Development of molecularly imprinted polymer membranes with specificity to triazine herbicides, prepared by the "surface photografting" technique

Development of molecularly imprinted polymer membranes with specificity to triazine herbicides, prepared by the "surface photografting" technique

«Surface photografting» of polypropylene (PPy) microporous membranes by molecularly imprinted polymers selective to triazine herbicides has been carried out by the UV irradiation-initiated co-polymerization of the functional monomer (2-acrylamido-2-methyl-1-propane sulphonic acid) and a cross-linker...

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Datum:2004
Hauptverfasser: Sergeyeva, T.A., Matuschewski, H., Piletsky, S.A., Schedler, U., Ulbricht, M.
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Sprache:English
Veröffentlicht: Інститут молекулярної біології і генетики НАН України 2004
Schriftenreihe:Біополімери і клітина
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Структура та функції біополімерів
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spelling irk-123456789-1579852019-06-23T01:25:09Z Development of molecularly imprinted polymer membranes with specificity to triazine herbicides, prepared by the "surface photografting" technique Sergeyeva, T.A. Matuschewski, H. Piletsky, S.A. Schedler, U. Ulbricht, M. Структура та функції біополімерів «Surface photografting» of polypropylene (PPy) microporous membranes by molecularly imprinted polymers selective to triazine herbicides has been carried out by the UV irradiation-initiated co-polymerization of the functional monomer (2-acrylamido-2-methyl-1-propane sulphonic acid) and a cross-linker (N,N?-methylene-bis-acrylamide) in the presence of the template (terbumeton) onto photoinitiator (benzophenone)-coated samples. The grafting reaction occurs in a thin liquid layer on the membrane substrate, which is pre-soaked in a dimethyl formamide solution containing template, functional monomer and cross-linker. After irradiation with a 500 W mercury lamp for 10 min at room temperature, the membranes covered with the layer of imprinted polymer were obtained. The recognition sites complementary to terbumeton were formed in the membranes after extraction of the template molecules with methanol. Alternatively, reference polymeric membranes were prepared with the same monomer composition, but without the template. The membranes' recognition properties were estimated by their capability to herbicide adsorption from its aqueous solution. The membranes modified by the mixture of monomers containing terbumeton showed significantly higher adsorption capability to this herbicide than to analogous compounds (terbuthylazine, atrazine, desmetryn, metribuzine). The effect of the polymer composition on the binding properties of the membranes has been investigated. High affinity of these membranes to triazine herbicides together with their inexpensive preparation, provide a good basis for applications of molecularly imprinted polymer membranes in separation and solid-phase extraction. Синтезовано новий тип матричних полімерних мембран шля­хом поверхневої модифікації мікрофільтраційних поліпропі­ ленових мембран, яка полягала в нанесенні на поверхню тонкого шару матричного полімеру, селективного до триазинового гербіциду тербуметону. Матричну полімеризацію здійснювали в диметилформаміді, використовуючи гербіцид тербуметон як матрицю, 2-акриламідо-2-метил-1-пропан-сульфонову І метакрилову І акрилову кислоту як функціональний мономер і N ,N' -метилен-бісакриламід як зшивальний агент на поверхні мікрофільтраційної мембрани, покритої тонким ша­ром фотоініціитора бензофенону. Екстракція матричних мо­лекул спричинювала формування в структурі мембрани сай­тів, які за формою та проепюровим розташуванням функ­ціональних груп були комплементарними тербуметону. Конт­рольні мембрани модифікували з використанням подібної су­міші мономерів, що не містила тербуметону. Здатність мембран до селективної адсорбції тербуметону досліджено в залежності від типу та концентрації функціонального моно­мера, а також від концентрації зшивального агента в мономерній суміші. Показано, що тербуметон-імпринтовані мат­ричні полімерні мембрани характеризуються високою селек­тивністю стосовно тербуметону та здатністю до незначної адсорбції його структурних аналогів — тертбутилазину, атразину, десметрину і метрибузину. Такі властивості синтезо­ваних мембран забезпечують їхнє ефективне використання у твердофазовій екстракції. Синтезирован новый тип матричных полимерных мембран методом поверхностной модификации микрофильтрационных полипропиленовых мембран, заключающемся в нанесении на поверхность тонкого слоя матричного полимера, селективно­го к триазиновому гербициду тербуметону. Матричную поли­меризацию проводили в диметилформамиде с использованием триазинового гербицида тербуметона в качестве матрицы, 2-акриламидо-2-метил-1-пропан-сульфоновойї метакриловой акриловой кислоты как функционального мономера и N,N'-метилен-би сак рилам ида как сшивающего агенпш на поверхности микрофильтрационной мембраны, покрытой тонким слоем фотоинииштюра бензофенона. Экстракция матричных моле­кул приводила к формированию в структуре мембраны сай­тов, комплементарных тербуметону по форме и простран­ственному расположению функциональных групп. Контроль­ ные мембраны синтезоровали с использованием той же моно­мерной смеси в отсутствие тербуметона. Способность мем­ бран к селективной адсорбции тербуметона исследовали в зависимости от типа и концентрации функционального моно­мера, а также концентрации сшивающего агента, в мономер­ной смеси. Показано, что тербуметон-импринтированные матричные полимерные мембраны характеризуются высокой селективностью к тербуметону и демонстрируют незначительную адсорбцию его структурних аналогов — тертбутилазина, атразина, десметрина и метрибузина. Такие свойства синтезованных мембран обеспечивают возможность их эф­фективного использования в твердофазной экстракции. 2004 Article Development of molecularly imprinted polymer membranes with specificity to triazine herbicides, prepared by the "surface photografting" technique / T.A. Sergeyeva, H. Matuschewski, S.A. Piletsky, U. Schedler, M. Ulbricht // Біополімери і клітина. — 2004. — Т. 20, № 4. — С. 307-315. — Бібліогр.: 26 назв. — англ. 0233-7657 DOI:http://dx.doi.org/10.7124/bc.0006B4 http://dspace.nbuv.gov.ua/handle/123456789/157985 544.725 + 544.722.21 + 577.21 en Біополімери і клітина Інститут молекулярної біології і генетики НАН України
institution Digital Library of Periodicals of National Academy of Sciences of Ukraine
collection DSpace DC
language English
topic Структура та функції біополімерів
Структура та функції біополімерів
spellingShingle Структура та функції біополімерів
Структура та функції біополімерів
Sergeyeva, T.A.
