I'm still slowly going through Rob Freitas' book chapter in the Future of Aging volume, there's an interesting part where he lists the immense benefits of nanomedical robots. Since I am especially interested in materials science I thought this part on materials was interesting:
Superior Materials. Typical biological materials have tensile failure strengths in the 106-107 N/m2 range, with the strongest biological materials such as wet compact bone having a failure strength of ~108 N/m2, all of which compare poorly to ~109 N/m2 for good steel, ~1010 N/m2 for sapphire, and ~1011 N/m2 for diamond and carbon fullerenes (Freitas 1999aa), again showing a 103-105 fold strength advantage for mechanical systems that use nonbiological, and especially diamondoid, materials. Nonbiological materials can be much stiffer, permitting the application of higher forces with greater precision of movement, and they also tend to remain more stable over a larger range of relevant conditions including temperature, pressure, salinity and pH. Proteins are heat sensitive in part because much of the functionality of their structure derives from the noncovalent bonds involved in folding, which are broken more easily at higher temperatures. In diamond, sapphire, and many other rigid materials, structural shape is covalently fixed, hence is far more temperature-stable. Most proteins also tend to become dysfunctional at cryogenic temperatures, unlike diamond-based mechanical structures (Freitas 1999ab), so diamondoid nanorobots could more easily be used to repair frozen cells and tissues.
I thought it was interesting that steel is about ten times stronger than wet compact bone, and that sapphire is ten times that, and diamond/fullerenes ten times that. Imagine replacing all your flesh and bone with fullerene materials that perform the same functions.
"Become ten thousand times stronger with nanotechnology!"
Reading this puts into perspective how biological efforts to improve the human body still leave you with what is essentially an unstable tower of delicate stringy proteins and water. The tower is so unstable that it requires realtime balancing to even stay upright, and a stiff breeze can knock it down.