Antifouling ultrafiltration membrane composed of polyethersulfone and sulfobetaine copolymer

A new random copolymer was synthesized by reacting hydrophilic N,N-dimethyl-N-methacryloxyethyl-N-(3-sulfopropyl) (DMMSA) with hydrophobic butyl methacrylate (BMA) through a conventional radical polymerization. The as-prepared sulfobetaine copolymer (DMMSA–BMA) was blended with polyethersulfone (PES) to fabricate antifouling ultrafiltration membrane for BSA separation. The X-ray photoelectron spectroscopy analysis of blend membranes revealed concentration of sulfobetaine groups at the membrane surfaces that endowed the membrane with higher hydrophilicity and better antifouling property. For the membrane with 8.0 wt% DMMSA–BMA copolymer concentration (No. 5), irreversible fouling has been considerably reduced and the flux recovery rate of the blend membrane reached as high as 82.8%. Furthermore, the blend membrane could effectively resist BSA fouling in a wide pH range from 4.0 to 8.0.     

Synthesis of a series of monomeric styrene sulfobetaine precursors

Procedures for the synthesis of five sulfobetaine monomers as styrene derivatives are given. The five molecules form a homologous row differing in the distance between the inner quaternary amine and the outer sulfonic acid from one methylene group to five methylene groups. Syntheses are achieved by a sequence of nucleophilic substitutions starting from commercially available precursors.     

Polysulfobetaine films prepared by electrografting technique for reduction of biofouling on electroconductive surfaces

The sulfobetaine films were prepared on stainless steel and golden surfaces. In the first step, the poly(2-(dimethylamino)ethyl methacrylate) film was created by employing the electrografting polymerization technique. In the second step, this film was modified to polysulfobetaine, i.e. the polymer film bearing the zwitterionic groups. The presence of the electrografted film and its modification were determined by contact angle measurements, infrared spectroscopy in reflectance mode and X-ray photoelectron spectroscopy. The prepared films were homogeneous with the thickness from about 5 to 26 nm as determined by X-ray photoelectron spectroscopy. The atomic force microscopy measurements showed the increase of surface roughness upon the surface coating. In vitro tests using adherent RAT-2 fibroblast cells and fluorescently labelled bovine serum albumin proteins showed that prepared polysulfobetaine films can be used in applications requiring the resistance against cell attachment and biofouling.     

Synthesis and surface properties of new semi-fluorinated sulfobetaines potentially usable for 2D-electrophoresis

New semi-fluorinated amidosulfobetaines, homologs of hydrocarbon amidosulfobetaines (ASB) commonly used in two-dimensional gel electrophoresis (2DE), were prepared in three steps from 2-F-alkylethyl iodide or F-alkyl iodide. Their synthesis was described and their air-water interface properties were investigated and compared with their perhydrogenated counterpart properties. The influence of the relative lengths of the perfluorinated and hydocarbonated moieties was discussed. 2DE of a rat testicular membrane fraction was performed comparatively using one of these fluorinated sulfobetaines and its hydrocarbon homolog; these preliminary results showed the great potential of the semi-fluorinated sulfobetaines in proteomic analysis.     

Zwitterionically modified hydroxypropylcellulose for biomedical applications

Novel polyelectrolytes have been synthesized by grafting sulfobetaine side chains onto hydroxypropylcellulose backbone. Polymers with various degrees of grafting have been obtained. The polymers do not interact with model anionic, cationic and zwitterionic surfactants as found in fluorescence studies using pyrene as a molecular probe. Dynamic light scattering (DLS) studies indicated that in the graft polymer solution two types of polymers are present. The films were formed from the grafted polymers. Using atomic force microscopy (AFM) technique it was found that they are resistant to the adhesion of proteins and can be used for the preparation of antiadhesive surfaces which may find biomedical applications.     

Radical polymerization behavior of 3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate in water

The homogeneous polymerization of 3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate (MDAPS) with potassium peroxydisulfate (KPS) was kinetically in situ investigated in water by means of FT-near IR spectroscopy. The overall activation energy of the polymerization was calculated to be 16.0 kcal/mol. The initial polymerization rate (R_p) at 40 °C was expressed by R_p=k[KPS]^0.65[MDAPS]^1.0. The presence of alkaline metal salts was observed to accelerate the polymerization. The order of acceleration at 40 °C was CsCl > KCl > NaCl > LiCl when the chloride salts were used. NaCl showed higher acceleration effect than NaF. NaBr and NaI exhibited retardation and inhibition effect, respectively, because of reduction of KPS and its primary radical with bromide and iodide ions. The polymerization of MDAPS with KPS in water in the presence of NaCl at 2.0 mol/l gave R_p=k[KPS]^0.70[MDAPS]^1.4 at 40 °C. The overall activation energy of the polymerization in the presence of NaCl was estimated to be 11.6 kcal/mol being considerably lower value compared with that in its absence. The syndiotacticity of poly(MDAPS) tended to increase with rising temperature and decrease in the presence of NaCl.     

