Gryzelda Poźniak

Modification of polysulfone membranes 4. Ammonia plasma treatment

Abstract The effect of NH3 and NH3/Ar plasma on ultrafiltration polysulfone membranes have been studied. Results of contact angle, FTIR–ATR and X-ray photoelectron spectroscopy experiments clearly showed that both plasmas introduced hydrophilic, nitrogen- and oxygen-containing moieties on the polymer surface and that NH3/Ar plasma was more efficient. That plasma was also more aggressive––signs of strong etching could be seen on the SEM pictures. Redeposition of etched material seemed to take place inside the pores. On the contrary, ammonia plasma was soft and caused cleaning the surface and pores enlargement. Performance of ammonia plasma modified membranes was greatly improved and independent on solution pH. The last observation proved amphoteric character of the surface. NH3/Ar plasma treatment gave membranes of acidic surface and filtration indices not so good as for ammonia plasma.

Urease immobilized on modified polysulphone membrane : preparation and properties

Porous asymmetric membranes were formed by the phase inversion method from one-to-one blends of polysulphone and its aminated derivative. Amino groups were introduced into polysulphone UDEL P 1700 by chlorosulphonation followed by amination. Urease was immobilized on the modified polysulphone membranes. The properties of the immobilized urease were investigated and related to the free enzyme. The Michaelis constant was 4.4 times higher for the immobilized than for the free urease. Immobilization improved the pH stability of the enzyme at pH < 6.5 as well as its temperature stability. However, the immobilization did not protect the enzyme against heat inactivation at 70 degrees C; the half-times for the activity decay were equal to 120 and 50 min for the free and immobilized enzymes, respectively. The immobilized urease exhibited good storage and operational stability, and good reusability, properties that prove the applicability of the obtained system in enzymatic-membrane reactors.

Plasma modified polymers as a support for enzyme immobilization II. Amines plasma

Polysulfone films were modified by ammonia, n-butylamine and allylamine remote plasma using various sample-toplasma distances. Contact angle measurements, FTIR-ATR and XPS spectroscopy proved the presence of polar, including amine, groups on the modified surface. Presence of argon in the plasma environment made the plasma more stable and in most cases left the surface more hydrophilic but with a lower amount of nitrogen moieties on it. Glucose isomerase was successfully immobilized on the plasma-treated samples. Its activity correlates well with the concentration of C–N bonds on the surface. The highest enzyme activity was achieved for samples treated with allylamine/Ar plasma close to the plasma edge. � 2003 Elsevier Ltd. All rights reserved.

Plasma modified polymers as a support for enzyme immobilization 1. Allyl alcohol plasma

The paper describes deposition of plasma polymerized allyl alcohol on polysulfone film. It is shown that film surface becomes more hydrophilic after plasma treatment independently on presence of argon in a reaction mixture. The chemistry of the new surface layer was established by FTIR-ATR and ESCA spectroscopy. The substrate placed close to the plasma edge was the most hydrophilic but the amount of hydoxyl groups was not the highest there. Presence of argon stabilized the plasma but the deposited layer contained relatively less oxygen-bearing functionalities. The plasma treated polymer was subjected to xylose isomerase immobilization. For this purpose the divinylsulfone method was adapted. The studies revealed no correlation between the surface hydrophilicity and efficiency of immobilization.

Ultrafiltration membranes from polysulfone/aminated polysulfone blends with proteolytic activity

Abstract Ultrafiltration membranes with “self-cleaning” ability are presented in this work. Porous asymmetric membranes were formed by the phase inversion method from one-to-one blends of polysulfone and its aminated derivative. The characteristics of trypsin immobilized by static and dynamic sorption with cross-linking by glutaraldehyde was carried out using N-α-benzoil- l -arginine ethyl ester (BAEE). The self-cleaning properties are demonstrated in experiments where proteolytic membranes were used for concentration of casein solution. The essential improvement of ultrafiltration flux can be observed as a result of hydrolysis of protein blocking membrane pores.

N-butylamine plasma modifying ultrafiltration polysulfone membranes

Abstract Some properties of ultrafiltration polysulfone membranes modified with n-BuNH2 and n-BuNH2/Ar plasmas were studied. Contact angle measurements, XPS and SEM were used to characterize the surface changes. Pore size estimation, water transport and filtration parameters helped to describe changes in filtration performance. Presence of argon in plasma environment stabilized plasma but made it more aggressive; pore size increased and surface etching took place. This plasma grafted a smaller number of nitrogen features — most of them in the form of amine. Excellent filtration performance was observed for BuNH2/Ar plasma-modified membranes in an acidic environment.