Matuschewski, H.
Piletsky, S.A.
Schedler, U.
Ulbricht, M.
Development of molecularly imprinted polymer membranes with specificity to triazine herbicides, prepared by the "surface photografting" technique
Біополімери і клітина
description «Surface photografting» of polypropylene (PPy) microporous membranes by molecularly imprinted polymers selective to triazine herbicides has been carried out by the UV irradiation-initiated co-polymerization of the functional monomer (2-acrylamido-2-methyl-1-propane sulphonic acid) and a cross-linker (N,N?-methylene-bis-acrylamide) in the presence of the template (terbumeton) onto photoinitiator (benzophenone)-coated samples. The grafting reaction occurs in a thin liquid layer on the membrane substrate, which is pre-soaked in a dimethyl formamide solution containing template, functional monomer and cross-linker. After irradiation with a 500 W mercury lamp for 10 min at room temperature, the membranes covered with the layer of imprinted polymer were obtained. The recognition sites complementary to terbumeton were formed in the membranes after extraction of the template molecules with methanol. Alternatively, reference polymeric membranes were prepared with the same monomer composition, but without the template. The membranes' recognition properties were estimated by their capability to herbicide adsorption from its aqueous solution. The membranes modified by the mixture of monomers containing terbumeton showed significantly higher adsorption capability to this herbicide than to analogous compounds (terbuthylazine, atrazine, desmetryn, metribuzine). The effect of the polymer composition on the binding properties of the membranes has been investigated. High affinity of these membranes to triazine herbicides together with their inexpensive preparation, provide a good basis for applications of molecularly imprinted polymer membranes in separation and solid-phase extraction.
format Article
author Sergeyeva, T.A.
Matuschewski, H.
Piletsky, S.A.
Schedler, U.
Ulbricht, M.
author_facet Sergeyeva, T.A.
Matuschewski, H.
Piletsky, S.A.
Schedler, U.
Ulbricht, M.
author_sort Sergeyeva, T.A.
title Development of molecularly imprinted polymer membranes with specificity to triazine herbicides, prepared by the "surface photografting" technique
title_short Development of molecularly imprinted polymer membranes with specificity to triazine herbicides, prepared by the "surface photografting" technique
title_full Development of molecularly imprinted polymer membranes with specificity to triazine herbicides, prepared by the "surface photografting" technique
title_fullStr Development of molecularly imprinted polymer membranes with specificity to triazine herbicides, prepared by the "surface photografting" technique
title_full_unstemmed Development of molecularly imprinted polymer membranes with specificity to triazine herbicides, prepared by the "surface photografting" technique
title_sort development of molecularly imprinted polymer membranes with specificity to triazine herbicides, prepared by the "surface photografting" technique
publisher Інститут молекулярної біології і генетики НАН України
publishDate 2004
topic_facet Структура та функції біополімерів
url http://dspace.nbuv.gov.ua/handle/123456789/157985
citation_txt Development of molecularly imprinted polymer membranes with specificity to triazine herbicides, prepared by the "surface photografting" technique / T.A. Sergeyeva, H. Matuschewski, S.A. Piletsky, U. Schedler, M. Ulbricht // Біополімери і клітина. — 2004. — Т. 20, № 4. — С. 307-315. — Бібліогр.: 26 назв. — англ.
