Sensitive analysis of α-synuclein by nonlinear laser wave mixing coupled with capillary electrophoresis

Anal Biochem. 2016 May 1;500:51-9. doi: 10.1016/j.ab.2016.01.010. Epub 2016 Feb 11.


Multi-photon nonlinear laser wave-mixing spectroscopy is a novel absorption-based technique that offers excellent detection sensitivity for biomedical applications, including early diagnosis and investigation of neurodegenerative diseases. α-Synuclein is linked to Parkinson's disease (PD), and characterization of its oligomers and quantification of the protein may contribute to understanding PD. The laser wave-mixing signal has a quadratic dependence on analyte concentration, and hence the technique is effective in monitoring small changes in concentration within biofluids. A wide variety of labels can be employed for laser wave-mixing detection due to its ability to detect both chromophores and fluorophores. In this investigation, two fluorophores and a chromophore are studied and used as labels for the detection of α-synuclein. Wave-mixing detection limits of PD-related protein conjugated with fluorescein isothiocyanate, QSY 35 acetic acid, succinimidyl ester, and Chromeo P503 were determined to be 1.4 × 10(-13) M, 1.4 × 10(-10) M, and 1.9 × 10(-13) M, respectively. Based on the laser probe volume used, the corresponding mass detection limits were determined to be 1.1 × 10(-23) mol, 1.1 × 10(-20) mol, and 1.5 × 10(-23) mol. This study also presents molecular-based separation and quantification of α-synuclein by laser wave mixing coupled with capillary electrophoresis.

Keywords: Electrophoresis; Parkinson's disease; Ultrasensitive nonlinear spectroscopy; α-Synuclein.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Electrophoresis, Capillary / methods*
  • Molecular Weight
  • Nonlinear Dynamics
  • Spectrophotometry, Ultraviolet
  • alpha-Synuclein / analysis*
  • alpha-Synuclein / chemistry


  • alpha-Synuclein