Two-photon control of melanopsin activation in cell culture and intrinsically photosensitive retinal ganglion cells (ipRGCs)

Melanopsin is a photopigment found in intrinsically photosensitive retinal ganglion cells (ipRGCs) implicated in the regulation of circadian rhythms. Despite extensive knowledge of the spectroscopic properties of melanopsin, how it responds to two-photon activation has yet to be investigated. Here, we report successful two-photon activation in melanopsin-expressing HEK293T cells and ipRGCs following illumination with a supercontinuum of light between 900-1160 nm. We also report the ability to drive its activation kinetics in HEK293T cells by modulation of the spectral amplitude and phase of the supercontinuum source.