Photoreceptor degeneration is an important cause of blindness. Enabling near-infrared light sensitivity in a blind human retina may supplement or restore visual function in patients with regional retinal degeneration. Researchers induced near-infrared light sensitivity using gold nanorods bound to temperature-sensitive engineered transient receptor potential (TRP) channels. When the nanorods absorbed light and converted it into heat, the coupled ion channels were gated by infrared light.
The researchers expressed mammalian or snake TRP channels in light-insensitive retinal cones in a mouse model of retinal degeneration. Near-infrared stimulation increased activity in cones, ganglion cell layer neurons, and cortical neurons, and enabled mice to perform a learned light-driven behavior.
They tuned responses to different wavelengths, by using nanorods of different lengths, and to different radiant powers, by using engineered channels with different temperature thresholds. They targeted TRP channels to human retinas, which allowed the postmortem activation of different cell types by near-infrared light.