series Біополімери і клітина
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fulltext ISSN 0233-7657. Біополімери і клітина. 2004. Т. 20. № 4 Development of molecularly imprinted polymer membranes with specificity to triazine herbicides, prepared by the «surface photografting» technique T. A. Sergeyeva1, H. Matuschewski2, S. A. Piletsky1 3 , U. Schedler2, M. Ulbricht4 Institute of Molecular Biology and Genetics National Academy of Sciences of Ukraine 150 vul. Acad. Zabolotnoho, Kyiv, 03143 , Ukraine 2 Poly-An GmbH Rudolf-Baschant-Str. 2, 13086 Berlin, Germany 3 Institute of Bioscience and Technology, Cranfield University at Silsoe Bedfordshire, MK45 4 DT, UK 4 Universitat Duisburg-Essen Universitat-Str. 5, 45117 Essen, Germany E-mail: t_sergeyeva@yahoo.co.uk «Surface photografting» of polypropylene (PPy) microporous membranes by molecularly imprinted polymers selective to triazine herbicides has been carried out by the UV irradiation-initiated co- polymerization of the functional monomer (2-acrylamido-2-methyl-l-propane sulphonic acid) and a cross-linker (N,N'-methylene-bis-acrylamide) in the presence of the template (terbumeton) onto pho- toinitiator (benzophenone)-coated samples. The grafting reaction occurs in a thin liquid layer on the membrane substrate, which is pre-soaked in a dimethyl formamide solution containing template, functional monomer and cross-linker. After irradiation with a 500 W mercury lamp for 10 min at room temperature, the membranes covered with the layer of imprinted polymer were obtained. The recognition sites complementary to terbumeton were formed in the membranes after extraction of the template molecules with methanol. Alternatively, reference polymeric membranes were prepared with the same monomer composition, but without the template. The membranes' recognition properties were estimated by their capability to herbicide adsorption from its aqueous solution. The membranes modified by the mixture of monomers containing terbumeton showed significantly higher adsorption capability to this herbicide than to analogous compounds (terbuthylazine, atrazine, desmetryn, metribuzine). The effect of the polymer composition on the binding properties of the membranes has been investigated. High affinity of these membranes to triazine herbicides together with their inexpensive preparation, provide a good basis for applications of molecularly imprinted polymer membranes in separation and solid-phase extraction Introduction. In many applications of bioorganic and environmental chemistry it is desirable to utilize a membrane filter, which is mechanically strong, ther­ mally stable, insoluble in most organic solvents, relatively inert chemically and has affinity to certain analyte [1—3]. The binding properties of affinity membranes are determined by specific receptor-ligand interactions. However, synthesis of the membranes selective for a broad range of neutral molecules is challenged by the difficulty of incorporating specific © T A SERGEYEVA, H. MATUSCHEWSKI, S A PILETSKY, U. SCHEDLER, M. ULBRICHT, 2 0 0 4 receptors for such molecules. Therefore, the develop­ ment of synthetic membranes , which possess the selectivity of natural receptors and stability of syn­ thetic polymers in harsh environments , is of great importance. Recently, a considerable attention has been paid to the development of molecular imprinting technique, which allows one to obtain synthetic po­ lymers mimicking biological receptors [4—6 ]. Ac­ cording to this approach, highly cross-linked polymers are formed around a template molecule. The template is then removed leaving cavities capable of binding template molecules back. As widely recognized, mo- 307 mailto:t_sergeyeva@yahoo.co.uk SERGEYEVA Т. A. ET AJL lecularly imprinted polymers (MIPs) can provide high selectivity to low-molecular weight compounds [7—8 ], very good thermal and mechanical stability [9 ], their production is inexpensive. Polymers of this type have been used as sta­ t ionary-phase materials to make highly selective liq­ uid chromatography columns [10] , as substitutes for antibodies in competitive binding assays [11—13], and as selective elements of chemical sensors [14] . Chromatographic and SPE applications traditionally utilize МІР particles prepared by grinding and sieving of synthesized polymer blocks or the particles pre­ pared by suspension polymerization. T h e first ap­ proach is time consuming, may lead to the destruction of some binding sites in the polymer and produces a relatively low yield of the fraction with a narrow size distribution. In the second approach, the choice of monomers is limited to those, which are not soluble in the dispersion phase. Additionally the synthesized beads are not always uniform in their shape and size. Thus , again a sieving procedure is required which makes column packing t ime-consuming, expensive and ineffective. Use of polymer particles of a small size in chromatography is also associated with too high backpressure. Therefore, the method of mo­ lecular imprinting was also combined with the mem­ brane technology in order to develop new generation of stable affinity membranes for the separation of the target molecules from a mixture of structurally similar compounds [15—17] . However, the high selectivity and stability of these membranes were shaded by their ineffective performance, particularly due to small fluxes. Typically, the fluxes observed were not larger than 10~4 mo l -m" 2 -h _ 1 [18] . This effect can be related to the high degrees of cross-linking of MIPs, which is a prerequisite for the imprinted membranes selectivity. Other