Biofunctionalized Magnetic Nanoparticles for Specifically Detecting Biomarkers of Alzheimer's Disease in Vitro

Magnetic nanoparticles biofunctionalized with antibodies against beta-amyloid-40 (A beta-40) and A beta-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-A beta antibody. In combination with immunomagnetic reduction technology, it is demonstrated such biofunctionalized magnetic nanoparticles are able to label A beta s specifically. The ultralow-detection limits of assaying A beta s in vitro using the magnetic nanoparticles via immunomagnetic reduction are determined to a concentration of similar to 10 ppt (10 pg/mL). Further, immunomagnetic reduction signals of A beta-40 and A beta-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 A beta s as reagents for assaying low-concentration A beta s through immunomagnetic reduction, and also provide a promising new method for early diagnosis of Alzheimer's disease from human blood plasma.