Nanosurface Energy Transfer From FAM‐Labeled Aptamer to Gold Nanorods for Sensing of Di(2‐ethylhexyl) Phthalate in Complex Environmental Samples

Di(2‐ethylhexyl) phthalate (DEHP) is an important emerging contaminant, and its sensitive detection is critical for environmental monitoring and risk control. In this work, we developed a fluorescence aptasensor based on nanosurface energy transfer (NSET) between a FAM‐labeled aptamer (FAM‐DNA) and cetyltrimethylammonium bromide‐stabilized gold nanorods (CTAB‐AuNRs) for DEHP detection in complex environmental samples. Owing to electrostatic adsorption, negatively charged FAM‐DNA is readily adsorbed onto the positively charged CTAB‐AuNR surface, resulting in efficient NSET effect and fluorescence quenching. Upon DEHP binding, the aptamer undergoes a conformational and interfacial‐state change that weakens its association with CTAB‐AuNRs and restores fluorescence. The sensor reaches response equilibrium within about 40 min and exhibits a linear response toward DEHP from 5 to 500 nM, with a detection limit of 1.12 nM. It shows high anti‐interference ability to common interfering ions and obtains recoveries of 93.97%–114.20% in spiked soil extracts. The method was successfully applied to three field‐collected soil samples and a commercial PVC film, with results in acceptable agreement with high‐performance liquid chromatography–mass spectrometry. Overall, this fluorescence aptasensor provides a simple, sensitive, reliable approach for trace DEHP analysis, facilitating the monitoring of DEHP in complex environmental samples.