppressed or the non-suppressed conductivity detection method is applicable for detection of the analyte ions. Urine and serum were chosen as the model real samples and were analysed with direct sample injection; the results of successful determination of a number of inorganic anions (SO4(2-), Cl-, NO2-, Br- and NO3-) in both samples have demonstrated the usefulness of this new IC system.     

Novel approaches for the preparation of silica-based zwitterionic hybrid copolymers

Two novel routes for the preparation of silica-based zwitterionic hybrid copolymers were proposed. A series of zwitterionic hybrid copolymers were prepared by the sulfonation of phenyl groups and the quaternary amination of tertiary amine groups alternately. Both FT-IR and ¹H NMR spectra confirm the step products. TGA and DrTGA analyses indicate that the thermal stability of these zwitterionic hybrid copolymers is higher than 400 °C. The determination of sulfonation degree reveals that the zwitterionic hybrid copolymer (c) from sulfonation-quarteramination (Route I) has the minimal value; meanwhile the anion-exchange capacity exhibits that the zwitterionic hybrid copolymer (e) from quarteramination-sulfonation (Route II) has the minimal value. These findings demonstrate the impact of electrostatic effect on the charge content of ionic groups. MALDI-TOF mass spectra exhibit that the decrease in the stability of the charged hybrid copolymers can be ascribed to the electrostatic effect between the molecular chains. The surface SEM images demonstrate that the surface of zwitterionic hybrid copolymer (e) from quarteramination-sulfonation (Route II) has some aggregated particles and form clusters regions in the hybrid matrix, which can also be attributed to the ionic interactions between those charged groups.     

Synthesis, spectroscopic, and thermal properties of polyurethanes containing zwitterionic sulfobetaine groups

A series of novel polyurethanes (PUs) containing zwitterionic sulfobetaine groups were synthesized from polycarbonatediol with alkyne groups and 3-((2-azidoethyl)dimethylammonio)propane-1-sulfonate using the copper-catalyzed 1,3-dipolar cycloaddition (click) reaction. All the polyurethanes were fully characterized by ¹H NMR, Fourier transform infrared spectrometer, gel permeation chromatography, and elemental analysis; the thermal properties were investigated by thermogravimetric analysis and differential scanning calorimetry. It has been proved that the thermal stability of zwitterionic sulfobetaine functionalized polyurethanes were greater than the starting alkyne-containing polyurethane. Protein adsorption was measured and it was indicated that PUs with zwitterionic sulfobetain structure are a kind of biocompatible materials with a better anti-protein fouling property compared to the corresponding alkyne-containing polyurethanes.     

正负离子表面活性剂与两性表面活性剂的相互作用

本文研究正负离子表面活性剂与两性表面活性剂混合水溶液的表面性质, 以及两性表面活性剂对正负离子裘面活性剂溶解度的影响。结果表明: (1) 两性表面活性剂的加溶作用,有助于正负离子表面活性剂的溶解; (2) 加入两性表面活性剂的量适当, 混合溶液基本保持原正负离子表面活性剂的表面活性; (3) 正负离子表面活性剂与两性表面活性剂在表面层和胶团中分子间的相互作用比正负离子表面活性剂与非离子表面活性剂分子间的相互作用稍强HC-FC正负; 离子表面活性剂与两性表面活性剂混合体系在表面层中有可能形成双分子或多分子层结构。     

Zwitterionic phosphorylcholine-protected water-soluble Ag nanoparticles

The water-soluble Ag nanoparticles capped with novel zwitterionic thioalkylated phosphorylcholine were synthesized. The Ag nanoparticles showed remarkable stability in saline media with salt concentrations as high as 2.0 mol/L and plasma using UV-vis absorption spectroscopy. Similarly, compared with tiopronin and citrate-protected Ag nanoparticles, the zwitterionic phosphorylcholine Ag nanoparticles did not precipitate out of solution when charged polyelectrolytes or biopolymers were added. The zwitterionic phosphorylcholine might be a better ligand for stabilizing metal nanoparticles. Supported by the National Natural Science Foundation of China (Grant Nos. 20774082 and 50703036), National High Technology Research and Development Program of China (Grant Nos. 2006AA03Z329 and 2006AA032444) and Science and Technology Projects of Zhejiang Province (Grant No. 2007C24G2010020)     

