Zwitterionic Monomer Research Articles

Gradation of proteins and cells attached to the surface of bio-inert zwitterionic polymer brush

A self-assembled monolayer (SAM) of a 2-bromoisobutyryl end group-carrying initiator for atom transfer radical polymerization (ATRP) was constructed on the surface of silicon wafer or glass substrates via a silane-coupling reaction. When the initiator SAM was irradiated with UV light at 254nm, the surface density of bromine atoms was reduced by the scission of CBr bonds as observed by XPS. With the surface-initiated ATRP of the zwitterionic vinyl monomer, carboxymethyl betaine (CMB), the surface density of PCMB brushes could be easily varied by changing the irradiation period of UV light prior to the polymerization. Furthermore, by using a UV-cut shutter sliding above the initiator SAM-modified substrate at a constant speed, the degree of bromine atom removal could be linearly varied along the direction of movement of the shutter. Consequently, the amount of both proteins adsorbed and cells adhered to the PCMB brush-covered substrate could easily be controlled by the gradation of the surface density of PCMB brushes, which suppressed protein adsorption and cell adhesion. Such a technique is very simple and useful for the regulation of the surface density of adsorbed proteins and adhered cells on an originally bio-inert surface.

In Situ Synthesis of Antimicrobial Silver Nanoparticles within Antifouling Zwitterionic Hydrogels by Catecholic Redox Chemistry for Wound Healing Application.

A multifunctional hydrogel that combines the dual functionality of both antifouling and antimicrobial capacities holds great potential for many bioapplications. Many approaches and different materials have been employed to synthesize such a material. However, a systematic study, including in vitro and in vivo evaluation, on such a material as wound dressings is highly scarce at present. Herein, we report on a new strategy that uses catecholic chemistry to synthesize antimicrobial silver nanoparticles impregnated into antifouling zwitterionic hydrogels. For this purpose, hydrophobic dopamine methacrylamide monomer (DMA) was mixed in an aqueous solution of sodium tetraborate decahydrate and DMA monomer became soluble after increasing pH to 9 due to the complexation between catechol groups and boron. Then, cross-linking polymerization of zwitterionic monomer was carried out with the solution of the protected dopamine monomer to produce a new hydrogel. When this new hydrogel comes in contact with a silver nitrate solution, silver nanoparticles (AgNPs) are formed in its structure as a result of the redox property of the catechol groups and in the absence of any other external reducing agent. The results obtained from TEM and XRD measurements indicate that AgNPs with diameters of around 20 nm had formed within the networks. FESEM images confirmed that the silver nanoparticles were homogeneously incorporated throughout the hydrogel network, and FTIR spectroscopy demonstrated that the catechol moiety in the polymeric backbone of the hydrogel is responsible for the reduction of silver ions into the AgNPs. Finally, the in vitro and in vivo experiments suggest that these mussel-inspired, antifouling, antibacterial hydrogels have great potential for use in wound healing applications.

Functional Choline Phosphate Polymers.

Zwitterionic polymers have been widely implemented in surface modification and as biomaterials that exhibit exceptional hydrophilicity, biocompatibility, and antifouling properties. However, a wider breadth of applications for polymer zwitterions is hindered by their inherent lack of functionality, requiring the integration of chain-end functionality or incorporation of functional comonomers along the polymer chain. Here we demonstrate the facile placement of unsaturated groups directly into zwitterionic methacrylate monomers, specifically choline phosphate structures, and show the utility of these monomers in controlled free radical polymerization. These versatile functional zwitterions are converted easily to polymer prodrugs, hydrogels, and other derivatives that establish the versatility of this novel materials platform.

