Molecular Photovoltaics and Artificial Sight

Abstract

Abstract: : Purpose:The purpose of this project is insertion of purified Photosystem I (PSI) reaction centers or other photoactive agents into retinal cells where they will restore photoreceptor function to people who suffer from age–related macular degeneration (AMD) or retinitis pigmentosa (RP). Methods: PSI is a robust integral membrane molecular photovoltaic structure. Depending on orientation, it can depolarize or hyperpolarize the cell membrane with sufficient voltage to trigger an action potential. PSI proteoliposomes were prepared and incubated with mammalian cells. Results: Using previously determined molecular photovoltaic properties of isolated Photosystem I reaction centers, photoreceptor activity was imparted to mammalian cells. Incubation of WERI Rb–1 retinoblastoma cells with functional PSI reaction centers that were isolated from spinach leaves and reconstituted into proteoliposomes resulted in a light–induced PSI–dependent increase in intracellular Ca²⁺dependent on the presence of extracellular Ca²⁺ ions. The increase in the intracellular levels of Ca²⁺ occurred cooperatively in all cells of the culture. Treatment of rat retinal progenitor cells and retinal ganglion cells with the same formulation of PSI–proteoliposomes imparted onto the cells an ability to respond to light stimulus by the increase in intracellular Ca²⁺. Conclusions: Proof–of–principle, that a molecular photovoltaic structure can impart photoactivity to a mammalian cell, has been demonstrated.

Keywords: retina • age-related macular degeneration