Molecularly Imprinted Membranes

SENSORS BASED ON FREE-STANDING MOLECULARLY IMPRINTED POLYMER MEMBRANES. COMPUTATIONAL MODELLING OF SYNTHETIC MIMICKS OF BIORECEPTORS... 

Recently, an in-depth review on molecular imprinted membranes has been published by Piletsky et al. [4]. Four preparation strategies for MIP membranes can be distinguished (i) in-situ polymerization by bulk crosslinking (ii) preparation by dry phase inversion with a casting/solvent evaporation process [45-51] (iii) preparation by wet phase inversion with a casting/immersion precipitation [52-54] and (iv) surface imprinting. 

Several selective interactions by MIP membrane systems have been reported. For example, an L-phenylalanine imprinted membrane prepared by in-situ crosslinking polymerization showed different fluxes for various amino acids [44]. Yoshikawa et al. [51] have prepared molecular imprinted membranes from a membrane material which bears a tetrapeptide residue (DIDE resin (7)), using the dry phase inversion procedure. It was found that a membrane which contains an oligopeptide residue from an L-amino acid and is imprinted with an L-amino acid derivative, recognizes the L-isomer in preference to the corresponding D-isomer, and vice versa. Exceptional difference in sorption selectivity between theophylline and caffeine was observed for poly(acrylonitrile-co-acrylic acid) blend membranes prepared by the wet phase inversion technique [53]. 

Possible applications of MIP membranes are in the field of sensor systems and separation technology. With respect to MIP membrane-based sensors, selective ligand binding to the membrane or selective permeation through the membrane can be used for the generation of a specific signal. Practical chiral separation by MIP membranes still faces reproducibility problems in the preparation methods, as well as mass transfer limitations inside the membrane. To overcome mass transfer limitations, MIP nanoparticles embedded in liquid membranes could be an alternative approach to develop chiral membrane separation by molecular imprinting [44]. 

Zougagh, M., Valcarcel, M., and Rios, A., Automatic selective determination of caffeine in coffee and tea samples by using a supported liquid membrane-modified piezoelectric flow sensor with molecularly imprinted polymer. Trends Anal. Chem., 23, 399, 2004. 

The most widely employed techniques for the extraction of water samples for triazine compounds include liquid-liquid extraction (LLE), solid-phase extraction (SPE), and liquid-solid extraction (LSE). Although most reports involving SPE are off-line procedures, there is increasing interest and subsequently increasing numbers of reports regarding on-line SPE, the goal of which is to improve overall productivity and safety. To a lesser extent, solid-phase microextraction (SPME), supercritical fluid extraction (SEE), semi-permeable membrane device (SPMD), and molecularly imprinted polymer (MIP) techniques have been reported. 

Size-related problems may become important for all microsensors. Leakage of sensing materials from a small membrane may lead to rapid deterioration of sensor properties [104], While the lipophilicity of membrane components cannot be increased infinitely, immobilization of ionophore and ion exchanger in the polymer by covalent attachment or molecular imprinting along with utilization of plasticizer-free membranes could help solve the leakage problem. 

Piletsky SA, Matuschewski H, Schedler U, Wilpert A, Piletska EV, Thiele TA, Ulbricht M. Surface functionalization of porous polypropylene membranes with molecularly imprinted polymers by photograft copolymerization in water. Macromolecules 2000 33 3092-3098. 

Sergeyeva TA, Piletsky SA, Brovko AA, Slinchenko EA, Sergeeva LM, El skaya AV. Selective recognition of atrazine by molecularly imprinted polymer membranes. Development of conductometric sensor for herbicides detection. Anal Chim Acta 1999 392 105-111. 

Wang HJ, Zhou WH, Yin XF, Zhuang ZX, Yang HH, Wang XR. Template synthesized molecularly imprinted polymer nanotube membranes for chemical separations. J Am Chem Soc 2006 128 15954-15955. 

Wang HY, Kobayashi T, Fujii N. Surface molecular imprinting on photosensitive dithiocar-bamoyl polyacrylonitrile membranes using photograft polymerization. J Chem Technol Biotechnol 1997 70 355-362. 

Keywords Membranes Microgels Microparticles Microspheres Molecular imprinting Monoliths Nanogels Nanoparticles Nanospheres... 

Molecularly imprinted composite membranes have been developed based on the functionalisation of a commercial membrane with an MIP in order to improve the mechanical stability of the imprinted polymer phase, similarly to the preparation of MIP composite beads, discussed in Sect. 2.2.2. 

Ceolin G et al (2009) Accelerated development procedure for molecularly imprinted polymers using membrane filterplates. J Comb Chem ll(4) 645-652... 

Abstract Molecular imprinting has grown considerably over the last decade with more and more applications being developed. The use of this approach for the generation of enzyme-mimics is here reviewed with a particular focus on the most recent achievements using different polymer formats such as microgels and nanogels, beads, membranes and also silica nanoparticles. 

PTT.F.TSKY S A, PILETSKAYA E V, ELGERSMA A V, YANO K and KARUBE I (1995), Atrazine sensing by molecularly imprinted membranes , Biosens Bioelectro, 10, 959-964. 

Kochkodan, V., W. Weigel, and M. Ulbricht (2002). Molecularly imprinted composite membranes for selective binding of desmetryn from aqueous solutions. Desalination, 149 323-328. 

There are several future trends for the development of passive sampling techniques. The first is the development of devices that can be used to monitor emerging environmental pollutants. Recently, attention has shifted from hydrophobic persistent organic pollutants to compounds with a medium-to-high polarity, for example, polar pesticides, pharmaceuticals, and personal care products.82 147148 Novel materials will need to be tested as selective receiving phases (e.g., ionic liquids, molecularly imprinted polymers, and immunoadsorbents), together with membrane materials that permit the selective diffusion of these chemicals. The sample extraction and preconcentration methods used for these devices will need to be compatible with LC-MS analytical techniques. 

A wide variety of polymeric membranes with different barrier properties is already available, many of them in various formats and with various dedicated specifications. The ongoing development in the field is very dynamic and focused on further increasing barrier selectivities (if possible at maximum transmembrane fluxes) and/ or improving membrane stability in order to broaden the applicability. This tailoring of membrane performance is done via various routes controlled macro-molecular synthesis (with a focus on functional polymeric architectures), development of advanced polymer blends or mixed-matrix materials, preparation of novel composite membranes and selective surface modification are the most important trends. Advanced functional polymer membranes such as stimuli-responsive [54] or molecularly imprinted polymer (MIP) membranes [55] are examples of the development of another dimension in that field. On that basis, it is expected that polymeric membranes will play a major role in process intensification in many different fields. 

Molecularly imprinted polymers with a variety of shapes have also been prepared by polymerizing monoliths in molds. This in situ preparation of MIPs was utilized for filling of capillaries [20], columns [21], and membranes [22, 23]. Each specific particle geometry however needs optimization of the respective polymerization conditions while maintaining the correct conditions for successful imprinting. It would be advantageous to separate these two processes, e.g., to prepare a molecularly imprinted material in one step, which then can be processed in a mold process in a separate step to result the desired shape. 

A number of approaches have been reported towards forming molecularly imprinted polymer membranes, which are intended to selectively transport the... 

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