Surface modification of polysulfones via one-pot ATRP and click chemistry: Zwitterionic graft complex and their hemocompatibility

Zwitterionic sulfobetaine groups were grafted onto polysulfone (PSU) membrane surface with 2-azidoethyl methacrylate and N,N-diethyl-N-propargyl-N-(3-sulfopropyl) ammonium (DEPAS) via surface-initiated Atom Transfer Radical Polymerization (ATRP) and “click” chemistry in a two-step process. The PSU membranes were fully characterized by attenuated total reflectance Fourier transform infrared spectra (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and static water contact angle (WCA) measurement. Results showed that zwitterionic monomers were efficiently grafted onto PSU surfaces. The water contact angle, bovine serum albumin (BSA) protein adsorption and platelet adhesion were obviously decreased after grafting zwitterionic sulfobetaine groups onto the membrane surface. These indicated that the zwitterionic sulfobetaine modified PSU membranes presented good biocompatibility. This study provides a new approach for surface modification of polysulfone with different functionalities.

Fabrication of electro-neutral nanofiltration membranes at neutral pH with antifouling surface via interfacial polymerization from a novel zwitterionic amine monomer

A kind of novel electro-neutral nanofiltration (NF) membrane at neutral pH was fabricated by interfacial polymerization from a novel zwitterionic amine monomer PEI-g-SBMA. The zwitterionic amine endowed the resultant NF membrane with an electro-neutral separation layer under neutral condition and enhanced antifouling property via regulation of surface charge balance. The electro-neutral zwitterionic NF membranes (PEI-g-SBMA/TMC) showed a high water flux of 132L/ (m2hMPa), i.e. over 2 times higher than that of the PEI/TMC membranes without grafted SBMA. The PEI-g-SBMA/TMC membrane exhibited a high dye rejection (90.6% for Orange GII) but a low salt rejection (7.1% for NaCl and 50.4% for Na2SO4). Meanwhile, the antifouling property against bovine serum albumin (BSA), sodium alginate (SA) and humic acid (HA) was significantly improved compared with the PEI/TMC membranes. The as-fabricated electro-neutral PEI-g-SBMA/TMC membranes with high organics rejection and low salt rejection as well as good antifouling property may find promising application potential in food, pharmaceutical, chemical industry and membrane bioreactor (MBR) processes.

High-flux and fouling-resistant reverse osmosis membrane prepared with incorporating zwitterionic amine monomers via interfacial polymerization

Zwitterionic monomers have aroused great attraction for membrane preparation due to their tremendous hydrophilicity and antifouling properties. Zwitterionic diamine monomer N-aminoethyl piperazine propane sulfonate (AEPPS) was added into m-phenylenediamine (MPD) aqueous solution to react with trimesoyl chloride (TMC) via interfacial polymerization to fabricate zwitterionic thin film composite reverse osmosis membrane (TFCMZs). The membrane preparation conditions, including AEPPS content, TMC concentration and curing temperature, were systematically evaluated. The membrane surface hydrophilicity and antifouling properties of TFCMZs were greatly enhanced via introducing AEPPS into membranes. When tested with brackish water desalination conditions (2000ppm NaCl feed solution at 1.5MPa and 25°C), the water flux of TFCMZs containing 10% AEPPS was significantly increased to be 54.5±3.2L·m−2·h−1, which is about an 82% increase compared with the pristine membrane, while the NaCl rejection remains above 98%. Furthermore, using tannic acid (TA) and sodium alginate (NaAlg) as model foulants, the TFCMZs displayed outstanding fouling-resistant and easy-cleaning properties. TFCMZs present both admirable separation and fouling-resistance performance, which indicates that TFCMZs have wide application potential for brackish water desalination.

Synthesis and characterization of monodisperse-porous, zwitterionic microbeads

Zwitterionic, monodisperse-porous polymer beads were newly synthesized using a hydrophilic acrylic crosslinker (glycerol dimethacrylate, GDMA) or a hydrophobic one (ethylene dimethacrylate) including a zwitterionic functional monomer sulfopropyl-2-vinylpyridinium hydroxide (SVP) in a modified-staged shape template polymerization. The effects of monomer/seed latex ratio and diluent/seed latex ratio on the particle size, mean pore size, pore size distribution and specific surface area of the poly(1-(3-sulfopropyl)-2-vinylpyridinium hydroxide-co-glycerol dimethacrylate) poly(SVP-co-GDMA) and poly(1-(3-sulfopropyl)-2-vinylpyridinium hydroxide-co-ethylene glycerol dimethacrylate) poly(SVP-co-EDMA) microbeads were investigated. For both types of microbeads, the mean size decreased with decreasing monomer/seed latex ratio and decreasing diluent/seed latex ratio. Almost tenfold higher specific surface area was achieved using a hydrophobic crosslinking agent (EDMA) with respect to the hydrophilic one. Poly(SVP-co-GDMA) microbeads were satisfactorily used as a stationary phase in HILIC mode for the isocratic separation of polar organics with the plate heights up to 124 microns.

