Issue 22, 2019

Parallel multiphase nanofluidics utilizing nanochannels with partial hydrophobic surface modification and application to femtoliter solvent extraction

Abstract

In the field of microfluidics, utilizing parallel multiphase flows with immiscible liquid/liquid or gas/liquid interfaces along a microchannel has achieved the integration of various chemical processes for analyses and syntheses. Recently, our group has developed nanofluidics that exploits 100 nm nanochannels to realize ultra-small (aL to fL scale) and highly efficient chemical operations. Novel applications such as single-molecule analyses and single-cell omics are anticipated. However, the formation of parallel multiphase flows in a nanochannel remains challenging. To this end, here we developed a novel method for nanoscale partial hydrophobic surface modification of a nanochannel utilizing a focused ion beam. Hydrophobic and hydrophilic areas could be patterned beside one another even in a 60 nm glass nanochannel. Because this patterning maintained the liquid/liquid interface in the nanochannel based on the difference in wettability, stable aqueous/organic parallel two-phase flow in a 40 fL nanochannel was realized for the first time. Utilizing this flow, nanoscale unit operations involving phase confluence, extraction and phase separation were integrated to demonstrate solvent extraction of a lipid according to the Bligh–Dyer method, which is a broadly used pretreatment process in lipidomics. We accomplished the separation of a lipid and an amino acid in a sample volume of 4 fL (250 times smaller than the pL volume of a single cell) with a processing time of 1 ms (10 000 times faster than that in a microchannel). This study therefore provides a technological breakthrough that advances the field of nanofluidics to allow multiphase chemical processing at fL volumes.

Graphical abstract: Parallel multiphase nanofluidics utilizing nanochannels with partial hydrophobic surface modification and application to femtoliter solvent extraction

Supplementary files

Article information

Article type
Paper
Submitted
10 Aug 2019
Accepted
27 Sep 2019
First published
28 Sep 2019

Lab Chip, 2019,19, 3844-3852

Author version available

Parallel multiphase nanofluidics utilizing nanochannels with partial hydrophobic surface modification and application to femtoliter solvent extraction

Y. Kazoe, T. Ugajin, R. Ohta, K. Mawatari and T. Kitamori, Lab Chip, 2019, 19, 3844 DOI: 10.1039/C9LC00793H

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