Interactions between zwitterionic and conventional anionic and cationic surfactants

Critical micelle concentration (cmc) values have been determined for the mixed zwitterionic/anionic surfactant systems of N-dodecyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (ZW3-12)/sodium dodecyl sulfate (SDS), N-dodecyl-N,N-(dimethylammonio)butyrate (DDMAB)/SDS, N-octyl-N,N-dimethyl-3-ammonio-1-propanesulfonate (ZW3-08)/sodium octyl sulfate (SOS), and the zwitterionic/cationic systems of ZW3-12/dodecyltrimethylammonium bromide (DTAB), DDMAB/DTAB. Conductivity studies and nuclear magnetic resonance (NMR) spectroscopy were the methods employed for cmc determinations. The degree of nonideality of the interaction in the micelle (beta(m)), for each system, was determined according to Rubingh's nonideal solution theory. Evidence was found for the existence of strong interactions between zwitterionic and anionic surfactants in each of the zwitterionic/anionic systems. The ZW3-08/SOS and DDMAB/SDS systems behaved synergistically at all mole fractions studied while the ZW3-12/SDS system exhibited synergistic behavior above mole fractions of 0.30. Greater negative deviations from ideal behavior were demonstrated in the DDMAB/SDS system than in the other two zwitterionic/anionic systems. The zwitterionic/cationic systems of ZW3-12/DTAB and ZW3-08/OTAB displayed only slight deviations from ideal behavior, therefore indicating near ideal mixing.     

单宁酸/两性离子改性油-水分离膜的制备及性能

以不锈钢网为基材, 利用单宁酸对不锈钢网进行表面预处理并功能化接枝两性离子基团, 制备了新型亲水和水下超疏油的单宁酸/两性离子改性油-水分离膜(TA-ZW-SSM). 利用X射线光电子能谱仪(XPS)、 扫描电子显微镜(SEM)及接触角测量仪等表征了其化学结构、 形态和润湿性. 研究结果表明, 两性离子基团通过化学键接枝在单宁酸预处理的不锈钢网表面. 油-水分离实验结果表明, 对于不同类型的油-水混合物, 本文制备的超亲水和水下超疏油特性的TA-ZW-SSM可实现重力驱动的高效油-水分离, 并具有较好的化学稳定性及再循环性.     

Integrated Antimicrobial and Nonfouling Zwitterionic Polymers

Zwitterionic polymers are generally viewed as a new class of nonfouling materials. Unlike their poly(ethylene glycol) (PEG) counterparts, zwitterionic polymers have a broader chemical diversity and greater freedom for molecular design. In this Minireview, we highlight recent microbiological applications of zwitterionic polymers and their derivatives, with an emphasis on several unique molecular strategies to integrate antimicrobial and nonfouling properties. We will also discuss our insights into the bacterial nonfouling performance of zwitterionic polymers and one example of engineering zwitterionic polymer derivatives for antimicrobial wound‐dressing applications.     

Stationary phase-related investigations of quinine-based zwitterionic chiral stationary phases operated in anion-, cation-, and zwitterion-exchange modes

The concept of recently introduced Cinchona alkaloid-type zwitterionic chiral stationary phases (CSPs) is based on fusing key cation- and anion-exchange (CX, AX) moieties in one single low-molecular mass chiral selector (SO) with the resulting CSPs allowing enantiomer separations of a wide range of chiral ionizable analytes comprising acids, bases, and zwitterionic compounds. Herein, we report principal, systematic investigations of the ion-exchange-type retention mechanisms available with the novel zwitterionic CSPs in nonaqueous polar organic mode. Typical CX and AX processes, corresponding to the parent single ion exchangers, are confirmed also for zwitterionic CSPs. Also the mechanism leading to recognition and retention of zwitterions was found to be ion exchange mediated in a zwitterion-exchange (ZX) mode. In both AX and CX modes the additional ionizable group within the SO besides the site responsible for the respective ion-exchange process could be characterized as an intramolecular counterion (IMCI) that effectively participates in the ion-exchange equilibria and thus, contributes to solute elution. In the ZX mode both oppositely charged groups of the zwitterionic SO were found not only to be the sites for simultaneous ion pairing with the analyte but also functioned as IMCIs at the same time. The main practical consequences of the IMCI feature were significant reduction of the amounts and even elimination of acidic and basic additives required in the eluent systems to afford analyte elution while still providing faster analysis than the parent single ion-exchanger-type CSPs. The set of ten structurally different zwitterionic CSPs employed in this study facilitated the establishment of correlations between chromatographic behavior of the CSPs with particular SO elements, thereby supporting the understanding of the working principles of these novel packing materials on a molecular level.     

