Development of an ultra-high sensitive immunoassay with plasma biomarker for differentiating Parkinson disease dementia from Parkinson disease using antibody functionalized magnetic nanoparticles.
BACKGROUND
It is difficult to discriminate healthy subjects and patients with Parkinson disease (PD) or Parkinson disease dementia (PDD) by assaying plasma α-synuclein because the concentrations of circulating α-synuclein in the blood are almost the same as the low-detection limit using current immunoassays, such as enzyme-linked immunosorbent assay. In this work, an ultra-sensitive immunoassay utilizing immunomagnetic reduction (IMR) is developed. The reagent for IMR consists of magnetic nanoparticles functionalized with antibodies against α-synuclein and dispersed in pH-7.2 phosphate-buffered saline. A high-Tc superconducting-quantum-interference-device (SQUID) alternative-current magnetosusceptometer is used to measure the IMR signal of the reagent due to the association between magnetic nanoparticles and α-synuclein molecules.


RESULTS
According to the experimental α-synuclein concentration dependent IMR signal, the low-detection limit is 0.3 fg/ml and the dynamic range is 310 pg/ml. The preliminary results show the plasma α-synuclein for PD patients distributes from 6 to 30 fg/ml. For PDD patients, the concentration of plasma α-synuclein varies from 0.1 to 100 pg/ml. Whereas the concentration of plasma α-synuclein for healthy subjects is significantly lower than that of PD patients.


CONCLUSIONS
The ultra-sensitive IMR by utilizing antibody-functionalized magnetic nanoparticles and high-Tc SQUID magnetometer is promising as a method to assay plasma α-synuclein, which is a potential biomarker for discriminating patients with PD or PDD.
MagQu Co., Ltd., Xindian District, New Taipei City, 231, Taiwan. syyang@magqu.com.|Institute of Electro-optical Science and Technology, National Taiwan Normal University, Taipei, 116, Taiwan. syyang@magqu.com.
Shieh-Yueh
SY
Yang
Department of Neurology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, 100, Taiwan.|Graduate Institute of Brain and Mind Sciences, College of Medicine, National Taiwan University, Taipei, 100, Taiwan.|Department of Psychology, National Taiwan University, Taipei, 100, Taiwan.|Graduate Institute of Biomedical Engineering and Bioinformatics, National Taiwan University, Taipei, 116, Taiwan.
Ming-Jang
MJ
Chiu
Department of Neurology, National Taiwan University Hospital, College of Medicine, National Taiwan University, Taipei, 100, Taiwan.
Chin-Hsien
CH
Lin
Institute of Electro-optical Science and Technology, National Taiwan Normal University, Taipei, 116, Taiwan.
Herng-Er
HE
Horng
MagQu Co., Ltd., Xindian District, New Taipei City, 231, Taiwan.
Che-Chuan
CC
Yang
Institute of Electro-optical Science and Technology, National Taiwan Normal University, Taipei, 116, Taiwan.
Jen-Jie
JJ
Chieh
MagQu Co., Ltd., Xindian District, New Taipei City, 231, Taiwan.
Hsin-Hsien
HH
Chen
MagQu Co., Ltd., Xindian District, New Taipei City, 231, Taiwan.
Bing-Hsien
BH
Liu
D000328:Adult; D000368:Aged; D055910:Antibodies, Immobilized / Q000737:chemistry*; D015415:Biomarkers / Q000097:blood; D003704:Dementia / Q000097:blood* / Q000175:diagnosis; D005260:Female; D006801:Humans; D007118:Immunoassay / Q000379:methods; D057230:Limit of Detection; D008280:Magnetics / Q000379:methods; D058185:Magnetite Nanoparticles / Q000737:chemistry*; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000097:blood* / Q000175:diagnosis; D051844:alpha-Synuclein / Q000097:blood*
D055910:Antibodies, Immobilized; D015415:Biomarkers; D058185:Magnetite Nanoparticles; D051844:alpha-Synuclein
Immunomagnetic reduction; Parkinson disease; α-synuclein