Electrochemically covalent lock stabilizes aptamer conformation and strengthens its sensing performance for PFOA

PER: and polyfluoroalkyl substances (PFAS) are widely detected emerging pollutants, yet their accurate identification in complex water remains a major challenge. Herein, we developed an innovative aptamer (Apt) -based electrochemical molecularly imprinted polymer (MIP) sensor for high-sensitivity detection of perfluorooctanoic acid (PFOA) in complex water samples. Here, the Apt structure was stabilized by electrochemical polymerization of o-phenylenediamine (o-PD), and the sensor provided dual recognition sites to enhance its specific recognition ability. AuNPs with excellent electrical conductivity provide binding sites for loading both the amphiphilic antifouling peptide CEAK16 and the aptamer, forming a robust antifouling sensing interface that resists non-specific adsorption in complex samples. When PFOA existed, the Apt-assisted imprinted cavities with specific recognition ability bound to PFOA through forces such as hydrogen bonds, resulting in a decreased current from the signaling probe ferrocene carboxylic acid (FcCOOH), enabling sensitive and quantitative detection of PFOA. After optimizing the experimental parameters, the sensor achieved a detection limit of 0.097 nM (S/N = 3) over range of 0.1-100 nM and outstanding long-term stability (only 6% current loss over 20 days) in underground water sample. Importantly, the PL PFOA@Apt sensor exhibited an excellent recognition performance for PFOA, which is 4.3-6.7 times higher than that of other perfluorinated analogs. Validation against LC-MS in water samples demonstrated consistency with the sensor's results for PFOA quantification, indicating that the sensor holds great promise as a point-of-care tool for monitoring PFOA contamination and assessing water quality.