Chemistry Reference
In-Depth Information
Scheme 15.3 Noncovalent imprinting of
L
-phenylalanine anilide in a methacrylic acid
(MAA)/ethylene glycol dimethylcrylate (EGDMA) polymer matrix. Adapted from
Sellergren et al. (1998). Copyright 1988 American Chemical Society.
imprint a diverse array of basic organic template molecules that can form complemen-
tary hydrogen bonding and electrostatic interactions (Table 15.2).
Disadvantages of the noncovalent imprinting process arise from the instability of
the noncovalent monomer-template complexes. This instability reduces the fidelity
of the imprinting process because monomer-template complexes of varying
stoichiometries and structures are present in the prepolymerization mixtures. In
addition, typical noncovalent imprinting conditions utilize a large excess of func-
tional monomers in order to favor the formation of weak monomer-template com-
plexes. Consequently, the majority of functional monomers are not incorporated
into the binding site, which leads to a very high percentage of low-affinity and
low-selectivity binding sites.
Hybrid MIPs.
More recently, hybrid imprinting strategies have been developed that
combine the advantages of both the covalent and noncovalent imprinting strategies
(Whitcombe et al. 1995; Lubke et al. 2000). A recent example by Whitcombe's
group is presented in Scheme 15.4 (Klein et al. 1999). The monomer-template pre-
polymerization complex is formed via a combination of covalent amide bonds and