Betaine microgel preparation from 2-(methacryloyloxy) ethyl] dimethyl (3-sulfopropyl) ammonium hydroxide and its use as a catalyst system

Abstract We demonstrate the synthesis of poly(sulfobetain methacrylate) (p(SBMA)) hydrogels of micro dimensions by inverse suspension polymerization of a zwitterionic monomer 2-(methacryloyloxy) ethyl] dimethyl (3-sulfopropyl) ammonium hydroxide (SBMA). The prepared microgels were used as microreactors for the synthesis of nickel (Ni) nanoparticles by in situ reduction of Ni (II) loaded into microgels from an aqueous medium. The prepared microgels and microgel metal nanoparticle composites were characterized by Fourier Transformation Infrared (FT-IR) Spectroscopy, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). Thermal properties of the microgels were studied by thermal gravimetric analysis (TGA). The amount of Ni nanoparticles generated within the microgels was determined by Atomic Absorption Spectroscopy (AAS) after dissolving the Ni nanoparticles to form Ni (II) ions by treating with concentrated hydrochloric acid (5 M HCl). The prepared composites were used as catalysts for the reduction of nitro aromatic compounds such as 4-nitrophenol (4-NP), 2-nitrophenol (2-NP) and 4-nitroaniline (4-NA) and excellent catalytic performances were observed. The effects of temperature and amount of catalyst were also evaluated. A mild activation energy in comparison to the literature was calculated as 35.64 kJ/mol, and very high kapp value of 0.42 min−1 as a function of temperature was estimated for the reduction of 4-NP catalyzed by p(SBMA)-Ni composite catalyst system.

Ultrafiltration membranes with markedly different pH- and ion-responsivity by photografted zwitterionic polysulfobetain or polycarbobetain

Stimuli-responsive ultrafiltration (UF) membranes were synthesized via photo-initiated “grafting from” of the zwitterionic monomers N-(3-sulfopropyl)-N-methacroyl-oxyethyl-N,N-dimethyl-ammonium betaine (sulfobetaine methacrylate, SPE) and 2-carboxy-N,N-dimethyl-N-(2′-(methacryl-oyloxy)ethyl)ethan-aminium inner salt (carbobetaine methacrylate, CBMA) onto commercial polyethersulfone UF membranes. The effects of kosmotropic and chaotropic potassium salts and pH on flux were determined in order to investigate the stimuli-responsive behavior of the polyzwitterion-grafted membranes. PolySPE showed the expected stimuli-responsiveness based on the “anti-polyelectrolyte” effect. The degree of swelling of grafted sulfobetaine polymer increased and water permeability decreased with increasing salt concentration; and the results can be related to the “Hofmeister series”, i.e. the magnitude of the effect increased with increasing chaotropic character of the anion, in the order: SO42−<H2PO4−<Cl−<ClO4−. However, the carbobetaine polymer (polyCBMA) did not show such anti-polyelectrolyte behavior at pH values in neutral and basic range. In contrast to the “strong–strong” type zwitterionic material polySPE, the swelling behavior of the “strong-weak” polyCBMA was significantly influenced by pH value because protonation of carboxylic acid side groups changes the grafted chains from net neutral zwitterionic into polycationic with ordinary polyelectrolyte properties. Hence, permeability of polyCBMA-grafted membranes increased with increasing salt concentration at pH=3. Furthermore, the rejection of dextrans as a function of electrolyte concentration and pH was determined and all results were in agreement with changes of water fluxes. For specific salt conditions, large and reversible changes of dextran rejection were found, confirming the possibilities of adjusting the sieving properties of the responsive zwitterionic membranes. Detailed studies by zetapotential measurements were also performed to investigate the specific effects of ion type, electrolyte concentration and pH onto the stimuli-responsive changes of surface charge of grafted membranes. All results support that the effects of the grafted zwitterionic polymers on the barrier properties of the UF membranes can be described with a pore-opening/-closing mechanism based on reversible deswelling/swelling of grafted chains on the pore walls in response to composition changes with respect to salt (for polySPE) or salt and pH value (polyCBMA).

