Molecularly imprinted sorbent assays

Figure 15.6 Comparison of the values measured by an enzyme-multiplied immunoassay technique (EMIT) assay and a molecularly imprinted sorbent assay (MIA) for determination of theophylhne in 32 patient semm samples. The correlation coefficient was 0.98. Reprinted from Vlatakis et al. (2003). Copyright 1993 Macmillan Ltd.

Atrazine herbicide in solution MAA MIP-based competitive inhibition assay (molecularly imprinted sorbent assay) 1 ug/ml Muldoon and Stanker, 1995... 

MIP-based sensors and molecularly imprinted sorbent assays... 

SURUGIU I, YE L, YILMAZ E, DZGOEV A, DANIELSSON B, MOSBACH K and HAUPT K (1999), An enzyme-linked molecularly imprinted sorbent assay , Analyst, 125, 13-16. 

Muldoon, M.T. and L.H. Stanker (1995). Polymer synthesis and characterization of a molecularly imprinted sorbent assay for atrazine. J. Agric. Food Chem., 43 1424-1427. 

Batch use of imprinted polymers has been applied in the evaluation of polymers by saturation binding tests and in the applications of molecularly imprinted sorbent assays [1,23,24]. In a common procedure, imprinted polymers obtained as blocks were crushed, ground and sieved to prepare sized polymer particles. The resultant particles were then distributed into each vial and recovered by filtration after use. Recently, a new batch-type in situ procedure has been reported. It utilises a polymer coating prepared on an inner surface at the bottom of a vial and allows direct assessment of the polymers. In this section, this type of in situ preparation of imprinted polymers and an application to combinatorial chemistry are described. 

Vlatakis et al. [104] demonstrated that MIPs could replace antibodies as the selective binding moiety in a competitive Molecularly Imprinted sorbent Assay (MIA). MIPs prepared for theophylline and diazepam were shown to possess high affinity and to demonstrate cross-reactivity akin to antibody systems. In general, MIPs have been shown to be analogous to polyclonal antibodies, although, in some cases, their affinity and specificity can approach that of monoclonal antibodies [18, 19, 105-107]. 

Many compounds have now been used as template molecules in molecular imprinting. Basically, imprinted polymers can be used directly as separation media. Since all separation applications cannot be described here, some studies recently reported are bsted in Table 7.1. In this chapter, only selected topics, including sensor applications, signaling polymers, molecularly imprinted sorbent assays, molecularly imprinted membranes, affinity-based solid phase extraction, in situ preparation of imprinted polymers, and molecularly imprinted catalysts are discussed. For the reader requiring information on other applications, there are many review articles dealing with these, Recent review articles and books are summarized in Table 7.1. For further development of molecular imprinting techniques, newly designed functional monomers would be desirable. Various functional monomers have been reported and many applications have been conducted. These are summarized in Table 7.2. 

Molecularly imprinted sorbent assays represent one of the most typical applications of biomimetic use, where imprinted polymers are used as substitutes of natural antibodies in immunoassays. The assays usually involve competitive binding of an analyte with a certain quantity of labeled ligands, in which the labeled ligand unbound is proportional to the analyte added. Because dissociation constants of common imprinted polymers are around 10 6-10 9 M, competitive binding assays could easily be performed. In practice, many molecularly imprinted sorbent assays have been developed for biologically active compounds, including theophylline, diazepam [26], S-propranolol [27], morphine, Leu-enkephalin [28], cyclosporin A [29], yohimbine [30], methyl-a-glucoside [31], corticosteroid [32], atrazine [33, 34], and 2,4-D [35]. 

Ge, Y., and Turner, A. P. (2009). Molecularly imprinted sorbent assays Recent developments and applications, j fl2i2 CLXl Ml iHl an der Berastrasse. Germany). 15f331.8100-8107. 

MIPs have attracted increasing interest as substitutes for biological antibodies in such procedures, which are then commonly referred to as Molecular Imprint Sorbent Assays or MIAs [4-8]. Like antibodies, MIPs can exhibit selective binding for a chosen analyte. Unlike antibodies they are not individual soluble macromolecules but, most often, insoluble particles or films. However, this is not a problem since in most immunoassay formats the biological antibodies are in any case coupled first to a solid phase. 

Figure 7 Schematic of molecular imprint sorbent assay (MIA), (a) molecular imprinting process, (b) imprinted polymer containing trapped template-monomer complexes (c) extraction of template, (d) analyte and probe are added to the MIP, (e) analyte and probe compete for the available binding sites. In the conventional radiolabel MIA, the analyte is identical to the template, and the probe is the radiolabelled form of the analyte. In later, alternative MIA designs, template, analyte, and probe are not neeessarily identical.

Muldoon, M.T. Stanker, L.H. Polymer synthesis and characterization of a molecularly imprinted sorbent assay for atrazine. J. Agric. Food Chem. 1995, 43, 1424-1427. Siemann, M. Andersson, L.I. Mosbach, K. Selective recognition of the herbicide atrazine by noncovalent molecularly imprinted polymers. J. Agric. Food Chem. 1996, 44, 141-145. 

Haupt, K Molecularly imprinted sorbent assays and the use of non-related probes. React. Funct. Polym. 1999, 41, 125-131. 

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