The molecular imprinting process by Ian A. Nicholls and Jesper G. Karlsson of the University of Kalmar.

How Molecular Imprinting works

The majority of molecular imprinting follows the process illustrated to the right. There are three basic ingredients required: the template molecule, functional monomers, and a cross-linker.

The template molecule can range from small organic molecules to large biopolymers, although larger molecules are typically more difficult to imprint. The template is the molecule to be purified, catalyzed or detected with the final product. The template should be in pure form, which is often a problem for purification if one wishes to purify a compound that has not already been purified by other methods. Templates used for catalysis are generally transition state analogues, meaning that they behave similarly to high energy intermediates in the chemical reaction to be catalyzed.

The functional monomers should each have 2 functional groups. On one end, they should interact with the template with weak interactions (non-covalent) such as hydrogen bonding, Van der Waals forces or even hydrophobic effects. On the other side of the monomers (the side that is not interacting with the template) should be a group that is able to bind covalently with the cross-linker.

The cross-linker is a molecule that can be polymerized around the template, binding covalently to the functional monomers and holding them in place after the template is removed. A major problem that can be minimized by selecting the appropriate cross-linker is accessibility to the binding site. If the entire binding site is covered, then it may be difficult or impossible to remove the template, or for the binding site to be used at all. Thus, porous cross-linkers (with networks of small holes) or ones that can be broken into small pieces (pulverized) are typical.

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