Thin films of molecularly imprinted polymer for the selective extraction of proteins

Molecularly imprinted polymers (MIPs) can be defined as polymeric networks with selective cavities towards an analyte or structural-related substances. MIPs present some advantages over their natural counterparts, the immunosorbents, since they present higher stability and reusability. Moreover, MIPs can be easily tuned depending on the target analytes. The latter aspect is a consequence of the synthetic process which simply consists on the creation of the polymer in the presence of the target analyte which acts as template of the polymeric network. After the synthesis, the template is conveniently removed leaving cavities with an enhanced selectivity towards the analyte.

This synthetic procedure can be easily applied to a wide variety of organic compounds but it presents an obvious limitation when biomolecules, like proteins, are processed. In fact the three-dimensional structure of proteins, which is essential in their activity, is instable in the reaction media or it can be affected by the employed monomers. Therefore, the preparation of MIPs for protein recognition requires an extra-step in order to avoid the contact between protein and monomers after polymerization.

In a recent article published in Analytica Chimica Acta, researchers from the University of Texas at Austin, reported a novel procedure to avoid the mentioned shortcomings. Commercial glass microscope slides and their cover slips are the elements of this simple and efficient process (see Figure 1). Briefly, the procedure consists of various and well defined steps such as:

1. Preparation of the slides by silanization of the glass surface with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS). This step is crucial to make possible the final attachment of the MIP to the glass surface.
2. Adsorption of the target protein in the cover slips which will be used as protein stamps.
3. Application over the treated slides of the solution that contains the monomer mixture (functional and crosslinking ones) and the polymerization initiator.
4. Location of the cover slips with the immobilized proteins over the polymerization solution.
5. Final polymerization of the mixture assisted by a UV-lamp.

Figure 1. General scheme for the synthetic procedure

After the polymerization, the cover slips are removed leaving selective cavities towards the model protein, in this case bovine serum albumin. Finally, the MIP film is cleaned to remove the remaining template and unreacted materials.

The evaluation of this MIPs film shows a high reproducibility in the protein extraction which is one of the shortcomings of precedent approaches. Moreover, the films present a high selectivity when other proteins are considered.

For further details, readers are referred to the original work. In the article, the readers will find the optimal synthetic procedure, the optimization of the MIP composition as well as the main studies related to the selectivity of the films.

Link to article: Surface imprinted thin polymer film systems with selective recognition for bovine serum albumin