approaches to the synthesis of affinity membranes are chemical or the photografting of a thin layer of the imprinted polymer to the surface of a porous membrane . The re have been two recent re­ ports on the polymers [19] and membranes [20] grafted with MIPs. In the last case the laboratory- made membranes from photo-reactive polymer (poly- acrylonitrile-co-diethylaminodithiocarbamoyl methyl- sty rene) were grafted with acrylic acid and N , N ' - methylene-bis-acrylamide in the presence of theo­ phylline yielding theophylline-specific membranes . Unfortunately, the use of a special polymer for the membranes formation together with long reaction times for МІР functionalization (24 h) substantially reduce the areas of the membranes ' applications. Much more efficient method for the membrane surface functionalization is currently being explored [21 ]. The aim of the present research is the develop­ ment of a general method for molecular imprinting the surface of a stable synthetic polymer membrane. Surface photograft co-polymerization in the presence of a template should introduce specific binding sites into the porous membrane without damaging its pore structure and, thus , preserving its t ransport pro­ perties. T h e present paper describes the procedure of modification of commercially available microporous membranes with a herbicide-imprinted polymer using technique of «surface photografting» from organic solvents. This substantially broadens the number of potential templates allowing one to use a wide range of substances poorly soluble in aqueous environment. The membranes modified with the imprinted poly­ mers possess high selectivity to the analyte without significant change in their original permeability. Materials and Methods. Polypropylene (PPy) and polyamide (PA) membranes (Accurel PP 2E HF, nominal pore size dp = 0.2 jum; membrane thickness dm = 1 5 0 jum) were purchased from Akzo Nobel. Acrylic acid (AA), methacrylic acid (MA) and 2- a c r y l a m i d o - 2 - m e t h y l - l - p r o p a n e s u l p h o n i c acid (AMPS) were obtained from «Aldrich» (USA), benzo- phenone (BP) and N,N'-methylene-bis-acrylamide were purchased from «Мегск» (Germany) . Terbu­ meton, desmetryn, terbutylazin (NMR, HPLC grade) were obtained from «Sigma» (USA). All other che­ micals and solvents (HPLC grade) were obtained from the commercial sources and used as received without further purification. Preparation of membranes modified by mole- cularly imprinted polymers. Circular PPy or PA mem­ brane samples (A = 5 cm 2 ) were extracted with chlo­ roform in Soxhlet apparatus during 4 h, dried and weighted. The membranes were then pre-soaked in 0.15 M solution of BP in acetone for 5 min and dried under vacuum. The pre-coated with photoinitiator membranes were transferred to a dimethyl formamide (DMF) solution, containing 10 mM of terbumeton, 50 mM of functional monomer (acrylic, methacrylic or 2 -acry lamido-2-methy 1-1 -propane sulphonic acid) , 150—500 mM of N,N' -methylene-bis-acrylamide. To prevent desorption of the photoinitiator from pre­ viously coated membranes 5 mM of BP was added to the monomer mixture. The pre-soaked for 5 min in the monomer mixture membranes were then UV irradiated on a pilot-scale UV curing system (500 W mercury lamp; Beltron G m b H , Germany) for 10 cycles (1 cycle = 1 min) . To remove the homopolymer, residual chemicals and template, the resulting mem­ branes were extracted by hot methanol in Soxhlet apparatus for 2 hours. After drying the membranes 308 D E V E L O P M E N T OF MOLECULARLY IMPRINTED POLYMER MEMBRANES were weighted again and the degree of modification (DM) was calculated from weight differences. Membranes' characterization. The binding pro­ perties of the membranes were estimated by their capability to herbicide adsorption from its aqeous solution. Adsorption of the herbicide from water by the membrane was estimated in filtration experiments using syringe connected to a filtration cell holder (d = = 25 mm, «Schleicher & Schulb , Germany) . In the adsorption experiments 10 ml of 5 10" 7—10~ 4 M herbicide solution were filtered through the mem­ branes, typically at a ra te of 10 ml /min . The filtrate was extracted with 10 ml of chloroform. The herbicide concentrations in both feed and permeate solutions were determined by gas chromatography after the extraction procedure using Hewlet Packard GC sys­ tem HP 6890 with the mass selective detector HP 5973 (column HP5MS). Results and Discussion. During the last decades, within the field of surface modification of various substrates, photografting from organic solvents has received wide attention [22—25]. In general, such technique has involved immersion of the substrate to be grafted in a solution of monomer in an organic solvent, and subsequent exposure to irradiation. Such photo-induced grafting is accompanied by extensive homopolymerization and often causes uneven modi­ fication of the substrate surface. Recently Ranby et al. have proposed a new method of «surface photo- 1. The scheme of the «sur- photografting» modificati- of the porous membrane molecularly imprinting po- grafting» for polymer modification, where the sub­ strate is pre-soaked in a solution of monomer and then UV-irradiated in an inert a tmosphere [26]. According to this technique, the grafting reaction occurs in a thin layer of the solution on the substrate surface. Little homopolymerization occurs under these grafting conditions and small amounts of the formed homopolymer can be removed by the washing proper procedure. To modify PPy and PA membranes by a thin layer of the imprinted polymer, the