Controllably Prepared Aptamer–Molecularly Imprinted Polymer Hybrid for High-Specificity and High-Affinity Recognition of Target Proteins

Molecularly imprinted polymers (MIPs) and aptamers, as effective mimics of antibodies, can overcome only some drawbacks of antibodies. Since they have their own advantages and disadvantages, the combination of MIPs with aptamers could be an ideal solution to produce hybrid alternatives with improved properties and desirable features. Although quite a few attempts have been made in this direction, a facile and controllable approach for the preparation of aptamer–MIP hybrids still remains lacking. Herein, we present a new approach for facile and controllable preparation of aptamer–MIP hybrids for high-specificity and high-affinity recognition toward proteins. An aptamer that can bind the glycoprotein alkaline phosphatase (ALP) with relative weak affinity and specificity was used as a ligand, and controllable oriented surface imprinting was carried out with an in-water self-polymerization system of dopamine. A thin layer of polydopamine was formed to cover the template to an appropriate thickness. After removing the template from the polymer, an aptamer–MIP hybrid with apparently improved affinity and specificity toward ALP was obtained, giving cross-reactivity of 3.2–5.6% and a dissociation constant of 1.5 nM. With this aptamer–MIP hybrid, a plasmonic immunosandwich assay (PISA) was developed. Reliable detection of ALP in human serum by the PISA was demonstrated.