title: Disposable molecular valve consisting of alginate gel.
abstract: A disposable molecular valve, consisting of a membrane coated with alginate gel, which is partially cross-linked with Ca(2+), was developed based on a volume change and/or dissolution of the gel in response to the cation concentration. The valve automatically opened upon an increase in the concentration of cations such as H(+), Na(+), Ca(2+), Mg(2+), Cu(2+), or Al(3+). The concentration where the valve opens was 1 x 10(-4) to 2 x 10(-4) M for Ca(2+), Cu(2+), and Al(3+), but the solution volume passed vs. concentration increased in the order of Ca(2+), Cu(2+), and Al(3+). For Na(+) and Mg(2+) the valve opening concentration was ca. 1 x 10(-2) and 1 x 10(-3) M, respectively. Two mechanisms were proposed to account for the opening of the valve. One is due to a shrinking of the gel caused by cations; the other is due to dissolution of the gel. The former corresponds for the cases of Ca(2+), Cu(2+), and Al(3+), and the latter does for Na(+) and Mg(2+). The valve closed over the pH range from 3 to 12, whereas it opened below and above this range. The effects of anions and pressure were also studied.
authors.affiliation: Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan. takada.kazutake@nitech.ac.jp
authors.forename: Kazutake
authors.initials: K
authors.lastname: Takada
authors.forename: Kazuhisa
authors.initials: K
authors.lastname: Kadota
authors.forename: Akio
authors.initials: A
authors.lastname: Yuchi