Sensitive detection of prion protein through long range resonance energy transfer between graphene oxide and molecular aptamer beacon

Abstract

The traditional molecular aptamer beacon (MAB) is designed by combining an aptamer to a molecular beacon, and its two terminals are labelled with a fluorescent moiety (donor) and quenching moiety (acceptor), respectively. However, it usually has a high background because of the low energy transfer efficiency between the donor and the acceptor. In order to overcome these drawbacks, we have developed a novel MAB with just one fluorescently labelled end, which acts as the donor, and graphene oxide (GO) introduced as the acceptor for target detection by employing long range resonance energy transfer (LrRET) as the signal-transduction mechanism from GO to MAB. To test the validity of the designed MAB system, cellular prion protein (PrP^C) has been used as the model target. It was found that the fluorescence of the designed MAB is completely quenched by GO, supplying a very low background. Conversely, the quenched fluorescence is recovered significantly with the addition of PrP^C, so that PrP^C can be detected over a wide range of 10.2–78.8 μg mL⁻¹ with a detection limit as low as 0.309 μg mL⁻¹ and with high selectivity. This GO-based MAB approach is a successful application of LrRET for the detection of PrP^C, with advantages such as low costs, high quenching efficiency and good specificity, and it opens up new opportunities for the sensitive detection of biorecognition events.