Hybrid sensor with aptamer and molecularly imprinted polymers based on AgNPs/NiMOF-Ni for ultra-trace recognition of 17β-estradiol

The sensitive and accurate detection of 17β-estradiol (E2) is crucial for assessing environmental and food safety risks. To this end, we developed a novel electrochemical hybrid sensor by integrating an aptamer (Apt) with molecularly imprinted polymers (MIP) on a glassy carbon electrode (GCE) modified with AgNPs/NiMOF-Ni composites. This unique design leverages the large conductive surface of AgNPs/NiMOF-Ni to immobilize the recognition elements, while the Apt-MIP dual-recognition system ensures exceptional target specificity. The fabricated sensor demonstrated high sensitivity, excellent selectivity, and satisfactory stability for E2 detection. It achieved a broad linear range from 1.0 × 10⁻¹⁵ M to 1.0 × 10⁻⁶ M and an ultra-low detection limit of 0.44 fM (S/N = 3). When applied to spiked water and milk samples, the sensor delivered reliable recoveries of 95.2% - 109% with a relative standard deviation (RSD) ≤ 4.8%. These results affirm the strong potential of our hybrid sensor for the practical monitoring of trace E2 contamination.