Molecular imprinted network

The catalytic activity of molecularly imprinted networks is still well below that of enzyme systems. However, even though imprinted materials cannot as yet compete with their biological counterparts, their high chemical stability and the possibility to use them in organic phases give them a promising future. 

Sellergren, B. Dauwe, C. Schneider, T. Pressure-induced binding sites in molecularly imprinted network pol mers. Macromolecules 1997, 30, 2454—2459. 

Thus far, in this chapter, organic polymers have been used to create molecular imprinted networks but alternative supports have also been employed. Indeed, the first reported example of molecular imprinting was achieved with silica. Dickey precipitated silica gel using a dye as a template, and the corresponding matrix exhibited an increased affinity... 

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

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]. 

Fig. 1. Preparation of configurational biomimetic imprinted networks for molecular recognition of biological substrates. A Solution mixture of template, functional monomer(s) (triangles and circles), crosslinking monomer, solvent, and initiator (I). B The prepolymerization complex is formed via covalent or noncovalent chemistry. C The formation of the network. D Wash step where original template is removed. E Rebinding of template. F In less crosslinked systems, movement of the macromolecular chains will produce areas of differing affinity and specificity (filled molecule is isomer of template).

Fig. 1. Concept of molecular imprinting - the non-covalent approach. 1. Self-assembly of template with functional monomers. 2. Polymerization in the presence of a cross-linker. 3. Extraction of the template from the imprinted polymer network. 4. Selective recognition of the template molecule...

Molecular imprinted polymers MIPs exhibit predetermined enan-tioselectivity for a specific chiral molecnle, which is nsed as the chiral template dnring the imprinting process. Most MIPs are obtained by copolymerization from a mixture consisting of a fnnctional mono-nnsatn-rated (vinylic, acrylic, methacrylic) monomer, a di- or tri-nnsatnrated cross-linker (vinylic, acrylic, methacrylic), a chiral template (print molecnle) and a porogenic solvent to create a three-dimensional network. When removing the print molecnle, chiral cavities are released within the polymer network. The MIP will memorize the steric and functional binding featnres of the template molecnle. Therefore, inclusion of the enantiomers into the asymmetric cavities of this network can be assumed as... 

Hydrogels are used as molecular imprinting matrix for proteins for their loose networks enabling the diffusion of the protein and for their aqueous environment and thus compatibility with biomacromolecules [106, 107]. If the MIP precursors mixture contains a very low concentration of monomers, nanometer-sized microgels are sometimes formed upon polymerization rather than macrogels. In order to generate... 

The technique of molecular imprinting was successfully used to create a polymer with specific recognition sites. [9] A template was used to organise monomers during the polymerisation process. After the polymerisation, it was washed away from the insoluble network, leaving behind domains of complementary size and shape (Scheme 10). 

Molecularly Imprinted Materials Hydrogels are insoluble, cross-linked networks of hydrophilic homo- or heterocopolymers, with the ability to take up... 

LI.2 Synthetic polymeric type CSPs. With the aim of mimicking nature and naturally occurring biopolymeric SOs like polysaccharides or proteins, researchers have developed several approaches for the preparation of new types of synthetic macromolec-ular SOs. These new polymeric SOs may be divided into (a) SOs synthesized from achiral monomers including helical polyacrylates and molecular imprint type CSPs and (b) SOs synthesized from chiral monomers including polyacrylamides and network polymers based on tartaric acid diamides. 

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