title: Development of a surface-reaction system in a nanoliter droplet made by an ink-jet microchip.
abstract: A surface-reaction system in a nanoliter water pool using an ink-jet microchip was developed. The reaction system in the nanodroplets formed on a poly(dimethylsiloxane) (PDMS) coated glass slide increased the diffusion-controlled reaction without using a nano-pump, specialized connector or highly sensitive detector. When nanoliter droplets were placed on the PDMS surface with a distance of 100 microm between them by the ink-jet microchip, the repeatabilities of the fluorescence intensity were 2.9% RSD (n = 7). The used ink-jet microchip had 4 different injection ports, and the distance between the ports was 0.995 mm. It was necessary to correct the distance in order to mix or dilute samples in a small droplet. The correction was successfully performed by moving the X-Y stage using inhouse-made software. A linear relationship was obtained between the Resorufin concentrations and the fluorescence intensity. We applied this system to an enzyme-linked immunosorbent assay (ELISA) for immunoglobulin A (IgA), and observed a difference in the fluorescence intensity derived from the amount of IgA (blank, 6.25 ng/mL, 12.5 ng/mL). These results show the usefulness of the open-type micro-analytical systems proposed by us.
authors.affiliation: Faculty of Urban Environmental Sciences, Tokyo Metropolitan University, Tokyo, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Kudo
authors.forename: Takako
authors.initials: T
authors.lastname: Nakahara
authors.forename: Tatsuro
authors.initials: T
authors.lastname: Nakagama
authors.forename: Nobuko
authors.initials: N
authors.lastname: Seino
authors.forename: Masaki
authors.initials: M
authors.lastname: Shinoda
authors.forename: Katsumi
authors.initials: K
authors.lastname: Uchiyama