Page 77 - Plastics News September 2016

TECHNOLOGY
Scientist develop new method to produce ultra-high molecular
weight PE implants
Scientists at NUST MISIS`s - Russia's National University
of Science and Technology MISiS, have developed a
new method to produce ultra-high molecular weight
polyethylene implants intended to replace bone tissue
defects in humans and animals. The new implant imitates
bone tissue structure and consists of a porous inner layer
and a solid outer layer. In an organism, its spongy structure
enables newly formed blood vessels and tissues to grow
into the implant.
The solid layer is
added for strength
and bears the bulk
of the pressure.
Finely divided
100-mikrometer
ultra-high molecular A new class of star-shaped polymers has proven
weight polyethylene powder is used in the manufacture
of the implants, with high-purity salt introduced to form
pores. Special presses reduce the mixture to a solid
mass. Next salt is washed out under conditions where
water is liquid in temperatures ranging from 100 to 374
degrees Celsius and under pressure of 218+ atmospheres
(subcritical water). The next step is to dry the implant and
to reinforce it with a solid layer of ultra-high molecular
weight polyethylene. An antibacterial additive is infused
into the implant’s upper layers, where it forms a stratum
that will protect the organism from in?ammation and
help to avoid infection. The porous part is seeded with
cells taken from the patient’s bone marrow and proteins
stimulating their ingrowth into bone tissue.
Implants will be used to replace sections of tubular bone
tissue in injuries or cancer cases, including ?at bones —
pelvic, cranial, shoulder-blade, etc. — exposed to low and
medium loads. The technology can also be used in animals.
“Our implants have several important advantages. First,
they are made from light but strong material that can
sustain low and medium pressures (its total compression
strength is up to 80 MPa). Due to their unique structure,
our implants are superior to their counterparts from
Europe and the US in terms of strength. Second, the
material is highly plastic: a surgeon can cut the implant to
size, something that can’t be done with titanium implants.
Third, the porous structure ?lls 80% of the implant blank,
enabling the implant to be quickly overgrown with tissues
and blood vessels. On top of that, the material is rather
cheap: a 50 cm3 implant blank without sown cells and
proteins costs about Fedor 10,000 rubles,” Senatov of
the Center for Composite Materials at NUST MISIS said.
It took four years to develop the new implant-making
method and the effort is still in progress. Initial preclinical
tests have been successful. Researchers have applied
for two Russian patents and are planning to patent the
method internationally.
New star-shaped polymer can shred
bacteria membranes
effective at killing drug-resistant bacteria, opening new
potential treatment options in the future. A team from
the Melbourne School of Engineering has developed
a new class of star-
like protein chains or
“peptide polymers,”
that can effectively
kill bacteria which are
impervious to current
antibiotics. Professor
Greg Qiao from the
school’s Department
of Chemical and Biomolecular Engineering and his team
said that the only real avenue of treatment currently
available for infections caused by bacteria is antibiotics.
But he’s worried that if we continue the arms race with
bacteria in this way, we will be left defenseless in a
few decades. The team has been working with peptide
polymers for the past few years, looking for a way to
weaponize them in our favor. Recently, they developed
a star-shaped polymer that might become one of the
best foot-soldier in this ?ght. And the upshot is that the
substance is harmless to the patient. Tests undertaken on
mice have shown that the polymer is extremely effective
at killing Gram-negative bacteria — a class known for its
propensity to develop antibiotic resistance. discovery is
the beginning of unlocking a new treatment for antibiotic-
resistant pathogens.
77 S e p t e m b e r 2 0 1 6 | Plastics News