Various applications are being developed for the use of small robots to deliver therapeutic drugs to targeted areas in the body. In this way, it is aimed to deliver the active substances in the drugs to the area to be treated and to ensure their controlled release.
Transferring drugs to certain parts of the body with micro and nano-sized particles, which are actively directed and moved, attracts attention among the subjects that researchers have been focusing on recently.
While the robots that carry drugs in the circulatory and digestive system are easier to move, it becomes difficult to move and difficult to reach the target in areas such as the glassy body region of the eye, where the density is high and the tissue networks are complex. Researchers seem to have overcome this problem with the nano-sized robot designs they are working on.
To date, few micro systems that can be directed in biological environment have been developed. These systems generally consist of structures that are pushed by chemical, mechanical or magnetic means in the fluid-containing areas of the body, such as the circulatory and digestive system.
In animal studies, some restrictions on the use of small robots in drug transportation have been identified. For example, in studies conducted with cylindrical magnetic structures with a diameter of 285 µm (micrometer) and 1800 µm length, it has been determined that movement is restricted in the glassy body region of the eye.
In the light of previous research, it was concluded that issues such as the suitability of size, shape and surface coatings for movement are important factors in order to enable the robots used in drug transfer to move easily in different and more dense areas of the body. As a result, there are obstacles to overcoming the use of robots for drug transfer in areas of the body that are made up of more complex tissue networks or where the density is high.
Designed to advance in the gel-like eye fluid in the eye, nano robots promise significant advances in the field of ophthalmology (the medical branch dealing with visual diseases and surgery). While conventional drug delivery systems work with irregular and passive diffusion principles, they can be inadequate in sending drugs to the targeted areas in the back of the eye.
In addition, tight macromolecular structures in many tissue areas are the biggest obstacle to the reach of the targeted drugs with traditional systems. Zhiguang Wu and her friends announced that they have found a way to overcome this problem with their published article.
In the research conducted on controlled drug release under the leadership of the Max Planck Institute Intelligent Systems Department, robots that can move easily in dense tissue areas such as the eyes and resemble the auger were developed. Robots with a diameter less than 500 nm wide (about 1 / 200th of the diameter of a strand of hair) are designed to move easily in gel-like areas like eye fluid.
The shapes and surface coatings of nano-sized robots have also been developed in a way that they do not harm the biological structures in the regions where they progress. Thus, the movement of nano robots in a dense tissue environment was performed for the first time. The purpose of future research is to load these nano robots with therapeutic elements and effectively deliver them to the targeted area in the body.
With their work, the researchers have developed very small robots that can reach the retina by passing through the vitreous region of the eye (the gel-like, colorless and transparent region located between the lens and the retina). Considering that the pores in the vitreous region are about 500 nm in size, it seems possible for robots smaller than these sizes to proceed without any problems.
In the studies carried out by creating vitreous region-like environments in the laboratory, the magnetic featured auger robots with a diameter of 120 nm and a length of 400 nm successfully reached the retina region of the eye by crossing the targeted distances. These nano-sized robots basically consist of head and tail parts. The diameter of the head part is about one hundredth of the diameter of a hairdo. This means that the tiny robots are small enough to pass through the mesh in the vitreous region.
The tail part of the robots are auger-like structures with a length of about 2 µm. Another important point about the structure of the robots is the use of nickel or iron to enable them to move with the magnetic field.
Thanks to the magnetic field applied from the outside, the controlled movement of the nano robots coated on the surface was ensured and the nano robot swarms were transported from the eyeball to the retina in 30 minutes. Meanwhile, the movements of the robots were visualized by Optical Coherence Tomography (OCT).
In the study, it is determined that there are two important criteria for the movement of robots in the biological environment.