SEPARATION OF HUMIC SUBSTANCES BY POROUS ION-EXCHANGE MEMBRANES FROM SULFONATED POLYSULFONE

Abstract Ultrafiltration involving sulfonated polysulfone membranes provides high efficiency for humic matter removal from water. The increase in ion-exchange capacity of the polymer matrix from 0.24 to 0.96 mmol SO3H groups per 1 g of dry membrane increases the membrane pore diameter and its hydrophilicity, and thus the permeate flux from 0.05 to 3.69 m3/m2·d. In order to decrease the manufacturing cost, membranes from polysulfone and sulfonated polysulfone blends were investigated. It was shown that a one-to-one blend resulted in a membrane having similar antifouling properties to pure sulfonated polysulfone. Both membranes reject humic matter in the 91–98% range and show a flux decline of 5–30% as a result of surface fouling.

Properties of Interpolymer PESS Ion-Exchange Membranes in Contact with Solvents of Different Polarities

Abstract PESS membranes with sulfonic ion-exchange groups were prepared by chemical modification of a polyethylene/poly(styrene-co-divinylbenzene) interpenetrating polymer network with varying content of the crosslinking agent (DVB). PESS membranes were loaded with different alkali metal ions as counterions. Swelling and pervaporation properties of these membranes in contact with water and aliphatic alcohols were obtained. The obtained data show that properties of PESS membranes depend strongly on the kind of counterions, the degree of crosslinking, and the solvent polarity.

The effect of bacteriophages T4 and HAP1 on in vitro melanoma migration

BackgroundThe antibacterial activity of bacteriophages has been described rather well. However, knowledge about the direct interactions of bacteriophages with mammalian organisms and their other, i.e. non-antibacterial, activities in mammalian systems is quite scarce. It must be emphasised that bacteriophages are natural parasites of bacteria, which in turn are parasites or symbionts of mammals (including humans). Bacteriophages are constantly present in mammalian bodies and the environment in great amounts. On the other hand, the perspective of the possible use of bacteriophage preparations for antibacterial therapies in cancer patients generates a substantial need to investigate the effects of phages on cancer processes.ResultsIn these studies the migration of human and mouse melanoma on fibronectin was inhibited by purified T4 and HAP1 bacteriophage preparations. The migration of human melanoma was also inhibited by the HAP1 phage preparation on matrigel. No response of either melanoma cell line to lipopolysaccharide was observed. Therefore the effect of the phage preparations cannot be attributed to lipopolysaccharide. No differences in the effects of T4 and HAP1 on melanoma migration were observed.ConclusionWe believe that these observations are of importance for any further attempts to use bacteriophage preparations in antibacterial treatment. The risk of antibiotic-resistant hospital infections strongly affects cancer patients and these results suggest the possibility of beneficial phage treatment. We also believe that they will contribute to the general understanding of bacteriophage biology, as bacteriophages, extremely ubiquitous entities, are in permanent contact with human organisms.

Tubular interpolymer ion-exchange membranes. Donnan dialysis through strong-base membranes

Abstract Strong-base tubular membranes prepared from the system polyethylene/poly (styrene-co-divinylbenzene)[PE/poly(St-co-DVB)] were tested in a Donnan dialysis process. The membranes had various amounts of DVB—0.5, 2 and 10 wt.%—in the aromatic component of the polymeric material and various types of functional groups—trimethylamine (TMA), triethylamine (TEA), dimethylaminoethanol (DMAE) and diethylaminoethanol (DEAE). Transport properties of the membranes were examined in the system 0.01 M HCl ¦membrane¦ 1 M NaOH to determine the OH− ion interdiffusion coefficient, rate of dialysate deacidification and flux of Na + ions in the temperature range 25–55°C. It was found that the efficiency of Donnan dialysis depended on the type and molar concentration of functional groups and on the DVB content. The best results, i.e., reasonable rate of dialysate deacidification with low co-ion flux from concentrated to dilute solution, were obtained at 35°C for the membrane with TMA groups and 2% of DVB.