Imprinting molecular

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

SENSORS WITH RESPONSE ON SOME XANTHENE DYES BASED ON MOLECULARLY IMPRINTED ELECTROSYNTHESIZED POLYMERS... 

The development of highly selective chemical sensors for complex matrixes of medical, environmental, and industrial interest has been the object of greate research efforts in the last years. Recently, the use of artificial materials - molecularly imprinted polymers (MIPs) - with high recognition properties has been proposed for designing biomimetic sensors, but only a few sensor applications of MIPs based on electrosynythesized conductive polymers (MIEPs) have been reported [1-3]. 

METAL-LOADED SORBENTS AND MOLECULARLY IMPRINTED POLYMERS IN SPE-LC... 

Recently, molecularly imprinted polymers (MIPs) have gained attention as new, selective sorbents for chromatography and SPE. The cavities in the polymer... 

B. Sellergren, Noncovalent molecular imprinting antibody-like molecular recognition in polymeric network materials . Trends. Anal. Chem. 16 310-320 (1997). 

The sorbents that are most frequently used in environmental analysis are Cig-silica based sorbents, polymeric sorbents (usually styrenedivinilbenzene) and graphitized carbon. In order to increase the selectivity of these sorbents, immunosorbents (35, 36) have been developed and used with good results, while recently, molecularly imprinted polymers have started be to used (35, 36). 

B. Sellergren, Enantiomer separation using tailor-made phases prepared by molecular imprinting in A practical approach to chiral separations by liquid chromatography, G. Subramanian, VCH, Weinheim (1994) Chapter 4. 

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. 

Fig. 5-5. Schematic representation of the preparation procedure of molecular imprinted polymers (MIP).

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]. 

Molecularly imprinted polymers (MIPs) can be prepared according to a number of approaches that are different in the way the template is linked to the functional monomer and subsequently to the polymeric binding sites (Fig. 6-1). Thus, the template can be linked and subsequently recognized by virtually any combination of cleavable covalent bonds, metal ion co-ordination or noncovalent bonds. The first example of molecular imprinting of organic network polymers introduced by Wulff was based on a covalent attachment strategy i.e. covalent monomer-template, covalent polymer-template [12]. 

Some restrictions of this molecular imprinting technique are obvious. The template must be available in preparative amounts, it must be soluble in the monomer mixture, and it must be stable and unreactive under the conditions of the polymer-... 

In spite of the fact that molecular imprinting allows materials to be prepared with high affinity and selectivity for a given target molecule, a number of limitations of the materials prevent their use in real applications. The main limitations are ... 

Gel materials are utilized in a variety of technological appUcations and are currently investigated for advanced exploitations such as the formulation of intelligent gels and the synthesis of molecularly imprinted polymers. 

Toth E, Hehn L, Merbach AE (2002) Relaxivity of MRI Contrast Agents. 221 61-101 Tovar GEM, Krauter I, Gruber C (2003) Molecularly Imprinted Polymer Nanospheres as Fully Affinity Receptors. 227 125-144... 

Ansell, RJ Mosbach, K, Magnetic Molecularly Imprinted Polymer Beads for Drug Radioligand Binding Assay, Analyst 123, 1611, 1998. 

Ekberg, B Mosbach, K, Molecular Imprinting A Technique for Producing Specific Separation Materials, Trends in Biotechnology 7, 92, 1989. 

Kriz, D Ramstrom, O Mosbach, K, Molecular Imprinting, New Possibilities for Sensor Technology, Analytical Chemistry June 1, 345A, 1997. 

Piletsky, SA Andersson, HS Nicholls, LA, Combined Hydrophobic and Electrostatic Interaction-Based Recognition in Molecularly Imprinted Polymers, Macromolecules 32, 633, 1999. 

Tan, ZJ Remcho, VT, Molecular Imprint Polymers as Highly Selective Stationary Phases for Open Tubular Liquid Chromatography and Capillary Elechophoresis, Elechophoresis 19, 2055, 1998. 

Ye, L Ramstrom, O Mansson, MO Mosbach, K, A New Application of Molecularly Imprinted Materials, Journal of Molecular Recognition 11, 75, 1998. 

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