Analysis of cooperative interactions in molecularly imprinted polymer nanoparticles

Abstract Cooperative binding is commonly observed in biological receptor systems. This study investigates whether it is possible to prepare nano-sized molecularly imprinted polymers (nanoMIPs) that show cooperative binding. NanoMIPs which exhibit cooperative binding would have increased affinity for immobilised template molecules making them useful for advanced applications in diagnostics and sensors. The use of a templatederivatised solid support provides a facile route to prepare nanoMIPs with surface imprints, and the method is ideally suited to study this topic. Although not observed during the course of this study, positive interbinding site cooperativity was hypothesised by way of an increase in the number of binding sites imprinted on the nanoMIPs, by increasing template density on the solid support surface. After synthesis, the affinity of nanoMIPs was analysed using surface plasmon resonance (SPR) technique. Under the conditions investigated, a ten fold increase in binding affinity was measured as template density was increased. SPR results could be explained by an increase in cooperative binding; however calculations showed that the increase in affinity was not significant enough to prove cooperative binding interactions. The main conclusion obtained was that MIP nanoparticles contain only one “high-affinity” binding site that interacts with immobilised template in an SPR assay.