MSU scientists have developed the perfect implant

An international group of scientists with the participation of Moscow State University professor Dmitry Ivanov has developed a polymer material that can become an ideal implant. The result of the work was published on November 12, 2020 in one of the most cited scientific journals in the world, Advanced Materials. The article is a continuation of the work on biomimetic materials based on brush copolymers.

Scientists take the ideas of biomimetic (literally – imitating living) materials from life. In this case, work was carried out to create polymers that are as close as possible in properties to the tissues of the human body. In 2018, Professor Dmitry Ivanov and his colleagues synthesized and studied an artificial analogue of chameleon skin: a material that changed color and strength depending on mechanical impact. The developed concept made it possible to create polymers, the mechanical properties of which exactly reproduced the given living tissues of humans and animals.

“Earlier, we showed that our polymers can reproduce the mechanical behavior of living tissues,” said Dmitry Ivanov, “and they can be programmed . We can reproduce any curve corresponding to the deformation of living tissues. That is, our polymers stretch to the required limit and then become much stronger. And now we have added one more functionality to these systems. Now our “smart” polymers respond to another factor – temperature. They are solid at room temperature, but upon contact with a living body (in this work, at 37 degrees Celsius), they turn into liquid. Due to this phase transition during implantation, polymers can spread and fill the cavities in the body, creating an ideal implant. “

The ideal is achieved due to the fact that the bonds between the side chains of the brush break down in the polymer. It is the side chains of this brush that are capable of crystallizing, creating a solid crystalline phase. The researchers adjusted the melting point of the brushes to match body temperature. Such a material can be formed in the form of a needle, which spreads after insertion, because its mechanical modulus changes by several orders of magnitude. And instead of a needle, a liquid is obtained that can fill cavities.

As Dmitry Ivanov explained, the phase transition temperature can be selected with amazing accuracy. It can range from room temperature to 50-60 degrees Celsius. “In this case, we made the transition threshold in the region of 37 degrees, adjusting it to the temperature of the human body, but you can adjust the parameters for any animal.”

Scientists are now focused on understanding the extent to which brush density and hair branching affect the rate of phase transition. “We are just running an experiment at the synchrotron in Grenoble, where we began to study the details of the phase transition using X-ray analysis.”

As the professor noted, the structural part of the work was done mainly at Moscow State University: “Something was done in Grenoble, for which special thanks to them, but the bulk of the work was done on a diffractometer at Moscow University.”

Another property that can be used in medicine is that during crystallization, medicine can be placed in a brush polymer needle. And as the needle dissolves, it will release medicinal substances: “Our materials are quite versatile. We can create polymer meshes from these brushes. And depending on the density of the brushes, we can change such parameters as the rate of release of substances embedded in the structure of our polymer crystal. This work is just beginning with us. We plan to carry it out in cooperation with a new laboratory, which is currently being created at the Faculty of Chemistry of Moscow State University within the framework of a mega-grant . “

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