An international research team has developed microscopic particles that can make blind retinas respond to light. The technology was developed at Aarhus University, and the preclinical testing was carried out at the University of Eastern Finland. The findings were published in Nature Biomedical Engineering.
In experiments using mice with retinitis pigmentosa, a blindness-causing disease of the retina, the light-sensitive nanoparticles were injected into the eye. The particles settle close to nerve cells in the retina. When light hits the particles, it triggers electrical and chemical processes that can activate the nerve cells and prompt them to send signals towards the brain.
A new pathway from light to nerve cells
To understand how the technology works, we need to look at the back of the eye, where the retina is located. Its light-sensitive photoreceptors normally capture light and initiate the signals that the brain uses to create vision.
In retinitis pigmentosa, these photoreceptors gradually degenerate. Other nerve cells and connections within the retina, however, can remain intact. The new nanoparticle technology aims to make use of these surviving cells.
The microscopic nanoparticles are made from the light-sensitive semiconductor graphitic carbon nitride. Their hollow structure makes them effective at capturing visible light. When exposed to light, they trigger a series of physical and chemical processes in their immediate surroundings. These processes can influence signaling in living cells.
After being injected into the eyes of mice with advanced retinitis pigmentosa, the nanoparticles accumulated on the surface of the retina, close to the retinal ganglion cells that transmit information from the eye towards the brain.
When the researchers illuminated the eyes, they detected activity in the visual cortex of the brain. The mice also changed their behavior in response to the light. Additionally, it was shown that the technology can activate nerve cells in retinal tissue from pigs.
The results do not mean that normal vision was restored in the mice, but the technology can generate a measurable biological response to light even when the photoreceptors that normally detect light have largely degenerated.
According to study lead, Associate Professor Menglin Chen from Aarhus University, the goal is to develop the technology into a retinal prosthesis, but its long-term safety and function must be studied in much greater detail before the technology could be tested in humans.
“Once the photoreceptors are lost, the options for restoring light sensitivity are still very limited, and each approach in development carries its own constraint. Gene therapies are mutation-specific, optogenetics requires genetically modifying the surviving cells, and electronic implants require surgery. That is why it is worth testing many different types of strategies. What we show here is a light-evoked response in a degenerated retina, which is an early step rather than a finished prosthesis,” says co-author, Associate Professor Henri Leinonen whose Retina Laboratory carried out the experiments at the University of Eastern Finland.
Aarhus University press release
For further information, please contact:
Associate Professor Henri Leinonen, University of Eastern Finland, School of Pharmacy https://uefconnect.uef.fi/en/henri.leinonen/
Research article:
Müller, C.A., Klompmaker, K.K., Zhang, Y. et al. Biomimetic graphitic carbon nitride nanoparticles for multiscale photomodulation and therapeutic intervention. Nat. Biomed. Eng (2026). https://doi.org/10.1038/s41551-026-01773-w
