Aptamers-Based Sensing Strategy for 17β-Estradiol Through Fluorescence Resonance Energy Transfer Between Oppositely Charged CdTe Quantum Dots and Gold Nanoparticles

A novel aptamers-based fluorescence resonance energy transfer (FRET) assay was developed employing the oppositely charged thioglycolic acid-capped CdTe quantum dots (TGA-CdTe QDs) and cysteamine-stabilized gold nanoparticles (cysteamine-AuNPs). The fluorescence of TGA-CdTe QDs was significantly quenched with addition of cysteamine-AuNPs via the FRET. The FRET process can be modulated by 17 beta-estradiol in that the specific recognition between 17 beta-estradiol and aptamers could show different effects on the aptamers-mediated aggregation of cysteamine-AuNPs, and correspondingly adjust the FRET process. The feasibility of the method has been demonstrated by carrying out the detection of 17 beta-estradiol with the wide linear range from 0.5 ng.mL(-1) to 150 ng.mL(-1) and the low detection limit of 0.057 ng.mL(-1). The established assay exhibited favorable selectivity towards 17 beta-estradiol over other endocrine disrupting compounds and probably coexisting chemicals in real samples. Furthermore, the assay has been successfully applied to detect 17 beta-estradiol in real tap water samples and feeds samples with good performance. The results were in full consistence with those from HPLC method, indicating the reliability of the detection system. The aptamers-based FRET assay is expected to offer a new opportunity for the rapid analysis of 17 beta-estradiol in real samples.