Mesoporous Thin Films, Zwitterionic Monomers, and Iniferter-Initiated Polymerization: Polymerization in a Confined Space

Polymer modification of mesoporous materials is a relevant topic for applications from sensing and separation to drug delivery. Especially the combination of structure and responsive, charged polymer functionalization opens new possibilities, such as gating of drug release. Thereby, zwitterionic polymers are interesting, because of their antifouling characteristics and their influence on ionic permselectivity. The control on polymerization in confinement of a mesopore including spatial polymer location is crucial for the resulting mesopore function such as ionic permselectivity. The amount of generated polymer and polymerization kinetics should be influenced by the confinement of mesopores: Diffusion is limited by the pore size, pore connectivity, and wall charge. These parameters influence termination, which depends on radical concentration and proximity. Concerning the total surface area, the size of the internal surface area of mesoporous materials largely dominates over the size of the outer surface a...

Self-associations and temperature dependence of aqueous solutions of zwitterionically modified N-isopropylacrylamide copolymers

Thermosensitive copolymer solutions are prepared from various molar ratios of N-isopropylacrylamide (NIPAM) and the zwitterionic monomer N-(methacryloxypropyl)-N,N-dimethyl-N-(3-sulfopropyl) ammonium betaine (Zw) by free radical polymerization. In the current study, we examined the rheological properties of poly (NIPAM/sulfobetaine) copolymer solutions. We found that the rheological properties are conceptually linked with the copolymer chemical structure and chain topology. We also report the effects of bulk molar mass and zwitterions on flow curve ɳ ( $$ \overset{\cdot }{\upgamma} $$ ). With the introduction of the charged group in the PNIPAM-chain, its viscoelastic phase behavior and lower critical solution temperature (LCST) are affected. At varying concentrations of zwitterionic copolymer, they showed a shear thinning behavior with two relaxation regimes for entanglement relaxation and zwitterionic interaction. Interestingly, the zwitterionic interactions are related to the molar concentration of zwitterionic monomer. This is eventually associated with the topology of the copolymer chain. Our results also showed that there was a linear increase in the LCST of these solutions as a function of zwitterionic moieties.

The Effects of the Column Length on the Efficiency of Capillary Zwitterionic Organic Polymer Monolithic Columns in HILIC Chromatography

Organic polymer monolithic columns of different lengths have been prepared in 320 µm i.d. fused silica capillary by in situ radical polymerization of N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl) ammonium betaine as a zwitterionic functional monomer and bisphenol A glycerolate dimethacrylate as a crosslinking monomer in the presence of porogenic solvents. The zwitterionic monolithic columns are intended for separations of polar compounds in hydrophilic interaction chromatography (HILIC). The effects of the capillary column length, from 115 to 175 mm, on separation efficiency, were investigated under HILIC conditions, using 95:5 acetonitrile in water as the mobile phase. The extra-column contributions to band broadening significantly decrease the efficiency (apparent height equivalent to a theoretical plate), especially for weakly retained samples, and increase with diminishing column length. The experimental height equivalents of theoretical plate, HETP, were corrected for the extra-column contributions, which were determined for a series of columns by extrapolation to zero column length. On a 175 mm long column, the column efficiency, HETP = 16.5 μm, measured at the optimum linear flow velocity of 0.5 mm s−1, improved to HETP = 5 µm, after correction for extra-column contributions. For more strongly retained small polar compounds, interactions with zwitterionic groups and (or) water adsorbed inside the pores decrease the column efficiency at higher flow rates.

