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Washington: Harvard scientists have created a type
of the first ever "cyborg" tissue, by marrying a three-dimensional
network of functional, bio-compatible nano-scale wires with
modified human tissues.
A team led by Charles M. Lieber, professor of chemistry at Harvard
and Daniel Kohane, professor of anaesthesia at the Harvard Medical
School, developed a system for creating nano-scale "scaffolds",
which could be seeded with cells that later grew into tissue.
"Ultimately, this is about merging tissue with electronics in a
way that it becomes difficult to determine where the tissue ends
and the electronics begin," said Lieber, the journal Nature
Materials reported.
"In the body, the autonomic nervous system keeps track of pH,
chemistry, oxygen and other factors, and triggers responses as
needed," Kohane explained, according to a Harvard statement.
"We need to be able to mimic the kind of intrinsic feedback loops
the body has evolved in order to maintain fine control at the
cellular and tissue level," said Kohane.
Using the autonomic nervous system as inspiration, Bozhi Tian,
former doctoral student under Lieber and former postdoctoral
fellow in the Kohane and Robert Langer's labs from the MIT and
collaborator Jia Liu, worked in Lieber's lab at Harvard to build
mesh-like networks of nanoscale silicon wires -- about 30-80
nanometres in diameter -- shaped like flat planes or in a
reticular conformation.
The process of building the networks, is similar to that used to
etch microchips. Once complete, the networks were porous enough to
allow the team to seed them with cells and encourage those cells
to grow in 3D cultures, Lieber said.
"Previous efforts to create bio-engineered sensing networks have
focused on 2D layouts, where culture cells grow on top of
electronic components, or on conformal layouts where probes are
placed on tissue surfaces," said Tian.
"It is desirable to have an accurate picture of cellular behaviour
within the 3D structure of a tissue, and it is also important to
have nano-scale probes to avoid disruption of either cellular or
tissue architecture."
Using heart and nerve cells, the team successfully engineered
tissues containing embedded nano-scale networks without affecting
the cells' viability or activity.
Using the embedded devices, they were able to detect electrical
signals generated by cells deep within the tissue, and to measure
changes in those signals in response to cardio or neuro-stimulating
drugs.
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