Hybrid aptamer-molecularly imprinted polymer (AptaMIP) nanoparticles selective for the antibiotic moxifloxacin

Modified thymine bases, each containing a polymerizable group (either carboxymethylvinyl or acrylamide) at the 5-position, have been incorporated multiple times into an aptamer sequence allowing the sequence to act as the key recognition element in an aptamer-molecularly imprinted polymer (MIP) hybrid nanoparticle (aptaMIP NP) system for the molecular recognition of the antibiotic moxifloxacin. These materials combine the recognition properties of an aptamer, with the robustness and stability of a MIP, offering a “best-of-both-worlds” approach. Both aptaMIP nanoparticles offer 10-fold superior binding affinity and selectivity over conventional MIP nanoparticles (nanoMIPs), with K_D values of 3.65 × ±0.9 nM, 5.72 ± 0.6 nM and 48.60 ± 7.0 nM for the carboxy aptaMIP, acrylamide aptaMIP and nanoMIP, respectively; and 100-fold superior affinity compared to the unfunctionalized aptamer only (0.325 ± 0.16 μM), all with excellent selectivity for the template antibiotic. When applied to a sensor platform (Surface Plasmon Resonance), the limit of detection based on the aptaMIP nanoparticles was approximately three-fold lower (0.51 nM and 0.56 nM for the carboxy aptaMIP and acrylamide aptaMIP, respectively) compared to the nanoMIP (1.4 nM). The introduction of the aptamer as a “macro-monomer” into the imprinted polymer scaffold is a promising strategy for significantly improving the properties of both components of the hybrid material (aptamer and MIP). These hybrid polymers, bearing nucleic acid recognition materials offer a powerful tool for robust high affinity selective molecular recognition.