(399c) Effect of Electrode Functionalization on the Electrosynthesis of Molecular Imprinted Polymers for PFOS Detection

Per- and polyfluoroalkyl substances (PFAS) are toxic synthetic chemicals with no bio-degradability properties and, therefore, becoming persistent contaminants in water sources and soil. Recently, the US Environmental Protection Agency has proposed a maximum of 4 ppt for PFOS (perfluorooctane sulfonic acid), a PFAS compound. Although such low concentrations can be detected by chromatography techniques such as HPLC and LC/MS, these techniques lack portability and are time-consuming and cost-prohibitive for on-site and comprehensive detection. Electrochemical sensors made of molecular imprinting polymers (MIPs) have the potential to provide a cost-effective and portable alternative with sufficient selectivity and sensitivity. These selective MIPs are synthesized through the electrochemical oxidation of the monomer (o-phenylenediamine, o-PD) mixed with the template molecule (PFOS) on the electrode surface. In this study, we tested the hypothesis that the effect of physicochemical properties of the electrode surface underpins the physical morphology and the sensing properties of the resulting MIPs. Specifically, we functionalized the electrode surfaces with either a hydrophilic or a hydrophobic compound prior to electro-polymerization. We observed that the MIP prepared on hydrophobic surfaces exhibited better sensing performances than the ones prepared on hydrophilic surfaces. We attributed the increased sensitivity to the better PFOS imprinting in the coating. In fact, the results showed that PFOS had a stronger attraction with hydrophobic surfaces than with hydrophilic surfaces, which led to enhanced imprinting. Moreover, we found that a polymer coating with better mechanical properties was obtained when synthesized on hydrophobic surfaces than in hydrophilic surfaces. Our results demonstrated that the physical and sensing properties of a MIP can be tuned by adjusting the surface energy of the electrode.