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. 2011 Sep 21;2(9):500-5.
doi: 10.1021/cn200028j. Epub 2011 May 30.

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

Che-Chuan Yang  1 , Shieh-Yueh Yang, Jen-Jie Chieh, Herng-Er Horng, Chin-Yih Hong, Hong-Chang Yang, K H Chen, B Y Shih, Ta-Fu Chen, Ming-Jang Chiu
Affiliations

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

Che-Chuan Yang et al. ACS Chem Neurosci. .

Abstract

Magnetic nanoparticles biofunctionalized with antibodies against β-amyloid-40 (Aβ-40) and Aβ-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-Aβ antibody. In combination with immunomagnetic reduction technology, it is demonstrated such biofunctionalized magnetic nanoparticles are able to label Aβs specifically. The ultralow-detection limits of assaying Aβs 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 Aβ-40 and Aβ-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 Aβs as reagents for assaying low-concentration Aβs through immunomagnetic reduction, and also provide a promising new method for early diagnosis of Alzheimer's disease from human blood plasma.

Keywords: Magnetic nanoparticles; immunomagnetic reduction; β-amyloid.

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Figures

Figure 1
Figure 1
Size distributions of reagents (a) Aβ-40 and (b) Aβ-42, (c) magnetic hysteristic curve of reagent, and (d) the mean diameter of reagents as a function of the storage time at 2–8 °C.
Figure 2
Figure 2
(a) Real-time χac signal of reagent mixed with to-be-detected sample, and Aβ-concentration-dependent (b) IMR (%) via IMR and (c) optical density (OD) via ELISA.
Figure 3
Figure 3
Interference tests for IMR assays on (a) Aβ-40 and (b) Aβ-42. In (a), reagent Aβ-40 is used, and reagent Aβ-42 is used in (b).
Figure 4
Figure 4
Values of parameter ϕAβ-42′/ϕAβ-40′ in human plasma for control group (normal sample) and AD group (AD patients).
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