The eye is a sensitive organ, fragile and difficult to repair. Currently, a large quantity of drugs for the treatment of ocular diseases are administered as drops that are applied to the cornea and then slowly diffuse into the eye. However, this technique causes a lot of problems, the main one being that drugs can reach all the cells of the eye before reaching their target. This often leads to irritation, dryness and a host of more problematic side effects.
Displeased by this extreme vagueness, a group of German researchers have devised a technique based on nanotechnology, conceiving a type microscopic devices able to swim inside the eye.
Despite the unusual side of these small eye explorers, this method allows for the introduction of specific doses of drugs precisely where they are needed, which could change the treatment of diseases such as glaucoma or macular degeneration.
To succeed, the researchers had to design devices capable of swimming in several types of liquids with very different densities and textures. Indeed, the eye is divided into two chambers, and each contains a liquid of its own. The anterior chamber, which begins under the cornea at the surface of the eye and stops at the iris (the colored region of the eye), is filled with a clear liquid, similar to water, named the aqueous humor. The rest of the eye, called the posterior chamber, is filled with a much denser, gel-like liquid called the vitreous humor.
These two regions have very different properties that must be taken into account when treating the eye.
However, these robots are autonomous devices moving of their own free will. They are in fact fixed structures composed of two segments: a head containing the drug to be delivered, and a tail in the form of a spiral. These segments are just 500 nanometers long, a measurement 200 times smaller than the thickness of a sheet of paper.
These thrusters are formed of molecules that are both magnetic and biodegradable. They are also covered with a slippery substance allowing them to move easily through the thick vitreous humor.
These robots are controlled remotely using magnetic fields, which allows researchers to move them in all directions. As of now, these robots have been tested only in preliminary studies with eyes from pigs, isolated in the laboratory. The researchers injected a solution containing 10,000 of these thrusters, then put the eyes in an apparatus capable of generating the magnetic fields necessary for the displacements of the nanobots.
They then delivered their medicinal goods exactly where the researchers wanted them, all in 30 minutes instead of the five hours that the traditional drops take.
Although the technique is a success, there is still a lot of work to be done before these robots roam our eyes or find themselves anywhere else in our body. Although nanobots have already been tested in animals, these experiments must be redone, since the eye is a completely different medium from the bloodstream.
Many researchers believe that within a decade, medical nanobots will change the way people are treated, both in the precise administration of drugs and in the fight against cancer.