Moscow, July 1, 2024
Researchers have
synthesized tannic acid-coated magnetic beads capable of
extracting membrane vesicles called “exosomes” from
biological fluids with 60% efficiency. This novel method
will make it easier and faster to isolate exosomes from
laboratory samples, while the chemical composition of the
exosomes will help detect cancer in its early stages. The
study supported by a grant from the Presidential Program of
the Russian Science Foundation (RSF) was published in the
Journal of Materials Chemistry B.
Cells in the human
body “communicate” through exosomes — tiny membrane
vesicles that are released into the intercellular space and
carry proteins, fats, nucleic acids, and other molecules.
Since the exosomes’ contents replicate the chemical
composition of the cell they split off from, they can be
used as molecular markers to identify various diseases. For
example, the presence in exosomes of proteins and RNA
typical of cancer cells is compelling evidence of incipient
cancer.
However, exosome-based diagnostics
is not yet widely used in clinical practice because these
vesicles are as small as viruses and therefore difficult to
isolate. A recently proposed approach uses magnetic beads to
capture exosomes from biological samples, such as blood. The
surface of the beads is coated with molecules, such as
antibodies, that specifically bind to exosomes and hold them
in place, and the bead-exosome complexes are then extracted
from the biological sample using a magnet. However, this
approach has been rather inefficient, prompting researchers
to improve the beads’ ability to bind to
exosomes.
Advertisement – scroll to continue reading
A joint team from the Skolkovo
Institute of Science and Technology, Lomonosov Moscow State
University and the Kulakov National Medical Research Center
for Obstetrics, Gynecology and Perinatology of the Russian
Ministry of Health has improved magnetic beads by applying a
layer of tannic acid onto their surface. The researchers
synthesized beads of iron oxide and calcium carbonate (chalk
and marble are the most common forms of the latter) and then
coated their surface with a layer of polyvinylpyrrolidone
and polyallylaminohydrochloride polymers or albumin, which
specifically bind to exosomes. Finally, the resulting
complexes were held in tannic acid which settled on the
surface along with the other molecules.
The
researchers placed the magnetic beads in a solution
containing a predetermined amount of exosomes to assess the
efficiency of binding, then removed the beads with a magnet
and measured the remaining amount of membrane
vesicles.
of the shell of magnetic microparticles and the principle of
their interaction with exosomes. Source: Grishaev et al. /
Journal of Materials Chemistry B,
2024.
They found that the tannic
acid-coated beads captured 50% to 60% of the exosomes,
depending on the type of the second molecule in the coating
(polymer or albumin). Other samples coated with just
polymers or albumin showed an efficiency of only
34%.
The tannic acid-coated beads performed better
because the acid formed hydrogen bonds with fats and
proteins on their surface, acting as an additional anchor
for the exosomes. Tannic acid also helps to form whole
complexes, with membrane vesicles adhering to the bead and
to each other, allowing more of them to be extracted from
the solution.
The exosome capture efficiency achieved
by the team is comparable to the quality of the widely used
but extremely cumbersome exclusion chromatography method, in
which exosomes are sieved through a layer of gel to separate
them from other components of the liquid. The new approach
is also less time-consuming — 2.5 hours versus 4 hours —
which will speed up the entire procedure and enable its
wider use in clinical practice.
“In the future,
the widespread use of exosome chemical composition analysis
will help facilitate the early diagnosis of various types of
cancer. Going forward, we plan to improve the surface
structure of the magnetic beads to further increase their
efficiency,” said Alexey Yashchenok, an associate
professor at the Skoltech Photonics Center and the head of
the RSF-supported project.
*****
Note:
Skoltech is a private international university in
Russia, cultivating a new generation of leaders in
technology, science, and business, conducting research in
breakthrough fields, and promoting technological innovation
to solve critical problems that face Russia and the world.
Skoltech focuses on six priority areas: life sciences,
health, and agro; telecommunications, photonics, and quantum
technologies; artificial intelligence; advanced materials
and engineering; energy efficiency and the energy
transition; and advanced studies. Established in 2011 in
collaboration with the Massachusetts Institute of Technology
(MIT), Skoltech was listed among the world’s top 100 young
universities by the Nature Index in its both editions (2019,
2021). On Research.com, the Institute ranks as Russian
university No. 2 overall and No. 1 for genetics and
materials science. In the recent SCImago Institutions
Rankings, Skoltech placed first nationwide for computer
science.
© Scoop Media
Advertisement – scroll to continue reading