The central objective of the proposed research was to demonstrate that plasmon resonating nanostructures can resonantly transfer charge carriers (electrons or holes) to biological components to drive redox reactions. The central objective will be achieved through the specific project aims listed below: Aim 1: Synthesize and characterize metal-semiconductor core-shell structures composed of Ag/Au alloy cores andTiO2 or CuO2 shells. Solution-based approaches will be used to synthesize Ag:Au alloy nanoparticles with ~30 nm diameter and varied compositions from 100% Au to 100% Ag. This will allow a tuning of the plasmon resonance wavelength from 400-600 nm. Thin semiconducting TiO2 (n-type) and CuO2 (p-type) shells will be grown on top of the metal cores to control the transfer of electrons or holes to biological components. Pinhole free and porous semiconductor shells will be synthesized to allow for half reactions or complete redox reactions. The structures will be characterized using electro microscopy and optical spectrophotometry. Aim 2: Demonstrate resonant control of cytochrome c oxidation and reduction mediated by the photoexcitation of plasmonic-semiconducting nanostructures. Photoexcitation wavelength dependent cytochrome c oxidation and reduction reactions will be executed. The plasmonic metal core composition will be varied, thus varying the plasmon resonance wavelength, to show the ability to create digital on/off switches for charge transfer. TiO2 coated metal will be used in cytochrome c reduction and CuO2 coated metal will be used for cytochrome c oxidation. Porous semiconductors coupled with appropriate hole/electron scavengers will be examined to study complete redox processes. Ag coated with TiO2 and Au coated with CuO2 will be explored simultaneously to demonstrate the independent control of cytochrome c oxidation and reduction in a cyclic manner in the same pot.