Nanoscale photosynthesis, the photophysics of neural cells, and artificial sight

Using the technique of Kelvin force microscopy, we have performed the first measurements of photovoltages from single photosynthetic reaction centers. The measured values, typically 1 V or more, are sufficiently large to trigger a neural response. The goal 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), diseases that are the leading causes of blindness world-wide. Although the neural wiring from eye to brain is intact, these patients lack photoreceptor activity. It is the ultimate goal of this proposal to restore photoreceptor activity to these patients using PSI as the optical trigger. In principle, the approach should work. PSI is a robust integral membrane molecular photovoltaic device. Depending on orientation, it can depolarize or hyperpolarize the cell membrane with sufficient voltage to trigger an action potential.