Qualitative and Quantitative Detection of PrP(Sc) Based on the Controlled Release Property of Magnetic Microspheres Using Surface Plasmon Resonance (SPR)

Prion protein (PrP(Sc)) has drawn widespread attention due to its pathological potential to prion diseases. In this work, we constructed a novel surface plasmon resonance (SPR) detection assay involving magnetic microspheres (MMs) and its controlled release property, for selective capture, embedding, concentration, and SPR detection of PrP(Sc) with high sensitivity and specificity. Aptamer-modified magnetic particles (AMNPs) were used to specifically capture PrP(Sc). Amphiphilic copolymer was used to embed the labeled PrP(Sc) and form magnetic microspheres to isolate PrP(Sc) from the external environment. Static magnetic and alternating magnetic fields were used to concentrate and control release the embedded PrP(Sc), respectively. Finally, the released AMNPs-labeled PrP(Sc) was detected by SPR which was equipped with a bare gold sensing film. A good linear relationship was obtained between SPR responses and the logarithm of PrP(Sc) concentrations over a range of 0.01–1000 ng/mL. The detection sensitivity for PrP(Sc) was improved by 10 fold compared with SPR direct detection format. The specificity of the present biosensor was also determined 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 AMNPs conjugates.