Silicon in Medicine

2023: Rough surface of implants will help cells catch on better

Scientists at NUST MISIS have studied the effect of the surface of silicon wafers on viability and cellular adhesion - the ability of cells to attach to the material. Representatives of the university shared the results of the study on March 15, 2023 with Zdrav.Expert. According to scientists, silicon has a number of advantages, and in the future, silicon plates with a porous surface can find their niche in biomedical technologies, for example, for creating biointerfaces, sensors for reading electrical signals from tissues and interfaces for stimulating cells.

SEM images of cells on the surface of porous plates
Illustration: NITU MISiS

As noted in NUST MISIS, of particular interest to scientists and doctors working in the field of reconstructive surgery is the development and production polymeric scaffolds of "scaffolds" that serve as the basis for bone tissue repair. For better engraftment, such scaffolds are usually populated with patient cells.

Often, research does not pay enough attention to the peculiarities of the surface structure of the material on which the cells are fixed. However, cell adhesion - the attachment of cells to the surface of the material - is a major factor for cell survival in scaffold. The influence of hardness and surface roughness on the vital activity of cells is extremely important, since these parameters greatly affect the activity of genes and, ultimately, the behavior of cells - whether they will die or grow vigorously, migrate or stay in place, the scientists explained.

"Researchers have been working with silicon for a long time - they learned to etch it well, that is, to form micro/nano pores in solutions of strong acids using chemical or electrochemical etching. Silicon plates with a porous surface can find their niche in biomedical technologies, although at the moment it is not obvious, "said Artyom Ilyasov, author of the study, engineer of the Biomedical Engineering Research Center.

MISiS University scientists have examined in detail the effect of silicon wafer pore depth on cellular adhesion. To do this, the researchers made plates with a different structure of porous layers: crystalline nanoporous layers with a pore size of about 20 nm and microporous with a columnar pore structure with a diameter of 100 times larger - about 2 microns.

"On silicon, it is convenient to study the effect of surface roughness and hardness on processes occurring in cells because it is possible to create pores in a wide range of sizes on it. Moreover, the material is non-toxic, biodegradable and easy to functionalize, such as by drug loading or by attaching different ligands - functional groups or molecules - to the surface. In this work, we conducted elemental analysis of two variants of porous layers, cytotoxicity tests, and also measured the wettability angles of samples before and after cell deposition, "said Artyom Ilyasov.

It turned out that nanoporous layers are much more hydrophilic, that is, they are able to absorb water well, and have a smaller contact angle compared to microporous layers. After the 1st cell inoculation, the contact angle values for the nanopores were closer to optimal compared to micropores. Different porosity has been indirectly shown to promote different cell adhesion - cells adhere more strongly to nanopore plates and are weaker to micropores.

In the future, scientists plan to continue research with other types of cells, as well as study the effect of roughness and hardness of plates on the stiffness of the cell membrane.

The study was carried out as part of the Priority 2030 development program. The results of the work are published in the scientific journal Silicon.

See also

• Polymers in medicine