Patent ID: 7902353

Claim:
A biosensor comprising: (a) a nucleic acid enzyme dependent on an ion to produce a product from a substrate; (b) the substrate, wherein the substrate comprises a fluorophore and the enzyme comprises a quencher of the fluorophore, or the enzyme comprises a fluorophore and the substrate comprises a quencher of the fluorophore, and the ion is selected from the group consisting of K + , Na + , Li + , Tl + , NH 4 + , Ag + , Ca 2+ , Mn 2+ , Co 2+ , Ni 2+ , Zn 2+ , Cd 2+ , Cu 2+ , Pb 2+ , Hg 2+ , Pt 2+ , Ra 2+ , Ba 2+ , Sr 2+ , Co 3+ , Cr 3+ , Ln 3+ , and Ce 4+ .