Latest advances in zwitterionic structures modified dialysis membranes

End-stage renal diseases are affecting many patients and as a result, demand to receive dialysis service is growing annually. Morbidity and mortality rates are reported to be higher in comparison with healthy humans. The reason is reported to be the hemoincompatiblity of blood purification membranes, which hinders patients’ lives. Activation of different immune systems in the body, in case of blood-membrane interaction, results in several side effects, of which cardiovascular shocks have been mentioned to be a major one. Efforts to solve this issue have resulted in different generations of dialysis membranes. Zwitterionic immobilized membranes are the latest (third) generation, which owns a higher degree of hemocompatiblity with more stability of immobilized structures. This critical review intends to cover recent efforts conducted over the zwitterionization of polymeric membrane surfaces with the goal of improving hemocompatibility. Different aspects of third-generation membranes are discussed for a better understanding of the current gap and gathering the knowledge to further develop the field. Accordingly, this critical survey provides an in-depth understanding of blood purification membranes zwitterionization for paving the way for the optimum enhancement of hemodialysis membrane hemocompatibility.     

Study of retention behaviour and mass spectrometry compatibility in zwitterionic hydrophilic interaction chromatography for the separation of modified nucleosides and nucleobases

A study has been made of the chromatographic behaviour of modified nucleosides and nucleobases using different stationary phases with functional groups of polar nature, all of them compatible with aquoorganic mobile phases. The stationary phases assayed were a pentafluorophenylpropyl (PFP) column for reverse phase separation, and another two for hydrophilic interaction chromatography (HILIC) separation. Six modified nucleosides and nucleobases (hydroxylated and methylated derivatives) were chosen as the target analytes. In the study, chromatographic resolution as well as the sensitivity in detection by mass spectrometry were taken into account. The results obtained showed that the zwitterionic (ZIC-HILIC) column was the most suitable one for the separation of these analytes. From the study of the different parameters affecting separation it may be concluded that in the ZIC-HILIC column separation is based on a mechanism of partition and interaction through weak electrostatic forces.     

GRAFTING OF SULFOBETAINE ONTO A POLYURETHANE SURFACE TO IMPROVE BLOOD COMPATIBILITY

On the molecular level, it is believed that polymers containing zwitterionic structures should be compatible withblood. In this work polyurethane films were grafted with sulfobetaine by a three-step procedure. In the first step, the films'surfaces were treated with hexamethylene diisocyanate (HDI) in toluene at 50℃ in the presence of di-n-butyl tin dilaurate(DBTDL) as a catalyst. The extent of the reaction was monitored by ATR-IR spectra; a maximum number of free NCOgroups was obtained after a reaction time of 90 min. In the second step, the hydroxyl groups of N,N-dimethylethylethanolamine (DMEA) were allowed to react in toluene with NCO groups bound on the surface. In the thirdstep, sulfobetaines were formed on the surface through the ring-opening reaction between tertiary amine of DMEA and 1,3-propanesultone (PS). The surfaces of the films were characterized by ATR-IR and XPS showing that the grafted surfaceswere composed of sulfobetaine. The results of the contact angle measurement show that the surface was strongly hydrophilic.The platelet adhesion test demonstrated that the films grafted with sulfobetaine have excellent blood compatibility.     

New insights into the solubilization of Bodipy dyes

Several Bodipy dyes were synthesized with various substituents designed to improve the water solubility. Among the different synthetic strategies protection of sulfonate groups by pyrrole of indopyrrole appears efficient but the deprotection step does not offer viable routes. Conversion of the bromopyrene or iodo Bodipy compounds to sulfobetaine derivatives is feasible either by cross-coupling directly the ethynylsulfobetaine or by first cross-coupling 1-(N,N-dimethylamino)-prop-2-yne followed by quaternization of the dimethylamino residue with 1,3-propanesultone. Some of these dyes (Bodipy’s and pyrene) are reasonably soluble in water and remain highly fluorescent in polar solvents and water.