Attoliter order droplet formation using nanochannels and enzyme reaction inside a droplet

This paper reports a droplet formation device having nanochannels fabricated with femtosecond-laser-assisted etching. With the combination of nanochannels embedded in a substrate and microchannels on the substrate surface, approximately 650 nm diameter water phase liquid droplets (approximately 150 aL in volume) have been produced. In addition, we confirmed that enzyme reaction inside a femtoliter or attoliter droplet was digitally observed by fluorescence for the first time. Such droplets can be used for single-molecule enzymology instead of conventional arrays of femtoliter chambers [1].