Light Sensitive Nanoparticles Bypass Dysfunctional Photoreceptor Cells
Researchers here provide an initial proof of concept demonstration of a novel foundation for replacing lost visual capacity in cases of retinal degeneration, without addressing the underlying pathology that causes loss of function in photoreceptor cells. Recall that direct stimulation of retinal cells by grid electrodes implanted in the retina has been used to produces a poor substitute for actual vision, but a substitute that allows blind people at least some capacity to navigate and even read. Here, researchers introduce light sensitive nanoparticles into the retina that can in principle provide the basis for a more refined artificial substitute for normal vision. Based on the results of the electrode grids, one would expect the result to be a view of the world painted in glowing shades of phosphenes at various intensities.
The possibility to electrically stimulate living tissue creates new opportunities for therapeutic applications. Interfaces between biology and nanomaterials open an array of possibilities for non-genetic modulation of bioelectric activity with subcellular spatiotemporal control. Nanoparticles (NPs) have shown to be able to build tight interfaces with both intra- and extracellular membranes. Importantly, light can trigger electrochemical or photothermal effects at the semiconductor NP/cellular interface acting as a leadless electrophysiological modulator.
Here, drawing inspiration from photosynthesis, we develop hollow-sphere graphitic carbon nitride nanoparticles (hg-C3N4 NPs) that can modulate biological activity from subcellular processes to whole-tissue function. The homogeneous hg-C3N4 NPs show responsiveness to light via both photoelectrochemical and photothermal mechanisms and can be spontaneously internalized with excellent cytocompatibility.
We demonstrate that hg-C3N4 nanoparticles can be safely delivered and elicit measurable cortical and behavioural light responses in a model of advanced retinal degeneration. The application of hg-C3N4 NPs to porcine retinal tissue ex vivo confirms their modulation capability to directly activate retinal ganglion cell activity under light-emitting diode photostimulation.