Medical Design Briefs - December 2022 - 25

" Current pacemakers record basically
a simple threshold, and they will tell you,
'This is going into arrhythmia, now
shock!' " Gutruf says. " But this device has
a computer on board where you can input
different algorithms that allow you
to pace in a more sophisticated way. It's
made for research. "
Because the system uses light to affect
the heart, rather than electrical signals,
the device can continue recording information
even when the pacemaker needs
to defibrillate. In current pacemakers,
the electrical signal from the defibrillation
can interfere with recording capabilities,
leaving physicians with an incomplete
picture of cardiac episodes.
Additionally, the device does not require
a battery, which could save pacemaker
patients from needing to replace the battery
in their device every five to seven
years, as is currently the norm.
Gutruf's team collaborated with researchers
at Northwestern University on
the project. While the current version of
the device has been successfully demonstrated
in animal models, the researchers
look forward to furthering their
work, which could improve the quality of
life for millions of people.
This
article was written by Emily
Dieckman, College of Engineering, University
of Arizona. For more information,
visit https://news.arizona.edu. Contact:
Philipp Gutruf, pgutruf@arizona.edu,
Department of Biomedical Engineering.
Soft but Tough: Biohybrid Material Performs Like Cartilage
The composite material
has the essential
characteristics of a
natural tissue.
Cornell University
Ithaca, NY
Producing biomaterials that match
the performance of cartilage and tendons
has been an elusive goal for scientists,
but a new material created at Cornell
demonstrates a promising new
approach to mimicking natural tissue.
The results were published in the
Proceedings of the National Academy of Sciences
and provide a new strategy for synthesizing
clinical solutions for damaged
tissue.
Tissue has to be soft enough to bend
and flex, but durable enough to withstand
prolonged loading - for example,
the weight a knee tendon must support.
When tissue wears out or is
damaged, collagen hydrogels and synthetic
materials have the potential to
serve as replacements, but neither
alone possesses the right combination
of biological and mechanical properties
of natural tissue.
Now, Cornell researchers have engineered
a biohybrid composite material
with the essential characteristics of a
natural tissue. The material consists of
two main ingredients: collagen -
which gives the material its softness
and biocompatibility - and a synthetic
zwitterionic hydrogel, which contains
positively and negatively charged molecular
groups.
" These charge groups interact with
the negatively and positively charged
Medical Design Briefs, December 2022
Micrograph of a biohybrid composite material developed at Cornell shows cells
(red) seeded on the
fibrous domains (yellow) of collagen. The material mimics natural tissue in its softness, toughness,
and ability to recruit cells and keep them alive. (Credit: Bouklas Lab)
groups in the collagen, and this interaction
is what enables the materials to dissipate
energy and achieve high levels of
toughness, " says Lawrence Bonassar,
the Daljit S. and Elaine Sarkaria Professor
in Biomedical Engineering in the
college of engineering and co-lead author
of the study.
The biohybrid composite approaches
the performance of articular cartilage and
other biological tissues, possessing 40 percent
more elasticity and 11 times the fracture
energy - a measure of durability -
of the zwitterionic material by itself.
Nikolaos Bouklas, assistant professor
in the Sibley School of Mechanical and
Aerospace Engineering and co-lead author
of the study, says the material's biocompatibility
means it can recruit cells
and keep them alive.
" Ultimately, we want to create something
for regenerative medicine purwww.medicaldesignbriefs.com
poses,
such as a piece of scaffold that
can withstand some initial loads until
the tissue fully regenerates, " Bouklas
says. " With this material, you could 3D
print a porous scaffold with cells that
could eventually create the actual tissue
around the scaffold. "
In addition, the biohybrid material is
self-assembling once the two ingredients
are mixed, Bouklas says, creating
" the same interconnected network of
collagen seen in natural cartilage,
which otherwise would be extremely
hard to produce. "
The research brought together four
research labs from three different departments
thanks to a seed grant from
the Cornell Center for Materials Research.
The collagen used in the biohybrid
composite had already been under
development in Bonassar's lab, while
the zwitterionic hydrogel was developed
25

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Medical Design Briefs - December 2022

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