Biofunctionalized magnetic nanoparticles for specifically detecting biomarkers of Alzheimer's disease in vitro.

ABSTRACT

Magnetic nanoparticles biofunctionalized with antibodies against ß-amyloid-40 (Aß-40) and Aß-42, which are promising biomarkers related to Alzheimer's disease (AD), were synthesized. We characterized the size distribution, saturated magnetizations, and stability of the magnetic nanoparticles conjugated with anti-Aß antibody. In combination with immunomagnetic reduction technology, it is demonstrated such biofunctionalized magnetic nanoparticles are able to label Aßs specifically. The ultralow-detection limits of assaying Aßs in vitro using the magnetic nanoparticles via immunomagnetic reduction are determined to a concentration of ∼10 ppt (10 pg/mL). Further, immunomagnetic reduction signals of Aß-40 and Aß-42 in human plasma from normal samples and AD patients were analyzed, and the results showed a significant difference between these two groups. These results show the feasibility of using magnetic nanoparticles with Aßs as reagents for assaying low-concentration Aßs through immunomagnetic reduction, and also provide a promising new method for early diagnosis of Alzheimer's disease from human blood plasma.