## 3 Discussion  
In addition to the development and study of the mechanisms of action of spherical nanoparticles of various origins, in recent years, active work has been carried out on the synthesis of nanostructures of various shapes and the study of their physiological effects. Research is underway on various types of scaffolds, including electrospun nanofibers, which can be an effective substrate for neuron differentiation, axon growth, and the formation of new cell-cell and cell-matrix interactions [34, 35]. Nanofibers may be a platform for the selective and controlled release of drugs to brain cells, protecting them from damage [36]. Carbon nanotubes have been developed that have shown their electrically conductive capacity, strong mechanical properties, and morphological similarity to neurites [37]. The great advantage of nanotubes is that they are highly flexible, very strong, and can be easily modified with active agents [38, 39]. It has been shown that carbon nanotubes can be widely used as bone implants and for the treatment of rheumatoid arthritis or osteoporosis [38, 40], while the use of these nanostructures in neuroprotection has not been practically studied. Using carbon nanotubes as an example, it has been shown that they penetrate cells through 2 pathways, active endocytosis, and passive nano penetration [41]. The use of nanotubes for the treatment of neurodegenerative diseases depends on their physicochemical properties, origin, and method of preparation. At the same time, their large surface area, ability to be easily modified with drug molecules, and biocompatibility with the neural system suggests a high efficiency of nanotubes [42]. Nanostructures in the form of filaments can enhance the ability of neurons to attach to the substrate and the ability of their neurites to grow [43]. Scaffolds grown from nanofilaments are able to improve their integration into the Parkinsonian brain and improve the re-inervation of the striatum of Parkinsonian mice, especially when these nanostructures have been doped with GDNF [44]. Loading nanofilaments with drugs showed that nanofilaments started to float immediately with zero floating lag time; the formulations did not sink after 24-h. The floating nanofilaments showed a lower first release between 20% and 57% when compared to non-floating nanofilaments (40-82% within 2 h). This indicates that drugs that should be administered frequently might be taken orally 'once a day' and improve patient compliance [45]. One-dimensional (1D) nanostructural materials such as nanotubes, nanowires, nanorods, and nanothreads have recently received much attention due to their interesting properties and are potential candidates for application in different fields. The one-dimensional nanostructured selenium nanowires have been widely studied because of their functional properties in superconductivity [46], high photoconductivity, and catalytic activity. Selenium nanowires have field application in the areas of photoelectric cells, xerography, light-measuring devices, and solar batteries [47]. Similar physical properties should be assumed for selenium nanorods. The shape of rods or tubes have pronounced properties to remain in the body for a long time and exert their targeted effects on tissues. It is shown that the residence time of long rod nanoparticles and short rod silica nanoparticles in the gastrointestinal tract is significantly higher compared to spherical nanoparticles [9; 48; 49]. It has also been found that oral administration of rod-shaped silica nanoparticles leads to a greater accumulation of Si in the liver and kidney. It was also found that the short rod nanoparticles reached a higher content in all the organs at 2-h and 24-h, while the long rod nanoparticles attained a higher content in all the organs at 7 days. These results indicated that it was more difficult to remove the long rod nanoparticles from the reticule-endothelial system (RES) organs and they were protected from macrophages, resulting in a longer blood-circulation [9].