Molecularly Imprinted Polymers for Chemical Detection on a Paper Substrate

Abstract

Molecularly imprinted polymers (MIPs) have become one of the most promising materials for achieving superior performance in detecting numerous biological molecules, chemical compounds, and water pollutants. Integrated with a paper substrate, MIPs can be fabricated into a paper-based sensor that is low-cost, flexible, and easy to be processed and modified. In this study, we have demonstrated the detection of two typical perfluorinated compounds (PFCs), perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), with the molecularly imprinted polyaniline (MIP-PANI) paper sensor platform. The detection limits of PFOA (20.55 ppt) and PFOS (7.12 ppt) with linear ranges of 1–200 ppt have been estimated. In addition, the surface of the MIP structure upon exposure to PFCs was characterized to propose the detection mechanism and visualize the molecular imprinting process.

We also demonstrated the integration of MIP-PANI with ultra-high frequency (UHF) wireless communication function for detecting multiple volatile organic compounds such as ammonia and ethanol. Wireless responses of the reduced reflection coefficient as a function of frequency are summarized, and the potential characteristic peaks and regions with trends in gas concentrations were identified. The calibration curves using a linear regression model were calculated to estimate the limit of detection of ammonia gas, which is 122 ppb.

To further expand the applications of the MIP-PANI platform, lentiviruses were imprinted in the polymer electrode. The calibration curve showed a considerably better signal response upon exposure to virus samples compared with the non-molecularly imprinted control, suggesting its potential in biomedical sensing.

This paper-based sensor incorporated with molecularly imprinted polymer electrodes adapts to various chemical as well as biological compounds with excellent sensitivity and selectivity at a low-cost compared with conventional assays, providing the potential in environmental monitoring and biomedical applications.