Polyelectrolyte multilayer films as backflushable nanofiltration membranes with tunable hydrophilicity and surface charge

A diverse set of supported polyelectrolyte multilayer (PEM) membranes with controllable surface charge, hydrophilicity, and permeability to water and salt was designed by choosing constituent polyelectrolytes and by adjusting conditions of their deposition. The membranes were characterized in terms of their water and MgSO4 permeabilities and resistance to colloidal fouling. The commercial nanofiltration membrane (NF270) was used as a comparative basis. Highly hydrophilic and charged PEMs could be designed. For all membranes, MgSO4 permeability coefficients of NF270 and all PEM membranes exhibited a power law dependence on concentration: Ps [is proportional to] C-[tau], 0.19 < [tau] < 0.83. PEM membranes were highly selective and capable of nearly complete intrinsic rejection of MgSO4 at sufficiently high fluxes. With the deposition of colloids onto the PEM surface, the separation properties of one type of polyelectrolyte membrane showed similar rejection and superior flux properties compared to NF270 membranes. We hypothesize that a PEM-colloid nanocomposite was formed as a result of colloidal fouling of these PEM films. The feasibility of regenerating the PEM membranes fouled by colloids was also demonstrated. In summary, the PEM-based approach to membrane preparation was shown to enable the design of membranes with the unique combination of desirable ion separation characteristics and regenerability of the separation layer

Епоксиіміди ряду норборнана в реакціях з фенилацетиленілмагнійбромідом

Разработан метод синтеза N-замещенных 5-фенилацетиленил-9-экзо-гидрокси-3-оксо-4-азо-11-оксатетрацикло[5.2.1.15,8.02,6]ундеканов на основе доступных эпоксиимидов ряда норборнана, строение полученных соединений подтверждено с помощью данных ИК-спектров и спектров ЯМР 1Н.Розроблено метод синтезу N-заміщених 5-фенілацетиленіл-9-екзо-гідрокси-3-оксо-4-азо-11-оксатетрацикло[5.2.1.15,8.02,6]ундеканів на основі доступних епоксиімідів ряду норборнана, будову отриманих сполук підтверджено за допомогою даних ІЧ-спектрів і спектрів ЯМР 1Н

Інноваційна домінанта в сучасній освітній парадигмі

Подано  аналіз  моделі  вищої  освіти  в  інноваційному  постіндустріальному  суспільстві, досліджено проблеми інноваційного менеджменту в університетах України та запропоновані шляхи їх вирішення, підкреслено роль держави у трансформаційних процесах

Эпоксиимиды ряда норборнана в реакциях с фенилацетиленилмагнийбромидом

Разработан метод синтеза N-замещенных 5-фенилацетиленил-9-экзо-гидрокси-3-оксо-4-азо-11-оксатетрацикло[5.2.1.15,8.02,6]ундеканов на основе доступных эпоксиимидов ряда норборнана, строение полученных соединений подтверждено с помощью данных ИК-спектров и спектров ЯМР 1Н

MOLECULAR DYNAMICS STUDY OF CYTOCHROME C – LIPID COMPLEXES

The interactions between a mitochondrial hemoprotein cytochrome c (cyt c) and the model lipid membranes composed of zwitterionic lipid phosphatidylcholine (PC) and anionic lipids phosphatidylglycerol (PG), phosphatidylserine (PS) or cardiolipin (CL) were studied using the method of molecular dynamics. It was found that cyt c structure remains virtually unchanged in the protein complexes with PC/PG or PC/PS bilayers. In turn, protein binding to PC/CL bilayer is followed by the rise in cyt c radius of gyration and root-mean-square fluctuations. The magnitude of these changes was demonstrated to increase with the anionic lipid content. The revealed effect was interpreted in terms of the partial unfolding of polypeptide chain in the region Ala15-Leu32, widening of the heme crevice and enhancement of the conformational fluctuations in the region Pro76-Asp93 upon increasing the CL molar fraction from 5 to 25%. The results obtained seem to be of utmost importance in the context of amyloidogenic propensity of cyt c

SPECTRAL BEHAVIOR OF INDICATOR DYES IN THE MODEL PROTEIN – LIPID SYSTEMS

The protolytic and partition equilibria of the indicator dyes in the model lipid and protein-lipid systems have been analyzed. A methodological approach has been developed allowing the partition coefficients of the protonated and deprotonated dye forms to be derived from the spectrophotometric measurements. The partitioning of the indicator dye bromothymol blue into the model bilayer membranes composed of phosphatidylcholine and cardiolipin (9:1, mol:mol) has been examined. The partition coefficient of the protonated dye species into a lipid phase has been found to be 5 orders of magnitude higher than that of the deprotonated dye form. This effect has been interpreted in terms of the differences in the charge distribution over the protonated and deprotonated dye ions, preventing the hydrophobic dye-lipid interactions in the latter case. The reduction of the bromothymol blue partitioning into lipid bilayer in the presence of hemoglobin has been attributed to the protein-induced changes in the structure and physicochemical characteristics of the interfacial membrane region. In the practical aspect, the obtained findings may prove of significance in the design of hemosome-based blood substitutes and elucidating the role of hemoglobin in the molecular etiology of the amyloid disorders, particularly, Alzheimer's disease

Adsorption of Anionic or Cationic Surfactants in Polyanionic Brushes and Its Effect on Brush Swelling and Fouling Resistance during Emulsion Filtration

Atom transfer radical polymerization of ionic monomers from membrane surfaces yields polyelectrolyte brushes that swell in water and repel oil droplets to resist fouling during filtration of oil-in-water emulsions. However, surfactant adsorption to polyelectrolyte brushes may overcome this fouling resistance. This work examines adsorption of cationic and anionic surfactants in polyanionic brushes and the effect of these surfactants on emulsion filtration. <i>In situ</i> ellipsometry with films on flat surfaces shows that brushes composed of poly­(3-sulfopropyl methacrylate salts) (pSPMK) swell 280% in water and do not adsorb sodium dodecyl sulfate (SDS). pSPMK-modified microfiltration membranes reject >99.9% of the oil from SDS-stabilized submicron emulsions, and the specific flux through these modified membranes is comparable to that through NF270 nanofiltration membranes. Moreover, the brush-modified membranes show no decline in flux over a 12 h filtration, whereas the flux through NF270 membranes decreases by 98.7%. In contrast, pSPMK brushes adsorb large quantities of cetyl­trimethyl­ammonium bromide (CTAB), and at low chain densities the brushes collapse in the presence of this cationic surfactant. Filtration of CTAB-stabilized emulsions through pSPMK-modified membranes gives minimal oil rejection, presumably due to the brush collapse. Thus, the fouling resistance of polyelectrolyte brush-modified membranes clearly depends on the surfactant composition in a particular emulsion