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2016-05-01

Bioresorbable technology: passing the human-machine barrier?

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.

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