Optimized Gold Dendritic Nanostructures on Laser-Induced Graphene as an Electrochemical Platform for Improved Performance of Aptamer-Based Perfluorooctanoic Acid Sensing

Per- and polyfluoroalkyl substances (PFAS) are persistent organofluorine pollutants with carcinogenic, immunotoxic, and endocrine-disrupting effects, necessitating sensitive, scalable, and user-friendly sensing technologies. While a fluorescence-based sensor using a perfluorooctanoic acid (PFOA)-specific aptamer was recently reported, the effect of metal nanostructures on an electrochemical aptamer-based (EAB) platform for PFOA measurement has not yet been explored. Herein, we report the first EAB sensor for PFOA, a major PFAS, using a gold nanostructure-modified laser-induced graphene (AuLIG) platform. The AuLIG substrate provides an excellent surface for the gold–thiol linkage and enhances the electrochemical activity. Gold electrodeposition was optimized by using chronoamperometry and cyclic voltammetry, yielding a stable, optimal electrochemical surface. The sensor exhibited a logarithmic response to PFOA over a concentration range of 15 nM to 2 μM, with a detection limit of 6.6 nM (2.7 ppb). Interference studies demonstrated a high selectivity against competing PFAS compounds. Reliable PFOA quantification in tap water was achieved and validated against liquid chromatography–mass spectrometry (LC–MS) measurements. This AuLIG-based EAB platform offers a scalable and selective approach for PFAS monitoring and holds promise for future extension to complex wastewater matrices.