Hybrid Aptamer-Molecularly Imprinted Polymer (aptaMIP) Nanoparticles from Protein Recognition—A Trypsin Model

Abstract

Aptamers offer excellent potential for replacing antibodies for molecular recognition purposes however their performance can compromise with biological/environmental degradation being a particular problem. Molecularly imprinted Polymers (MIPs) offer an alternative to biological materials and while these offer the robustness and ability to work in extreme environmental conditions, they often lack the same recognition performance. By slightly adapting the chemical structure of a DNA aptamer it is incorporated for use as the recognition part of a MIP, thus creating an aptamer-MIP hybrid or aptaMIP. Here these are developed for the detection of the target protein trypsin. The aptaMIP nanoparticles offer superior binding affinity over conventional MIP nanoparticles (nanoMIPs), with KD values of 6.8 × 10−9 (±0.2 × 10−9) m and 12.3 × 10−9 (±0.4 × 10−9) m for the aptaMIP and nanoMIP, respectively. The aptaMIP also outperforms the aptamer only (10.3 × 10−9 m). Good selectivity against other protein targets is observed. Using surface plasmon resonance, the limit of detection for aptaMIP nanoparticles is twofold lower (2 nm) compared to the nanoMIP (4 nm). Introduction of the aptamer as a “macro-monomer” into the MIP scaffold has beneficial effects and offers potential to improve this class of polymers significantly.