Development of an ultra-high sensitive immunoassay with plasma biomarker for differentiating Parkinson disease dementia from Parkinson disease using antibody functionalized magnetic nanoparticles

Shieh Yueh Yang, Ming Jang Chiu, Chin Hsien Lin, Herng Er Horng, Che Chuan Yang, Jen Jie Chieh, Hsin Hsien Chen, Bing Hsien Liu

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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 0.3fg/ml and the dynamic range is 310pg/ml. The preliminary results show the plasma α-synuclein for PD patients distributes from 6 to 30fg/ml. For PDD patients, the concentration of plasma α-synuclein varies from 0.1 to 100pg/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.

Original languageEnglish
Article number41
JournalJournal of Nanobiotechnology
Issue number1
Publication statusPublished - 2016 Jun 8



  • Immunomagnetic reduction
  • Parkinson disease
  • α-synuclein

ASJC Scopus subject areas

  • Bioengineering
  • Medicine (miscellaneous)
  • Molecular Medicine
  • Biomedical Engineering
  • Applied Microbiology and Biotechnology
  • Pharmaceutical Science

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