Stimulus-Responsive Imprinted Polymer-Based Potentiometric Sensor for Reversible Detection of Neutral Phenols

Nowadays, polymeric membrane potentiometric sensors based on the molecularly imprinted polymers (MIPs) have been successfully developed for detection of various organic and biological species. However, it is difficult for these sensors to perform reversible detection of the targets due to the high affinities of the MIPs toward the targets. In this work, we propose a novel method for fully reversible potentiometric detection of neutral phenols based on the stimulus-responsive MIP as the selective receptor. Since such smart receptor can switch its recognition abilities according to the external environmental stimuli, the MIP binding sites in the polymeric membrane can be regenerated via the stimulus after each measurement. Thus, potentiometric reversible detection of the target can be achieved. As a proof of concept, the pH-responsive MIP is used as the selective receptor, which can be synthesized by using 4-vinylphenylboronic acid as the functional monomer. The boronate-affinity MIP can covalently bind with a cis-diol containing compound to form a five- or six-membered cyclic ester in a weakly alkaline aqueous solution, while the produced ester dissociates when the surrounding pH is changed to acidic. By using catechol as a model, the proposed smart sensor exhibits a significantly improved reversibility compared to the conventional MIP-based sensor. We believed that the stimulus-responsive MIP-based sensing strategy could provide an appealing way to design reversible MIP-based electrochemical and optical sensors.