A novel cross-linked pH-responsive tetrapolymer: Synthesis, characterization and sorption evaluation towards Cr(III)

A novel cross-linked acidic tetrapolymer (CPZA) was synthesized via the cyclopolymerization of different zwitterionic monomers bearing amino, carboxylate, phosphonate and sulfonate motifs and a cross-linker using ammonium persulfate as the initiator. The cross-linked tetrapolymeric anionic polyelectrolyte (CAPE) was obtained by the treatment of CPZA with NaOH. The sorption activity of CAPE was evaluated for the adsorption of chromium (III) using batch equilibrium technique. The experimental data fitted Langmuir, Freundlich and Temkin isotherm models. The maximum adsorption capacity was found to be 48.5mg/g at pH 5.5 and temperature of 296K. The adsorption process fitted pseudo-second order kinetic model well and the mechanism was studied by intraparticle diffusion model. Thermodynamic parameters reveal that the adsorption process was endothermic in nature. The resin has not only the advantages of fast uptake with high capacity but also the ease of reusability and good stability. The resin demonstrates an excellent ability to remove chromium (III) ions even from real wastewater samples, suggesting that the resin could be a good candidate for real sorption applications.

Thermoresponsive self-assembled NiPAm-zwitterion copolymers

We incorporated temperature sensitive NiPAm with zwitterionic monomers (CBMA and SBMA), synthesized the statistical copolymers poly(NiPAm-co-CBMA) and poly(NiPAm-co-SBMA), and investigated their self-assembly and thermoresponsive properties.

A thermoresponsive poly(N-vinylcaprolactam-co-sulfobetaine methacrylate) zwitterionic hydrogel exhibiting switchable anti-biofouling and cytocompatibility

A new class of hydrogels were prepared from the combination of the non-ionic VCL with zwitterionic SBMA monomers, exhibiting anti-biofouling and cytocompatibility.

Making polymeric membranes antifouling via “grafting from” polymerization of zwitterions

ABSTRACTProtein‐fouling of membranes has negative effects on the wide applications of membrane materials, such as poly(vinylidene fluoride) (PVDF), poly(ether sulfone) (PES)/polysulfone (PSf). Zwitterionic materials have recently been used and identified from high throughput screens of large libraries of monomers to modify membranes due to their stable anti‐protein‐fouling properties. “Grafting from” polymerization is a technique involving monomers that are polymerized using an initiation reaction on the membrane surface. It is regarded as a simple, useful, and versatile modification approach to increase the anti‐fouling properties of a membrane. This strategy provides controllable introduction of graft chains with a high density and a long‐term chemical stability due to covalent attachment of graft chains. Graft density, chemistry, chain length, and conformation are all important parameters that need to be considered. This article presents a mini‐review of recent progress on the “grafting from” polymerization of zwitterionic monomers on the surfaces of PVDF and PES/PSf membranes, including an introduction of zwitterions and methods of graft polymerization. Various approaches such as free radical graft polymerization, photo‐induced graft polymerization, and plasma‐induced graft polymerization were compared based on uniformity and amount of grafted zwitterionic polymer, relative flux of modified membranes, simplicity and environment pollution of operation, and cost of technique. The application of different approaches and the performance of poly(zwitterion)‐grafted PVDF and PES/PSf membranes are summarized according to recent research. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41781.

Temperature-responsive copolymer brush constructed on a silica microparticle by atom transfer radical polymerization

A polymer, poly(2-(2-methoxyethoxy)ethyl methacrylate) (PMDM), was accumulated on a silica microparticle by surface-initiated atom transfer radical polymerization (ATRP). The hydrodynamic diameter of the polymer-grafted silica particle (PMDM-SiP) dispersed in water was observed to decrease above 24 °C, which could be ascribed to a coil-globule transition of PMDM chains. This is in accordance with the increase in turbidity of an aqueous solution of free PMDM, which was produced parallel in liquid phase at the ATRP, above 23 °C. The lower critical solution temperature (LCST), defined as the temperature at which the absorbance reached the optical density of 0.30, was 27.6 °C for free PMDM. An introduction of zwitterionic vinyl monomer, carboxymethylbetaine (CMB), into both a polymer brush and a free polymer (P(MDM-r-CMB)) raised the LCST. In addition, the hydrodynamic diameter (Dh) of the polymer-modified particles was not affected by the presence of NaBr nor lysozyme at 15 °C, whereas it was largely affected at 35 °C due to the decrease in hydrophilicity of the polymer graft chain above the LCST. In contrast, bovine serum albumin did not affect the Dh value of the polymer-modified particles both below and above the LCST. The usefulness of the PMDM brush having CMB as a comonomer in the biomedical field was suggested.

