Mospolitech: Method of contactless diagnostics and control of hydrogels in 3D bioprinting

Main article: Organ cultivation (Bioprinting, bioprinting)

2022: Announcement of the method of contactless diagnostics and control of hydrogels during bioprinting

On January 23, 2021, Moscow Politech announced that scientists at the Faculty of Chemical Technology and Biotechnology developed a technique and special equipment that allows using the optical method to control and control processes inside hydrogels when performing their 3D bioprinting.

Moscow Polytechnic proposed a method of contactless diagnostics and control of hydrogels during bioprinting

As reported, the experimental methods and devices developed by the authors of the project contribute to the development of the fundamental foundations of the control of heat and mass transfer processes in relation to 3D bioprinting systems based on gel materials. The tasks related to the delivery of substances to printed cells and the development of methods for their diagnosis, the development of 3D bioprinting based on hydrogel matrices are carried out by a research team of employees and students of Moscow Polytechnic, head - associate professor, Ph.D. Nikolai Zakharov. The use of gels in bioprinting is one of the promising areas for the development of regenerative medicine. Hydrogels are effective as a material for growing human tissues and organs or restoring them. In 3D bioprinting, hydrogels are used as a basis on which layers of living cells are applied in a certain order. After that, cells of the same type are grouped and form a finished organ. Hydrogels have special properties, since they are biologically neutral, can restore the structure after mechanical destruction or transition from a liquid state to a gel state and back when heated, which is important for 3D bioprinting.

To work with hydrogels, non-contact methods for investigating and measuring data are required, which is the optical method. The need for a non-invasive approach to the study of hydrogels in relation to 3D bioprinting technology is due to three tasks. First, it is necessary to monitor the heat distribution in the object to be printed. Maintaining the temperature regimes of cells inside the gel is a vital condition for them. If you make the temperature higher than certain indicators, the cells inside the gel can die, if lower, they will stop developing and fall into anabiosis or die. The second task is technological. In the printing process, which must go continuously, the temperature of the gel has to be repeatedly affected, since the gel is applied to the substrate by the printing device, often cooled, then there are thermal differences that need to be corrected. Finally, the importance of subsequent cell growth management. Once the helium bio object is printed, it can be controlled by thermal effects. Since cells need nutrition, which can be supplied through artificially created microchannels, the optical method of holographic interferography allows you to observe which cells do not receive nutrition, and which are obtained with excess. By controlled heating and cooling of the gel sample, the delivery of nutrient components can be controlled by locally reducing or increasing the diameter of the microchannels, or the access can be blocked altogether.

The device for hydrogel examination is an optical complex placed on a special plate with an automatic vibration insulation system. The source of scanning radiation is a helium-neon laser with low power. Optical system consists of lenses, holographic plate, high-speed video recording system and working section with examined helium sample. The peculiarity of this method is that all the changes that occur in the object of study can be observed in real time. This method allows you to not just shoot a video, like on a phone camera, it captures the temperature distribution in the volume of the object under study.

Application of optical method allows to obtain technological parameters by temperature characteristics and thermal heating of hydrogels. In other words, to get answers to the question of what temperature the gel with cells warmed up to, and what is the most characteristic - in what time, because the test process is non-stationary, that is, it changes both in the entire volume of the gel sample and in time. The implemented optical method allows, in particular, to see to what depth the gel material has warmed up, during what time, as well as to study its thermophysical properties. The method will determine the technological parameters of future 3D bioprinting devices.

Method of contactless diagnostics and control of hydrogels in 3D bioprinting

The peculiarity of the obtained results is that for the first time we obtained a distribution of the temperature field in such a complex-structured material as a hydrogel. The obtained data, on the basis of which the technological parameters of printing processes can be formed, are data on various types of hydrogels: agarose, gelatin, as well as various mixed samples based on them. We learned that in different gels the temperature distribution goes differently, they heat differently, to different depths. As a rule, thermocouples are used to measure the temperature in the volume of the substance. The peculiarity of our method is that it allows you to measure the temperature over the entire volume of the gel used for bioprinting in a non-contact mode. told Nikolai Zakharov, project manager