Ratiometric Electrochemical Aptasensor Based on PtPd@HOF and Au@MXene for Ultrasensitive Detection of Perfluorooctanoic Acid

A ratiometric electrochemical aptasensor was developed for ultrasensitive PFOA detection. • Fc-PtPd@HOF-101 served as the sensing platform and Au@MXene as the signal label. • The sensor achieves an ultralow detection limit of 6.04 fg/mL with excellent linearity from 10 fg/mL to 10 ng/mL. • Fc and MB signals provided self-calibration, improving accuracy and reproducibility. • Validated in real samples: tap, landscape, and PTFE-cooked water from Zhengzhou. Perfluorooctanoic acid (PFOA), as the most representative perfluorinated compound, is a persistent organic pollutant with exceptional chemical stability and resistance to natural degradation. Traditional detection methods, which rely on sophisticated instrumentation, exhibit limited sensitivity and often struggle to meet the requirements for trace-level analysis. In this study, a ratiometric electrochemical aptasensor was developed based on a ferrocene and hydrogen-bonded organic framework co-modified gold electrode (Fc-PtPd@HOF-101) combined with an Au@MXene signal tag, achieving ultrasensitive PFOA detection in water. The sensor utilizes an Fc internal reference and MB response indicator, with DPV detection. Au@MXene/cDNA/MB probe was constructed. In the presence of target PFOA, the sensor forms a stable Apt-PFOA complex, triggering the displacement of complementary DNA and the subsequent release of the signal probe, leading to a decrease in MB signal. The large specific surface area of Au@MXene enables high loading of cDNA and MB, significantly amplifying the signal while Fc remains stable. A ratiometric aptasensor was established using the current ratio I MB /I Fc . Under optimized conditions, the sensor exhibited a linear range of 10.0 fg mL -1 to 10.0 ng mL -1 and a low detection limit of 6.04 fg mL -1 , with outstanding selectivity, reproducibility, and stability. This study provides a novel technical approach for the rapid and sensitive detection of trace PFOA in environmental water samples. Download: Download high-res image (203KB) Download: Download full-size image