method of «sur- face photografting» has been applied. The main reason for this is very high reactivity of the cross- linker (N,N'-methylene-bis-acrylamide) and a prob­ lem of its homopolymerization in heterogeneous reac­ tion systems. This generally leads to low degrees of the membranes ' modification, poor reproducibility and difficulty in recovering copolymer in the non- contaminated form, especially at high grafting yields. The scheme of the «surface photografting» modifi­ cation of the porous membrane with МІР is presented in the Fig. 1. In this polymerization scheme, the stabilizing effect of highly cross-linked molecularly imprinted polymer in a combination with a flexible, chemically inert and wide pore PPy or PA membrane is utilized. It is reasonable to assume, that the composition of the monomer mixture determines the ability of the resulting membranes to bind the template selectively 309 S ERG EYE V А Т. A. ET AL. 14 12- ^ 10 6- AA MA AMPS Fig. 2. Influence of the type of the functional monomer on the specific adsorption of terbumeton on the imp­ rinted membranes, 10 ml of 10~ 5 M aqueous solution of terbumeton was used in filtration experiments (see note to the Table) and , thus — the membranes adsorption capacity. Therefore, the influence of the type and concentration of the functional monomer and cross-linker, as well as the template concentration in the monomer mixture, on the ability of the modified membranes to effective adsorption of the template has been investigated. Influence of a type of the functional monomer on the membranes adsorption capability. Modification of the PPy membranes with imprinted polymers was performed using acrylic, methacrylic or 2-acrylamido- 2-methyl- l -propane sulphonic acids as functional mo­ nomers and N,N ' -methy lene-b i s -acry lamide as a cross-linker. Triazine herbicide terbumeton was used as a model template in the present research. A set of the imprinted and reference membranes with AA, MA or AMPS as functional monomers has been obtained and tested in filtration experiments. AA and MA were demonstrated to be ineffective as functional mono­ mers. The imprinted membranes prepared in the presence of AA and MA as functional monomers demonstrated either the same or lower adsorption capability as reference ones. T h e membranes imp­ rinted with terbumeton and prepared in the presence of AMPS as a functional monomer demonstrated significantly higher adsorption capability than the reference membranes of the same composition (Fig. 2) . It is assumed that AMPS as a strong acid (pKa< < 1) can protonate terbumeton (pKa = 4.2) and an ion-pair complex is formed between the template and AMPS in the initial monomer mixture. For weaker acidic monomers MAA (pKa = 4.65) and AA (pKa = = 4.2) this mechanism is less effective. This has been also confirmed by the investigations of the template- functional monomer complex formation by UV-dif- ference spectroscopy. These data verify that the complex AMPSA-terbumeton is significantly stronger (K d i s = 3.0 10~5 ± 0.3 10" 5 M) as compared to AA (K d i s = 2 . 0 1 0 " 4 ± 0.3-10" 4 M) a n d MAA (K d i s = = 8 . 0 1 0 " 5 ± 1 . 0 1 0 " 5 M). Influence of the cross-linker concentration on photografting and the membranes' adsorption capa­ bility. As widely recognized, the effective performance of the imprinted polymer is provided by high degrees of the polymer cross-linking. In this case, the selective cavities can retain their shapes even after extraction of the template. At the same time, a certain degree of the polymer chains ' flexibility is important to provide rapid equilibration with the template to be bind. Hence, the influence of a type and amount of the monomer and cross-linker in the monomer mixture used for the membranes modification on both the degree of modification and adsorption capability of the resulting membranes was investigated. The former was explored as a function of the cross-linker con­ centration (N,N'-methylene-bis-acrylamide) in the monomer mixture. The degree of the modification was shown to increase with the increase in the cross-linker con­ centration in the monomer mixture and to comprise 150—500/^g/cm 2 of membrane surface (Fig. 3, a). At the same time, the increase in MBAA concentration up to 225 mM caused also the increase in the membranes ' adsorption capability (Fig. 3 , b). How­ ever, further increase in the MBAA caused a decrease in the membranes ' adsorption capability. To increase the specific adsorption of the herbicide by МІР 310 D E V E L O P M E N T OF MOLECULARLY IMPRINTED POLYMER MEMBRANES § 500 14 12 10- Щ Fig. 3. Dependence of the degrees of modification of the imprinted (gray bars) and reference (white bars) membranes on the concentration of the cross-iinker in the monomer mixture (a). Dependence of the specific adsorption of terbumeton on the imprinted membranes on the concentration of the cross-linker in the monomer mix­ ture (b) (see note to the Table). Templa­ te — terbumeton, 10 mM, functional mo­ nomer — 2-acrylamido-2-methyl-l-pro­ pane sulphonic acid, 50 mM, cross-lin­ ker — N,N'-methylene-bis-acrylamide, 150—400 mM 60 Fig. 4. Dependence of the specific ad­ sorption of terbumeton on МІР membranes on the concentration of the functional monomer in the monomer mixture (see note to the Table). Template — terbu­ meton, 10 mM, functional monomer — 2 -acry lamido-2 -methy l - l -propane sul­ phonic acid, 0—80 mM, cross-linker — N,NT'-methylene-bis-acrylamide, 225 mM 311 SERGEYEVA Т. A ET AL. 5 10 Terbumeton, mM Fig. 5. Dependence of the specific ad­ sorption of terbumeton on МІР mem­ branes on the concentration