A new photoelectrochemical aptasensor for prion assay based on cyclodextrin and Rhodamine B

Herein, a simple and novel photoelectrochemical (PEC) aptasensor for the detection of prion protein was developed based on beta-cyclodextrin (beta-CD) and Rhodamine B (RhB). HS-beta-cyclodextrin, which was introduced to the Au-TiO2 composite (Au nanoclusters were loaded on the surface of nano-TiO2)/ITO electrode surface through Au-S bond, provided a channel to transfer the electron donor to the electrode surface and a support for Rhodamine B labeled prion-aptamer through host-guest interactions. In the presence of prion protein, the specific prion-aptamer affinity made the cavity of beta-CD be sealed, which blocked the transfer channel of the electron donor (ascorbic acid) to the surface of Au-TiO2 composite and resulted in the decrease of the photocurrent. The developed PEC aptasensor showed excellent analytical performance towards prion protein with a linear range of 200-2000 fM, and the detection limit was 50.9 fM (3 sigma), which was much lower than that of the most reported prion biosensors. Moreover, this method could be easily generalized for the assay of other proteins by altering the corresponding aptamers. (C) 2017 Elsevier B.V. All rights reserved.