Molecularly imprinted sorbent assays MIAs

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.

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]. 

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.

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. 

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