Abstract: The invention provides systems having an electron transfer moiety tethered to an electrode by a conductive spacer moiety. A biasing potential applied to the electrode reduces the electron transfer moiety to form a reduced electron transfer species capable of absorbing a photon, to form an excited electron transfer species. An electron accepting moiety accepts an electron from the excited electron transfer species, to form a reduced electron acceptor. The reduced electron acceptor may for example be used in hydrogen generation reactions.

Abstract: In one aspect, the invention provides methods and apparatus for detecting a mismatch in a nucleic acid duplex by measuring the impedance of a nucleic acid layer on an electrode, for example by AC impedance spectroscopy.

Abstract: In one aspect, the invention provides methods and apparatus for detecting a protein binding to a nucleic acid by measuring the impedence of a nucleic acid layer on an electrode, for example by AC impedance spectroscopy. In one embodiment, such methods may for example be used to detect a mismatch in a nucleic acid duplex.