In laboratories where the boundary between biology and engineering grows ever thinner, researchers have developed injectable nanoparticles capable of restoring light sensitivity to retinas that have lost their natural photoreceptors. Made from biomimetic graphitic carbon nitride, these particles slip into damaged eye tissue and perform the missing function — converting light into electrical signals the brain can still receive and interpret. The work, demonstrated in mouse models, addresses conditions like macular degeneration and retinitis pigmentosa that rob millions of their sight with no cu