Quick and sensitive SPR detection of prion disease-associated isoform (PrPSc) based on its self-assembling behavior on bare gold film and specific interactions with aptamer-graphene oxide (AGO).

Herein, we constructed a novel sandwich surface plasmon resonance (SPR) detection assay for sensitive prion disease-associated isoform (PrPSc) detection, utilizing bare gold film and apatamer-graphene oxide (AGO). Due to the self-assembling behavior of PrPSc on gold surface, the non-modified gold surface can be directly used as sensing surface for the quick detection, for the purpose to avoid the interference from the traditional, complex and changeable probe-modified sensing surface. And due to the highly specific affinity of AGO towards PrPSc, the sandwich type SPR sensor exhibits excellent analytical performance towards the discrimination and quantitation of PrPSc. A good linear relationship was obtained between SPR responses and the logarithm of PrPSc concentrations over a range of 0.001-1ng/mL. The detection sensitivity for PrPSc was improved by ∼156 orders of AGO compared with SPR direct detection format. Besides, morphological changes of the sensing film surfaces were investigated by high resolution AFM imaging, confirming the capture of PrPSc molecules and their further specific recognition by AGO. The specificity of the present biosensor was also investigated by PrPC and other regents as controls. By compared with other reported methods, the AGO enhanced sandwich SPR assay was confirmed to be efficient, sensitive, and with wide working range.