Sensing by Molecularly Imprinted Polymer: Evaluation of the Binding Properties with Different Techniques.

Maria Pesavento,Nunzio Cennamo,Luigi Zeni,Simone Marchetti,Letizia De Maria

doi:10.3390/s19061344

Abstract

The possibility of investigating the binding properties of the same molecularly imprinted polymer (MIP), most probably heterogeneous, at various concentration levels by different methods such as batch equilibration and sensing, is examined, considering two kinds of sensors, based respectively on electrochemical and surface plasmon resonance (SPR) transduction. As a proof of principle, the considered MIP was obtained by non-covalent molecular imprinting of 2-furaldehyde (2-FAL). It has been found that different concentration ranges of 2-FAL in aqueous matrices can be measured by the two sensing methods. The SPR sensor responds in a concentration range from 1 × 10−4 M down to about 1 × 10−7 M, while the electrochemical sensor from about 5 × 10−6 M up to about 9 × 10−3 M. The binding isotherms have been fit to the Langmuir adsorption model, in order to evaluate the association constant. Three kinds of sites with different affinity for 2-FAL have been detected. The sites at low affinity are similar to the interaction sites of the corresponding NIP since they have a similar association constant. This is near to the affinity evaluated by batch equilibration too. The same association constant has been evaluated in the same concentration range. The sensing methods have been demonstrated to be very convenient for the characterization of the binding properties of MIP in comparison to the batch equilibration, in terms of reproducibility and low amount of material required for the investigation.

Highlights

Chemical sensors are based on the strict integration of a receptor with an instrument able to generate a signal upon the combination of a substrate with the receptor
As a proof of principle, in the present study we investigated a synthetic receptor for a small molecule, 2-furaldehyde (2-FAL), obtained by molecular imprinting (MIP-2FAL)
With respect to the batch equilibration methods, based on the determination of the target substance left in solution after equilibration, the methods based on sensing devices are convenient in terms of amount of binding material required for the investigation, for example a few mg of molecularly imprinted polymer (MIP) instead of tens of mg, and of the time required for obtaining the information, and because they make it possible to investigate the interactions at lower concentrations due to their high sensitivity

Summary

Introduction

Chemical sensors are based on the strict integration of a receptor with an instrument able to generate a signal upon the combination of a substrate with the receptor. The characteristics of the binding reaction, in particular the affinity of the receptor for the substrate, are of overwhelming relevance for determining the performance of a sensor. Sensors can be used to investigate the combination of the receptor with the substrate. Has been proposed as transduction method for a number of sensing applications since more than two decades ago [1], it has been even more widely applied to evaluate the equilibrium and kinetical characteristics of the ligand-substrate interaction in investigations of biochemical and pharmaceutical interest [2,3,4]. SPR is considered as one of the most robust and sensitive biosensing techniques that have been implemented in pharmaceutical research worldwide.

Methods

Results

Discussion

Conclusion