A newer method of molecular imprinting, called the epitope approach, is being explored. While imprinting MIPs with protein is becoming a popular concept, many challenges, including the accessibility of binding sites, nonspecific binding, and flexible conformation of the molecules, remain in creating materials that selectively bind the desired molecules. The chemical structure of proteins, with their numerous functional groups, allows many binding opportunities for a variety of functional monomers. Recently however, proteins have become the focal point of many MIP studies for uses in medical diagnostics, drug delivery, biomaterial compatibility, and tissue engineering. On the right, a small polypeptide sequence from the protein creates small imprints that bind the template molecule at only a specific location.įor many MIPs, small biomolecules, such as sugars, cholesterols, and certain drugs, have been used as templates because of their simplicity and stability. On the left, the entire protein molecule creates large imprints with high surface availability. Ĭartoon representation of whole protein- and peptide-imprinting. The resulting structure of the polymer at these locations is a mirror of the template molecule that is able to preferentially rebind that molecule over competitor molecules, which do not share the same physical and chemical structure. Because the functional monomers bind to the template in a specific position within the polymer, removal of the molecule in will result in an imprint with preservation of both spatial and chemical features ( Figure 1). The cross-linking agent binds to the functional monomers upon polymerization, which embeds the template molecule in a polymer matrix. The template molecule is mixed with the functional monomer so that chemical bonds between the two are formed. In general, MIPs are made with three main reaction components: cross-linking agent, functional monomer, and template molecule. Molecularly imprinted polymers (MIPs) are used for molecular recognition because preparation is usually straight forward, they are robust, and they are chemically, mechanically, and thermally stable. These initial studies suggest there is potential for using peptide-imprinting to create specific protein-binding sites on porous inorganic surfaces, although further development of the materials is needed.

However, while whole lysozyme-imprinted scaffolds showed about 4:1 preferential binding of lysozyme to RNase, peptide-imprinted scaffolds failed to show statistical significance, even though a slight preferential binding trend was present. When comparing protein- to peptide-imprinted scaffolds, similar amounts of lysozyme and RNase were bound from single protein solutions. After removing template, scaffolds were exposed to lysozyme and/or RNase A, which was used as a competitor molecule of comparable size.

Whole lysozyme or the 16 residue lysozyme C peptide was imprinted into porous silica scaffolds using sol-gel processing. One method, termed the ‘epitope approach’, involves imprinting a short peptide fragment of the protein into the polymer to promote specific adsorption of the entire protein, similar to the way an antigen binds to an antibody via the epitope. Of the many types of biomolecules used for molecular imprinting applications, proteins are some of the most useful, yet challenging, templates to work with.

Scaffold solutions