Synthesis of Fe(3)C@C from Pyrolysis of Fe(3)O(4)-Lignin Clusters and Its Application for Quick and Sensitive Detection of PrP(Sc) through a Sandwich SPR Detection Assay

The prion protein (PrP(Sc)) has drawn widespread attention due to its pathological potential to cause prion diseases. Herein, we successfully synthesized Fe(3)C@C by carbonizing Fe(3)O(4)-lignin clusters, which were prepared through a facile hydrogen bonding interaction between ≡Fe-OH and hydroxyl groups of lignin. Our in-depth investigation confirmed that the composites were Fe(3)C@C core/shell particles. We constructed a novel sandwich surface plasmon resonance (SPR) detection assay for sensitive PrP(Sc) detection, utilizing bare gold surface and aptamer-modified Fe(3)C@C (Fe(3)C@C-aptamer). Due to the highly specific affinity of Fe(3)C@C-aptamer towards PrP(Sc), the sandwich type SPR sensor exhibited excellent analytical performance towards the discrimination and quantitation of PrP(Sc). A good linear relationship was obtained between the SPR responses and the logarithm of PrP(Sc) concentrations over a range of 0.1–200 ng/mL. The detection sensitivity for PrP(Sc) was improved by ~10 fold compared with the SPR direct detection format. The required detection time was only 20 min. The specificity of the present biosensor was also confirmed by PrP(C) and other reagents as controls. This proposed approach could also be used to isolate and detect other highly pathogenic biomolecules with similar structural characteristics by altering the corresponding aptamer in the Fe(3)C@C conjugates.