Nanochannel chromatography and photothermal optical diffraction: Femtoliter sample separation and label-free zeptomole detection

Yoshiyuki Tsuyama; Kyojiro Morikawa; Kazuma Mawatari

doi:10.1016/j.chroma.2020.461265

Nanochannel chromatography and photothermal optical diffraction: Femtoliter sample separation and label-free zeptomole detection

J Chromatogr A. 2020 Aug 2:1624:461265. doi: 10.1016/j.chroma.2020.461265. Epub 2020 May 21.

Authors

Yoshiyuki Tsuyama¹, Kyojiro Morikawa², Kazuma Mawatari³

Affiliations

¹ Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656, Japan.
² Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656, Japan.
³ Department of Bioengineering, Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656, Japan; Department of Applied Chemistry, Graduate School of Engineering, The University of Tokyo, 7-3-1, Hongo, Bunkyo, Tokyo 113-8656, Japan. Electronic address: kmawatari@icl.t.u-tokyo.ac.jp.

PMID: 32540055
DOI: 10.1016/j.chroma.2020.461265

Abstract

Column miniaturization of liquid chromatography is a major trend in separation sciences with the advent of single-cell proteomics and metabolomics. Nanochannel chromatography is one of the promising tools for single-cell analyses because it provides ultra-small sample volume and high separation efficiency. However, non-fluorescent molecular detection in such small channels is still quite difficult due to fL-aL sample volume, which hinders further miniaturization of nanochannels. In this study, we overcame the size limitation of nanochannel chromatography by our label-free molecular detection method: photothermal optical diffraction (POD), which utilizes the photothermal effect of analytes and optical diffraction by nanochannel. The combination of the nanochannel chromatography and the POD enables 1.8 fL sample separation and label-free molecule detection in nanochannels with 800 nm width and 300 nm depth at the optimized experimental conditions. The limit of detection is 5.4 zmol (3300 molecules), approximately 50 times lower than the conventional label-free detection method. Furthermore, the theoretical plate number is calculated to be 10⁵ plates/m, and the separation performance is discussed. Our label-free detection method will be widely used as a universal detector for nanochannel chromatography.

Keywords: Diffraction; Label-free detection; Nanochannel; Nanofluidics; Normal-phase chromatography; Photothermal effect.

MeSH terms

Azo Compounds / chemistry
Calibration
Chromatography, Liquid / methods*
Light*
Nanoparticles / chemistry*
Reproducibility of Results
Single-Cell Analysis
Staining and Labeling*
Temperature*

Substances

Azo Compounds
Scarlet Red