Separation, molecular imprinting

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. 

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]. 

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

Molecularly imprinted polymers have recently attracted much attention because they are denoted as artificial antibodies which are made from simple chemical components via polymerization and can be used for the preparation ofbiomimetic sensors, affinity separation matrices, catalysts, etc. (Figure 1). 

Molecular hydrogen, 23 759 Molecular imprinting, 6 397 Molecular interactions, 25 103 Molecular interaction theories, 24 38 Molecular Laser Isotope Separation (MLIS) process, 25 416 417 Molecular level machine, 2 7 58 Molecularly imprinted plastics (MIPs) smart, 22 717)... 

To prepare artificial enzymatic systems possessing molecular recognition ability for particular molecules, molecular imprinting methods that create template-shaped cavities with the memory of the template molecules in polymer matrices, have been developed [22, 30-35] and established in receptor, chromatographical separations, fine-chemical sensing, etc. in the past decade. The molecular... 

Fig. 21. Molecular imprinting of (R)-propranolol using methacrylic acid (MAA) as the functional monomer and trimethylolpropane trimethacrylate (TRIM) as the crosslinking monomer. (Reprinted with permission from [126], Copyright 1998 Elsevier). The enantiose-lectivity of a given polymer is predetermined by the configuration of the ligand, R-propranolol present during its preparation. Since the imprinted enantiomer possesses a higher affinity for the polymer, the separation is obtained with a predictable elution order of the enantiomers...

An interesting example of MIP-LC analytics was presented in a paper, which focused on the separation of antibiotics of similar structures. Columns are (commercially) available to separate penicillins ( 3-lactams) from other antibiotics. However, if the quantification of each of the 3-lactam compounds is required, a more selective stationary phase has to be found. Molecular imprinting allows the fabrication of phases specifically for each 3-lactam. If for instance the concentration of the P-lactam oxacillin in a food sample has to be selectively determined, a polymer imprinted with oxacillin is the right choice. Compared to a standard stationary phase, which only allowed the separation of the entire group of (5-lactams from other non-(3-lactam analytes (e. g., bacitracin), the MIP enables the separation of the imprinted species from the pair of non-imprinted 3-lactams penicillin V and penicillin G see Fig. 6 [29,30]. 

One direct approach to the separation of chiral compounds is called molecular imprint polymers (MIPs) that involves the formation of a three-dimensional cavity with the shape and electronic features that are complementary to the imprinted or target molecule. 

Haupt, K., Molecularly imprinted polymers Artificial receptors for affinity separations, in Handbook of Affinity Chromatography, 2nd edn., Hage, D.S., Ed., CRC Press, Boca Raton, FL, 2005, Chap. 30. 

Glad M, Reinholdsson P, Mosbach K. Molecularly imprinted composite polymers based on trimethylolpropane trimethacrylate (TRIM) particles for efficient enantiomeric separations. React Polym 1995 25 47-54. 

Kempe M, Fischer L, Mosbach K. Chiral separation using molecularly imprinted heteroaromatic polymers. J Mol Recognit 1993 6 25-29. 

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