RULES TO PREPARE PEPTIDE-IMPRINTED NANOGELS WITH HIGH-AFFINITY BINDING SUITABLE FOR SENSING AND ASSAYS BY PRECIPITATION POLYMERIZATION

Molecular imprinting is a technique for preparing polymeric scaffolds (Molecularly Imprinted Polymers, MIPs) that function as synthetic receptors and show affinity and selectivity towards a target analyte. The most attractive characteristic of MIPs is the possibility to tailor the binding selectivity so to gain recognition levels on the par of biological receptors. When MIPs are downsized to the nanoscale (nanoMIPs), they show an increase in the number of accessible imprinted binding cavities per material weight and an enhanced molecular recognition ability, leading to faster binding kinetics, higher affinity and selectivity, thus strengthening the resemblance to antibodies and natural receptors. Being the recognition properties of the nanoMIPs strictly correlated to the effective formation of the imprints in the chosen synthetic conditions, a deeper comprehension of the polymerization at the nanoscale is required. In order to fill this lack, we studied the best conditions to form imprints at the nanoscale when the synthesis occurs by a precipitation polymerization protocol by means of an one-pot synthesis via free radical initiation in aqueous solution, using as target analyte the peptide of Troponin I, clinical marker of cardiac failure. By exploring a range of monomers combinations, polyacrylamide-based MIP nanogels having homogeneous nano-dimensions and a low number of binding sites per nanoparticle were synthesized. To this purpose, we evaluated the influence of the monomer composition and the total monomers to template molar ratio on the hydrodynamic sizes and on the recognition properties, respectively, defining the conditions to tune the nanoMIP dimensions (from 60 to >600 nm) and to improve the efficacy of the imprinting process. In the light of the achieved results, the present work contributes to define the best conditions to obtain imprinted peptides at the nanoscale and impact on the production of synthetic recognition materials suitable for sensing and assays.