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2023
Russian scientists have found the optimal way to obtain a polymer with a shape memory effect
Employees of the Center for Biomedical Engineering at MISIS University conducted a series of experiments to determine how it is better to produce a polymer material with a shape memory effect (EPF). According to the results of studies, the polymer obtained by extrusion (drawing) returns to its original form faster than the sample produced by casting from solution. Such materials are optimal for creating stents for vessels, self-aligning and self-fixing bone implants, as well as adaptive medical devices (clips, staples, clips, etc.), MISIS representatives said on November 7, 2023 Zdrav.Expert.
 | "Unlike metal alloys with shape memory effect, polymers with EPF have a number of advantages: they are cheaper, capable of bioresorption, have a significantly higher percentage of deformation and respond to a variety of stimuli, their properties are easier to manage," said Polina Kovaleva, an engineer at the Center for Biomedical Engineering at MISIS University. |  |
As scientists explained, the shape memory effect in polymers is due to their unique supramolecular structure. The molecular chains of the EPP polymer contain soft and rigid segments. At room temperature, all parts of the molecular chain are in a glass-like state, which allows to maintain the original shape and fix temporary. When heated above a certain temperature, the soft segments become viscous, allowing the material to be easily deformed into any other shape. After cooling and removing the load, the soft segments return to the glassy state and retain the strain energy, allowing the temporary shape to be fixed; upon reheating, the soft segments release the stored energy, and the fixed temporary shape is restored to the original one.
When considering several methods of forming polymer materials with different supramolecular structure and crystallinity, scientists have determined that extrusion contributes to the formation of an amorphous structure, since at this rate of cooling, crystalline regions do not have time to form. The solution casting method, on the contrary, involves slow evaporation of the solvent and contact with the substrate, which contributes to the formation of a crystalline structure.
| | "The best result in restoring the original form was demonstrated by a polylactide-based material with a predominant amorphous structure, while the semi-crystalline sample loses its ability to fix and restore form," said study co-author Anna Zimina, an engineer at the Biomedical Engineering Center at MISIS University. | |
Further study, experts intend to devote to the search for optimal dispersed fillers, the addition of which to the polymer composition will improve the process and the degree of return of the material to its original form, as well as provide opportunities for remote activation of the effect.
According to Alevtina Chernikova, rector of NITU MISIS, in September 2023, the Institute of Biomedical Engineering was created at NITU MISIS, one of the main tasks of which is the development and commercialization of new products that can significantly improve the quality of life of people.
| | "For several years, scientists at MISIS University have been developing in the field of tissue engineering, biophysics, bioprinting, new technologies and materials for medicine. Within the framework of the Priority 2030 program, the university is implementing the strategic project Biomedical Materials and Bioengineering, and the Health Engineering consortium has been formed, which includes leading universities, research centers, and innovative enterprises, "added Alevtina Chernikova. | |
According to MISIS, the study was carried out with the financial support of the RNF (No. 21-73-205). The study of the supramolecular structure was carried out in the center of collective use "High Resolution Visualization" Skoltech; scanning probe microscopy was carried out on the equipment of the research center "Materials Science and Metallurgy" NUST MISIS with the financial support of the Ministry of Education and Science of Russia (Agreement No. 075-15-2021-696).
Individual polymer implants created at the Kurchatov Institute
On July 13, 2023, representatives of the Kurchatov Institute announced the creation of individual polymer implants for the spine.
As reported, the spinal cage is a structure that during surgery on the spine is installed in place of the destroyed intervertebral disk to fuse neighboring vertebrae damaged as a result of injuries or diseases. For July 2023, non-decomposable materials are used to create such structures, which remain inside the body forever, and can potentially cause complications. Scientists at the Kurchatov Institute Research Center have created a biodegradable cage that tightly connects the vertebrae, and after their fusion, at a given time, is replaced by the patient's bone tissue.
Read more here.
Russian scientists have created nanofibers from polymers for antiseptic wound dressings
Scientists from MISIS University and the Skolkovo Institute of Science and Technology have created a fiber for antiseptic wound dressings, which will avoid complications in patients in the postoperative period. This was announced on May 31, 2023 by Zdrav.Expert representatives of MISIS. According to them, ultra-thin threads were obtained from various polymers by electrospinning. Read more here.
The first "tissue pistol" stitching wounds with biopolymers was printed in Russia
The University of MISiS presented the first "tissue pistol" in Russia, which can stop bleeding and trigger regenerative processes in light and moderate injuries. This was announced on April 5, 2023 to Zdrav.Expert by representatives of NUST MISIS. Read more here.
| | "Before work, two standard 20 ml syringes are filled with biopolymers and medical products. A third syringe is connected through a special port and the device is filled with a stitching agent, then the filling syringe is turned off. When the trigger is pressed, the ultrasonic system simultaneously collects all components in the field of printing, thereby forming a polymer crosslinked biomaterial capable of stopping bleeding and accelerating tissue regeneration, "explained the author of the development Timur Aydemir, Ph.D., engineer at the NUST MISiS Biomedical Engineering Center. | |
Scientists have proposed a filler with improved antibacterial properties for polymeric bone "3D-scaffolds"
An international team of scientists with the participation of researchers at NUST MISIS has proposed an alternative filler of bone "3D-scaffolds" based on calcium silicate. The material prevents the formation of a biofilm of bacteria on the surface of the framework and in the future can be used for implants of low-load bones, for example, a skull. The study was supported by an RSF grant. The results of the work are published in the scientific journal Polymer. This was announced on January 25, 2023 by representatives of NUST MISIS. Read more here.
