A Trimodal Sensing Platform Based on AIE-Active Conjugated Polymer Photosensitizers for Precise and Selective On-Site Detection of Perfluorooctanesulfonate

Abstract The widespread contamination of water bodies by perfluorooctanesulfonic acid (PFOS), a persistent organic pollutant, has become a significant societal concern, creating an urgent need for effective monitoring methods. Most existing PFOS sensors rely on a single detection mode, rendering them susceptible to background interference. Herein, we present a first-of-its kind trimodal sensing platform for PFOS based on aggregation-induced emission (AIE)-active conjugated polymer (TPEDM) and 3,3′,5,5′-tetramethylbenzidine (TMB). Leveraging the unique AIE property of TPEDM, a fluorescence turn-on detection platform was first developed. Subsequently, upon white light irradiation, reactive oxygen species (ROS) generated by the TPEDM photosensitizer drive the oxidation of TMB, producing both a colorimetric response and a localized photothermal effect, thereby enabling a trimodal PFOS assay. This sensing platform demonstrates excellent analytical performance across fluorescence, colorimetric, and photothermal assays, with detection limits at the nanomolar level. Furthermore, by integrating these three assays with smartphone-based color recognition and a portable temperature measurement device, a multifunctional sensing system featuring logic-gate analysis was constructed. This system has been successfully applied for the convenient, sensitive, and rapid on-site detection of PFOS in real water samples, providing a practical solution for the environmental monitoring of persistent organic pollutants.