A new zwitterionic electrochromatographic stationary phase based on poly(3‐chloro‐2‐hydroxypropyl methacrylate‐co‐ethylene dimethacrylate) reactive monolith

A new reactive monolith, poly(3‐chloro‐2‐hydroxypropyl methacrylate‐co‐ethylene dimethacrylate), poly(HPMA‐Cl‐co‐EDMA) was synthesized and post‐functionalized by taurine (2‐aminoethane sulfonic acid) to obtain a zwitterionic stationary phase for capillary electrochromatography. The new stationary phase contained charged groups such as secondary amine providing anodic electroosmotic flow and sulfonic acid groups providing cathodic electroosmotic flow. Hence, the capillary electrochromatography separations with the new zwitterionic monolith were performed with either anodic or cathodic electroosmotic flow. The electrochromatographic separation of alkylbenzenes and phenols was successfully performed. The zwitterionic monolith also allowed the separation of nucleosides using only electrokinetic mode. Theoretical plate numbers up to ~10⁵ plates/m were achieved. Our study is the first report based on poly(HPMA‐Cl‐co‐EDMA) reactive monolith post‐functionalized with a zwitterionic ligand allowing to operate in both anodic and cathodic electroosmotic flow modes. Copyright © 2014 John Wiley & Sons, Ltd.     

Preparation of zwitterionic sulfobetaine end‐functionalized poly(ethylene glycol)‐b‐poly(caprolactone) diblock copolymers and examination of their thermogelling properties

To investigate thermogelling behavior, in this study, we prepared a methoxy poly(ethylene glycol)‐b‐poly(ε‐caprolactone) diblock copolymer (MPC) with varying hydrophobic poly(ε‐caprolactone) (PCL) lengths and an MPC featuring a zwitterionic sulfobetaine (MPC‐ZW) at the chain end of the PCL segment. The terminal zwitterionic sulfobetaine was stoichiometrically modified to the terminal MPC diblock copolymer. The introduction of the zwitterionic end group lowered the crystallization enthalpies of the PCL block segments and increased the solubility of the diblock copolymer. The MPC and MPC‐ZW copolymers thus obtained formed translucent emulsions at room temperature when prepared as 20 wt %. When the temperature was increased above room temperature, MPC and MPC‐ZW exhibited a sol‐to‐gel phase transition. The phase transition and the gelation time of MPC and MPC‐ZW were affected by the length of the hydrophobic segments and the zwitterionic end group. Furthermore, introducing a zwitterionic end group into the PCL segment altered the onset temperature of gelation. Thus, we conclude that zwitterionic end groups introduced into PCL segments of distinct lengths could serve as key determinants in the thermogelling behavior of copolymers. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2185–2191     

Anhydrous proton transport system based on zwitterionic liquid and HTFSI

Novel binary ionic liquids based on zwitterionic liquid and HTFSI for anhydrous proton transport were prepared and showed ionic conductivity of about 10(-2) S cm(-1) at 150 degrees C and a zwitterionic liquid content of 60 mol%.     

Poly(N-ethyl-4-vinylpyridinium) cation-zwitterionic surfactant complexes

The interaction between poly(N-ethyl-4-vinylpyridinium bromide) and a zwitterionic surfactant has been studied in the presence of a low-molecular-mass electrolyte, sodium bromide. Both soluble and insoluble complexes have been formed. There are two essential differences between interactions of the polycation with the zwitterionic surfactant and of polycations with anionic surfacants: interaction between the polycation and the zwitterionic surfactant may proceed only in the presence of low-molecular-mass electrolytes, while interaction between the polycation and the zwitterionic surfactant in the presence of sodium bromide may take place only at surfactant concentrations above the CMC.