2022: Russian scientists have created material based on biopolymers for "growing" organs and tissues
Scientists at NUST MISIS together with colleagues from Tomsk Polytechnic University have proposed a way to modify biopolymers for tissue engineering. This was announced on December 9, 2022 to the medical portal Zdrav.Expert by representatives of MISIS. Adding a small amount of reduced graphene oxide particles to the material contributes to improved mechanical properties and shape memory effect, the scientists said. In the future, such material can be used for soft tissue regeneration, for example, for nervous tissue and skin. Read more here.
2021: Russian physicists offered material for the development of self-fitting implants
Specialists of the National Research Technological University "MISIS" together with other Russian scientists were able to improve the main medical material with the shape memory effect. The university announced this to Zdrav.Expert on September 14, 2021. According to the authors, their development will greatly facilitate the work of surgeons and increase the quality of therapy. The study is published in the journal Polymers.
Polylactide is a polymer used in surgery for fixing sutures and other auxiliary tasks. It is characterized by high biocompatibility and complete biodegradability, since it consists of molecules of lactic acid, which plays an important role in metabolism. It is produced from cheap vegetal raw materials with high sugar content.
Polylactide is distinguished by a pronounced shape memory effect (EPF): after deformation, it is able to quickly accept its original state. Thanks to this, the polymer, according to scientists at NUST "MISIS," is optimal for the development of self-aligning implants. They are used to treat defects in bones that do not carry the support load.
The use of such implants will avoid a laborious adjustment to the injured area, which will greatly facilitate the surgeon's work and reduce the time of the operation, the scientists explained. The product of the required shape can be compressed to convenient dimensions and, having placed the defect in place, heated - due to the EPF, the implant itself will take the desired position.
Polylactide, according to scientists, has only one noticeable drawback. The temperature at which the shape memory effect is activated (55-65 ° C) is too high to work with human tissues. NITU MISIS specialists have developed another polymeric composite based on polylactide, which takes the old form already at a temperature of 45 ° C, which is quite permissible with a short-term effect on the body.
| | Studies of self-aligning implants are carried out mainly on inert polymers, achieving the desired EPF activation temperature due to the chemical crosslinking of polymers and the introduction of additional components. The peculiarity of our work is that we used only biocompatible biodegradable polymers, having achieved a decrease in temperature due to simple physical mechanisms. This provides a reduction in not only temperature, but also activation energy, explained the engineer of the scientific project of NUST "MISIS" Polina Zhukova.
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The developed material is a polylactide matrix with spherical inclusions of another polymer, polycaprolactone. The material is obtained by extrusion, i.e. by mechanical stirring in a hot chamber. Specialists of NUST "MISIS" fully described the parameters of EPF, thermal and mechanical characteristics of this composite.
The work was attended by scientists of the Russian State University. A.N. Kosygin. In the future, the scientific team plans to increase the regenerative abilities of the material by adding special bioactive ceramics, as well as develop non-temperature methods for activating the shape memory effect.
2020
Scientists of the RCTU named after D.I. Mendeleev learned to synthesize a conductive polymer polyaniline locally on the surface of silica gel particles
On October 21, 2020, it became known that scientists of the Russian Chemical Technical University named after D.I. Mendeleev, together with Russian and Greek colleagues, learned to synthesize a conductive polyaniline polymer locally on the surface of silica gel particles. The researchers plan to use this material to create carriers for farm preparations, as well as to work out the method using the example of other polymers and substrates. The article appears in the August issue of Polymer magazine.
As explained, polyaniline is one of the polymers of molecular electronics. Transistors, capacitors, coatings for electrical stimulation of the growth of biological tissues and other devices can be made from it, and it is also promising for targeted delivery of drugs and therapy of cancer. However, working with polyaninyline is not easy. It is poorly soluble in most solvents, not melts and in its pure form it is a powder from which it is difficult to make the desired product.