of the tem­ plate in the monomer mixture (see note to the T a b l e ) . Template — terbumeton, 0 .5—20 mM, functional monomer — 2- acrylamido-2-methyl-l -propane sulphonic acid, cross-linker — N,N'-methylene-bis- acrylamide, 2 2 5 mM. Ratio templa- te:functional monomer = 1:5 Influence of the support on a degree of modification (DM) and adsorption capability of terbumeton-imprinted (МІР) and reference (Blank) membranes (the monomer mixture, containing 10 mM terbumeton, 10 mM 2-acrylamido-2-methyl-l-propane sulphonic acid and 225 mM-N,N'-methylene-bis-acrylamide was used for modification of МІР membranes; Blank membranes were prepared with the same monomer composition, but without the template) Support PA, P P y , ,um Support МІР Blank МІР Blank DM, rag/cm2 443.4 510 277 261 Specific adsorption, nmol/cm 2 0 0 12.5 12.5 N o t e . The value of specific adsorption corresponds to the difference t one, prepared with the same monomer composition but in the absence с either to the cases of the same adsorption of terbumeton on МІР and terbumeton on reference membranes. membranes , i. e. to decrease the level of nonspecific binding, the other cross-linker (trimethylolpropan trimethacrylate) was used. Although the degrees of modification were higher, than in the case of N , N ' - methyiene-bis-acrylamide, the values of specific ad­ sorption were twice lower. This indicates, that high degrees of modification together with excessive deg­ rees of cross-linking are not necessary for the ef­ fective performance of МІР membranes . Evidently, at these conditions most of the template molecules are trapped in the excessively cross-linked domains of imprinted polymer and not accessible for the reac­ tions, which results in a decreased amount of the binding sites. Structure of the binding sites. T h e AMPS con­ centration in the monomer mixture was varied to optimize the ratio between the template and a func­ tional monomer used for the membranes ' modifi­ cation. No difference between adsorption capability of imprinted and reference membranes was obtained in the absence of AMPS in the monomer mixture or when its concentration was too low (10 mM). Ob- >etween terbumeton adsorption on а МІР membrane and a reference )f the template. The «zero» values of specific adsorption correspond reference membranes or to the cases of preferential adsorption of viously, these ratios yield the imprinted polymers with insufficient extents of the template complexation and, thus , low number of binding sites. Use of AMPS in concentrations of 10—50 mM produced МІР mem­ branes with the improved adsorption capability as compared to reference ones. However, the further increase in AMPS concentration (60—80 mM) leads to formation of the membranes with too high degrees of non-specific binding (Fig. 4) . Apparently, this can be explained by an abundance of the polar functional groups distributed randomly throughout the polymer matrix, that results in the reduced selectivity. Influence of the template concentration. To define the optimal number of binding sites in the resulting membranes , influence of the template concentration on the membrane adsorption capability has been studied. The highest value of specific adsorption was observed at the template concentration of 10 mM. Both decrease and increase in the template concen­ tration resulted in either lower or no imprinting effects (Fig. 5) . Evidently, a decrease in the template concentration results in the insufficient number of the 312 D E V E L O P M E N T OF MOLECULARLY IMPRINTED POLYMER MEMBRANES Fig. 6. Selectivity of the terbumeton-im- printed membrane. Template-terbumeton, 10 mM, functional monomer — 2-acrylami- do-2-methyl-l -propane sulphonic acid, 50 mM, cross-linker — N,N'-methylene-bis- Terbumeton Desmetryn Metribuzine Atrazine Tertbuthylazine acrylamide, 225 mM imprinted sites in the polymer. No imprinting effect at 20 mM of terbumeton in the monomer mixture can be explained by its ability to form aggregates in the solution of high concentrations, that results in for­ mation of the increased number of non- and weakly- selective binding sites. Influence of the support. Importantly, PA mem­ branes modified by the molecularly imprinted poly­ mer layer under optimized conditions, demonstrated higher degree of modification as compared to PPy membranes. However, no improvement in the her­ bicide binding was achieved. Practically no difference or even preferential herbicide adsorption was ob­ served for reference membrane as compared to the imprinted one (Table) . This effect can be related to the increased ability of PA membranes to swell in organic solvents in contrast to PPy membranes . Since there is no swelling of PPy membranes in organic solvents, we can assume that the functionalization takes place in a thin layer on the entire surface of the membrane. In contrast to this, in the case of PA membranes the polymerization reaction takes place in the entire membrane volume, i. e. mainly in the swollen PA matrix. Therefore, the degrees of mo­ dification achieved under same conditions are sig­ nificantly higher for PA than for PPy (Table) . However, one can assume that most of the polymer entrapped in PA is not accessible for binding with the template molecules during the fast filtration step. From the other side, swelling of the support changes the three-dimensional configuration of the functional groups participating in the recognition process and may lead to the loss of selectivity. The other exp­ lanation can be interaction between amide func­ tionalities in the PA support and the functional monomer, that hinders binding