A novel ternary copolymerized polyzwitterionic of poly (AM/DMAM/MAEDAPS): synthesis and solution properties

3-[2-(N-methylacrylamido)-ethyldimethylammonio] propanesulfonate (MAEDAPS), a novel zwitterionic monomer, was designed and synthesized in this study. Then it reacted with acrylamide and N, N-dimethyl acrylamide by free radical polymerization in aqueous solution with ammonium persulfate ((NH4) 2S2O8) and sodium sulfite (NaHSO3) as initiator. The structure of MAEDAPS was characterized by 1H NMR and IR. Thermal stability of the obtained copolymer was tested by DSC, TGA and TG-IR analysis. Glass transition temperature (Tg) and melt temperature (Tm) was observed by DSC, meanwhile, the thermal degradation process was studied via TGA and TG-IR. It turned out that the thermal degradation process can be divided into three stages including removal of physically absorbed water, decomposition of side groups and degradation of polymer main chain. Anti-polyelectrolyte behavior was observed based on the intrinsic viscosity. Solution properties of ternary copolymer were exhibited by reduced viscosity. The result showed that the addition of small molecular electrolytes weakened the coulomp attraction between sulfonic acid group and quaternary ammonium group, and the conformation became extend, which led to the increase of hydrodynamic volume and reduced viscosity. The ability of monovalent and divalent cationic charges influencing the viscosity of zwitterionic copolymer obeyed the following sequence: K+ < Li+ < Na+, Cu2+ < Ca2+ < Mg2+, and anions was in the order: Cl−< I−< Br−.

Separation of nucleobases, nucleosides, and nucleotides using two zwitterionic silica-based monolithic capillary columns coupled with tandem mass spectrometry

The capability of employing synthesized zwitterionic silica-based monolithic capillary columns (140mm×0.1mm) for separation of highly polar and hydrophilic nucleobases, nucleosides, and nucleotides in hydrophilic interaction chromatography is reported. The suitability of the columns for on-line conjunction with electrospray tandem mass spectrometry was explored. Our results show that the grafted layer of zwitterionic monomer ([2-(methacryloyloxy)ethyl]-dimethyl-(3-sulfopropyl)-ammonium hydroxide or 2-methacryloyloxyethyl phosphorylcholine) on the silica monolithic surface significantly improved the separation selectivity and reproducibility, as compared to the bare silica monolith. The stepwise elution from 90% to 70% of acetonitrile enabled separation of a complex sample mixture containing 21 compounds with a total analysis time less than 40min.

Preparation of hydrophilic vinyl chloride copolymer hollow fiber membranes with antifouling properties

Hydrophilic vinyl chloride copolymer hollow fiber membranes with antifouling properties were prepared from brominated vinyl chloride-hydroxyethyl methacrylate copolymer (poly(VC-co-HEMA-Br)). The base membrane was grafted with two different zwitterionic monomers, (2-methacryloyloxyethylphosphorylcholine) (MPC) and [2-(methacryloyloxy) ethyl] dimethyl (3-sulfopropyl) ammonium hydroxide) (MEDSAH), and poly(ethylene glycol) methyl ether methacrylate (PEGMA). The effect of the grafting on the base membrane hydrophilicity and antifouling properties was investigated. For comparison of the results, the pure water permeabilities and pore sizes at the outer surfaces of the grafted hollow fiber membranes were controlled to be similar. A poly(VC-co-HEMA-Br) hollow fiber membrane with similar pure water permeability and pore size was also prepared as a control membrane. A BSA solution was used as a model fouling solution for evaluation of the antifouling properties. Grafting with zwitterionic monomers and PEGMA improved the antifouling properties compared with the control membrane. The PEGMA grafted membrane showed the best antifouling properties among the grafted membranes