The optimal yield is the application of polyaniline to the substrates. Thus, by electropolymerization, polyaniline coatings can be obtained on the surface of electrically conductive materials, but in the case of non-conductive substrates, this method is not available. Instead, chemical polymerization is carried out: a non-conductive substrate is added to the aniline monomer solution and an oxidizing agent is added there. Gradually, a polymer film is formed on the surface, but in parallel with this, insoluble polymer granules also appear in the volume of the solution, which settle on the substrate, making it difficult to control the properties and morphology of the coating. The coating becomes heterogeneous and defects appear in it, which negatively affects its properties. A different approach was used in this study.
| | We localized the reaction zone directly on the surface of the substrate and polymerized on it. To do this, we took silica gel particles, precipitated an insoluble oxidizer on them, and then brought them into contact with an aniline solution: polymerization began on the surface of the particles, and in a volume where there was no oxidizer, the process was suppressed. And so a method was developed that is promising for the targeted formation of polyaniline layers and control of their properties. told Yaroslav Mezhuev, one of the authors of the work, professor at RCTU | |
In additional experiments, the scientists studied the process in detail. Thus, using the electron paramagnetic resonance method, the kinetics of the ongoing reactions were monitored, and it was proved that the polymerization takes place only at the interface between the solid support (silica gel) and the liquid monomer solution. In addition, it is assumed that the process takes place mainly in the pores of the carrier of small size.
Now the researchers want to extend this approach to nano-objects and test particles coated with polyaniline as carriers of pharmacological drugs: the polyaniline molecule is electrically charged and therefore it is quite easy to immobilize various substances on it.
| | In general, the proposed approach is much wider and, apparently, is not fundamentally limited to the substrate, monomer and oxidizer used. It is not necessary to synthesize polyaniline - it is not essential to obtain another conductive or non-conductive polymer by an oxidative polymerization reaction. It is not necessary to take silica gel - any other substrate can be modified in the same way, most importantly only that it is inert to the insoluble oxidant, which in turn should be sufficiently active in the polymerization reaction of the selected monomer. That is, this method of conducting oxidative polymerization at the solid-liquid interface is apparently universal. supplemented by Yaroslav Mezhuev, one of the authors of the work, professor at RCTU | |
Russian scientists developed aerogels that stop bleeding in a few minutes, and tested them on pigs
On September 24, 2020, it became known that scientists RKHTU named after D.I. Mendeleev they had developed it chitosan biopolymer-based aerogel to quickly stop massive bleeding. These are porous particles that can be injected locally into wounds: they swell, absorbing red blood cells and other blood components, and as a result a dense blood clot forms. Together with colleagues from the SPCFU Ministry of Health Russia scientists conducted tests on laboratory animals (pigs), which showed that aerogel particles stop bleeding in 2-3 minutes, and do not have characteristic disadvantages or side effects of direct analogues on the market. An article about the study was published in September in the journal Polymers. More. here
A team of MISiS students presented a project to develop a self-soluble material for bone implantation
On July 23, 2020, it became known that a team of students at NUST MISIS presented a project to develop a self-soluble material for bone implantation. The combination of the properties of various polymers in combination with a mineral additive will allow the creation of implants that take on the load and allow the patient's own bone to grow actively. Having fulfilled its function, the materials will gradually and without side effects dissolve in the body.
As reported, as of July 2020, three types of materials are used to replace bone defects: metals, ceramics and polymers. At the same time, metals tend to take on too much load, which leads to embrittlement of the bone, and ceramics in themselves are quite fragile and expensive. Polymers are the best option: they are closest to natural bone in hardness and strength characteristics. In addition, their structure can be modified - for example, to form pores, as in the middle part of a real bone.
However, any foreign body, even a biocompatible polymer, remains foreign to the human body anyway. In the case of small bone defects, an implant that gradually dissolves and gives way to growing bone would be most suitable - similar to self-absorbing sutures. The team of students of NUST MISIS is engaged in the development of precisely such materials for implants - polymer and bioresorbable.
Young scientists took as a basis two polymers from the group of polyhydroxyalkoanates - polyhydroxybutyrate (PGB) and polyhydroxyvalerate (PGB). These materials are grown using bacteria, and until a few years ago such production was extremely expensive. As of July 2020, technologies have improved, materials have fallen in price, and they began to be regarded as promising for implantation.
By combining the advantages of PGB and PGB, the researchers plan to obtain the necessary polymer. The PGB is sturdy, hard but quite fragile, meaning it withstands high pressures, hard to scratch, yet easy to break in half. PGV elastic, but fragile, cannot withstand long-term high loads.
| | Our task is to conduct some selection of the properties of both polymers. We prepare mixtures of powders of various compositions, make samples by thermal pressing and 3D printing, and then measure important characteristics for us. one of
the developers, 2nd year student of the iPhD program "Biomaterial Science" and an employee of the Center for Composite Materials of NUST "MISIS" | |
To simulate the structure of bone, spherical food salt is added to the mixture - its crystals are almost identical in size to bone pores. The salt is then easily removed by soaking.
The last, but no less important component is hydroxyapatite - a mineral, of which natural bone is 50-70%. This mineral is also added to the mixture of powders - so that osteoblasts (bone cells) "feel" more comfortable and multiply faster inside the implant.
Thus, the team will create samples of biocompatible polymer bone implants that will dissolve over time, giving way to natural bone.
See also
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