Review articleExtended-nano chromatography

•Chromatography using an extended-nano (10-1000 nm) fluidic channel is reviewed.•Instruments for aL-fL sample injection and sensitive detection are described.•Fabrication methods of nanochannel separation columns are introduced.•Femtoliter scale separation in various mode was realized.

A novel liquid chromatographic method utilizing the extended-nano space called extended-nano chromatography, encompassing the 10-1000 nm region, has emerged recently. It utilizes an extended-nano fluidic channel, which is fabricated on a glass chip, as a separation column. The advantages of extended-nano chromatography are that it uses extremely small sample volumes (attoliter to femtoliter) and demonstrate high separation efficiency. In this review, the fundamentals of extended-nano chromatography are summarized. Instrumentations to realize attoliter sample injections and sensitive detection methods are described. A fabrication method for nanochannel separation columns, including substrate-bonding and surface modification, is also introduced. A highly efficient separation was performed within several seconds, as predicted by the theory. Future perspectives, including living single cell analysis and ultrahigh performance separation, are also discussed.