the herbicide by the functional monomer. Specificity of molecularly imprinted polymer mem­ branes and their herbicide-binding efficiency. A series of terbumeton analogs were used to examine the selectivity of the obtained membranes . The capability of the terbumeton-imprinted membranes to bind her­ bicides of the related chemical s t ructure was tested in filtration exper iments . T h e te rbumeton- impr in ted membranes were shown to be capable of binding terbumeton analogs much less effectively than ter­ bumeton (Fig. 6) . It was demonstra ted that the terbumeton-imprinted membranes modified under the optimized conditions were able to recover 95—99 % of terbumeton from its 5-Ю" 7 —10~ 4 M aqueous so­ lutions (Fig. 7) . The adsorption capability of the terbumeton-imprinted membranes was determined in filtration experiments using saturat ion with 10~5 M solution of terbumeton. T h e value determined was 5 jug/cm2 ( - 2 2 n M / c m 2 ) , which corresponds to ap­ proximately 40 % of the theoretical value calculated from the degree of modification and the stochiometry of the template-functional monomer complex. The ­ refore, they can be successfully used for both water purification and herbicide pre-concentration in en­ vironmental analysis. Conclusions. The new type of composite membra­ nes, having artificial recognition sites for terbumeton, was prepared by «surface photografting» of 2-ac- ry lamido-2-methyl - l -propane sulphonic acid, N , N ' - methylene-bis-acrylamide in the presence of ter­ bumeton as a template on a benzophenon-coated polypropylene 0.2 jum membranes . The membranes imprinted with terbumeton demonst ra ted significantly higher adsorption capability to this herbicide than to analogous compounds ( terbuthylazine, atrazine, des­ metryn, and metribuzine). No affinity for terbumeton was observed for МІР-photografted polyamide mem­ branes , which indicates significant influence of the support on both the imprinting procedure and the process of template recognition. T h e type and con- 313 4.00 5.00 6.00 7.00 8.00 9.00 10.00 11.00 12.00 13.00 14.00 Tame, min Fig. 7. Chromatograms of the 10" 5 M terbumeton solution before (a) and after (b) filtration through the terbumeton-imprinted (МІР) membrane centration of the functional monomer as well as the concentration of cross-linker have a crucial influence on the resulting membranes ' adsorption capability. High affinity of these membranes to triazine her­ bicides together with their simple and inexpensive preparation, provides a good basis for the applications of imprinted polymers in separation, solid-phase ex­ traction, and in a pre-concentration step for the determination of photosynthesis-inhibit ing herbicides in water. Acknowledgements. Financial support from AIF, INTAS (grant YSF-00-25), and National Academy of Sciences of Ukraine is gratefully acknowledged. Т. А. Сергеева, X. Матушевскі, С. А. Пілецький, У. Шидлер, М. Ульбріхт Синтез матричних полімерних мембран, селективних до триазинових гербіцидів, методом «поверхневого фотографтингу» Резюме Синтезовано новий тип матричних полімерних мембран шля­ хом поверхневої модифікації мікрофільтраційних поліпропі­ ленових мембран, яка полягала в нанесенні на поверхню тонкого шару матричного полімеру, селективного до три- азинового гербіциду тербуметону. Матричну полімеризацію здійснювали в диметилформаміді, використовуючи гербіцид тербуметон як матрицю, 2-акриламідо-2-метил-1-пропан- сульфонову І метакрилову І акрилову кислоту як функціональний мономер і N ,N' -метилен-бісакриламід як зшивальний агент на поверхні мікрофільтраційної мембрани, покритої тонким ша­ ром фотоініціитора бензофенону. Екстракція матричних мо­ лекул спричинювала формування в структурі мембрани сай­ тів, які за (/юрмою та проепюровим розташуванням функ­ ціональних груп були комплементарними тербуметону. Конт­ рольні мембрани модифікували з використанням подібної су­ міші мономерів, що не містила тербуметону. Здатність мембран до селективної адсорбції тербуметону досліджено в залежності від типу та концентрації функціонального моно­ мера, а також від концентрації зшивального агента в моно- мерній суміші. Показано, що тербуметон-імпринтовані мат­ ричні полімерні мембрани характеризуються високою селек­ тивністю стосовно тербуметону та здатністю до незначної адсорбції його структурних аналогів — тертбутилазину, ат- разину, десметрину і метрибузину. Такі властивості синтезо­ ваних мембран забезпечують їхнє ефективне використання у твердофазовій екстракції. Т. А. Сергеева, X. Матушевски, С. А. Пилецкий, У. Шидлер, М. Ульбрихт Синтез матричных полимерных мембран, селективных к триазиновым гербицидам, методом «поверхностного фотографтинга» Резюме Синтезирован новый тип матричных полимерных мембран методом поверхностной модификации микрофильтрационных полипропиленовых мембран, заключающемся в нанесении на поверхность тонкого слоя матричного полимера, селективно­ го к триазиновому гербициду тербуметону. Матричную поли­ меризацию проводили в диметилформамиде с использованием триазинового гербицида тербуметона в качестве матрицы, 2-акриламидо-2-метил-1-пропан-сульфоновойї метакриловойї акриловой кислоты как функционального мономера и N,N'-ме­ тилен-би сак рилам ида как сшивающего агенпш на поверхности микрофильтрационной мембраны, покрытой тонким слоем фотоинииштюра бензофенона. Экстракция матричных моле­ кул приводила к формированию в структуре мембраны сай­ тов, комплементарных тербуметону по форме и простран­ ственному расположению функциональных групп. Контроль­ ные мембраны синтезоровали с использованием той же моно­ мерной смеси в отсутствие тербуметона. Способность мем­ бран к селективной адсорбции тербуметона исследовали в зависимости от типа и концентрации функционального моно­ мера, а также концентрации сшивающего агента, в мономер­ ной смеси. Показано, что тербуметон-импринтированные матричные полимерные мембраны характеризуются высокой селективностью к тербуметону и демонстрируют незначи­ тельную адсорбцию его структурних аналогов — тертбутила- зина, атразина, десметрина и метрибузина. Такие свойства синтезованных мембран обеспечивают возможность их эф­ фективного использования в твердофазной экстракции. REFERENCES 1. Kesting R. Е. Synthetic polymeric membranes. A structural perspective.