Medical Design Briefs - February 2021 - 42

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Xenon Improves Properties of Maxillofacial and Orthopedic Implants
Tomsk Polytechnic University
Tomsk Oblast, Russia

cientists of Tomsk Polytechnic
University (TPU) jointly with the colleagues from Siberian State Medical
University (SSMU) and Immanuel Kant
Baltic Federal University (IKBFU) studied the properties of calcium phosphate
coatings deposited on titanium implants
in various inert gases environment. The
researchers managed to discover that the
use of xenon positively affects the physicochemical, mechanical, and biological
properties of the coatings used in oral
and maxillofacial surgery, orthopedics,
and traumatology. Moreover, no comprehensive research related to the impact of
working gases on surfaces have been conducted before. The research findings are
published in Biomedical Materials.
" Our research team is engaged in biomedical materials. However, the engineering university context does not imply having in-house medical researchers. That is
why we cooperate with the researchers
from SSMU and IKBFU. This collaboration allows us to not only obtain the results
in form of academic articles, but also to
solve the real-world problems of medicine.
After all, practical application of our technological solutions without medical experts is simply impossible. This conjunction of technical and medical universities
will help us elevate the quality of patient
treatment and reduce treatment time, "
says Sergei Tverdokhlebov, head of the
TPU Laboratory for Plasma Hybrid
Systems.
The calcium phosphate coatings up to
1 μm thick were deposited on the titanium substrate by sputter deposition of
hydroxyapatite targets in the working gas.
Usually, an inert gas argon is used for
these purposes. However, the TPU scientists studied not only the effect of argon

Calcium phosphate coatings. (Credit: Tomsk
Polytechnic University)

Depending on a specific gas, the coating morphology - calcium to phosphorus ratio - differ
and the mechanical properties vary. (Credit:
Tomsk Polytechnic University)

but also experimented with neon, krypton, and xenon on the coatings. Then,
the scientists studied physicochemical,
mechanical, and biological properties of
the obtained biomedical materials. The
TPU researchers worked on coating formulation, morphology, and mechanical
properties, including adhesion and chemical composition, while SSMU and IKBFU
staff conducted the cellular research.
" The calcium phosphate coatings are
studied not only at our university. Their
properties are thoroughly studied, and
scientists work on their improvement.
Our joint research work was aimed at
obtaining new results in this direction and
researching the impact of different inert
gases on coatings. In our part of the
research work, we found out that depending on a specific gas, the coating morphology - calcium to phosphorus ratio - differ and the mechanical properties vary.
For instance, the coatings formed using
xenon show better adhesion, which is a
property that prevents the coating from
peeling off too quickly from the surface.
The results obtained with the use of cellular technologies surprised us because in
this case xenon proved itself best as well, "
says Anna Kozelskaya, research fellow of
the TPU Weinberg Research Center, one
of the authors of the article.
Mesenchymal stem cells isolated from
the donor's adipose tissue were used for
cellular research. These cells can transform into various types of cells, including

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adipose, bone, cartilage, muscle, and nervous cells. The cell research included testing cell viability, in vitro cell culture, and
gene expression. In this research work, it
was necessary to ascertain that the coatings
stimulate mesenchymal stem cell transition into bone tissue cells.
" The results turned out to be quite
interesting. Inert gases are considered to
be rather inert substances with similar
properties. Nevertheless, they differently
affect physicochemical properties of the
formed calcium phosphate coatings. In its
turn, it causes different cellular response
starting from their gene activation that ultimately leads to the stem cell transition into
osteoblasts, says Igor Khlusov, a professor
in the SSMU department of morphology
and general pathology.
At the same time, the scientists note
that xenon is quite an expensive inert gas
to use. However, the coatings formed
using it can be combined with thicker calcium phosphate coatings with a crystalline
structure. It will allow reducing gas expenses and obtaining coatings with improved properties. The fact is that the
coatings formed with xenon obtain entirely amorphous structure. It helps to stimulate bone formation in the first weeks
after implant insertion. Calcium and
phosphorus responsible for the bone tissue formation release well from this coating. Therefore, such thin coatings decompose very fast, uncovering the implant.
" We propose to apply such a coating
above calcium phosphate coatings with a
crystalline structure. Thus, we can obtain
another positive effect: an amorphous
layer will decompose during the first twofour weeks providing for a maximum
calcium and phosphate release, " says
Kozelskaya. " Then, the lower layers will
provide for a further longer release of the
elements, which will contribute to a prolonged process. The combination of such
coatings will be the next stage of our
research work. "
For more information, visit https://news.
tpu.ru.

Medical Design Briefs, February 2021

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Medical Design Briefs - February 2021

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