Fluorescence resonance energy transfer based aptasensor for the sensitive and selective detection of 17β-estradiol using a quantum dot-bioconjugate as a nano-bioprobe

A unique fluorescence resonance energy transfer (FRET)-based aptasensor was constructed for the determination of 17 beta-estradiol using a quantum dot (QD) bioconjugate as a nano-bioprobe and a high-affinity, high-specificity fluorescence-labeled anti-17 beta-estradiol aptamer as a bio-recognition molecule. Based on the principles of QD-FRET and competitive bioassays, a number of samples containing various 17b-estradiol concentrations and a given concentration of the fluorescence-labeled DNA aptamer were incubated with a certain concentration of the QD nano-bioprobe solution. A higher 17b-estradiol concentration led to fewer fluorescence-labelled DNA aptamers bound to the QD nano-bioprobe surface and thus a lower fluorescence signal. The compound 17b-estradiol was quantified over a concentration range of 0.82 nM to 20.5 nM with a detection limit of 0.22 nM. The high specificity and selectivity of the sensor were demonstrated by evaluating the response of the sensor toward a number of potentially interfering endocrine-disrupting compounds or other chemicals. This sensor was also sufficiently stable for practical applications. The performance of the FRET-based aptasensor with spiked water samples demonstrated good recovery, precision and accuracy, indicating that it had a low susceptibility to water matrix effects.