—New York: John Willey and Sons, 1985.—573 p. 2. Schultz S. С Basic principles of membrane transport.— Cambridge: Univ. press, 1970.—391 p. 3. Minoura N., I del K, Rachkov A., Matsuda K. Molecularly imprinted polymer membranes with photo-regulated template binding / / Chem. Mater.—2003. — 1 5 . — P . 255—266. 4. Wulff C, Vietmeyer J., Poll H.-G. Influence of the nature of the cross-linking agent on the performance of imprinted polymers in racemic resolution / / Macromol. Chem.—1987.— 188.—P. 731—740. 5. Damen J.. Neckers I) C. On the memory of synthesized vinyl polymers for their origins / / Tetrahedron Lett. — 1 9 8 0 . — 2 1 . — P. '1913—1916. 314 D E V E L O P M E N T OF MOLECULARLY IMPRINTED POLYMER MEMBRANES 6. Ramstrom O., Andersson L. I., Mosbach K. Recognition sites incorporating both pyridinyl and carboxy functionalities pre­ pared by molecular imprinting / / J. Org. Chem.—1993.— 58 .—P. 7562—7564. 7. Ramstrom O., Nicholls I. A., Mosbach K. Synthetic peptide receptor mimics: highly stereoselective recognition in non- covalent molecularly imprinted polymers / / Tetrahedron Asym.—1994.—5.—P. 649—656 . 8. Siemann M., Andersson JL / . Mosbach K. Selective recognition of the herbicide atrazine by non-covalent molecularly imprinted polymers / / J. Agr. Food Chem.—1996.—44.—P. 141 — 145. 9. Svenson Nicholls I. A. On the thermal and chemical stability of molecularly imprinted polymers / / Anal. Chim. Acta.—2001.—435, N 1.—P. 19—24. 10. Wulff G.y Minarmk M. Template-imprinted polymers for HPLC separation of racemates / / J. Liq. Chromatogr.— 1991.—13. N 5 .—P. 2987—3000 . 11. Valtakis G., Andersson L. I., Mailer R.f Mosbach K. Drug assay using antibody mimics made by molecular imprinting / / Nature.—1993.—361.—P. 645—647. 12. Piletsky S. A., Piletskaya E. K, El'skaya A. V., Levi R., Yano K., Karube J. Optical detection system for triazines based on molecularly imprinted polymers / / Anal. Lett .—1997.—30.— p. 4 4 5 _ 4 5 5 . 13. Ramstrom O., Ye L., Mosbach K. Artificial antibodies to corticosteroids prepared by molecular imprinting / / Chem. Biol .—1996.—3.—P. 471—477. 14. Sergeyeva T. A., Piletsky S. A., Brovko A. A., Slinchenko E. A., Sergeeva L. M., Panasyuk T. L., El'skaya A. V. Conduc- tometric sensor for atrazine detection based on molecularly imprinted polymer membranes / / Analyst .—1999.—124.— P. 331—334. 15. Yoshikawa M., Izumi J., Kitao T.} Koya S., Sakamoto S. Molecularly imprinted polymeric membranes for optical resolu­ tion / / J. Membr. Sc i .—1995 .—108 .—P. 171 — 175. 16. Mathew-Krotz J., Shea K. J. Imprinted polymer membranes for the selective transport of targeted neutral molecules / / J. Amer. Chem. S o c — 1 9 9 6 . — 1 1 8 . — P . 8154—8155 . 17. Sergeyeva T. A., Piletsky S. A., Piletska E. V., Brovko O. 0.y Karabanova L. V., Sergeeva L. M.t El'skaya A. V., Turner A. P. F. In situ formation of porous molecularly imprinted polymer membranes / / Macromolecules.—2003.—36, N 19.— P. 7352—7357. 18. Hong J.-M., Anderson P. E., Qian J., Martin C. R. Selective­ ly-permeable ultrathin composite membranes based on mole­ cularly imprinted polymers / / Chem. Mater.—1998.—10.— P. 1029—1033. 19. Dhal P. K.t Vidyasankar S., Arnold F. H. Surface grafting of functional polymers to macroporous poly(trimethylopropane trimethacrylate) / / Chem. Mater .—1995.—7.—P. 154—162. 20. Wang H. Y., Kobayashi Т., Fuji N. Surface molecular imprint­ ing on photosensitive dithiocarbamoylpolyacrylonitrile mem­ branes using photograft polymerization III. Chem. Technol. and Biotechnol.—1997.—70, N 4 .—P. 355—362 . 21. Ulbricht M. Photo-graft polymer modified microporous mem­ branes with environment-sensitive permeabilities / / React. Funct. Po lym.—1996 .—31.—P. 165—177. 22. Tazuke S. Surface photografting. I. Graft polymerization of hydrophilic monomers onto various polymer films III. Polym. Sci.: Polym. Lett. E d . — 1 9 7 8 . — 1 6 . — P . 497—500 . 23. Bellobono I. R., Tolusso F.y Selli E. Photochemical grafting of acrylated azo dyes onto polymeric surfaces. I. Grafting of 4-(ethyl, N-2-acryloxyethyl)amino, 4'-nitro, azobenzen onto polyamide and polypropylene fibers III. Appl. Polym. Sci.— 1981 .—26.—P. 619—628 . 24. Ang С. H., Garnett J. L.y Levot R., Long M. A. Radiation and UV grafting of monomers to polyolefins and cellulose acetate. Significance of these studies in reagent insolubilization reac­ tions / / J. Macromol. Sci. Chem.—1982 .—A17 .—P. 87—98. 25. Pashova V. S., Georgiev G. S., Dakov V. A. Photoinitiated graft copolymerization of glicydyl methacrylate and 2-hydro- xyethyl methacrylate onto polyacrylonitrile and application of the synthesized graft copolymers in penicillin-amidase immobi­ lization / / J. Appl. Polym. Sc i .—1994 .—51 .—P. 807—813 . 26. Ranby В., Guo F. Z. ^Surface photografting*. New applications to synthetic fibers / / Polym. Avd. Technol .—1994.—5.— P. 829—836. УДК 544 .725 + 544.722.21 + 577.21 Надійшла до редакції 22.12.03 315

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