In chemistry, molecular imprinting is a technique to create template-shaped cavities in polymer matrices with memory of the template molecules to be used in molecular recognition. This technique is based on the system used by enzymes for substrate recognition, which is called the "lock and key" model. The active binding site of an enzyme has a unique geometric structure that is particularly suitable for a substrate. A substrate that has a corresponding shape to the site is recognized by selectively binding to the enzyme, while an incorrectly shaped molecule that does not fit the binding site is not recognized.
In a similar way, molecularly imprinted materials are prepared using a template molecule and functional monomers that assemble around the template and subsequently get crosslinked to each other. The functional monomers, which are self-assembled around the template molecule by interaction between functional groups on both the template and monomers, are polymerized to form an imprinted matrix (commonly known in the scientific community as a molecular imprinted polymer i.e. MIP). Then the template molecule is removed from the matrix under certain conditions, leaving behind a cavity complementary in size and shape to the template. The obtained cavity can work as a selective binding site for a specific template molecule.
In recent decades, the molecular imprinting technique has been developed for use in receptors, chromatographic separations, fine chemical sensing, etc. Taking advantage of the shape selectivity of the cavity, use in catalysis for certain reactions has also been facilitated. Klaus Mosbach was the pioneer of the Noncovalent approach of Molecular Imprinting.
The first example of molecular imprinting is attributed to M.V. Polyakov in 1931. He studied the polymerization of sodium silicate with ammonium carbonate. When the polymerization process was accompanied by an additive such as benzene, the silica particles ultimately formed showed a higher uptake of this additive.