Molecular photovoltaics and the photoactivation of mammalian cells.

Photosynthetic reaction centers are integral plant membrane protein complexes and molecular photovoltaic structures. We report here that addition of Photosystem I (PSI)-proteoliposomes to retinoblastoma cells imparts photosensitivity to these mammalian cells, as demonstrated by light-induced movement of calcium ions. Control experiments with liposomes lacking PSI demonstrated no photosensitivity. The data demonstrate that PSI, a nanoscale molecular photovoltaic structure extracted from plants, can impart a photoresponse to mammalian cells in vitro.