Bioresorbable
materials are on their way to revolutionize manipulations of the human
body, to create previously unimaginable applications, and to take the concept
of minimally invasive medicine to a new level.
The idea of bioresorbable stents, fine meshes implanted in a vessel or
body cavity via catheter to keep it from closing up, has been around for some
time. Bioresorbable
drug-eluting coronary stents promise a significant breakthrough: most
physicians and patients would agree that a medical device that dissolves after
serving its useful function without need for additional intervention is
preferable to a permanent implant or one that requires removal with attendant
risk.
If bioresorbable metals (magnesium-,
iron- or zinc-based
alloys) are degraded safely within the body, the scope of application is highly
diverse. They must have an appreciable degradation rate in order to be absorbed
within a reasonable period relative to the application, and to avoid toxicity
or inflammation, their decomposition product needs to be capable of safe absorption, distribution,
metabolism and excretion (ADME).
Bioresorbable
bulk metallic glass made of a Magnesium-Zinc-Calcium
ternary alloy is cooled at a speed of one mega-kelvin per second. Because it
consists only of elements that exist naturally in the human body, it dissolves
in the body at a rate of approximately 1 mm per month (depending on zinc
content) and is replaced by bone tissue. Biocorrosion
can be exceptionally expedient: Ca65Zn20Mg15
alloys, for example, disintegrate in a biocorrosive environment within three
hours. Applications include orthopedic
fixations but may extend to other surgical uses, but
also have electronic and aerospace applications.
A quantum leap was the development of silicone-based
bioresorbable electronic sensors for implantation in the brain that can be
used to report and monitor temperature and pressure within the brain, for
example after accidental or surgical trauma. Because there is no need for
subsequent removal, the risk of complications is minimized. In animal trials,
the implants remained functional for approximately three days and were
completely resorbed within a few weeks. But this technology is by no means confined
to the brain and may be adapted for
use in other organs.
I have followed developments in transhumanism
for some time, not least the conceptual work done by Nick Bostrom and others at the Future of Humanity Institute at Oxford University. Bioresorbable implants and
their neurological applications promise to be essential to crossing the
man-machine barrier and thus integrating man with trans-human elements, in a
first step temporarily. At present, cybernetic concepts and AI are far ahead of
biomedical integration, so technologies and applications with benefits in that
area are of immense value for expedited research in neuroscience, brain-to-brain
interfaces as well as for exploring potential applications in biological
computing.
